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Old/New, Compact, "Convertible" Solid-Fuel Forge (photo heavy)


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After several months of having to deal with a number of more pressing matters in life, I’ve finally gotten back to modifying and finishing a couple of forges. One is a gas forge that I built last year and works very well, but I’m making a few minor mods to it to enhance its performance, after which I plan to post it on IFI. The other forge is a solid-fuel forge that I just built, which I’m describing here.

Both forges are experimental (to me). I use the term “experimental” loosely, since they do NOT represent any brand-new, far-out designs, but I have been playing with a couple of ideas and putting my own spin on a few features, for better or worse. Here’s what my solid-fuel forge looks like, and I’ll explain how I fabricated it.

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This solid-fuel forge project was inspired by the discovery of a nice antique cast-iron three-leg forge hearth (or “tray” as some of you may call it) for 20 US bucks at Liberty Tool Company, in Liberty, Maine. It was just the bare hearth...no legs or any other attachments. It had some light surface rust, but no pitting, no cracks, and no marks that would have been left by bolts, nuts, or washers around any of the attachment holes, so I think it could have been an NOS part that was cluttering up someone’s barn for a century or so. The underside has an embossed “145-3,” which makes me think it could be a three-leg version of the four-leg Champion Model 145 forge. Any ideas from the antique-forge-savvy crowd out there?

Here’s a four-leg Champion 145, as illustrated in an old Champion catalog. The hearth looks very similar to mine, except for the number of legs.

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After considering how many other projects I “should” have been working on instead of this forge, I abandoned logic and reason and began the process of converting this felicitous ferrous find into a functional forge.

One major factor that influenced my design is available space, or the lack thereof. I’m in the process of converting half of a double garage into a small shop area for my metal-related work, and space will be at an extreme premium, especially considering the size of some of the equipment that I want to squeeze into such a small space. Therefore, I wanted both of the forges to be very compact and to be able to roll them out into the driveway for use outdoors. It was easy to restrict the gas forge to a small footprint, but a bit more challenging for the solid-fuel forge.

My scheme for keeping it compact was to fit all of the working bits underneath the hearth, with nothing extending out more than a couple of inches, and I wanted to do this without sacrificing any whistles and bells, so there was a lot of kit that had to be stowed in that small space.

I had a bit of spare change available for this project, but since there are other things that I like to squander my hardly-earned dollars on, I tried to use surplus and leftover material that I had lying around, although I still had to buy a few items.

The first order of business was to add some legs and something to secure the legs. I had some 3/4” schedule 80 black pipe on hand, so I used that for the legs, and I found a round steel duct flange to secure the legs. To add mobility to the forge, I installed a 5/8” diameter axle rod from my scrap bin and a pair of cast-iron wheels from McMaster-Carr.

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I found an old electric Buffalo Forge blower on eBay for $76 USD plus shipping. I don’t know how old it is...maybe 1960s? It was in working order when I got it, but I discovered that the motor was probably not the original one, and consequently I had to shift the blower housing about 3/16” to re-center the fan in the housing. It has an ordinary, general-purpose 1/8 HP single-phase induction motor, rather than the universal motor that I believe I’ve seen on some old Buffalo Forge Company blowers. I also gave the blower a cosmetic touch-up while I was at it, including re-spraying it with hammer-tone paint like the original. I also replaced the dried-out rubber sleeve around the output port with a piece of 1/8"-thick fiberglass gasket tape saturated with silicone. It really pumps out the air now, with more volume and pressure than I need for this little forge, but I figure better too much than too little, since I can easily control its output with an air gate. It’s also a relatively quiet blower compared to some I’ve heard.

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The original forge probably would have had legs that splayed out a few inches at the bottom, something like the catalog illustration above, and while that does add stability, at the same time I think the splayed-out legs might constitute a tripping hazard for klutzes like me. Of course, I wanted the forge to be adequately stable. I "think" that I've managed to achieve a comfortable level of stability as a result of the following factors: 

  • It doesn’t have a heavy, cast-iron hand-crank blower protruding out to one side a foot or so like the original forge would have had.
  • All of the workings and accessories are installed directly under the hearth, which lowered the center of gravity considerably.
  • The cast-iron wheels added a few extra inches of base width in one dimension, as well as extra weight at the bottom.
  • The “clay” I’m using (which isn’t clay...more on that later) is lighter than fire clay that I’ve used when doing pottery stuff, which probably reduced the weight at the top of the forge.
  • For added stability, I fabricated a drop-down, adjustable 4th leg, and being adjustable, it adapts to uneven surfaces, so I don’t lose that particular advantage of a three-leg forge.

