Have time to critique this design?

[Vinito]

Hi folks. I'm going to build me a forge in the next couple weeks and in a goggle search this firebox design came up: https://www.calsmith.org/resources/Documents/CBA Coal Forge Drawings.pdf

It looks to be about what I've seen recommended other places. I was kinda wondering what you experienced folks think about it. Is there anything you'd change for some reason?

Should be pretty easy to fabricate one. I do that kind of stuff all the time, but I have done almost zero blacksmith stuff. So I don't mind making a firebox & forge but prefer to get something pretty workable the first time instead of having to remake something had I just known better beforehand.

The basic dimensions of the firepot are thus in case ya aren't into opening the link. But there are more pages in the document showing tubing, gate, clinker buster, etc.

Thanks for any input

[Irondragon Forge ClayWorks]

Seems a little more complicated than a firepot needs to be. I have used this one for years and it is better than any others I have used.

Bob Patrick Firepot

[Frosty]

Holy Mackerel! When I burn coal I'm set up as a "duck's nest" and use hard fire brick to make the fire whatever shape I need. 

A brake rotor set in a steel table makes a fie coal forge. Torch a hole the rotor slips into and rests on the rotor. I make a plate to screw to the rotor on the lugs after  knocking all but two out. The plate has a 3" dia. hole centered on the hub hole in the rotor. 

My air supply is truck exhaust pipe, 3" x 12" for the vertical and 2" long enough to reach the blower. I drill a 2" hole in the 3" about 4" from one end and weld the 2" horizontal in the hole. The short end of the 3" pipe gets welded to the disk that bolts to the rotor. The ash dump is a clamp on 2" flap cap. Like you see on semi stacks. Upside down the counter weight holds it closed and collects ash and debris that falls through the air grate. I just reach under the forge table with tongs, fire rake, piece of stock etc. and lift the counter weight and the ash falls into a bucket of water underneath. 

If you get an explosion of unburned gas in the tuyere it just blows the flap open and dumps everything into the bucket.

The air grate I prefer anymore is 3/8" or 1/2" round bar folded in hair pin bends with about 1/2" space and I just lay a few over the open 3" dia. in the rotor. This is called a bar grate ad there are lots of ways to do it, enough straight pieces to cover the hole, welded in place, etc. Some guys like drilled holes, some guys torch slots in a piece of plate, etc.

My larger coal forge has the tuyere described above pop riveted to a 14 ga. steel table and I cover the table with about 3/4" or better of compacted clayey soil. Later I was given a bunch of fire brick scrounged from a power plant boiler rebuild and I covered the table with those leaving a space about 5" sq clear around the air grate and rammed the "duck's nest" in clayey soil. 

I use fire brick around the air grate to shape and size the fire. 

I don't really have a fire pot on any of my coal / solid fuel forges.

Frosty The Lucky.

[Daswulf]

If you want to build it it should be fine. Compare it to the dimensions of what companies are selling commercially to see if it is on average for dimensions. 

Personally after a good bit of research, I started out with a brake rotor 2"deep and 9" diameter. Welded up the lug holes, welded on a 2" black pipe fitting to screw the T onto ((which the T is made of black pipe fittings and a welded up ash dump). Added a tacked on grate of round plate steel drilled with some holes and its done. 

Rotor sits in a hole in the forge table and is all disassemble able and replaceable, tho I haven't had to replace anything but the grate in over 5 years of hobby use. Went overboard with a stainless table top so I shouldn't ever have to replace that.  I did use a 3"deep by 9" dia. Rotor pot to use if Im forging a bigger piece, but rarely have needed it. 

Pokers and a scoop deal with clinker easily with just the grate. 

  

[George N. M.]

Vin, it looks like a good design to me.  We know that you have the welding equipment and skills to make the parts and assemble them.  It does seem to be a "robust" design and I think you could substitute a bit lighter material if you don't have what is called for.  For example, the handle for the clinker breaker specifies 1/2" round rod and the firebox is 1/2" plate.  If that wasn't available you could probably get by with a slightly lighter thickness but I wouldn't go less than 3/8", particularly for the firebox which will have thermal stress.

"By hammer and hand all arts do stand." 

[Charles R. Stevens]

Looks workable, tho bottom blast isn’t my first choice. I find side blast to be simpler and more versatile. 

[ThomasPowers]

Your first forge should get you started and then you can modify/build another as you figure out what YOU need to do YOUR forging.

