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Propane Ribbon Burner forge plans - Comments?


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I've been thinking of buying a pre-made forge online, but then after reading through the forge building stickies here, I decided to build my own. Hobby-level use consisting of some blacksmith tool manufacturing (tongs, punches, etc.), some hunting/kitchen knives, and some metal artwork. Some day I'd like to try my hand at damascus billet, but that will likely be down the road.

I drew up some plans based on what I read here, and some preferences I had. Fuel source will be propane, and I plan to build a forced-air ribbon burner. See attached picture which shows a cross-section view. I'm still in the early design stages, and am giving the doors some thought...

I'm thinking of splitting the body in half (clam-shell design) to make it easier to apply castable refractory, and to make future maintenance easier.  2 layers of 1" insulating thermal wool, each layer rigidized. Inside covered in a 1/2" layer of castable refractory. Floor will have 1" of castable refractory with a high alumina kiln shelf sitting on the floor. Tapered ribbon burner at TDC of body (I'm open to suggestions on placement - just at the drawing stage at this point.) Inside clearance at widest point will be 7". Clearance from ribbon burner to floor seems to be coming in at 6" (assuming a 1/2" shelf thickness). The plans are calling for an 8" long burner, but to be honest, I just made that number up. If I use a propane tank as the body, the floor of the forge may only be about 9" long, so that burner length would be overkill. If I get some steel pipe from the local scrap metal business, I can make the forge floor longer (12"?) and an 8" burner may make more sense. But then I might be making a forge that is much larger/longer than I need it to be for my uses...

Some questions:

  • For forges made from 20lb. propane bottles, how deep is the usable floor space in the forge? (9"?)
  • How long should the ribbon burner be compared to the forge's depth?
  • Where can I find high alumina kiln shelf that is only 5"-6" wide? Most places online seem to sell them in 10.5" and wider. Can they be cut?

I plan to support members on this site by purchasing my insulating materials here. If someone offers kiln shelf, let me me know! The pages here seem to only sell refractory, wool, rigidizer, coatings, etc.

Any feedback/suggestions on my design are much appreciated!



Propane Forge Plans.R1.png

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Welcome aboard Matt, glad to have you. The only thing I see that's unnecessary is a 1" castable refractory floor and okay 1/2" on the rest of the liner is maybe too much as well. Guys have been getting away with thinner hard liners for a while now.

I recommend building the floor up with ceramic blanket and covering it like the rest of the forge. Kastolite is darned tough refractory and if you're going to cover it with kiln shelf anyway it won't take much. 

Kiln shelf can be cut with serious abrasive disks, Mikey just lined out suitable saws in another thread. It isn't a trivial task, I'd be tempted to rent a tile saw. 

A 8" ribbon in a 9" forge should be okay. You could taper the crayons at the end so they are aimed away from the ends when you cast the burner block if you're concerned. Shorten it up is viable, you can make a multiple outlet burner any shape or size you need. Maybe 6" long and a little wider? 

I'd definitely align the burner so the flame impinges the forge wall tangentially or close to cause swirl in the chamber.

I've only ever worked at a clam shell forge one time and the amount of radiant heat you have to take when you opened it was horrific. It seems like a good idea intuitively but smoking clothes faster than I could take a piece out changed my opinion. 

Clam shell for construction and maintenance rather than use would be good for me. 

I think you have a good preliminary plan going. Have you looked at any of the proven forge plans available in the forges 101 section here?

Frosty The Lucky.

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Thanks for the tips. Good to know the castable liner can be thinner. I like the idea of angling the end-holes in the burner away from the openings. The clam shell idea was strictly for initial assembly and future maintenance! Although, with all the extra cutting and hinges/pins, it might be just as quick and easy to leave it whole - especially when using an easily replaceable kiln shelf. I'll take another look through the Forges 101 section for doors/plans to compare notes. Tons of posts on this site, and some very old, so hard to know if you're seeing the "latest and greatest" when it comes to advice and plans. Lots of trial and error in these types of builds.



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I cut kiln shelf with a DeWalt diamond blade for dry cutting masonry with a 4 1/2" angle grinder.  It cuts easily but I only recommend it if you have a bit of experience with an angle grinder.  Have a good fitting respirator. 

I like the idea of a forge which splits and continue to work on the idea but suspending the refractory in the top half is not easily accomplished if the refractory is thinner.  

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The part to much closely is cutting the shell in this kind of forge, because you will need to use it to smoothly support a straight edge, when scrapping down the drying excess refractory. This is the only way I found practical for ending up with a flame tight seam between the upper and lower sections on this kind of forge.

You don't need a tile saw to make good cuts in high alumina kiln shelf. Any diamond coated cutoff disc, or even a resin bonded disc which is rated for refractory (there are steel rated and refractory rated discs) will do an adequate job, if you layout both side of the kiln shelf, and grind a light groove in both surfaces. Then deepen both grooves, moving back and forth until you either cut completely through the shelf, or it fractures along the grooves.

hat should have read "watch" not "much."

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