Part one is here.
In our last lesson we covered laying out your pattern in cardboard. Now it is time to start building the real deal. The hood can be built from any spare sheet steel you have about, ranging from 16 gauge up to 1/4” thick plate stock. The thicker the material, the heavier it will be and the more difficult it will be to install and move your forge after it is in place, so keep that in mind. Ours is made of 1/8” plate from the scrap yard and cost us about 50 dollars US when we built it. All the steel does not need to be the same thickness either; if you have a mix of thicknesses, you can still build the hood.
If using mixed weight steels, your front, top and back take the most heat and strain, so you may want to use thicker stock for those. The base takes the least stress, so you can use lighter steel here. As the box heats up, the back wall may flex and make a heck of a bang, throwing dust and ash about and surprising you. Thicker steel or reinforcements (covered later) will help to prevent this.
Once you have your steel, take your cardboard patterns and either a marker or chalk and lay out all your parts. If needed, you can join two or more smaller pieces to make a section large enough for your use. If you do have to join plates, make sure the joint is airtight with either close set rivets, or a weld. Be aware, a single long, straight weld is likely going to warp the steel, so you will have to weld a few inches, move to another section of the joint and weld there and so on until the entire joint is welded to reduce warping. Rivets look great (very steampunk!) but a weld is easier to get airtight.
Once your pieces are laid out, cut them to shape using either a cutting torch or plasma cutter, or if in thinner steel some kind of metal cutting shear. Thinner steel will be harder to weld and may require some unusual modifications to the techniques given here to work. If needed, clean up your cuts a bit with an angle grinder or file, but be careful to not cut too much metal away. Having extra metal is far better than too little, as you can always grind or file away, but adding a bit is more tricky.
These instructions assume you are welding all the parts together. You can, however, use sections of thin 16g steel cut into long, 3 to 4 inch wide strips, folded to 90 degrees lengthwise and a LOT of rivets to rivet the entire hood together. Pop rivets are not as strong as hammer set rivets or roofing nails clipped short (which make workable make shift rivets and are less expensive by far). And this has not been tested with pop rivets either, it may well not work!
With your pieces cut out, you are ready to begin assembly. Start with the base plate and the back plate. Lay the base plate flat on a welding table or concrete, and place the back plate in place. It will need to be braced to keep the joint at 90 degrees the entire length. Tack it in a few spots on the inside and outside with 1” long tack welds. We welded ours entirely from the inside along the lower joints, you may as well, or turn the assembly over and weld from the outside. The inside welds allow the box to sit flatter on the forge table however.
With this weld complete, check the joint for square, and adjust if needed, then weld in one side piece. Again tack in a number of places before welding to help reduce any warping or shifting. You may want to tack the other side in place as well and test fit your front piece just to be sure everything fits. It will be easier to correct a problem now, with everything just tacked, than once it is welded in firmly.
Our hood has a section of light weight angle iron along each upright corner to make it look better, and add some strength to the structure. It is welded in place from the inside, tacking it in through a couple holes drilled at an angle through the corner joints. Once our corner covers were tacked in place, each corner was welded from the inside full length in one pass with enough heat to penetrate somewhat into the angle iron. You do not need to be this aggressive about it, as long as the joint is airtight. It can also be “skip welded”. That means you can weld a section, move to another and come back once the first weld has cooled, so long as the joint is clean and solid.
Next we suggest adding the extension to the face of the front. We welded this on from the inside as it looks better. With that in place, we welded the front on. Here is where it begins to get tricky, as you will have to lay the tacked assembly on its face and nearly climb into it to weld the bottom joint and the lower part of each upright joint. And you may have to support the front with bricks and connect your arc welder clamp directly to the assembly to keep the whole from rocking with the front shroud already in place.
Once you have the lower assembly together, you may want to weld in a pair of bars from the front to back plates to keep the walls from flexing. Angle iron works well here, with one section mounted on each side of the top of the intake opening. Putting a single bar across above the opening is not as effective, and heat will probably cause it to flex over time. These support struts are not critical, and are completely optional.
If you have decided to put in the angle plate that directs smoke upward, put it in and tack it in now. It does not need to be fully welded into place. Just make sure the front edge at the inlet is welded flush with the bottom so there is no gap.
Now that the lower assembly is complete, the upper half will now be assembled. This will be a little tricky, but not horrible.
First, tack the collar and check to make sure your pipe will flex and fit over it tightly. Then weld the collar into place and tack the top plate at 90 degrees to the back plate. Make sure the collar is on the outside! This plate will make lining up the rest of the plates a lot easier. Lay the assembly on its back, and fit and tack the front upper into place, then each upper side. If they are curved, you may have some fun trying to match the curves so the joint it tight and easy to weld. A heavy pipe in a heavy vice is one way to allow you to form the curve; just hold the steel over it and strike beyond the pipe with a wooden or rubber hammer. You can also put it across two bricks and stand on it, or if all else fails, drive over it with a car. Be creative but safe!
With all the parts tacked in place, weld all the uppers from the outside. There are some long welds here, so take your time and do a good job, as these will show. Once you are done with the welds, you can take an angle grinder and smooth your welds if needed.
Your side draft hood is now done! Now you (and probably a friend) will have to move it into place on your forge bed. Watch out for pinched fingers! If you like, the hood can be raised a bit with a layer of brick, and this can aid in creating a better draw, but is not critical.
Once the hood is in place, mount your riser pipe up to your stack (or straight up through a collar in your roof if in a shed or the like) making sure all is firesafe and sealed (another much larger topic!!). With that, your hood is ready to use.
We will cover making the “flip up hat” part in the next post, though you may want to make it and mount it before you install your hood. It allows you to suck up much more smoke when you first light the forge.
A few notes on using the side draft hood-
Before lighting the forge, put a ball of paper in the intake of the hood and light it to pre-warm the air and start the draft.
With the forge first lit, when the most smoke pours out, you may need to place a thick plate of steel on the forge angled up to the intake hole on the hood to get the hood warmer and suck up most of the smoke.
Once the hood is warm, the draft will be more effective. As soot and ash seal any tiny holes in your stack and hood, it will draft better. The more airtight the hood and riser pipe are, the better the draft. In fact, the draft can get quite strong. In the right situations, ours will suck up a piece of paper left on the forge table (much to our surprise). The trad off here is it will also suck any heat out of the room. You may need to make a cover for the intake for times you are not using the forge to prevent it from drawing all the heat out of your shop in the winter.
Once the hood is drawing well, you may notice the flame rising above the forge bending at a steep angle into the hood! Just because the heat is not rising directly does not mean the infrared coming from the forge is not... if your ceiling beams are low and wood, you may need some kind of heat shield still.
The forge hood will get warm in use, and in heavy use it will get hot. Be careful about brushing against it, as it can burn you. Also make sure it is well away from walls and nothing flammable is leaning on it.
A larger intake opening will still draft, though not as well. If you only have an 8” exit stack, you can still have a 12” by 14” intake with a tall chimney and good connector pipe. It will not draw as effectively, but it will still draw.
On some days, when the atmosphere is right and the hood is warm enough, you may hear a faint rumbling as air is drawn into the opening. This is normal and not a problem. If it is quite loud, something is amiss or something else in the shop is causing it. The large, flat walls of the hood may be resonating in sympathy with something else in the room. Try sticking a large magnet to the side, off center, and see if that stops the sound.
That about covers it for now, images and part three coming soon!
Showing posts with label blacksmith forge. Show all posts
Showing posts with label blacksmith forge. Show all posts
21 October 2011
Blacksmith Lessons – The Side Draft Forge Hood, part 1
In previous lessons, we covered building a few different forge beds, and more are coming soon. This lesson will help in getting the smoke and heat from your forge moved to some other place, preferably outside.
