2017 September 15    Metal & Shop  


Introduction


Blacksmithing requires a good heat source.  There are several ways to do this, but solid fuel is the most economical and reliable.

Plain wood scraps or sawn-up tree branches make a very usable fuel.  But how to contain the heat in a useful way?

Equally important:  how to do that with minimal complexity and materials?

What follows is basically a variant of the "Side Blast 55 Forge", a design which I think was originated by the chief admin at Iforgeiron.com.  (Check out the page here.  Great site!)

I didn't invent the basic idea;  I'm just providing construction details for my own variant.  By no means do I claim to be an expert at blacksmith forges;  this is sort of an experiment to see what works (and maybe what doesn't).  I put this up here in the hope it may be of some benefit to you, and also to me in case I want to build another one.

Metalworking and blacksmithing have some dangers;  please read the Disclaimer



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In This Article

Materials Selection

The Tools

Preparing the Drum

Cutting the Drum

The Side Notch

The Firebrick

The Tuyere and Supports

Performance Tips

Conclusion




Materials Selection


Is a 55-gallon drum too large for a forge?  Actually, the diameter is about right for a wood forge, based on everything I've tried so far.  A smaller container such as a brake drum can't hold the big pile of wood that's needed for a usable smithing fire.

As for the drum:  Don't use one that has any trace of gasoline, naphtha, lacquer thinner, alcohol, or any other flammable material in it.  Grinding or welding on that could cause an explosion. 

Look for one that was used to store something non-toxic and non-flammable.  Ask around your town.  Empty ones are often available for less than $10 each, sometimes even free.

Another thing:  the drum shouldn't be rusted clean through.  The metal should be sound.

The drum I used was a bit rusty, but still basically solid.



Kodak Tri-X 400 (35mm) @ EI 400
2017
Developed in DD-X 1+9



Table of Contents



The Tools


The main tool that I used was an angle grinder and a few cutoff wheels.  Avoid cheap wheels, because they shatter easily and can be extremely dangerous.  Get good ones like Norton, Dewalt, or Makita.  Lenox also has a new type of cutoff wheel which has a diamond-coated edge;  I haven't tried these yet, but they have the advantage of not disintegrating with use.

Don't even think of doing this job without a face shield, and please whatever you do, never take the guard off your angle grinder.  There's no reason to remove it.  I would also recommend wearing a heavy canvas coat and a leather apron.  Even with good cutoff wheels, it's always better to be safe.  Also, don't forget the gloves.  Wear a pair of heavy welding gloves for this job.

It's possible to use a cutting torch instead of an angle grinder.  The torch cuts through the metal faster, but the grinder makes a neater result with less grinding and filing needed.  Another possibility is a metal-cutting circular saw;  in theory this should work best of all, though I didn't try it.  (They're fantastic for cutting plate, angle, and square tubing, though.  Don't forget the battery and charger.)

Any time you're cutting metal with something that spins, be careful of kickback. 


Table of Contents



Preparing the Drum


One end was domed out.  I've no idea how it would have got that way.  I had to hammer it back in before the drum would stand upright. 



Kodak Tri-X 400 (35mm) @ EI 400
2017
Developed in DD-X 1+9


That end of the drum is pretty well rusted-through anyway;  other end was fairly sound.  That will be the bottom of the blacksmith forge.  It doesn't have to be brand-new looking;  it's going to have firebricks on it anyway.

After making sure there were no fumes or traces of flammable liquid in the drum, I set to work with the angle grinder.


Table of Contents



Cutting the Drum


First thing was to cut the drum around the outside.  What height, though?  The first ridge from the bottom seemed like a good height for a wood-fired forge.  (Be sure you've read The Tools for safety precautions.)

A coal forge could probably be shallower, but wood burns away quickly.  So you need a larger heap of it.  The deeper forge also makes the fire less oxidizing toward the workpiece.  Kind of important. 

Also, it's easy to make it shallower by cutting the sides down later.  It's a lot harder to make the sides taller if you start with them too short!

It takes some practice to keep the abrasive wheel from jumping out and lurching forward while you're trying to cut the metal.  When you move it upward the way it's shown in the picture, the wheel cuts from the topside of the metal.  That leading part of the wheel wants to drive up onto the surface of the metal. 



Kodak Tri-X 400 (35mm) @ EI 400
2017
Developed in DD-X 1+9


If you move the grinder in the opposite direction (downward), the wheel cuts from the underside of the metal.  Then it won't lurch up out of the track.  This is the opposite of a circular saw; with those, you move the saw forward and the blade cuts from the underside of the material.

Beware of kickback no matter what, and you should never be in the plane of the spinning wheel.  (Read that Disclaimer again.  Anything I describe on here is "at your own risk", and if you don't have metalworking experience, then it's "don't try this at home".)