Here's the added leg that I installed:

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Of course, every respectable solid-fuel forge needs some kind of tuyere, so I fabricated one that would connect to an air gate, using the following items:

  • One schedule 40 3-inch butt-weld steel pipe tee.
  • One Schedule 40 3-inch butt-weld 45-degree steel pipe elbow.
  • Two 5.5” OD, .25-inch-thick steel washers (one of which is shown in the photo below).
  • One 4” piece of 3.5-inch OD steel tube.
  • One 2” piece of 3.5-inch OD steel tube (shown attached to the air gate assembly).
  • One sliding air gate.

I used an off-the-shelf air gate that I found on McMaster-Carr and modified it a bit. I drilled and tapped holes in it so that it would mount securely to the tee of the tuyere, using four “extended tip” set screws. The extended tips fit into four corresponding holes drilled in the tee, and I used jam nuts to lock the set screws in place. I used the same technique to install a short piece of 3.5” OD steel tube on the other side of the air gate. The connections seem very solid. I also added a drag mechanism to the air gate (more on that later). Butt-weld steel pipe fittings can be expensive, but I found some online that were pretty reasonably priced. Here are the basic items used to make the tuyere:

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I welded the tee to the elbow, as shown below.

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Then I welded the two heavy washers together, drilled four mounting holes in the flange formed by the washers, drilled a hole sideways (edge-wise) through the washers to accommodate a clinker breaker shaft, and welded a couple of tabs over the shaft holes, just to add some thickness at those points.

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By laying a double-pass bead where I welded the flange to the tee, I had plenty of metal for touching up the weld to form a nice radius that almost makes the assembly look like a one-piece casting. The photo below shows the tuyere with the 4-inch length of 3.5-inch tube welded onto the elbow and the ash-dump door and the hinge brackets for the door welded onto the tube (more on the ash-dump door later).

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Now it was time to mount the tuyere under the hearth.

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Note that I mounted the tuyere with spring-loaded machine screws. This is one of the “personal touches” that I added to the design. My “theory” is that in addition to shock-heating, shock-cooling, and overheating, one of the reasons that cast-iron hearths develop cracks might be due to different expansion/contraction rates between the hearth and any objects that are bolted securely to the hearth (like a tuyere, for example). I figured that if I used some stiff and relatively heat-resistant springs to mount the tuyere, it would allow the hearth and the tuyere to expand and contract at different rates without stressing the hearth at the attach points. I made sure that the mounting holes were well-aligned with each other and drilled the holes a little larger than the mounting screws to allow a bit of differential movement.

On the top side of the tuyere mounting, you can see the clinker breaker, another 5.5” OD washer that I added, and the 3/8” flat-head internal-hex screws for mounting the tuyere, which are countersunk into the washer.

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I constructed the tuyere grate from a heavy washer that was about 1/4” thick (obtained from a marine chandler) by drilling 8 additional 1/2” holes in it. Please note that I ground off ALL of the zinc galvanizing before welding the modified washer into a small steel NON-galvanized duct flange. I don’t like toxic smoke and fumes from burning zinc (or anything else for that matter).

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I extended the handle of the clinker breaker downward and installed a brass knob at the end to act as a weight to help keep the clinker breaker centered. As I recall, the clinker breaker itself came from Centaur Forge, and it works just fine, but if I build another forge I might experiment with my own clinker breaker design, since I have a few ideas along that line.

To mount the blower, I fitted and bolted a couple of steel angles to the circular duct flange that secures the legs. The blower just happened to fit perfectly, requiring no alterations to the blower base,, other than drilling a couple of holes, but I’ll admit that I didn’t plan it that closely...some luck involved, I think.

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I constructed a handle for moving the forge, using some surplus 3/4” schedule 80 pipe and a few Kee Klamp® fittings, a couple of which I already had. The set-screw-type fittings allow the handle to be reconfigured or adjusted easily, and I added a sliding flat bar that could be used to hang a few tools on.

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I installed a steel plate alongside the forge, spring mounted to an existing flange at the edge of the original hearth casting. This plate accommodates the switch box for the motor toggle switch (which is adequately rated for the voltage and current load) and also supports the rod for controlling the air gate.