There are many types of forge hoods, including some positive pressure down draft hoods that we may cover in another lesson (uncommon, but used in some welding booths and chemistry work). This lesson is on building the side draft style forge hood we use in the shop. This project will require some fairly large sheets of steel, a fair bit of layout work and the ability to cut said steel using either a shear, saw or torch/plasma cutter. You may have to see if a friend has some of the gear needed for this build if you want to follow the plans below closely and do not have the equipment. It is intended to be electrically welded, but there are other ways to make this hood without a welder, which we will cover.
To create a pattern, we suggest cardboard boxes to build a mock up first, then use these pieces as pattern parts to layout and cut your steel with. You will need several large cardboard boxes, opened up, and tape to assemble the pieces. Of course, some method of cutting the cardboard will be needed as well.
The version of the hood we use also has a flip up “smoke hood” for the rush of heavy smoke when first starting the forge. You do not need to make this on yours, but it is quite helpful. Do not make it solidly mounted, however. It will get in your way more often than you would like to imagine.
We purposefully left out dimensions on the side draft forge hood drawings; you need to build this hood to stand on the table you have, so you will need to create a pattern based on your own system and measurements.
To start with, you will need to layout your base. The edge of the base should be very near the edge of your forge bowl. Ours is 1 1/2” from the top of the bowl, and sits against the projecting flange of the bowl. At first this may seem strange, but it needs to be close to make the draft effective. Cut a piece of cardboard that will lay on your forge table next to your firepot. Of course, make sure the forge table isn't still hot or the forge lit! Make this bottom plate as large as feasible, ours is 32” wide by 24” deep. This will allow a large expansion chamber inside the side draft and will help your smoke draw more effectively.
The next part to design is the back of the unit, which should be about twice as tall as the chamber is wide, or a bit more. In ours, and in the illustrations here, the side walls are straight for about as long as the box is wide, then have a sweeping taper to help the rising smoke gain velocity as it enters the flue pipe above. This is not critical, but it does look more graceful than flat angled upper sections. With the back made, tape that section to your base plate.
Next up come the two sides. Use measurements from the bottom and back to lay out two sheets of cardboard, cut and tape in place. Then comes the front.
Of note here; the opening in the front should not have as much volume as your riser stack pipe does. The larger the opening, the less draft the stack will have. If you have an 8” diameter stack, your front opening should be around 50 square inches or less. So an opening that is 10” by 6” may work, while an 8” x 6” opening will draw better. The problem here is that your fire pot will be larger than your intake in this case and some smoke will escape into the room. If at all possible, use 12” pipe since you get about a 112 square inch opening to work with. That is a nice 10” by 11” intake area, and is roughly what ours is. Once the hood warms and the stack begins to effectively draw, we have very little smoke in the room.
We made our opening with an arched, rounded top in the cut, which was outlined with the smoke lip (more on that in a bit). It is set to be centered with the forge inlet, so if your bowl is not right in the middle of your forge table (front to back) you may have to adjust where your opening is. Tape this in place with the other cardboard pattern pieces.
Now you will have to make the front upper part. This is the most complex part of the side draft forge. It is very similar to the upper part of the back pattern piece, but since it leans back, it is slightly elongated. There is a lazy way to do this however. Cut your two side uppers, with a long angle cut on one edge of each along the length. The upper edge should be the diameter of your inlet pipe, while the bottom edge will be the length of your side pieces. If you cut your back piece with sweeping uppers, you will need to measure how long the curved surface is using a piece of string or a flexible tape measure to get the length of your uppers. With these pieces cut and taped into place you can lay your uncut front upper against them, reach inside and trace the correct shape onto the cardboard then cut it to shape and tape it in place.
All that is left of the basic box is the top plate. Take the measurements from the uppers, and cut a piece. We will make a mount for your flue pipe that is slightly oval, as it will be easier to mount firmly and will make the stack draw better. Cut a strip of cardboard about 2” wide that is as long as the inside of your flue stack (use string or a flexible tape to measure this). Tape it end to end to make a circle, then squash it a little bit to make an oval, and put it on the top plate to draw the cut out hole. Cut the hole, then tape the collar in place.
The main body of your pattern is done! There are a couple more pieces to make though. A few more small strips are used to outline the front of your intake opening, and this is not needed but does give the hood more strength and makes it look better. It also increases the draft, since the opening is now extended closer to the forge fire. We also added an angled plate internally to help funnel the smoke up the expansion chamber and increase the draft. This is a piece as wide as your base, and several inches longer than it is deep (ie, in our, the base is 24” by 32”, so our plate is 32” square, and made of lighter steel than the main body of the hood). This is not a critical part however.
Now your pattern is complete! In our next installment we will cover the actual construction and discuss theory further.
(note, pictures are still in the works - they should be up soon)
There are many types of forge hoods, including some positive pressure down draft hoods that we may cover in another lesson (uncommon, but used in some welding booths and chemistry work). This lesson is on building the side draft style forge hood we use in the shop. This project will require some fairly large sheets of steel, a fair bit of layout work and the ability to cut said steel using either a shear, saw or torch/plasma cutter. You may have to see if a friend has some of the gear needed for this build if you want to follow the plans below closely and do not have the equipment. It is intended to be electrically welded, but there are other ways to make this hood without a welder, which we will cover.
To create a pattern, we suggest cardboard boxes to build a mock up first, then use these pieces as pattern parts to layout and cut your steel with. You will need several large cardboard boxes, opened up, and tape to assemble the pieces. Of course, some method of cutting the cardboard will be needed as well.
The version of the hood we use also has a flip up “smoke hood” for the rush of heavy smoke when first starting the forge. You do not need to make this on yours, but it is quite helpful. Do not make it solidly mounted, however. It will get in your way more often than you would like to imagine.
We purposefully left out dimensions on the side draft forge hood drawings; you need to build this hood to stand on the table you have, so you will need to create a pattern based on your own system and measurements.
To start with, you will need to layout your base. The edge of the base should be very near the edge of your forge bowl. Ours is 1 1/2” from the top of the bowl, and sits against the projecting flange of the bowl. At first this may seem strange, but it needs to be close to make the draft effective. Cut a piece of cardboard that will lay on your forge table next to your firepot. Of course, make sure the forge table isn't still hot or the forge lit! Make this bottom plate as large as feasible, ours is 32” wide by 24” deep. This will allow a large expansion chamber inside the side draft and will help your smoke draw more effectively.
The next part to design is the back of the unit, which should be about twice as tall as the chamber is wide, or a bit more. In ours, and in the illustrations here, the side walls are straight for about as long as the box is wide, then have a sweeping taper to help the rising smoke gain velocity as it enters the flue pipe above. This is not critical, but it does look more graceful than flat angled upper sections. With the back made, tape that section to your base plate.
Next up come the two sides. Use measurements from the bottom and back to lay out two sheets of cardboard, cut and tape in place. Then comes the front.
Of note here; the opening in the front should not have as much volume as your riser stack pipe does. The larger the opening, the less draft the stack will have. If you have an 8” diameter stack, your front opening should be around 50 square inches or less. So an opening that is 10” by 6” may work, while an 8” x 6” opening will draw better. The problem here is that your fire pot will be larger than your intake in this case and some smoke will escape into the room. If at all possible, use 12” pipe since you get about a 112 square inch opening to work with. That is a nice 10” by 11” intake area, and is roughly what ours is. Once the hood warms and the stack begins to effectively draw, we have very little smoke in the room.
We made our opening with an arched, rounded top in the cut, which was outlined with the smoke lip (more on that in a bit). It is set to be centered with the forge inlet, so if your bowl is not right in the middle of your forge table (front to back) you may have to adjust where your opening is. Tape this in place with the other cardboard pattern pieces.
Now you will have to make the front upper part. This is the most complex part of the side draft forge. It is very similar to the upper part of the back pattern piece, but since it leans back, it is slightly elongated. There is a lazy way to do this however. Cut your two side uppers, with a long angle cut on one edge of each along the length. The upper edge should be the diameter of your inlet pipe, while the bottom edge will be the length of your side pieces. If you cut your back piece with sweeping uppers, you will need to measure how long the curved surface is using a piece of string or a flexible tape measure to get the length of your uppers. With these pieces cut and taped into place you can lay your uncut front upper against them, reach inside and trace the correct shape onto the cardboard then cut it to shape and tape it in place.
