After completing NaNoWriMo this past November, we will soon have our first fiction novel ready for purchase. The Nexus Codex is a story of a down on his luck detective trying to sort out what happened to his only paying client, and getting entangled in a web of strange circumstances.
While there is no blacksmith related material in this book, it is still a fun read. Perhaps we will post a few chapters here for you to get a preview down the road a bit.
Stay tuned... much is in the works and coming soon.
Stay warm, keep the forges lit.
12 January 2012
29 October 2011
Preview - Lesson - Backpacker's bellows
This is one of the upcoming articles being worked on currently:
This article will be on building a small set of "backpacker's bellows" for use with a ground or bucket forge in the wilds, or souping up your bbq grill or fireplace. These little single chamber, dual valved bellows can also be scaled up for other uses including general blacksmithing (though a dual chamber bellows system is much more efficient).
This article will be on building a small set of "backpacker's bellows" for use with a ground or bucket forge in the wilds, or souping up your bbq grill or fireplace. These little single chamber, dual valved bellows can also be scaled up for other uses including general blacksmithing (though a dual chamber bellows system is much more efficient).
Blacksmith Lessons - The Ground Forge
The Ground Forge
In previous articles, I have mentioned the ground forge, and I figured I should cover it in more detail. The original mention is here: http://ironangelforge.blogspot.com/2009/08/blacksmith-basics-forge.html.
The ground forge is really the beginning of blacksmithing as we know it, and is a hold over from the bronze age that preceded it. In many areas of the world, in the deep mists of the past, bronze and iron workers worked side by side, adapting techniques of the older metal into forming the new iron. That transitional stage is a whole other series of posts that we will cover at a later time.
As mentioned in the first post, some parts of the world continue to use ground forges to this day, though most areas developed taller “table” style forges. For the modern backyard blacksmith, historical re-enactment smith or the like, the later table forges are usually a better choice. But when you need a forge and are away from your shop, or are camping and need to make a quick tool, the ground forge is certainly a usable and very simple solution. For those who are interested in bush craft and being able to pack in to the wild very lightly, the knowledge of how to build a ground forge is an invaluable tool.
All you really need is an air source (covered below), a method of getting that air to the underside of the fire, and ground soft enough to dig a hole in. You can use any handy tool to make your hole, but its best to not use your hands, just in case there is a sharp stone or root in the area you are digging. If you find a root, move your hole. If there is a large root in the ground, it could catch fire and that could lead to an issue you don't want. You will also need forge fuel and tools, along with some stock to work.
Once you have found a suitable location that seems reasonably rock free, clear any ground debris such as leaves and sticks back a few feet and make sure there is nothing flammable over head for at least 15 or more feet.
Dig a narrow trench long enough for your air tube and a round hole about 6-8” in diameter. The trench should be a few inches deeper than your forge hole and angle upward out of the hole. The forge hole should be round bottomed, so it will be between 3 and 5 inches deep, with the dirt removed piled up around the outside at a low angle. Lay your air tube in the trench and cover it, at least at the end nearest the fire pit. The dirt covering is there to protect it from heat and keep it from moving. Pack the dirt tightly. Put in fuel, assemble your air system and light it up. You are done!
In case you don't have a set of backpackers bellows (described in an upcoming article) or another portable air source, there are a number of ways you can get air into your forge in a number of ways. The simplest is to blow into the end of the pipe. This will likely make you light headed before you reach a decent heat. You can also make a funnel shape and fan it with something handy to focus more air into the inlet, and this will work pretty well in a pinch. If there is a decent wind, building your ground forge aiming into the wind with a large funnel to catch and focus it may allow you to work in relative ease, the problem is you can not control the amount of heat. This may or may not work at all, depending on wind and location.
If you don't have a portable inlet pipe, you can build one by simply finding something to cover your inlet trench, then sealing it up with dirt. The more fireproof, the better. Bark will work, but it will eventually burn at the forge bowl and the inlet will cave in. Stones may work, but be ware of this; many stones have some water in them, and under heat may split or break, possibly with some force (another reason to make sure you remove them all from your bowl). If you can scrounge up a bit of metal in the field, such as a steel can stomped flat, it will work better than bark or stones. Just be sure to recycle or throw the can away when you are done. And when done, make sure to fill in the hole and trench as well to prevent breaking your ankle in the middle of the night in camp.