The cut metal will have jagged edges.  Be really careful of these until they are all sanded.  Don't even do this project if you can't de-burr and smooth those edges right away.  It will probably take you a good half hour or more to do that.  Shown here, the cut off drum before de-burring:



Kodak Tri-X 400 (35mm) @ EI 400
2017
Developed in DD-X 1+9



Table of Contents



The Side Notch


This is going to be a side-blast forge, so it needs a large opening in the side.  This is where the air pipe will be set.  And this is also the access point where you'll place iron for heating.

I marked the outline with a soapstone pencil, then cut it out with the angle grinder and cutoff wheel.  The metal at the low point of the notch is lower than a firebrick on edge, but taller than a thin firebrick set flat.  (I guess it's about the same height as a standard brick set flat.)  That allows for some depth of fuel.  You want the workpiece to be "in" the coals, not under them.



If you're planning to heat long bar stock, you may want to cut an identical notch on the opposite side of the forge, 180 degrees away from the first one.  I didn't get to that step, but it's something that could always be added later. 


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The Firebrick


Once all the sharp edges are carefully sanded off, the plain metal edge will be relatively safe.  However, you could use a variety of tools to curl the metal edges over if you prefer.  Or, make a piece that folds over the edge as they suggested in the original article.

If you store the forge properly (we'll get to that later), there should be no need to curl the edges over, as long as you de-burr them correctly.

So, figure out where you're going to operate the forge.  Place it there, on cinderblocks if necessary, and line the bottom of the forge with firebricks.  There will be some gaps between them, but once you burn a couple heaps of wood, the ash will fill the voids.  (This I learned by reading Iforgeiron, and it works.)

Place some firebricks up on edge around the perimeter, if possible.  These will help reflect in the heat. 


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The Tuyere and Supports


The air-feed pipe, or tuyere, is usually made of steel or cast iron.  The end of the pipe actually burns away slowly in the heat of the forge.  You can heap wood ashes over the end to slow that process greatly.  I wonder if fire clay might work, too.

It just so happens I had a piece of automobile tailpipe that wasn't being used for anything.  And what do you know... the diameter was just right to accommodate the cheap hair dryer I just picked up...




There it is:  easy side-blast forge. 

The air feed shown in the picture is sort of temporary.  To make this safer, I would build a more steady support from bricks or stone and mortar them together.  Another possibility is to weld a ledge or shelf onto a metal stake.  Drive the stake into the ground securely, then clamp or wire the air-blast pipe to that. 

The cinderblocks, on the other hand, are stable the way they are.  Three cinderblocks, 120 degrees apart on solid ground, is pretty solid.

When there's a fire going in the forge, you should be the only one in the vicinity.  Don't have distractions nearby, or your pet dog, or anything like that. 


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Performance Tips


As long as you can keep adding dry wood, you can bring steel up to welding temperature.

Regular forging temperatures are very easy to attain. 

Use the hairdryer on "low" setting.  This supplies the air blast into the center of the burning coals.  "High" consumes wood too quickly.  (A shop-vac is even worse...)

Here's a trick to getting the most out of this forge.  Have several 5-gallon pails of dry wood chunks nearby.  In the off season (is there an off season for blacksmithing??), collect fallen tree branches from friends and neighbors, or wherever you can find them.  Ask your local arborist if you can haul away their unwanted branches;  usually people are delighted to get rid of these, because they are otherwise kind of a long-term waste of space. 

Take the tree branches and cut them down into 2-inch pieces.  Fill the pails with these.

Any dry branch sections up to about 3" diameter and less than a foot long can be used directly in this forge.  Smaller cut-down pieces work better because they can pack more closely;  but the larger pieces do allow more time between refuels.

One more thing:  covering the forge when it's not in use.  The whole point of making a 55 Forge, for me, was to avoid a mud pit that fills up with water every time it rains.  But if you want to realize the benefit, you'll have to cover the 55 Forge when it's not in use.  I used concrete backer board about 32" x 32".  You can actually cut this stuff by scoring it with a utility knife.


Table of Contents



Conclusion


Though it's not the only way to build a 55-gallon drum forge, this method seems to work well.  The sides are kind of tall, but that allows you to make the wood fire very deep.  That means it should reach welding temperature on sizeable chunks of iron.

The trade-off is that you can't place the workpiece from just any angle;  it has to go in the side notch, next to the tuyere.  But it's highly usable, I've found.

It's definitely one of the easiest designs out there.  No T-fittings, no valves, no brake rotors, no welding.  There aren't even any bolts.

This was really just a temporary version, though;  if you're thinking of building this, first read the Disclaimer again... and I would also recommend some stable way to secure the tuyere and the hair dryer.  And of course, build the forge away from flammable materials and buildings.

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