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Please note that I plan to keep close tabs on how hot the switch box gets during a long forging session. If it gets too hot, I may install a heat shield or else reposition the switch box...we’ll see. The wires from the switch to the blower motor are encased in flexible metal conduit (FMC) for some protection from impacts, and to the best of my knowledge I installed the appropriate connectors and bushings to prevent chafing where the wires enter and exit the conduit. I did the wiring myself, but I an NOT a professional electrician, so I will not guarantee the correctness, reliability, or safety of the wiring that I did. See the warning below.

Warning: Have a licensed electrician do all of the wiring on your forge to help avoid potentially fatal shock hazards. 

I used a silicone heat-resistant turbocharger hose to connect the blower outlet to the air gate. I can’t remember the temperature rating offhand. I don’t think it will get too hot in this location but I’ll be checking the hose during longer forging sessions to make sure it doesn’t overheat. If it gets too hot, I’ll replace it with some kind of metal elbow.

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The control linkage I made for the air gate is quite simple: It’s just a straight rod with a knob at the end, which is connected to the slider plate with some springs to provide some stress relief and prevent rattles. The rod passes through the same steel plate that holds the toggle-switch box.

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Here’s a little twist that I added: To make sure that the position of the air gate’s sliding plate doesn’t drift (and to reduce possible rattling of the sliding door in the gate frame), I drilled and tapped one of the original locking-screw holes in the air gate to 1/4-20 and installed a brass “twist-lock retractable spring plunger” from McMaster-Carr, which presses against the stainless-steel slide and acts as both a drag and anti-rattle mechanism. Adjusting the depth of the plunger determines the pressure against the slider. I added a jam nut to hold the adjustment. The brass plunger tip rides smoothly on the stainless slider and doesn’t scratch it...it just makes a polished streak.

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The linkage allows very quick and easy changes in air volume, and I will probably add marks on the control rod to indicate favorite settings as I get more practice with the forge.

Now, on to the “claying” of the forge.

The hearth has the words “CLAY FORGE BEFORE USING” cast into it, which I thought would be advisable to avoid overheating, shock-heating, or shock-cooling the cast iron. I would have used ordinary fire clay, which is cheap and would have worked just fine, BUT I already had a couple of different kinds of leftover castable refractory, including some Kast-O-Lite 30, that was getting close to the end of the shelf life, so I thought I’d use my remaining stock of castable refractory rather than let it go bad.

As long as I was using castable refractory, I decided to play with the castable approach and came up with the idea of making separate castings to create a “convertible” forge with two different duck’s nest sizes. It would have an outer casting that would form the larger duck’s nest, plus a removeable inner casting to form the smaller duck’s nest. A dual duck’s nest might not be a new idea within the greater scheme of things, but it was new to me.

I made a Styrofoam form for the larger duck’s nest by roughing out some 2” Styrofoam and then chucking it in a drill press and using coarse sandpaper to smooth it while it was spinning. It was a very messy job (Styrofoam dust...I used a respirator), but it created a nice symmetrical form. I coated the Styrofoam with some silicone, thinking that the refractory wouldn’t stick to it very much (which worked ‘reasonably’ well).

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I adhered the form to the top of the tuyere with some very sticky double-sided woven polyester tape, and I also lined the forge hearth with some polyethylene sheet that I cut and taped to obtain a smoother, snugger fit with no significant wrinkles. The threaded rod was just there to make it easier to pull the form out when the refractory had set.

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It was time to make the first casting. Note: I followed the refractory manufacturer instructions as closely as possible for all aspects of the casting and dry-out process, from start to finish.

Sorry, but I don’t have a photo of when I was making the outer casting.

After the initial set or “air cure” of the first casting, I removed the Styrofoam form for the larger duck’s nest, lined the duck’s nest with masking tape to act as a mold release, and made a smaller Styrofoam form for the smaller duck’s nest in the same way that I made the larger one. This time, for the temporary mold assembly, I used a bit of silicone to stick the form to the top of the grate and adhered the grate to the top of the tuyere with double-sided tape. I basically used the same procedure to cast the smaller duck’s nest.