As such I suggest folks start as simple and cheap as they can with the plan to do a better one once they have some experience.

Some folks try smithing and decide after a while that they prefer to do something else; be a shame if they spent 4 times longer building their set up than they did trying it out!

Also; can you visit other smiths local to you and see what they are using.  People choosing a design with no experience and no background seems a bit strange to me.

[Vinito]

Thanks for the thoughtful replies. Lots of good opinions.

I maybe should have mentioned my background again so you all had an idea what things I will and won't struggle with, i.e. what am able to do and what I'm ignorant about. So to that end - the design link I posted I estimate would take me about 4-6 hours to build since I do that kind of stuff all day for a living (machinist by trade and can do some welding). Honestly, I think it would take longer to patch up a brake drum to work than to just cut plate and weld up a pyramid-shaped box. As happens over decades, I have a bunch of material just piled up, so for only my time I could match or be pretty close to what was shown, or similar if changes are made. What I don't have experience with is blacksmithing/forging.

When it comes to visiting other smiths, in some ways in-person is hard to beat, but in others it's hard to beat a resource like the experience in this forum. Thus this thread.

Though unlikely, I can grok that I might dump this whole effort within a year. Of course the benefit of having something with a fairly decent basic design is that if that should happen, I can pass the thing off to the next guy rather than dump it in a landfill. Besides this option, I figure that I wouldn't do any worse building a moderate, generic, decent forge than if a guy purchased one from a commercial supplier. And since I could have one in a day or two for only my time, this seems more convenient than paying significant cash and then having to wait for shipping (which can be ridiculous lead times currently)

Anyway, I think I'll probably build something like this, meaning essentially a pyramidal firebox with a T arrangement air supply, counterweighted dump plate and slotted air grate. If nothing else, it seems to be time-tested and still being sold to this day. I'm leaning away from including the clinker breaker because a majority of smiths seems to not fuss with them to no bother, and as a beginner I expect that I will create a lot less clinker than even an avid hobbyist, thus less of a need in the first place (plus could easily add one later if it becomes a thing). In other words, yeah I'll build one, but try to keep it simple.

Thanks for the feedback.

[ThomasPowers]

Have you been to any ABANA Affiliate meetings yet?

[Vinito]

No, but there's a wrinkle with that. I don't do well around groups of people and usually have to recover for a day or two. I'm autistic or something. Since I'm old I've learned to just cope with it. I could do it, but it's not my first choice. Maybe someday I can hang out with a nearby smith or trade steak & beer for one to drop by my shop for a while. I'm in no hurry.

[Michael]

Hi, I've used these specific firepots a lot. CBA has 10 teaching forges set up like this. We transport them in a trailer to hammer ins and they set up (the forges, with the firepots) in just a few minutes. The design was for both consistancy across all the forges, CBA had a trailer of mismatched coal forges before this, and ease of build during a workshop-I think 15 were built over a weekend, with 10 slated for the trailer and the others went home with the crew members. These are also designed to drop into the forge tables and come out easily during breakdown. Here's what the whole forge looks like. 

Having worked on and demonstrated with these forges, I don't think I've ever used the clinker breaker. Each forge comes with a poker, rake, shovel and watering can and we just pull the clinkers out with the poker. These are also teaching forges, I wouldn't say they are abused, but they do see a lot of students new to solid fuel. So, blowers get left on, fires get too big and clinker builds up.

That said, I started out with a brake drum forge, originally in a plant stand, then a rolling metal cart and finally found a nice case iron table forge with a round Centaur forge firepot that I use now.

 

[Frosty]

Michael: Do you have a pic of one broken down for transport? 

I agree, fabbing one up would be an easy afternoon's work for a professional fabricator. It's a long way from a tough build.

Frosty The Lucky.

[Michael]

I looked thru my CBA pictures folder and it doesn't look like I have one. The legs are pipe (stored in buckets)and fit into sockets in the table, the sockets are inset so the tables all stack together. Pokers, rakes and watering cans go in the tables as they are stacked. Firepots are stored in angle iron racks on the walls of the trailer (the flange keeping the firepot in the table fits in the angle iron) I'll see if I can get someone to take a picture of them broken down. There's an event this weekend and I "think" the trailer is there. Here's a picture from the volunteer workshop when these were built (Photo credit to Paul Boulay, our VP and Photographer extraordinaire!) I was mistaken, they built 20, 10 for the trailer and 10 for the workshop participants.

Edited October 31, 2021 by Mod30
Remove excessive quote.