All that is left of the basic box is the top plate. Take the measurements from the uppers, and cut a piece. We will make a mount for your flue pipe that is slightly oval, as it will be easier to mount firmly and will make the stack draw better. Cut a strip of cardboard about 2” wide that is as long as the inside of your flue stack (use string or a flexible tape to measure this). Tape it end to end to make a circle, then squash it a little bit to make an oval, and put it on the top plate to draw the cut out hole. Cut the hole, then tape the collar in place.
The main body of your pattern is done! There are a couple more pieces to make though. A few more small strips are used to outline the front of your intake opening, and this is not needed but does give the hood more strength and makes it look better. It also increases the draft, since the opening is now extended closer to the forge fire. We also added an angled plate internally to help funnel the smoke up the expansion chamber and increase the draft. This is a piece as wide as your base, and several inches longer than it is deep (ie, in our, the base is 24” by 32”, so our plate is 32” square, and made of lighter steel than the main body of the hood). This is not a critical part however.
Now your pattern is complete! In our next installment we will cover the actual construction and discuss theory further.
(note, pictures are still in the works - they should be up soon)
04 February 2011
Snow and fire
Hello all!
Now that we are on the other side of "Snowmageddon 2011", let's talk a little about fire and snow. Ok, this will cover a bit more than that, but its an easy title.
In the past, I have done a number of demonstrations outdoors in winter weather and for a time I even worked outdoors without a proper building. This educated me on a number of interesting things I have not seen addressed in many other posts on blacksmithing online, and have not heard a lot of guys talk about at hammer-ins or around the table.
Let's start with working outdoors in snow. Visually, this can be very spectacular; thick falling snow, lit by the dancing light of a forge, a trailing flame-like ghost flame of mixed heat and steam from the snow touching hot steel... Ah! Male Romance right there my friends! But there are a few safety and technique considerations to be aware of beyond the obvious ones. First is footing; falling on slick snow or ice holding a hammer and hot bar of steel is not fun. And working on ice is even more dangerous since even if the hot bar does not hit you, it can hit ice and burn you with a jet of steam. Make sure your boots have good tread, and clear your work area as well as you are able. A thin layer of kitty litter may be in order to increase traction, or lay down a clean, dry sheet of plywood to stand on. Dropping hot steel on plywood will cause a scorch, but it will not catch fire and burn unless the steel is left on the board for a longer lenght of time, and you can grab snow and put out the fire easily.
The second consideration is frostbite. Even though you are standing next to a fire, you are outdoors in less than freezing temperatures. And you are sweating more than likely, and this can add to the possibility of frostbite. Make sure you are wearing proper, safe, warm clothing. A nylon snowmobile suit is far, far more dangerous than a pair of jeans over cotton long johns and two layers of socks. Once you have layers, your body will be more able to keep itself warm and the extra layers of natural fibers will also help to wick away sweat, keeping you safer from frostbite. If you start having numbness though, get inside and get warm! Winter is one of the few times I wear cotton jersey gloves to forge in, and I make a point of wearing a wool hat under my hearing protection.
The third consideration is less obvious; if you get your anvil wet, laying a hot bar of steel on it and strikign it with a hammer will cause a small steam explosion. This will crack like a gunshot (bad for your hearing) and throw some small amount of hot scale and steam which can burn you. Falling snow, wet gloves and other things are possible ways for your anvil to get wet. You can wipe it off, but it will take a lot of wiping. The other option is to hover the hot bar just over the anvil for a few seconds, letting the radiant heat from the bar drive the moisture away from where you are about to lay the bar. A quarter inch or so above the anvil works well, and keeps the cold anvil from rapidly pulling heat out of the bar which will happen if you lay the bar on the anvil to let it dry it.
Next we get the the heart of the title. Your forge won't like the snow. If you are running a basic coal forge, once it is lit it will keep the snow off the top of your banked fire without a problem. Unless the snow off your garage roof falls onto it, that would be bad... and you shouldn't have your forge set up that close to a building anyway! Safety first, remember! The big issue here is actually the melting water from your forge keeping itself clean of snow. This water will seek out the lowest point it can find, and that is often down in the firebowl where it will turn to steam and jet out. It could also crack a cast iron firebowl if enough water is present to suddenly change the temperature of the hot iron. If possible, keep a sheet of steel over the forge either suspended from above or on bricks to keep the snow off the top of the forge. Leave enough room above it for the heat to rise and dissipate and be careful of placing anything that could burn on top of the protective roof. A slight angle will help the steel shed water away from your forge as well, so if you can try to get it tilted and safely in place.
Another consideration to deal with is in winter the air is both heavier and colder. You are pushing this colder, heavier air into your hot forge fire. This will cause it to take just a bit longer to get to a given temperature, and if the air is wet may prevent you from being able to reach welding temps. The nice thing is the heavier air is easier for your bellows or blower to push, so depending on your system, you may not notice a huge difference. Test it with non critical projects however, just in case it comes to heat faster than you expect. Loosing a chunk of 3/8" round stock is much less frustrating than burning a five thousand layer Damascus billet.
If you are using a gas forge, there are some other special considerations. The refractory that most gas forges are cast from is much more sensitive to being wet than cast iron, so you should make every effort to prevent snow from touching the liner of the forge. Moisture can crack or spall the liner easily, depending on the type and condition of your liner. Atmospheric forges may also have problems with the colder, wetter air, and your propane tank will freeze much sooner than it does in summer. If possible, place a clamp light or other lightbulb near your tank to help keep it warm and your gas flowing. Never put your gas tank on a burner, cajun cooker or hotplate, or put a space heater directly on or aimed at your tank! All of these can end in serious trouble. If you can, a thermal bath will help to keep your tank from freezing. We use a large tub filled with heavily salted water to absorb the cold from the tank, but this bath must be kept from freezing. The expanding ice can damage a tank and make it leak. When I was working outside all the time, the thermal bath got hauled back into the mud room of the house when I wasn't working to keep it from freezing (which isn't going to be popular with a spouse, by the way). A better system may be to build a large insulated wooden box with a couple 40 watt light bulbs inside it, not touching the tank, to keep your gas from freezing quickly. Be very careful here! You will want some vent holes around the bottom, just in case you do have a slow leak in your regulator along with a door on the side facing away from you that opens easily. Keep your fire extinguisher close at hand, even with snow on hand!
Oh and of course, this is information for educational use only, you are on your own and take all responsibility if you choose to use any or all of this information. Study up on everything, ask your local propane dealer if they see any problems with your idea before hand and follow their advice.
That about covers snow and fire for now, be safe, stay warm and keep swinging that hammer.
Now that we are on the other side of "Snowmageddon 2011", let's talk a little about fire and snow. Ok, this will cover a bit more than that, but its an easy title.
In the past, I have done a number of demonstrations outdoors in winter weather and for a time I even worked outdoors without a proper building. This educated me on a number of interesting things I have not seen addressed in many other posts on blacksmithing online, and have not heard a lot of guys talk about at hammer-ins or around the table.
Let's start with working outdoors in snow. Visually, this can be very spectacular; thick falling snow, lit by the dancing light of a forge, a trailing flame-like ghost flame of mixed heat and steam from the snow touching hot steel... Ah! Male Romance right there my friends! But there are a few safety and technique considerations to be aware of beyond the obvious ones. First is footing; falling on slick snow or ice holding a hammer and hot bar of steel is not fun. And working on ice is even more dangerous since even if the hot bar does not hit you, it can hit ice and burn you with a jet of steam. Make sure your boots have good tread, and clear your work area as well as you are able. A thin layer of kitty litter may be in order to increase traction, or lay down a clean, dry sheet of plywood to stand on. Dropping hot steel on plywood will cause a scorch, but it will not catch fire and burn unless the steel is left on the board for a longer lenght of time, and you can grab snow and put out the fire easily.