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After the initial set of the castings, I decided to cut them into smaller sections, which I thought might be advantageous in several ways: First, the cut sections would be small enough that I could put them in a programmable heat treatment oven to follow the official dry-out schedule. Second, the saw-cut gaps would allow expansion and contraction of the refractory castings while the forge is in use without stressing the cast-iron hearth. Third, it could help prevent cracks from developing in the castings while the forge is in use. I dry-cut the pieces with a 7-inch diamond blade. They cut easily, but there was a LOT of airborne dust (be sure to wear appropriate protective gear). After cutting the pieces, I followed the manufacturer’s time/temperature dry-out schedule to safely remove both free and chemically-combined water.

WARNING: Always follow the castable refractory manufacturer’s exact instructions for all steps, including the controlled dry-out schedule, to avoid problems that could include potentially dangerous explosive spalling.

Because of the castable refractory liner, I plan to keep the forge DRY. If the refractory castings get wet it would require a controlled dry-out process to avoid possible explosive spalling when the forge is used. The need to keep the castable refractory dry might be considered a drawback, since I can’t apply water to the coals for modifying the shape of the fire or allow the forge to get rained on. However, even if I were using some other material instead of a castable refractory for the liner, I would still be a bit leery of using water with a cast-iron forge, since it seems to me that any crack or gap in any kind of liner could allow water to directly contact the cast-iron hearth, in which case I would worry about causing cracks in the cast iron from thermal shock. At least that's my take on it. Someone correct me if I'm wrong.

Like many cast-iron items, these old hearths are not perfectly formed, and the surfaces are not totally uniform and smooth, so to maintain a good fit I marked the refractory castings and their locations so that I could place them back in the hearth in exactly the same positions in which they were cast.

I coated the cast sections with some left-over ITC-100 that I already had on hand from building my gas forge. Yes, I KNOW...the ITC-100 is unnecessary and expensive, but I already had the stuff and I was curious to know if it might help the fire get up to working temperature a little faster. As usual, I followed the manufacturer’s instructions for applying the ITC-100.

The following photos show the cut pieces after they were initially coated with ITC-100. You can see that the inner casting is easily removeable to convert the duck’s nest to a larger size.

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In retrospect, I should have waited until I used the forge for a few sessions without the ITC-100 in order to get a baseline to compare the performance with and without the ITC-100, but that’s the way it goes sometimes. I get a bee in my bonnet, and off I go. Something to do with “project inertia,” I think.

Note: I filled the narrow gaps around the castings with some ash that can absorb a bit of movement as the castings expand and contract.

Next was how to deal with ashes and clinkers. I fabricated a custom “ash tray” that fits snugly into the space under the ash-dump end of the tuyere. It’s made from 1/8” hot-rolled mild steel. I welded and ground the corners and installed a piece of 3/4” schedule 40 pipe for a handle with the end welded shut (for looks). It’s not huge, but it holds enough to empty the ash dump several times, and it’s in keeping with the compact nature of the project. I might end up shortening the handle a bit if it gets in the way.

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I constructed a counterweight-type ash dump door with an adjustable hinge that incorporates a solid rod-end (as opposed to a spherical rod-end). It has only one adjustment, and there is just enough play in the hinge that it automatically makes perfect full contact against the tube every time it closes. Because of the geometry of the door and the angled bottom of the tuyere, it has the advantage of remaining open if I lift it all the way, which allows me to open the door and then (while it’s up out of the way) remove the ash tray in an easy one-hand operation. I ended up adding a little more weight to the counterweight, as you can see in the photo.

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As to how it all works, I've only fired it a few times so far. It seems to heat up quickly, the air is very easily controllable, the blower is relatively quiet, it cleans up easily, it’s easy to move around, and it’s compact. Despite being compact, the forge is hefty enough that I ask for help if I need to lift it into my truck (I want to avoid a second hernia operation), but once it’s back on the ground I can roll it around easily.

I will try to get some photos of it in operation over the next week or so and post them.

Here are a few images of the forge from different angles:

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Some of you might consider this project to be overkill for a little solid-fuel forge, but I’m totally unrepentant. I had fun designing and building it and learned a thing or two in the process. I’m one of those guys who likes making tools as much as using them. You might say that I’d rather take the back road and enjoy the scenery, even if the expressway is faster (not the best analogy, but you get the idea).

It would also have been easier and faster to fabricate the legs and other framework by doing more welding and using fewer fasteners, but I think it was worth the extra effort to use fasteners in several places, since it allows future modifications (and corrections) to be made more easily.

If I were to build another solid-fuel forge, I’d probably build the hearth and firepot from steel, which would be less work than adapting everything to the old cast-iron hearth, and of course steel is much more forgiving, more easily modified,  and more repairable than cast iron. Still, it was an interesting challenge to see what I could do with an antique hearth.

