Steve Voigt Posted January 20, 2015 Share Posted January 20, 2015 Hi all, I would like to make some improvements to my charcoal brake drum forge, and I need some help. The drum is 13" diameter and 6" deep, so pretty big as drums go. It's bottom blast with 1.5" pipe and a grate. The air supply is a wood-stove fan, plenty of power, with a gate valve for control. I'm very happy with the air supply. Here's what I propose: 1) wrap a single layer of 1" inswool around the inside (1 ft. will be enough) and coat with...what? I'm not sure. But the coating will be applied heavier at the bottom, so the firepot becomes an inverted cone shape, rather than the straight cylinder I have now. 2) set the fire pot in the top of a 30-gallon oil drum (like the 55 forge). Because of the lip on the brake drum, it will sit about 1" above the top of the oil drum. So, I think I will need to build up the top of the oil drum about an inch (with ???), so I can sweep charcoal off the deck and into the pot, without having to negotiate it over the lip. My questions: 1) Is the inswool overkill? It's only $10 plus shipping for a foot, but if I don't need it, I'll save my money. 2) Do I need to coat the inswool (or just the sides of the firepot, if I skip the inswool) with satanate, or is there a cheaper or better alternative? 3) what should I build up the top of the oil drum with? 4) Finally, does this sound like a good plan? Will this improve my ability to get up to welding temps? Thanks in advance for any help! - Steve Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 20, 2015 Share Posted January 20, 2015 I would not suggest inswool for a liner but the traditional fire clay mixtures.Why not bolt straps to the barrel so that the lip is even with the top?I assume this forge is in a protected *dry* location? You could use your extra fireclay mixed with sand to build up the top of the barrel---helps to have a ring you can attach to the barrel top and fill with the mixture.First time I did a charcoal forge---around 1981---I used creek clay mixed with wood ashes and pretty much the same after till I got out to NM and switched to adobe. Quote Link to comment Share on other sites More sharing options...
dablacksmith Posted January 20, 2015 Share Posted January 20, 2015 1 do not use the inswool save it for a propane forge.i have built several forges i like a inverted four sided pyramid for my firepot . it can be as thin as 14 ga for a portable forge (went to 1/4 plate for a permanent one) the size depends on what your working on . i usually use plate for the rest of the top with at least a 1 in lip. pipe for legs.anyway hope this helps. Quote Link to comment Share on other sites More sharing options...
NickOHH Posted January 21, 2015 Share Posted January 21, 2015 What size is the hole in your drum you may want to jump up to a. 2.5 inch pipe for air bigger cap more holes more air you don't really need the pressure just volume . Any kind of clay will work from creek clay to furnace cement mix it will some sand or vermiculight to shape the firepot and build up around the lip if you don't want to mount the drum from under the forge. Quote Link to comment Share on other sites More sharing options...
781 Posted January 21, 2015 Share Posted January 21, 2015 Inswoll is for gas forges bit I use loose fire brick to control the size (diameter) of my fire. This allows the fire to be deeper also Quote Link to comment Share on other sites More sharing options...
Steve Voigt Posted January 21, 2015 Author Share Posted January 21, 2015 Thanks for the replies. I will skip the inswool. A couple follow-up questions: - What is the recipe for fire clay? I see so many different mixes. Would something like 1/2 clay, 1/2 sand work? - Will increasing my pipe diameter to 2.5" (nominal) make a big difference? It's definitely true that the "hot spot" in my my fire seems to concentrated, so maybe as Nick says I have too much pressure and not enough volume? Thanks again! Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 21, 2015 Share Posted January 21, 2015 Steve: Fire clay is a high iron silica clay used specifically for containing fire, think fire brick and furnace liners. For your purpose river clay will work just fine. Mix it about 1pt. clay to 2-3 pts. sand and leave it sealed air tight so the moisture equalizes throughout. To put it in your forge do not mix it wet like modeling clay, you only want just enough moisture you can ram it hard with a mallet, etc. To test squeeze some in your hand, if it leaves your hand wet or streaked with mud it's too wet, let it dry. If it makes a hard clod you can break without crumbling it's good to go. If it crumbles add a LITTLE moisture, a spray bottle is good then cover it airtight and allow it to temper a day or so. Once it's tempered all you need do is ram it into the drum, you can use a mallet the end of a 2x4, B ball bat, punch your frustrations out on it. Just hammer it till the mallet bounces, smooth it and a final burnish with burlap really helps keep clinker from sticking. Last step is to score it with a butter knife to control shrink checking (cracks caused by drying) a simple pattern of scores from the center to the edge works well. Let it DRY, hang a light bulb over it if it's humid out but you really want it dry before building a fire. Once it's dry it's good to go. If you cut a hole in the drum end so the brake drum fits in and rests on it's rim you can ram more clay around it to make a nice smooth fire proof table. Don't worry about perfect, blacksmithing isn't about perfection, the real secret is being able to do with what you have and make what you need. Pretty is for the customer. <wink> Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
NickOHH Posted January 22, 2015 Share Posted January 22, 2015 - Will increasing my pipe diameter to 2.5" (nominal) make a big difference? It's definitely true that the "hot spot" in my my fire seems to concentrated, so maybe as Nick says I have too much pressure and not enough volume? Thanks again! From my little experience with forge design it seems like it s the way to go, im using a 2.3 inch pipe with a 50 cfm bathroom exhaust fan, i didnt want to go to crazy with amount/size of the holes tuyere so i started minimal on both aspects, but the more holes i got in it and the bigger they got, the more the size of the sweet spot has grown now with many holes 5/6 and some 3/8 on the sides and center, and the fan on high i get quite a big fire ball that will get some laregerish stock hot quick and can control the fire with fan speed or blocking the inlet off a bit. Quote Link to comment Share on other sites More sharing options...
Steve Voigt Posted January 22, 2015 Author Share Posted January 22, 2015 Nick and Frosty, thanks for following up. Thanks to you guys, I think I've got a plan now: - bigger inlet for the firepot. - clay/sand mix to make an inverted pyramid in the pot. - a deck for charcoal reserve, build up the deck a little with the clay. That should be a nice improvement. Thanks again for the help! - Steve Quote Link to comment Share on other sites More sharing options...
NickOHH Posted January 23, 2015 Share Posted January 23, 2015 You'll like the upgraded forge a lot! When your building up around the drum you will only need to smooth out the transition over the lip of the drum enough to be able to rack in more charcoal don't need to use a ton of clay. And I would suggest start with a bunch of smaller holes all over the cap and maybe one large in the center because you can always add more to suite your needs or enlarge them but I think you will find with your gate to control air flow as many holes as you can get in there with still maintaining a grate to keep the fire in the firepot will be perfect. Quote Link to comment Share on other sites More sharing options...
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