The second consideration is frostbite. Even though you are standing next to a fire, you are outdoors in less than freezing temperatures. And you are sweating more than likely, and this can add to the possibility of frostbite. Make sure you are wearing proper, safe, warm clothing. A nylon snowmobile suit is far, far more dangerous than a pair of jeans over cotton long johns and two layers of socks. Once you have layers, your body will be more able to keep itself warm and the extra layers of natural fibers will also help to wick away sweat, keeping you safer from frostbite. If you start having numbness though, get inside and get warm! Winter is one of the few times I wear cotton jersey gloves to forge in, and I make a point of wearing a wool hat under my hearing protection.
The third consideration is less obvious; if you get your anvil wet, laying a hot bar of steel on it and strikign it with a hammer will cause a small steam explosion. This will crack like a gunshot (bad for your hearing) and throw some small amount of hot scale and steam which can burn you. Falling snow, wet gloves and other things are possible ways for your anvil to get wet. You can wipe it off, but it will take a lot of wiping. The other option is to hover the hot bar just over the anvil for a few seconds, letting the radiant heat from the bar drive the moisture away from where you are about to lay the bar. A quarter inch or so above the anvil works well, and keeps the cold anvil from rapidly pulling heat out of the bar which will happen if you lay the bar on the anvil to let it dry it.
Next we get the the heart of the title. Your forge won't like the snow. If you are running a basic coal forge, once it is lit it will keep the snow off the top of your banked fire without a problem. Unless the snow off your garage roof falls onto it, that would be bad... and you shouldn't have your forge set up that close to a building anyway! Safety first, remember! The big issue here is actually the melting water from your forge keeping itself clean of snow. This water will seek out the lowest point it can find, and that is often down in the firebowl where it will turn to steam and jet out. It could also crack a cast iron firebowl if enough water is present to suddenly change the temperature of the hot iron. If possible, keep a sheet of steel over the forge either suspended from above or on bricks to keep the snow off the top of the forge. Leave enough room above it for the heat to rise and dissipate and be careful of placing anything that could burn on top of the protective roof. A slight angle will help the steel shed water away from your forge as well, so if you can try to get it tilted and safely in place.
Another consideration to deal with is in winter the air is both heavier and colder. You are pushing this colder, heavier air into your hot forge fire. This will cause it to take just a bit longer to get to a given temperature, and if the air is wet may prevent you from being able to reach welding temps. The nice thing is the heavier air is easier for your bellows or blower to push, so depending on your system, you may not notice a huge difference. Test it with non critical projects however, just in case it comes to heat faster than you expect. Loosing a chunk of 3/8" round stock is much less frustrating than burning a five thousand layer Damascus billet.
If you are using a gas forge, there are some other special considerations. The refractory that most gas forges are cast from is much more sensitive to being wet than cast iron, so you should make every effort to prevent snow from touching the liner of the forge. Moisture can crack or spall the liner easily, depending on the type and condition of your liner. Atmospheric forges may also have problems with the colder, wetter air, and your propane tank will freeze much sooner than it does in summer. If possible, place a clamp light or other lightbulb near your tank to help keep it warm and your gas flowing. Never put your gas tank on a burner, cajun cooker or hotplate, or put a space heater directly on or aimed at your tank! All of these can end in serious trouble. If you can, a thermal bath will help to keep your tank from freezing. We use a large tub filled with heavily salted water to absorb the cold from the tank, but this bath must be kept from freezing. The expanding ice can damage a tank and make it leak. When I was working outside all the time, the thermal bath got hauled back into the mud room of the house when I wasn't working to keep it from freezing (which isn't going to be popular with a spouse, by the way). A better system may be to build a large insulated wooden box with a couple 40 watt light bulbs inside it, not touching the tank, to keep your gas from freezing quickly. Be very careful here! You will want some vent holes around the bottom, just in case you do have a slow leak in your regulator along with a door on the side facing away from you that opens easily. Keep your fire extinguisher close at hand, even with snow on hand!
Oh and of course, this is information for educational use only, you are on your own and take all responsibility if you choose to use any or all of this information. Study up on everything, ask your local propane dealer if they see any problems with your idea before hand and follow their advice.
That about covers snow and fire for now, be safe, stay warm and keep swinging that hammer.
03 September 2009
Blacksmith lessons – building the colonial wooden forge
(images coming soon)
After covering the information in “building the bucket forge” you should have a pretty good feel for where this lesson is going. This is a larger version, and in place of the bucket we are going to build a wooden table with a box on it's top to contain our clay firepot. As this forge is more prone to cracking in the clay layer, I will cover repairs in more depth here as well.
These forges go back quite a ways historically, but most people seem to be familiar with them in a historical context during the colonial era of the United States, so we tend to refer to them as colonial forges for simplicity. You can also call them wooden box forges or what ever you like.
This forge is another variation on a ground forge, but puts the hole in the ground up at a comfortable waist height and with the addition of wheels on the legs of the forge, you can move the hole around for storage. That is much harder to go with a proper ground forge.
This forge can be built of any wood, even old pallets or the like. For the longest lasting version of this, I would suggest using 2x treated lumber. Just remember that anything that is used to make treated lumber isn't safe to eat, and shouldn't be inhaled. I leave it up to the person doing the project to be safe and take the required precautions. We are not going to cover a lot of woodworking safety here, so if you do not know how to run a table saw or what ever tool you are using FIND SOMEONE TO TEACH YOU how to do so safely. Seven finger Larry is not the guy here, OK?
I have provided a basic set of drawings with this post to guide you, but you may easily alter the dimensions of the forge to suit your need and materials. This version was designed for the most strength with the fewest cuts, just in case you are building it with a hand saw and no power tools at all. It also happens to use mostly off the shelf sizes of pieces, so you can probably find these boards pre-cut at your local lumber lot.
I tend to build these forges upside down, and add the legs last. This allows the body of the box to act as a brace as you mount the legs, making assembly a fair bit easier. So the first part to build is the box, which is quite simple. It is a box made from 2 foot long and 4 foot long sections of 2x6 (which are actually 1 1/2” x 5 1/2”). You really only need a single height of 2x6, though I have built these forges deeper using a second tier of 2x6s. The problem with deeper forges is the weight, while the problem with the single tier forge is the bowl is rather shallow. You can mound up the area around the bowl when you lay the clay in to compensate for this though. The box needs to be very sturdy, so feel free to go nuts with screws here on assembly... A screw every 4 inches is not at all excessive, and I strongly suggest heavy 3” long deck screws for this project. A big 5 pound box should not exceed 20 dollars even in the the most expensive store. If you are careful, large sinker nails can be used; I simply prefer screws, as they tend to hold tighter and stay in place longer.
I generally use a secondary strip of material inside each corner, and screw into that as well, driving the screws from the outside. A section of 2x4 or 2x2 cut to 5 1/2” long is quite nice, though be careful when you drive the screws into the wood from the outside; quite often the sharp tip of the screw will be exposed on the inside of the box, but this will not be a problem once the clay liner is put into place.
Once the main box is framed in, screw the bottom boards into place. The bottom is actually 27 inches across, as the end boards are 24” long and the sides are each 1 1/2” thick. Here you can continue to use 2x6 material, but it will require more pieces than if you use wider boards and will not line up exactly. 3 sections of 2x8 and one section of 2x4 could be used for example, and would not require you to cut a board lengthwise (this is known as “ripping a board”). You could even use a number of 2x4 sections. No matter what you choose to use, just be sure the boards are well secured at each end and are free of any cracks going across the board, as these will be supporting a fair bit of weight once the clay is in place. Get these boards as close together as you are able, so you do not have to worry about your clay draining out (though you can line the forge bed with plastic first just to be certain). Once these lengthwise boards are in place, three or four crosswise boards need to be screwed on underneath. I generally put one at each end, inset a few inches so I don't accidentally hit the screws that hold the long boards on when driving the next set of screws, and two more evenly spaced across the length. The illustrations will probably make this more clear. These cross ribs are screwed into each board in multiple places to help spread the weight of the clay bed once the forge is finished.