If you are in a clay area, you can “glaze” the inside of the bowl with a bit of water to smooth it and help it keep it's shape. If you are using wood or charcoal, the ash will help to harden the bowl somewhat, so if you use the ground forge for a long while it will get nearly concrete like in a clay bed.
In a ground forge, you will find there will be problems with clinker and slag build up at the air inlet, so you may have to tear down and clean your fire more often than in a cast iron pot table forge.
Now that you know how to build a ground forge, you can adapt this technology to make your own charcoal as well. Simply dig a much bigger ground forge, start the fire at the base near the inlet hole, and bury the top with the removed dirt leaving a small hole at the top for smoke to escape through. You don't want an open, flaming fire, just a slow smoldering one. Make sure if you are going to burn charcoal that you have a lot of time open; it will take a while. You can burn dry wood to make charcoal, but wet wood can also be used if you have nothing else at hand. It may not burn as easily or as well, and may even go out, so keep an eye on the smoke coming out the top. You may have to dig it out and relight it a few times with some dry kindling. We may put up a more extensive article on forging with charcoal in the future, and if we do it will have a much more extensive article on making your own charcoal with it.
In an extreme pinch, you can forge with just a wood fire. It will not be as hot as a coal or charcoal fire, and will pop and spit a lot more, so watch out for flying sparks. In a ground forge intended for use with only wood, you may have to dig your pit larger. The easiest way to do this is to dig a long trench with the air inlet coming in at a 90 degree angle. Lay your sections of wood in the trench and push them forward into the fire area as it burns away. You may have to wet it from time to time to keep the fire from spreading up into your fuel reserve. Be careful not to get your main fire area wet, and watch out for bursts of steam from the fire and from the inlet when you water it. Hot steam can blast out several feet, so be careful.
That about covers the ground forge for now. Keep on hammering.
In previous articles, I have mentioned the ground forge, and I figured I should cover it in more detail. The original mention is here: http://ironangelforge.blogspot.com/2009/08/blacksmith-basics-forge.html.
The ground forge is really the beginning of blacksmithing as we know it, and is a hold over from the bronze age that preceded it. In many areas of the world, in the deep mists of the past, bronze and iron workers worked side by side, adapting techniques of the older metal into forming the new iron. That transitional stage is a whole other series of posts that we will cover at a later time.
As mentioned in the first post, some parts of the world continue to use ground forges to this day, though most areas developed taller “table” style forges. For the modern backyard blacksmith, historical re-enactment smith or the like, the later table forges are usually a better choice. But when you need a forge and are away from your shop, or are camping and need to make a quick tool, the ground forge is certainly a usable and very simple solution. For those who are interested in bush craft and being able to pack in to the wild very lightly, the knowledge of how to build a ground forge is an invaluable tool.
All you really need is an air source (covered below), a method of getting that air to the underside of the fire, and ground soft enough to dig a hole in. You can use any handy tool to make your hole, but its best to not use your hands, just in case there is a sharp stone or root in the area you are digging. If you find a root, move your hole. If there is a large root in the ground, it could catch fire and that could lead to an issue you don't want. You will also need forge fuel and tools, along with some stock to work.
Once you have found a suitable location that seems reasonably rock free, clear any ground debris such as leaves and sticks back a few feet and make sure there is nothing flammable over head for at least 15 or more feet.
Dig a narrow trench long enough for your air tube and a round hole about 6-8” in diameter. The trench should be a few inches deeper than your forge hole and angle upward out of the hole. The forge hole should be round bottomed, so it will be between 3 and 5 inches deep, with the dirt removed piled up around the outside at a low angle. Lay your air tube in the trench and cover it, at least at the end nearest the fire pit. The dirt covering is there to protect it from heat and keep it from moving. Pack the dirt tightly. Put in fuel, assemble your air system and light it up. You are done!
In case you don't have a set of backpackers bellows (described in an upcoming article) or another portable air source, there are a number of ways you can get air into your forge in a number of ways. The simplest is to blow into the end of the pipe. This will likely make you light headed before you reach a decent heat. You can also make a funnel shape and fan it with something handy to focus more air into the inlet, and this will work pretty well in a pinch. If there is a decent wind, building your ground forge aiming into the wind with a large funnel to catch and focus it may allow you to work in relative ease, the problem is you can not control the amount of heat. This may or may not work at all, depending on wind and location.