I didn’t really keep track of my expenses for building this, which would have been difficult anyway, since I would have had to factor in the various leftover materials that I already had on hand. In any case, you can certainly build a forge that works very well for considerably less time and expense, assuming that your prime objective is to quickly get a forge up and running.

There are still a couple of improvements that I will probably make: I might fabricate a removeable windbreak/sunshade that would also incorporate about a one-inch raised ring around the hearth to prevent wayward lumps of coal from straying too far from the herd, jumping the fence, and ending up on the floor. The hearth currently has a raised edge, as you can see, but it could stand to be a touch higher. I’m also thinking about modifying the handle assembly to include an adjustable-height tool rest...très chic in fashionable blacksmith circles this season, or so I’ve heard. I made such an animal for my gas forge, and it’s really handy.

As mentioned, I will try to keep an eye on how hot the components under the forge get, especially during longer forging sessions.

DISCLAIMER: I am NOT a professional blacksmith, engineer, or electrician, and I built this forge as a personal project and experiment. I DO NOT guarantee its safety, reliability, or functionality, so if you copy or adapt any of my methods, or the features, materials, or characteristics of this forge, it is entirely at your own risk.

I welcome your feedback and suggestions. I'll post a few pix of it in use as soon as I have a bit of free time, which is kind of a rare thing for me these days.

Cheers,

Al (Steamboat)

 

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Very, very nice and innovative. I don't think the ITC100 will make any difference in a solid fuel forge which depends upon air for the heat, been better off to save it to touch up the propane forge as needed. Don't know if I missed it but what fuel are you using? The fire pot in my coal forge is made out of fire clay and has lasted 30+ years with only touch ups for some cracking early on.

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5 minutes ago, blacksmith-450 said:

Just wow !  What a post !  Congrats.

 

12 minutes ago, Irondragon Forge & Clay said:

Very, very nice and innovative. I don't think the ITC100 will make any difference in a solid fuel forge which depends upon air for the heat, been better off to save it to touch up the propane forge as needed. Don't know if I missed it but what fuel are you using? The fire pot in my coal forge is made out of fire clay and has lasted 30+ years with only touch ups for some cracking early on.

Thanks to both of you.

I'm sure that fire clay would have worked just fine. One "possible" positive note about the castable refractory is that I've trundled the forge numerous times over some pretty bumpy and hard surfaces, which has given it a good shaking up, especially with the cast-iron wheels, and so far, no cracking in the refractory castings. Maybe fire clay would also hold up well to some bumping around...possibly depends on the type of clay and mixture, etc. If I didn't already have some nearly-expired castable lying around I would have gone with some kind of fire clay, which I can get from a local pottery supply house.

I was thinking that inside the duck's nest an ITC-100 coating might reflect some heat back into the fire, but it's probably not a significant factor. I've still got some leftover ITC-100 for the gas forge. When that eventually runs out I might experiment with other coatings.

Steamboat

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Very impressive build. I only have two criticisms:

1. Typically, solid fuel forges have a clinker breaker or a grate, but not both*. The grate will keep larger clinkers from settling to the bottom of the fire where they can be broken up by the breaker. You can hook them out with a poker, but that defeats the purpose of having a clinker breaker in the first place. You might want to consider leaving out the grate when forging with coal, although you could leave it in place when using charcoal. 

2. You’ve set a horrible precedent for beginners making their own forges! After all the hard work that we JABOD proponents have put into promoting an easily built, low-tech, low-cost way to get people forging, you’ve come along with this beauty, and now all the newbies will think they need to build something this sophisticated in order to start smithing! What have you done?!? ;)

 

* I personally suspect that most rivet-type forges didn’t have clinker breakers because they were intended for light-duty occasional use, where clinker buildup wasn’t going to be a big issue. You do see them appear on the slightly larger rectangular cast iron forges, and definitely in the cast firepot for installation in masonry forges. 

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21 minutes ago, JHCC said:

You might want to consider leaving out the grate when forging with coal, although you could leave it in place when using charcoal. 

Very good observation, JHCC, and I had the same thought, which is why I designed it so that the grate can be easily lifted off, allowing either the large or small duck's nest to be used with or without the grate in place. That reminds me of one little tweak I'd like to make: For using the larger duck's nest with the grate in place, I'd like to make a ring to go around the flange of the grate so that the bottom of the duck's nest will be flat in that configuration. That should be an easy mod. It could just be a couple of large washers, or I could cut a couple of rings with my plasma cutter.