At this point, turn your forge bed over, and if you like, you can add reinforcing pieces to the corners. This can help to hold your forge together but does add more weight and uses more material.
Now the legs need to be cut, and these are not usually a normal length that you find precut at the woodlot. I usually make my forges about 32 inches high, but you can vary that somewhat. The goal here is to make the forge height roughly the same as your anvil height and that will vary from person to person. The easiest way to find out what this height should be is to have a friend help take a measurement from your knuckles to the ground, with your arm hanging straight down at your side and your hand rolled into a fist. By setting your forge and anvil at the same height, you allow yourself the ability to lay long rods of steel across the anvil and into the forge to heat the ends without having them fall over and possibly burn you or cause damage. It is not critical that your forge is the exact height though, so do not trouble yourself in trying to get it exact.
I generally use 2x4's to build the legs. They are more than strong enough, and 2x3's would probably work, but I like the extra material to hold the screws safely in the wood. Having a leg suddenly pop off when your forge is at nearly 2,000 degrees is excitement you simply do not need in your life. 2x6's are also certainly a possibility, giving even more material to hold the screws, but do cost more than 2x4's.
I strongly suggest some angle braces and cross braces, as shown in the illustrations, but they are not mandatory. Also, I generally drill a set of holes in each leg and the side of the forge box, and use ¼-20 3 1/2” long threaded carriage bolts at the center of the screw pattern for additional strength. The nut goes on the inside over a large “fender” washer. This washer spreads the force holding everything together over a larger area so it is less likely to crack the wood. Now the woodworking part of the colonial forge is complete, and in our next installment we will lay the clay firebowl and bed, and get everything ready to go. In later installments I will cover building a set of bellows that is fitting for a forge of this type as well.
Until then, stay out of trouble.
As a side note, I am sure I will realize I missed something and have to edit this over time to fill in those missed bits, so it may be wise to come back from time to time and reread old posts to see if new details have been added. I probably will not be rerecording the audio versions, unless it was something really major that was overlooked.
After covering the information in “building the bucket forge” you should have a pretty good feel for where this lesson is going. This is a larger version, and in place of the bucket we are going to build a wooden table with a box on it's top to contain our clay firepot. As this forge is more prone to cracking in the clay layer, I will cover repairs in more depth here as well.
These forges go back quite a ways historically, but most people seem to be familiar with them in a historical context during the colonial era of the United States, so we tend to refer to them as colonial forges for simplicity. You can also call them wooden box forges or what ever you like.
This forge is another variation on a ground forge, but puts the hole in the ground up at a comfortable waist height and with the addition of wheels on the legs of the forge, you can move the hole around for storage. That is much harder to go with a proper ground forge.
This forge can be built of any wood, even old pallets or the like. For the longest lasting version of this, I would suggest using 2x treated lumber. Just remember that anything that is used to make treated lumber isn't safe to eat, and shouldn't be inhaled. I leave it up to the person doing the project to be safe and take the required precautions. We are not going to cover a lot of woodworking safety here, so if you do not know how to run a table saw or what ever tool you are using FIND SOMEONE TO TEACH YOU how to do so safely. Seven finger Larry is not the guy here, OK?
I have provided a basic set of drawings with this post to guide you, but you may easily alter the dimensions of the forge to suit your need and materials. This version was designed for the most strength with the fewest cuts, just in case you are building it with a hand saw and no power tools at all. It also happens to use mostly off the shelf sizes of pieces, so you can probably find these boards pre-cut at your local lumber lot.
I tend to build these forges upside down, and add the legs last. This allows the body of the box to act as a brace as you mount the legs, making assembly a fair bit easier. So the first part to build is the box, which is quite simple. It is a box made from 2 foot long and 4 foot long sections of 2x6 (which are actually 1 1/2” x 5 1/2”). You really only need a single height of 2x6, though I have built these forges deeper using a second tier of 2x6s. The problem with deeper forges is the weight, while the problem with the single tier forge is the bowl is rather shallow. You can mound up the area around the bowl when you lay the clay in to compensate for this though. The box needs to be very sturdy, so feel free to go nuts with screws here on assembly... A screw every 4 inches is not at all excessive, and I strongly suggest heavy 3” long deck screws for this project. A big 5 pound box should not exceed 20 dollars even in the the most expensive store. If you are careful, large sinker nails can be used; I simply prefer screws, as they tend to hold tighter and stay in place longer.
I generally use a secondary strip of material inside each corner, and screw into that as well, driving the screws from the outside. A section of 2x4 or 2x2 cut to 5 1/2” long is quite nice, though be careful when you drive the screws into the wood from the outside; quite often the sharp tip of the screw will be exposed on the inside of the box, but this will not be a problem once the clay liner is put into place.
Once the main box is framed in, screw the bottom boards into place. The bottom is actually 27 inches across, as the end boards are 24” long and the sides are each 1 1/2” thick. Here you can continue to use 2x6 material, but it will require more pieces than if you use wider boards and will not line up exactly. 3 sections of 2x8 and one section of 2x4 could be used for example, and would not require you to cut a board lengthwise (this is known as “ripping a board”). You could even use a number of 2x4 sections. No matter what you choose to use, just be sure the boards are well secured at each end and are free of any cracks going across the board, as these will be supporting a fair bit of weight once the clay is in place. Get these boards as close together as you are able, so you do not have to worry about your clay draining out (though you can line the forge bed with plastic first just to be certain). Once these lengthwise boards are in place, three or four crosswise boards need to be screwed on underneath. I generally put one at each end, inset a few inches so I don't accidentally hit the screws that hold the long boards on when driving the next set of screws, and two more evenly spaced across the length. The illustrations will probably make this more clear. These cross ribs are screwed into each board in multiple places to help spread the weight of the clay bed once the forge is finished.
At this point, turn your forge bed over, and if you like, you can add reinforcing pieces to the corners. This can help to hold your forge together but does add more weight and uses more material.
Now the legs need to be cut, and these are not usually a normal length that you find precut at the woodlot. I usually make my forges about 32 inches high, but you can vary that somewhat. The goal here is to make the forge height roughly the same as your anvil height and that will vary from person to person. The easiest way to find out what this height should be is to have a friend help take a measurement from your knuckles to the ground, with your arm hanging straight down at your side and your hand rolled into a fist. By setting your forge and anvil at the same height, you allow yourself the ability to lay long rods of steel across the anvil and into the forge to heat the ends without having them fall over and possibly burn you or cause damage. It is not critical that your forge is the exact height though, so do not trouble yourself in trying to get it exact.
I generally use 2x4's to build the legs. They are more than strong enough, and 2x3's would probably work, but I like the extra material to hold the screws safely in the wood. Having a leg suddenly pop off when your forge is at nearly 2,000 degrees is excitement you simply do not need in your life. 2x6's are also certainly a possibility, giving even more material to hold the screws, but do cost more than 2x4's.
I strongly suggest some angle braces and cross braces, as shown in the illustrations, but they are not mandatory. Also, I generally drill a set of holes in each leg and the side of the forge box, and use ¼-20 3 1/2” long threaded carriage bolts at the center of the screw pattern for additional strength. The nut goes on the inside over a large “fender” washer. This washer spreads the force holding everything together over a larger area so it is less likely to crack the wood. Now the woodworking part of the colonial forge is complete, and in our next installment we will lay the clay firebowl and bed, and get everything ready to go. In later installments I will cover building a set of bellows that is fitting for a forge of this type as well.
Until then, stay out of trouble.
As a side note, I am sure I will realize I missed something and have to edit this over time to fill in those missed bits, so it may be wise to come back from time to time and reread old posts to see if new details have been added. I probably will not be rerecording the audio versions, unless it was something really major that was overlooked.