[ThomasPowers]

And the 21st?

[Michael]

I think that 21st one was either the prototype or was left at the shop.  McLelleen Blacksmithing in Loomis CA teaches classes and has a semi consistent set of solid fuel forges. I don't know the the shop owner was there that day, a lot of the CBA workshops at McLellen's go that way.

[Frosty]

I think the 21st. was to make the rows even. Nice bunch of forges it must've been a good weekend. 

Frosty The Lucky.

[Charles R. Stevens]

My forge. Side blast fire pot 6” deep with a 7/8”(3/4”schedule 40 pipe) ID tuyere out of 1/4” plate

[Vinito]

12 hours ago, Charles R. Stevens said:

My forge. Side blast fire pot 6” deep with a 7/8”(3/4”schedule 40 pipe) ID tuyere out of 1/4” plate

 

That's cool Charles! Do you have any more information, review, opinion, etc. on that firepot? I'd like to know more about it, especially comparison to the standard bottom blast types. I'd love to hear some stories, i.e. "my first forge was a brake drum, then found an antique bottom blast, but my current side blast does this & that..." etc. Maybe you've posted at length on it already?

Seems like it might not be a big deal to just orient the air hole like that. I've searched a little on side blast forges and everything that has come up for me so far is pretty large and complicated endeavors.

I also love that you've mounted your vise right to the table. I've been wondering why people don't do that more often. I mean I can guess advantage & disadvantage possibilities, but sure would be close & handy. Maybe folks just have more space at their disposal so separate vise location is easy. I dunno.

edit to add: I think I should make clear... I am guessing I will likely stick to building a standard bottom blast firebox in my forge since it seems to be a simple tried-and-true design. I am a beginner and don't need to get in over my head about something I know nothing about. I am just curious about your firebox and wouldn't mind reading up a bit about it. Seems like every side blast design has water cooling and a bunch of other complexities. In my case there is too much freezing risk of that so I won't even consider that for a long, long while if ever. But yours looks like just yer basic pyramidal firebox except the air comes in the side a little off the bottom. If that's the case, then it's actually simpler than a traditional bottom blast type and I'm into simple if it works... and also if a no-experience beginner like me could operate the thing without it melting a hole to china.

Anyways, just wanted to clarify that I'm curious but not going off the deep end.

[BIGGUNDOCTOR]

I have a vintage Champion cast iron forge, and will probably shift to a side blast to alleviate clinker issues I have with a bottom blast.  Side blast is also a tried and true design found all over Europe.  As to the water cooling, you can just make it to accept replaceable tubes that you can replace as they burn away.

A lot will depend on if you use coal or charcoal as a fuel. I have mostly used coal, and have dealt with the associated issues of noxious yellow green smoke on startup, clinkers, and stink in general. Really looking at using wood as I can get pretty much all I ever need for free.

BUT, if I get a shop built I would love to do an induction forge. Clean, and FAST heating.

 

Look at JABODS for a forge design as well.

[ThomasPowers]

He wheels his forge-barrow, through streets broad and narrow, crying "Forge Welding, twisting, I'm a py, a pyro!"

[Frosty]

Build a forge table and you can change fire pots until you find one you like. Hmmm? Side blast has been used in forges a long as humans have been hitting hot metal, bottom blast is relatively new on the scene. 

Frosty The Lucky. 

[Charles R. Stevens]

Sorry it has taken me so long to get back. I have been dealing with termite damage under Dad’s house. 
so the fire pot is made from a 12” square of 1/4” plate cut on the diagonal. Measure 1-1/2” up from the corner and drill a hole to take a piece of 3/4” schedule 40 pipe. Weld it in at a 5% angle or so. That would be sloping down to the bottom of the forge. This leaves about an inch under the tuyere and 4” above it. 
I made the pot 6” wide but I would have made it 4”, as I keep a fire brick in it to narrow the pot. I keep telling myself I will make a moving plate to adjust the width. 
I have a “T” with a gate valve on it, it is set up so there is strait shot to the vent and the tuyere is at 90 degrees. 
I power the forge with an electric blow up bed pump.

the table is 30”x60”  and made of all salvage, the top is plates from below ground transformer covers, the frame is welded up from bed frame and the wheels are salvage. I think they came from an old fire extiquiser. 
I melt bricks and burn steel if I am not carful.

tho I usually burn charcoal, coal burns just fine and the forge handles 1” stock easily and I have worked 1-1/2”.