I could also fabricate a flat grate, which would give me an even deeper duck's nest when using a fuel that doesn't need a clinker breaker. With the current raised grate, there is enough clearance over the clinker breaker that the breaker won't strike the grate. However, if I made a flat grate, the clinker breaker would strike it IF the clinker breaker is rotated. However, that might be useful, since "rattling" the grate with the clinker breaker might dislodge small clinkers or debris in the grate.

I plan to pick up some coke and charcoal soon to see how those fuels work with the forge.

As to the horrible precedent, (insert fiendish laugh here). :D

Cheers,

Al (Steamboat)

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Al, Awesome build!  Lots more patience than myself but fun to see what time, patience, and skill can do.  I understand that sometimes the build can be as much or more fun than the use.  Good humor on the part of JHCC and yourself on the "horrible precedent"!   Tom

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Oh Al: That is just a beautiful example of new guy OCD overbuild! It's gorgeous! Forget ITC - 100 it won't do anything but add $100 or so to the build cost. 

Does your electrical control panel have a rheostat? If not it shouldn't get warm even. If it does put a small hole in your air supply pointed in it's direction and let the blower (air blast) cool it.

You'll be much happier with rubber wheels.

Great job!

Frosty The Lucky.

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Beer Can Forge Blower "Test"

I made a short video the other day of my new solid-fuel forge. I was just curious as to how much pressure and volume the blower was putting out, and so I conducted a non-scientific and basically meaningless "test" (if you can call it that) using an empty beer can. It didn't really give me any data, other than demonstrating that the blower was pumping air in the right direction (which I already knew), but it was still kind of fun.

Al (Steamboat)

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On 8/1/2018 at 4:15 PM, Frosty said:

Does your electrical control panel have a rheostat? If not it shouldn't get warm even. If it does put a small hole in your air supply pointed in it's direction and let the blower (air blast) cool it. You'll be much happier with rubber wheels.

Glad you liked it, Frosty! I really try to pay attention to the details on everything that I build, which drives my wife crazy sometimes, since home-related projects sometimes (read "almost always") take longer than usual to complete. As to a rheostat, there's no speed control; I just use the air gate, which works fine. So far, in some short fire-up sessions, the hardware under the hearth does not seem to be getting too hot. I'll check it again after a longer session, but I suspect that it should be OK. If not, I'll post it here.

As mentioned, I know that the ITC-100 was unnecessary and probably insignificant as far as any positive effects in the duck's nest, but there it was, a neglected, half-used jar of the magical slurry, just sitting by itself on a shelf, staring me in the face and silently pleading to be used instead of left to gather dust. I couldn't help myself...I didn't have the heart not to use it. If nothing else, it made the castings look pretty until I got them dirty.

Al (Steamboat)

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I can honestly say that's one of the cleanest fabrication projects I've ever seen. Flawless welds, nice attention to details and a post modern industrial vibe. Very cool. I have a few rifles that are in the "too pretty to shoot" category and that little forge is getting pretty close! I would rather put a tempered glass top on it and use it as an end table than sully it with coal black and ash! The most functional thing I see there, that I haven't seen before, is the modular ducks nest. Well done. Great job on the forge and the presentation!

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6 minutes ago, ThomasPowers said:

Actually the blower looks to be way overpowered.

Thomas, I think the video makes the blower look more powerful than it really is. I've found that it doesn't take a massive amount of pressure and volume to float an empty aluminum can. While it might be more blower than "necessary" for this forge, it works beautifully. Using the air gate, I can adjust the air flow from what you saw in the video down to where it will barely lift a Kleenex. The fan (or impeller if you prefer) is actually quite small, and there is a large empty space inside the housing beyond the outer perimeter of the fan blades. 

As it happens, I did carry out one "real" test of the blower. I wanted to see how much current it draws at different air gate settings. Here are the results:

  • With the air gate completely closed (maximum restriction & minimum--virtually zero--flow), the motor drew 1.6 amps.
  • As I gradually opened the air gate, the current draw increased to 1.8 amps by the time the air gate was completely open. This is with the ash dump door closed and the grate in place.
  • When I removed the grate and opened the ash dump door, and with the air gate still completely open (minimum restriction & maximum flow), the current draw increased to 2.1 amps.