Blacksmith lessons – The bucket forge part two
Hello again all, and welcome to part two of the bucket forge lesson. In this lesson we will get some air into your bucket forge. If you happened upon this document, the first part can be found at http://ironangelforge.blogspot.com/ and the audio version can be found at http://alonetone.com/ironangel/playlists/blacksmith-lessons
The bucket forge is a very primitive little bugger, so no sense in cluttering it up with a good quality air source. We will cover those later in more appropriate sections. For this project quick and dirty is the best route.
Any item that moves air will work here, but first a quick concept must be explained to better help you choose which item you will use. For a forge, high pressure flow is not needed, and in many ways is more of a problem than you might expect. High pressure air can blow the lit coals right out of the forge, and this makes working far more challenging. High volume at low pressure is more useful, which a proper set of large and heavy blacksmith's bellows will produce. But for our small bucket forge, low pressure and low volume are probably enough to allow you to get going and start making needed equipment.
There are a number of quick and dirty ways to get low pressure, low volume air into your forge. A very common one is to put a hairdryer at the end of the inlet pipe, laying on it's side on a brick or stack of boards, and this can be quite effective. To vary the amount of air it pushes into the forge, move the end of the hairdryer closer or further away from the end of the inlet pipe. Closer will focus more air into the pipe. If you go this route, get a cheap hair dryer from either a yard sale or the salvation army. It is even better if it doesn't have a working heat system, or has a “no heat” setting. The problem with the heat system is this; the coils will draw more current, making your set up less efficient, and can overheat causing the hairdryer to shut off on its own, or if you are very unlucky, melt down and fail entirely. If it is a particularly weak hair dryer, you could tape the end of the dryer to the inlet pipe on your bucket forge.
Another option is a desk fan and a cone made of cardboard or the like. This is very primitive, but it can work fairly well considering what it is. Here, the end of the cardboard cone is simply taped over the end of the inlet pipe and the fan is set before it blowing into the pipe. Shoving the end of the cone into the pipe will restrict airflow quite a bit, and may block it off completely. Make sure your fan is set to not oscillate back and forth as well. It can easily knock your cone off, and wont funnel as much air where you want it. Also be careful to not set your cone on fire with falling bits of metal or the like.
There are as many other options as you have creativity to find or build; the cone system could even be used to catch the prevailing winds, but this will be harder to control and somewhat inconsistent, and doesn't work well on a calm day.
There are a couple things I can definitely suggest NOT using, including air compressors (high pressure, and they can be high flow – they tend to blow the fire out of the bucket all over you and the local area), leaf blowers (same problem, perhaps even worse than air compressors) and many large shop vacuums. Though a shop vac can be made to work by restricting how much air it is allowed to intake, but that is another project for another day. They also tend to be very noisy.
That covers this short section on getting air into your bucket forge, next is the larger colonial forge. Stay tuned!
(note, the reference to the rocks mentioned in the previous post has been omitted and will be covered in the next post - it applies to both forges)
The bucket forge is a very primitive little bugger, so no sense in cluttering it up with a good quality air source. We will cover those later in more appropriate sections. For this project quick and dirty is the best route.
Any item that moves air will work here, but first a quick concept must be explained to better help you choose which item you will use. For a forge, high pressure flow is not needed, and in many ways is more of a problem than you might expect. High pressure air can blow the lit coals right out of the forge, and this makes working far more challenging. High volume at low pressure is more useful, which a proper set of large and heavy blacksmith's bellows will produce. But for our small bucket forge, low pressure and low volume are probably enough to allow you to get going and start making needed equipment.
There are a number of quick and dirty ways to get low pressure, low volume air into your forge. A very common one is to put a hairdryer at the end of the inlet pipe, laying on it's side on a brick or stack of boards, and this can be quite effective. To vary the amount of air it pushes into the forge, move the end of the hairdryer closer or further away from the end of the inlet pipe. Closer will focus more air into the pipe. If you go this route, get a cheap hair dryer from either a yard sale or the salvation army. It is even better if it doesn't have a working heat system, or has a “no heat” setting. The problem with the heat system is this; the coils will draw more current, making your set up less efficient, and can overheat causing the hairdryer to shut off on its own, or if you are very unlucky, melt down and fail entirely. If it is a particularly weak hair dryer, you could tape the end of the dryer to the inlet pipe on your bucket forge.
Another option is a desk fan and a cone made of cardboard or the like. This is very primitive, but it can work fairly well considering what it is. Here, the end of the cardboard cone is simply taped over the end of the inlet pipe and the fan is set before it blowing into the pipe. Shoving the end of the cone into the pipe will restrict airflow quite a bit, and may block it off completely. Make sure your fan is set to not oscillate back and forth as well. It can easily knock your cone off, and wont funnel as much air where you want it. Also be careful to not set your cone on fire with falling bits of metal or the like.
There are as many other options as you have creativity to find or build; the cone system could even be used to catch the prevailing winds, but this will be harder to control and somewhat inconsistent, and doesn't work well on a calm day.
There are a couple things I can definitely suggest NOT using, including air compressors (high pressure, and they can be high flow – they tend to blow the fire out of the bucket all over you and the local area), leaf blowers (same problem, perhaps even worse than air compressors) and many large shop vacuums. Though a shop vac can be made to work by restricting how much air it is allowed to intake, but that is another project for another day. They also tend to be very noisy.
That covers this short section on getting air into your bucket forge, next is the larger colonial forge. Stay tuned!
(note, the reference to the rocks mentioned in the previous post has been omitted and will be covered in the next post - it applies to both forges)
28 August 2009
Basic blacksmithing – building the bucket forge
(Click on the image for a larger view)
Ok, we talked about this very primitive forge in previous posts, and here is the “how to” article to build your own bucket forge. Just so this is very clear, this is not going to be a really incredible forge, and it probably won't be very pretty, but it is simple and dirt cheap (that's a joke son, a joke... it will become apparent in a bit).
This bucket forge has not been covered anywhere else on the internet that I am aware of, but a lot of parallel evolution happens, so it is quite possible. You could think of this as a portable ground forge if you like, so any photos or information you might happen across on a ground forge could apply to this project.
So lets jump right into this then.
First you are going to need a bucket. A metal bucket or pail is certainly fireproof, but because of the way we are building this, any 3 to 5 gallon plastic bucket will work just fine.
Next, you will need some way of getting air into the fire. Here, I really suggest you use a section of steel pipe. Plastic pipe, such as PVC, is definitely going to melt and it won't last longer than it takes to get a good fire going. Copper pipe is going to carry a lot of heat back out of the fire, and could melt the side of your bucket, plus it is pretty expensive. Now for this project, any old hunk of 1 1/2” or larger pipe should suffice, though I wouldn't suggest much beyond about 3 inches in diameter. If it has an elbow or T connector on one end, that's even better. You will need a way to put a hole in the side of your bucket for the pipe to enter, but we will get to that in a bit.
Lastly, you are going to need some fireproof material to fill your bucket and make your bowl. This is where the “dirt cheap” joke comes in. Simple dirt can work just fine, with a layer of clay to make the bowl. And if clay is hard to come by in your area, kitty litter shouldn't be, and it is just pelleted clay. If you opt to go the kitty litter route, make sure it is the non-scented stuff, those scents could emit nasty fumes once they heat up.
Now that we have our materials, we just have to put it all together. The first thing is going to be a hole in the side of the bucket to allow the air pipe to come in under the fire. If your air pipe is just a straight section, it can come in higher up than if it has a T or elbow on it. The proper way to do this is to use a hole saw to cut a properly sized hole in the side of the bucket for the pipe to have a nice close fit. But hole saws are fairly costly, and this thing is to be done on the cheap, so... you will need to heat the section of pipe at one end, and find a means of safely holding the pipe to melt a hole in the side of the bucket. For this a propane torch can work, or a small camp fire. You only need to get the end of the pipe up to about 400 degrees, so even putting it in your grille or oven would work. Now wrapping a wet towel around the pipe might seem like a safe way to hold it, but go with me on this... it's not. If the pipe is long enough, you should be able to hold in with your hands, as long as you check it with the back of your hand first. By that I mean hold the back of your hand near the potentially hot pipe and feel for heat. Then get a bit closer and so on until you can touch it and know for certain it is a comfortable temperature. Why use the back of your hand, you may ask? Because the back of the hand is more sensitive to heat than the palm and fingertips, plus if you do burn yourself, it is in a place that wont cripple your ability to keep working. If the pipe is too short, or the heat moving though it has heated it up, you will need something like a pair of pliers or vice grips to hold the pipe. DO NOT put one end of the pipe in a bucket of water. This can cause the water in the pipe to turn to steam and shoot out the end like a shotgun, and steam is very effective at causing burns.
