Before we begin, I realized a possible problem with the information given in the prior lesson. That error is the size of the forge bed I specified. I designed this forge for my use, and realized I tend to use a much larger forge deck than most hobbyist smiths may have room or need for. Also, this amount of clay makes the forge bed quite heavy.
Here is a rethought size for the colonial forge, however it does not use standard sized pieces, so some ability to cut lumber will be required to construct this version.
The total materials list for this smaller forge would include these parts:
2 side pieces of 2x6 18” long (3 feet total)
2 rails of 2x6 24” long (4 feet total)
3 support rails under the forge of 2x4 20” long (5 feet total)
4 legs of 2x4 (or 2x6) 30” to 32” long
4 angle braces
And here is a cutting diagram to utilize the material fairly efficiently:
Keep in mind that this version will use a lot less material, weight a great deal less and take up less space in the garage than the prior version, and if these are considerations for you, you may be better served by this smaller forge. The construction methods and process is the same with either version.
Now with that out of the way, let's get back to the tasks at hand.
The air inlet pipe will be put into place before the clay bed is put in, and there are two options here. The first is to drill a hole through the end rail for the pipe to pass through. The second is to pass the air inlet over the top of the rail and hold it in place with a pair of nails or a wooden mount made from scrap.
To drill the large hole that will be required to pass the inlet pipe through the sidewall you will need a power drill and a hole-saw large enough to allow your pipe to fit, or alternately a series of overlapping smaller holes to make a hole large enough. I leave this option to you to sort out, as the plans here are designed for the pass over design. Of course, this step could also be done before the entire box is assembled, making the process of drilling the hole or holes a great deal simpler.
The pass over style inlet is designed for simpler construction, and uses a few scraps of wood to brace the inlet pipe for best results. This also sets the outlet at a slight angle which is something to be aware of once you start laying in the clay. Any scraps of wood you may have left over from the box construction can be used to brace the pipe, and I would suggest you put a thinner strip of material over the top of the inlet pipe for additional strength and stability.
A couple of heavy nails driven into the bottom of the forge bed hold the pipe in place before the clay is put in, and you will want to hammer them over the pipe so the heads do not stick up out of the clay after the forge bed is complete.
Mix up your clay with a small bit of water to make it easier to shape, and lay it in in layers, letting each layer dry a few days. This will help to allow trapped water to escape and reduce cracking that happens in a thicker layer of clay. I generally lay each layer about 1 to 1 1/2” thick. The first layer will help to hold the inlet pipe in place, with each successive layer making it even more stable. Build up a bowl around the mouth of the inlet pipe, much like the bucket forge, and refer to the illustration here for assistance.
You will need to let this clay bed dry for about a week before it can be used, though I do know of cases of these forges being built and used the same day in historical records. I am fairly sure the pressing need at the time outweighed any cracking that the heat may have caused in the clay layer.
Once the bed is dry, you will be able to start a small fire in the forge bed to drive even more moisture out of the clay. For this, a quarter bag of common BBQ charcoal works quite well, but a pile of dry sticks from the lawn will do just as well. There is no need to drive air into this first fire, you are simply drying the forge at this time. Allow it to cool and “rest” overnight before it will be ready for everyday use, as this gives the moisture in the clay time to migrate and even out throughout the clay bed.
In our next installment, I will detail building a set of bellows to get some air into your forge, and discuss possible alternatives.
Showing posts with label wooden forge. Show all posts
Showing posts with label wooden forge. Show all posts
20 September 2009
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.
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