If you don't have a portable inlet pipe, you can build one by simply finding something to cover your inlet trench, then sealing it up with dirt. The more fireproof, the better. Bark will work, but it will eventually burn at the forge bowl and the inlet will cave in. Stones may work, but be ware of this; many stones have some water in them, and under heat may split or break, possibly with some force (another reason to make sure you remove them all from your bowl). If you can scrounge up a bit of metal in the field, such as a steel can stomped flat, it will work better than bark or stones. Just be sure to recycle or throw the can away when you are done. And when done, make sure to fill in the hole and trench as well to prevent breaking your ankle in the middle of the night in camp.
If you are in a clay area, you can “glaze” the inside of the bowl with a bit of water to smooth it and help it keep it's shape. If you are using wood or charcoal, the ash will help to harden the bowl somewhat, so if you use the ground forge for a long while it will get nearly concrete like in a clay bed.
In a ground forge, you will find there will be problems with clinker and slag build up at the air inlet, so you may have to tear down and clean your fire more often than in a cast iron pot table forge.
Now that you know how to build a ground forge, you can adapt this technology to make your own charcoal as well. Simply dig a much bigger ground forge, start the fire at the base near the inlet hole, and bury the top with the removed dirt leaving a small hole at the top for smoke to escape through. You don't want an open, flaming fire, just a slow smoldering one. Make sure if you are going to burn charcoal that you have a lot of time open; it will take a while. You can burn dry wood to make charcoal, but wet wood can also be used if you have nothing else at hand. It may not burn as easily or as well, and may even go out, so keep an eye on the smoke coming out the top. You may have to dig it out and relight it a few times with some dry kindling. We may put up a more extensive article on forging with charcoal in the future, and if we do it will have a much more extensive article on making your own charcoal with it.
In an extreme pinch, you can forge with just a wood fire. It will not be as hot as a coal or charcoal fire, and will pop and spit a lot more, so watch out for flying sparks. In a ground forge intended for use with only wood, you may have to dig your pit larger. The easiest way to do this is to dig a long trench with the air inlet coming in at a 90 degree angle. Lay your sections of wood in the trench and push them forward into the fire area as it burns away. You may have to wet it from time to time to keep the fire from spreading up into your fuel reserve. Be careful not to get your main fire area wet, and watch out for bursts of steam from the fire and from the inlet when you water it. Hot steam can blast out several feet, so be careful.
That about covers the ground forge for now. Keep on hammering.
21 October 2011
Blacksmith Lessons – The Side Draft Forge Hood, part 2
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!
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!
Quick and easy solar heater
This post is pretty far off from the normal line of this blog, as it discusses something made with very little metal in it. Many years ago, my step brother built a set of solar collectors for our high school wood shop that were still in use 20 years later. They were entirely passive and built from simple pine 1x4 and a sheet of left over paneling. These simple collectors cut the heating costs by about a quarter over the colder months, which is pretty impressive! There were fans in the shop to push the heat down, but they were part of the existing heating system.
In this day and age, any free heat is a good thing, and these may help keep your forge or garage a little warmer in the winter. With some adaption, they might even be able to help heat your living space as well at the cost of loosing light coming in the windows they sit in.
Essentially, all these systems are is a large, shallow wooden box, with a labyrinth of wood inside to make the air travel a longer path through them. The entire interior is painted flat black to absorb as much infrared heat from the sun as possible. As the inside of the box warms, the air will begin to rise through it, creating draft at the inlet hole which will draw cooler air into the box, where it warms and rises continuing the cycle. The only real problem is the heat will come out the upper vent in the box and rise to heat the ceiling of your work space, so some kind of ceiling fan or other air circulation unit will be needed (and we will cover a clever one as well in another post).
Measure your south facing windows, and subtract 1/2” from that measurement for the outer dimensions of your box. Keep in mind that these boxes completely block most of the light coming in, so you may want to only cover a few windows, depending on how your shop is lit.
The outer frame is made of 1x3 or 1x4 pine with the uprights cut the the length you came up with above, and the cross members cut 1 1/2” shorter than your measurement to account for the thickness of the side rails. This box is assembled with glue and screws, making sure it is square at the corners. Measure and cut your back panel and glue and screw it onto the box. With that done, cut several 1 by sections about 90% as long as your side to side measurement. These will make up your labyrinth slats.