Once you get your pipe heated up, you simply hold it against the bucket and let it melt the plastic. Be sure to do this outside on a windy day, those fumes can not be good for you. Also be sure there is nothing flammable nearby, like a wooden deck or a bucket of gasoline soaked rags. If the plastic flares up and starts to burn pull the pipe off it and let the pipe cool somewhat, and put the flame out either with water or a hand full of sand. Don't blow on it to put it out though, as that could easily splash molten, burning plastic back into your face.
The objective here is to get a hole that is just about the size of your pipe, about halfway down the bucket. Of course if you have a hole saw, you can use that too, but this is the low dough way.
Now that you have a hole, let the bucket and pipe cool back to air temperature. Next fill the bottom of the bucket with whatever is handy to make up the space up to the level your pipe comes in at. Dirt is just fine, but is rather heavy. Since this area will not be exposed to much heat, it can be filled with wood scraps, a couple empty cool whip containers with lids or what have you. Just fill any air gaps with dirt and make sure you have a few inches of dirt under your pipe for insulation. If you choose to fill the entire bucket with dirt, the forge will be much more stable in use, which is safer, just be careful moving it, as the handles on many of these buckets are not designed for that much weight. Now slide your pipe in through the hole you made so the open part is at the center. If your pipe has and elbow or T, you will have to put the pipe in from the opening at the top of the bucket, on an angle and slide it into position. Now fill the bucket with some more dirt around the outer edge to create a basic bowl shape. Tamp this all down from time to time to make sure the dirt is packed as tightly as you can, so it wont collapse later.
Next comes the final part, making the bowl. If you have river clay, simply press it into place forming a nice bowl shaped depression with the sides packed tightly all the way to the top. If you are using cat litter, you will need to mix a little water into it so it is sticky, and pack it into place. There are illustrations on my blog to better show the shape and layout of this step, and that can be found at http://ironangelforge.blogspot.com/, along with other lessons.
Now you must have some patience, and let the clay dry for several days. Once you have let it dry, check it for cracks, and if some have formed, mix up a little clay and water and patch the up nicely, and let it all dry again. If you have no cracks, congratulations! You just built a bucket forge! You may want to build a small fire of paper and sticks in it to bake the forge bowl, but don't get to gung ho, you are just trying to drive out more of the wetness in the clay, not build a fire that can be seen from space.
Lastly, you will need to find a few nice rocks to put in your pipe to keep the coal from falling down into the pipe. These are easy to come by along side gravel roads and some driveways. Try to steer clear of any rocks that have been in creeks or rivers, they could still contain water and explode or turn to powder under heat. We will cover how to use those rocks in our next installment, which will also cover putting air into your bucket forge.
That's all for now, stay out of trouble til next time.
Blacksmith basics - the forge
Blacksmith basics – the forge
This post will cover more specific details on the forge a blacksmith uses in their craft than our previous post “absolute basics” did. This resource will cover mostly coal forges, with gas forges covered in a later article. I will be leaving out the exotic and semi-exotic heating sources here, such as electric resistance heating systems and solar forges. These other systems are more specialized in their application and generally financially out of the reach for the average hobbyist smith. In later articles we will cover some simple variations of the modern and historical forges that can be built very inexpensively and in short order.
The forge is a place that the smith can contain and control a fire to heat metal up to working range, which is usually hotter than a normal camp fire. The term also often means the building the forge is located inside of, and the term “forging” is something made in a forge. Forgery is not the correct term for making something in a forge though... that would be smithing, which comes from smite; to strike something. You know... blacksmith, a smith who strikes iron, which comes from the ground and fire black, as opposed to gold or silver.
The history of metal smithing is a long and varied one, and forges have undergone many variations and changes over the passage of time. Originally, the forge was a simple hole dug into the ground, and a blowpipe was used to increase the heat of the fire. As time passed, the smiths decided that standing up was a lot more comfortable than crouching down to work in a ground forge, but a few clever smiths dug holes to stand in next to their ground forges, and in a few parts of the world these ground forges are still used today.
The next evolution was to make the forge a roughly waist high table, either of laid stone or brick. This allowed the air-blast to come into the forge from under the fire, instead of from the side or above, which increased efficiency and allowed the smith to get even greater temperatures from his fuel. There are variations during this long age, including forge tables built of wood and covered in clay, side blast forges and long trough forges. For simplicity sake, we will only cover the generic, basic forge here for now though and save the unusual ones for later.
In modern times, the forge is often built as a steel table with a heavy walled cast iron firebowl or firepot at the center of the table to contain the fire. This forge bowl is usually several inches deep and a bit more than a handspan across. This allows a decent amount of fuel to be used, yet is not wasteful. It also allows the solid sides to absorb and reflect some of the infrared heat back into the center of the fire, increasing efficiency.
In all ages, the area around the forge bowl is often used to hold extra fuel and lay out work pieces and tools. Careful fire management will keep the fire contained in the smaller, central pot so as to not waste fuel. Many smiths build special fittings into the table to aid their work. These can be tool racks, special dies for forming or bending, or workpiece supports for long rods of steel.
So why build a large, heavy table for a forge in this day and age? Forges are an efficient means of heating steel compared to other options, such as a simple torch with either a fuel air mix or a fuel-oxidizer mix. The fuel air torches are things like a propane plumbers torch which have only a single gas cylinder. A fuel-oxidizer system like a oxy-acetylene cutting torch, will have a pair of tanks. The problem with using either style of torch is the amount of lost heat that is simply blown into the room and not absorbed by the work piece. The amount of fuel used by either of these torches in medium to heavy blacksmith work will make them prohibitively expensive in short order.
That about covers the basics of the forge, now we need to look at the fuel, air input assembly and the hood or draft system to remove smoke and heat.
Historically, forges burned coal, charcoal or in some rare cases peat moss as fuel. Raw wood is generally not clean burning enough to be used as is, so it was usually rendered down into charcoal, which gave a better heat and was less troublesome. Today, coal is probably the most common, as the amount of charcoal one uses for even simple projects makes it somewhat cost prohibitive in comparison to a coal forge. Coal is somewhat uncommon these days, but not terribly hard to find, and we will cover resources for finding it later on in our article about fire building and management.
For a moment I would like to diverge here to discuss gas forges in passing, just so the reader will have a bit of familiarity with them until we reach that chapter.
Most modern gas forges are a box like object with a pipe or set of pipes on top, so they can easily be put in a number of places like the tail gate of a pickup truck for field work. A gas forge can be built into a table like a coal forge, or sit on a stand or mount at any convenient height for work in a shop. The forge box is lined with a fireproof refractory material, much more resistant to heat than common brick, and this makes these forges rather heavy for their size. The pipes that enter the top of the forge are gas jets, and have a system to mix fuel and air from the room together to produce a clean burning flame inside the forge box. Most gas forges are set up to run on propane, but any flammable gas that can be pressurized can be used (such as hydrogen, methane or natural gas). More on gas forges later though...
Once we have a forge and something to burn in it, we need to consider how to get that fire hotter than normal. This was originally done with a blowpipe. It works, but is pretty tedious and can make you quite light headed very quickly. So some clever smith came up with a way to build an automatic lung, which we today know of as a set of bellows. There were a number of improvements in bellows tech over the years, but in this modern age most smiths use a much smaller mechanical fan system. Heck, you can even use the output from a vacuum cleaner or a hair dryer, but both of these have interesting problems we wont cover here yet. Most of these systems have some way to control either how fast the fan turns or how much air it is allowed to push into the fire to better control the heat in the forge. Too hot can burn the steel and too cold will make many jobs much harder if not impossible.