So, the motor uses LESS current when the flow is more restricted and it's pumping less air through the blower. And the motor gets its cooling air from outside the blower housing anyway, so I think we're good with this blower. Like everything else, I'll check the motor temperature with an IR thermometer during a long forging session, but I think it should be fine.

I'm hoping to use the forge again this weekend and post a few images of it in use.

Al (Steamboat)

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56 minutes ago, TwistedCustoms said:

I would rather put a tempered glass top on it and use it as an end table than sully it with coal black and ash!

Thanks for the positive feedback. My wife said almost the same thing about not wanting to get it dirty, and that I should put it tn the living room instead (well, to be honest she quickly corrected herself and suggested putting it in my office instead of the living room). She's actually looking forward to using it herself. I think my gas forge makes her a bit nervous, and she took a short blacksmithing course where they used coal forges, so she should be more comfortable with this one. As to putting my projects into use, as long as I have a few photos of my projects in their "BD" state (before dirt), I don't mind getting them dirty. It helps to think of dirt as the "patina" of honest toil.

56 minutes ago, Dylan Sawicki said:

Wow that' really cool.

Thanks, Dylan.

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  • 4 weeks later...

Never have I seen even anything so grossly over-engineered. Not even the most advanced propane forge I've seen has had half as much thought put into it. ITC100 in a solid fuel forge? really?

 

 

It's beautiful and I love it. Could do with a PID and/or arduino or two though.

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Thanks for the compliment, J.P. Hall. It's my nature to over-engineer things that I build. No plans for a PID or any computerized control for it (yet) :lol:.

On the other hand, it might be cool to install a manometer, flow sensor, and thermocouple, combined with a linear stepper motor on the air gate and programmable settings for different forging scenarios. Just kidding. That would be overkill...even for me!

By the way, welcome to the forum.

Al (Steamboat)

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Well, I finally got around to firing up the little forge again to give it a better test run. Today's firing was intended to check out the operation of the forge in more detail, particularly how hot things got under the hearth during an extended run, although my wife made a coal rake while we had it running. I tried both the small and large duck's nest sizes, and both of them worked great. I ran it continuously for about four hours, only taking a couple of minutes to change duck's nest sizes, and I'm glad to say that all of the equipment under the hearth stayed nice and cool. In fact, I could even put my hand on the tuyere right next to where it bolts onto the hearth, and it was barely even warm. As Frosty predicted, the electrical switch box remained cool to the touch, as did everything else under the hearth.

I could even touch the underside of the cast-iron hearth for a few seconds at a time without discomfort, due to the castable refractory liner, which, by the way, held up fine. There were some bits of slag sticking to the Kast-O-Lite, but they chipped off fairly easily. If the castable refractory ever does break down, I'd probably replace it with some kind of fire clay. The coal I used (ostensibly "smithing" coal) wasn't the cleanest I've used, leaving more rock chips and slag than I'd like. Nor was it very uniform in size. I had to break up a lot of larger chunks of coal. However, when I ran the forge with the grate removed, the clinker breaker did a good job in getting rid of clinkers without having to rake them out. Maybe this bag of coal was just a fluke, but If the next bag isn't any better, I may start looking for another coal source, or maybe even a good source of coke.

It's a very quiet blower, which is nice, and it doesn't have to work hard at all. For the larger duck's nest size and heating some heavier stock, I'd guestimate that I had the air gate roughly 30-35% open on average...maybe very briefly up to 40% at times. For the smaller duck's nest size, I had the air gate perhaps 20-25% open on average. So there's good reserve capacity for any situation where you might want extra volume and pressure. And as mentioned earlier in this topic, the blower motor draws less current when the air gate is mostly closed than when it's wide open, so the motor was just loafing along, and even if I were running it with the air gate wide open, it would still draw less current than the motor's continuous-use amperage rating.

I tried heating a couple of pieces of 1/2" and 3/4" square bar stock, and they reached welding temperature very quickly. The larger duck's nest size is nice for creating a wider and somewhat deeper sweet spot (see photo below), but I'll probably be using the smaller duck's nest most of the time.

firing-up.thumb.jpg.2de71a7898bfce28e53fd2b0da0ea61a.jpg

All in all, so far, so good. Now it's time to start putting it to use and making some stuff. One possible project might be a fireplace screen or two for the old house we're restoring.

Al (Steamboat)

 

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