Lay these out on the inside face of your unit, mark the positions and drill small pilot holes for the screws that will mount them. In our illustrations, the holes are large round openings, and either this shape or rectangular holes will work effectively. If you want to use rectangular holes, drill four holes in a rectangle at the top and bottom of the back corners as shown in the illustrations to cut out the intake and exit holes. The exit hole should be a bit bigger than the intake hole, perhaps as much as 50% bigger.
Once the labyrinth cross bars are in place, the entire inside should be painted with flat black paint and allowed to dry. It may take a couple coats of paint to get an even, complete coating. You may want to paint the back of the unit white to reflect any ambient light in the room back to help make up for the lack of light your covered window will have.
The purpose of the labyrinth is to make the path from the intake to exit longer. The cross laths can be mounted flat or slightly inclined upward. Both work, but in theory the slight inclines should cause the air to move through the box a bit more easily.
Once the paint is dry, place them in the windows they are made for, and secure them so the box doesn't suddenly fall out. The glass in the window frame acts as the front of the box, and a bit of foam weather stripping around the outer edge of the box should help seal the box into the window frame, hopefully incresing your amount of heat output.
That's all there is to it! These systems may not produce a lot of heat, but any free heat is still free heat. In closing, be aware that some glass restricts infrared more than others. The more infrared that gets into your collector, the more heat it will put out. These systems can be adapted for stand alone use, but that is a whole other topic. Have fun, be safe, stay warm!
In this day and age, any free heat is a good thing, and these may help keep your forge or garage a little warmer in the winter. With some adaption, they might even be able to help heat your living space as well at the cost of loosing light coming in the windows they sit in.
Essentially, all these systems are is a large, shallow wooden box, with a labyrinth of wood inside to make the air travel a longer path through them. The entire interior is painted flat black to absorb as much infrared heat from the sun as possible. As the inside of the box warms, the air will begin to rise through it, creating draft at the inlet hole which will draw cooler air into the box, where it warms and rises continuing the cycle. The only real problem is the heat will come out the upper vent in the box and rise to heat the ceiling of your work space, so some kind of ceiling fan or other air circulation unit will be needed (and we will cover a clever one as well in another post).
Measure your south facing windows, and subtract 1/2” from that measurement for the outer dimensions of your box. Keep in mind that these boxes completely block most of the light coming in, so you may want to only cover a few windows, depending on how your shop is lit.
The outer frame is made of 1x3 or 1x4 pine with the uprights cut the the length you came up with above, and the cross members cut 1 1/2” shorter than your measurement to account for the thickness of the side rails. This box is assembled with glue and screws, making sure it is square at the corners. Measure and cut your back panel and glue and screw it onto the box. With that done, cut several 1 by sections about 90% as long as your side to side measurement. These will make up your labyrinth slats.
Lay these out on the inside face of your unit, mark the positions and drill small pilot holes for the screws that will mount them. In our illustrations, the holes are large round openings, and either this shape or rectangular holes will work effectively. If you want to use rectangular holes, drill four holes in a rectangle at the top and bottom of the back corners as shown in the illustrations to cut out the intake and exit holes. The exit hole should be a bit bigger than the intake hole, perhaps as much as 50% bigger.
Once the labyrinth cross bars are in place, the entire inside should be painted with flat black paint and allowed to dry. It may take a couple coats of paint to get an even, complete coating. You may want to paint the back of the unit white to reflect any ambient light in the room back to help make up for the lack of light your covered window will have.
The purpose of the labyrinth is to make the path from the intake to exit longer. The cross laths can be mounted flat or slightly inclined upward. Both work, but in theory the slight inclines should cause the air to move through the box a bit more easily.
Once the paint is dry, place them in the windows they are made for, and secure them so the box doesn't suddenly fall out. The glass in the window frame acts as the front of the box, and a bit of foam weather stripping around the outer edge of the box should help seal the box into the window frame, hopefully incresing your amount of heat output.
That's all there is to it! These systems may not produce a lot of heat, but any free heat is still free heat. In closing, be aware that some glass restricts infrared more than others. The more infrared that gets into your collector, the more heat it will put out. These systems can be adapted for stand alone use, but that is a whole other topic. Have fun, be safe, stay warm!
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