This air system is connected to the underside of the forge with a section of fireproof pipe, and enters the bottom of the firepot through a specialized part of the bowl, usually called a tuyeer. (There are some variant spellings of this word.) Usually this section of the bowl also has a gate or some kind of door to allow the ash that falls out the bottom of the bowl to be cleared out.
Now that we have air in our forge, we have to do something with the smoke... that's where a stack and hood or some other system comes into play. Now if you are just outside, you can let the smoke drift away, but I have done this a lot, and I can tell you it will often drift right toward you (there really is a scientific reason too – you create turbulence in the air stream passing you, and the smoke can be pulled right to you even if you are up wind of the forge). Building a stack (or chimney) is a more complex process than it may at first look, but I will cover it in great detail later on, so do not fret. Connected to the stack is some kind of metal hood that collects and funnels the smoke, allowing it to leave the building through the stack. There are optimal ratios for the intake area vs the pipe size and stack height, and I will cover them in that article I just mentioned. For now, I just want you to be aware that most smiths use a steel hood over their forge, though some use what is called a sidedraft hood system. This is the system I prefer, and I will have a full article including pictures and plans up here soon as part of the aforementioned article.
That wraps up our lesson for today, and once we get past these most basic lessons we will begin to get into the real meat of it.
Until then, stay out of trouble.
The podcast for this will also be up at http://alonetone.com/ironangel under "albums and playlists - Blacksmith lessons".
This post will cover more specific details on the forge a blacksmith uses in their craft than our previous post “absolute basics” did. This resource will cover mostly coal forges, with gas forges covered in a later article. I will be leaving out the exotic and semi-exotic heating sources here, such as electric resistance heating systems and solar forges. These other systems are more specialized in their application and generally financially out of the reach for the average hobbyist smith. In later articles we will cover some simple variations of the modern and historical forges that can be built very inexpensively and in short order.
The forge is a place that the smith can contain and control a fire to heat metal up to working range, which is usually hotter than a normal camp fire. The term also often means the building the forge is located inside of, and the term “forging” is something made in a forge. Forgery is not the correct term for making something in a forge though... that would be smithing, which comes from smite; to strike something. You know... blacksmith, a smith who strikes iron, which comes from the ground and fire black, as opposed to gold or silver.
The history of metal smithing is a long and varied one, and forges have undergone many variations and changes over the passage of time. Originally, the forge was a simple hole dug into the ground, and a blowpipe was used to increase the heat of the fire. As time passed, the smiths decided that standing up was a lot more comfortable than crouching down to work in a ground forge, but a few clever smiths dug holes to stand in next to their ground forges, and in a few parts of the world these ground forges are still used today.
The next evolution was to make the forge a roughly waist high table, either of laid stone or brick. This allowed the air-blast to come into the forge from under the fire, instead of from the side or above, which increased efficiency and allowed the smith to get even greater temperatures from his fuel. There are variations during this long age, including forge tables built of wood and covered in clay, side blast forges and long trough forges. For simplicity sake, we will only cover the generic, basic forge here for now though and save the unusual ones for later.
In modern times, the forge is often built as a steel table with a heavy walled cast iron firebowl or firepot at the center of the table to contain the fire. This forge bowl is usually several inches deep and a bit more than a handspan across. This allows a decent amount of fuel to be used, yet is not wasteful. It also allows the solid sides to absorb and reflect some of the infrared heat back into the center of the fire, increasing efficiency.
In all ages, the area around the forge bowl is often used to hold extra fuel and lay out work pieces and tools. Careful fire management will keep the fire contained in the smaller, central pot so as to not waste fuel. Many smiths build special fittings into the table to aid their work. These can be tool racks, special dies for forming or bending, or workpiece supports for long rods of steel.
So why build a large, heavy table for a forge in this day and age? Forges are an efficient means of heating steel compared to other options, such as a simple torch with either a fuel air mix or a fuel-oxidizer mix. The fuel air torches are things like a propane plumbers torch which have only a single gas cylinder. A fuel-oxidizer system like a oxy-acetylene cutting torch, will have a pair of tanks. The problem with using either style of torch is the amount of lost heat that is simply blown into the room and not absorbed by the work piece. The amount of fuel used by either of these torches in medium to heavy blacksmith work will make them prohibitively expensive in short order.
That about covers the basics of the forge, now we need to look at the fuel, air input assembly and the hood or draft system to remove smoke and heat.
Historically, forges burned coal, charcoal or in some rare cases peat moss as fuel. Raw wood is generally not clean burning enough to be used as is, so it was usually rendered down into charcoal, which gave a better heat and was less troublesome. Today, coal is probably the most common, as the amount of charcoal one uses for even simple projects makes it somewhat cost prohibitive in comparison to a coal forge. Coal is somewhat uncommon these days, but not terribly hard to find, and we will cover resources for finding it later on in our article about fire building and management.
For a moment I would like to diverge here to discuss gas forges in passing, just so the reader will have a bit of familiarity with them until we reach that chapter.
Most modern gas forges are a box like object with a pipe or set of pipes on top, so they can easily be put in a number of places like the tail gate of a pickup truck for field work. A gas forge can be built into a table like a coal forge, or sit on a stand or mount at any convenient height for work in a shop. The forge box is lined with a fireproof refractory material, much more resistant to heat than common brick, and this makes these forges rather heavy for their size. The pipes that enter the top of the forge are gas jets, and have a system to mix fuel and air from the room together to produce a clean burning flame inside the forge box. Most gas forges are set up to run on propane, but any flammable gas that can be pressurized can be used (such as hydrogen, methane or natural gas). More on gas forges later though...
Once we have a forge and something to burn in it, we need to consider how to get that fire hotter than normal. This was originally done with a blowpipe. It works, but is pretty tedious and can make you quite light headed very quickly. So some clever smith came up with a way to build an automatic lung, which we today know of as a set of bellows. There were a number of improvements in bellows tech over the years, but in this modern age most smiths use a much smaller mechanical fan system. Heck, you can even use the output from a vacuum cleaner or a hair dryer, but both of these have interesting problems we wont cover here yet. Most of these systems have some way to control either how fast the fan turns or how much air it is allowed to push into the fire to better control the heat in the forge. Too hot can burn the steel and too cold will make many jobs much harder if not impossible.
This air system is connected to the underside of the forge with a section of fireproof pipe, and enters the bottom of the firepot through a specialized part of the bowl, usually called a tuyeer. (There are some variant spellings of this word.) Usually this section of the bowl also has a gate or some kind of door to allow the ash that falls out the bottom of the bowl to be cleared out.
Now that we have air in our forge, we have to do something with the smoke... that's where a stack and hood or some other system comes into play. Now if you are just outside, you can let the smoke drift away, but I have done this a lot, and I can tell you it will often drift right toward you (there really is a scientific reason too – you create turbulence in the air stream passing you, and the smoke can be pulled right to you even if you are up wind of the forge). Building a stack (or chimney) is a more complex process than it may at first look, but I will cover it in great detail later on, so do not fret. Connected to the stack is some kind of metal hood that collects and funnels the smoke, allowing it to leave the building through the stack. There are optimal ratios for the intake area vs the pipe size and stack height, and I will cover them in that article I just mentioned. For now, I just want you to be aware that most smiths use a steel hood over their forge, though some use what is called a sidedraft hood system. This is the system I prefer, and I will have a full article including pictures and plans up here soon as part of the aforementioned article.
That wraps up our lesson for today, and once we get past these most basic lessons we will begin to get into the real meat of it.
Until then, stay out of trouble.
The podcast for this will also be up at http://alonetone.com/ironangel under "albums and playlists - Blacksmith lessons".
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