Hey guys, so from advice I got on my introduction thread I read 're charcoal foundry' and learned a ton, but before that I'd read that charcoal doesn't require insulation so when i saw a piece of 8" pipe at work i thought it would do a good job.. By the time i read the book i'd already invested a couple of hours in my build and I didn't want to abandon it so I thought I'd keep going and hope for the best..
Im planning a false floor above the 2" shs but do t k ow if I need to or not, would appreciate suggestions Also I filled a 44 gallon drum with chipper waste I'd normally burn, I'll throw it on the burn hole next week and hopefully end up with some decent charcoal. I've done this once before and it worked great but I'm not too confident this time
Charcoal does effectively self-insulate if the burning coals are in physical contact with the crucible, go for it! Just as long as you don't mind eventually burning that unprotected pipe up. Not sure what you mean about a false floor. One thing that works well is to add a grate just above the tuyere so that the blower air can spread out in the bottom of the furnace before it rises up through the coals. If that is what you meant, this promotes even burning and worked really well for me and I believe Petee too (that is who I stole the idea from). This does cool down the bottom of the furnace, so don't count on a drain hole in the bottom not to freeze up if your crucible fails. To me the benefits of a grate outweigh that risk... If you take a few steps to tune the furnace atmosphere properly, holing out a decent crucible is unlikely to happen unexpectedly: Sit the crucible on as deep a bed of burning coals as your furnace has room for and keep the coals beside the crucible topped up. Before topping them up, it's helpful to occasionally lift the crucible up a little to let some coals fall down below it, to maintain the depth of the bed below (and to make sure it doesn't start tipping too much as things settle). A deep coal bed helps to break up the air flow and avoid cutting torch-like jets of concentrated oxidizing flame which can be rapid crucible killers. And go easy on the blower air - if jets of flame are shooting out of the vent hole in your lid, it's very oxidizing - turn the blower down until they recede to get closer to neutral, or just poking out a little for a just slightly oxidizing burn (suitable for aluminum casting if that is what you are doing). For my old Gingery charcoal burner, I had to put my hair dryer on a dimmer switch to make it blow way softer than its built in Low setting. That will vary from furnace to furnace; I imagine the tuyere size would affect blower settings greatly. Good luck! Jeff
Self insulating is a relative expression. Your pipe will still get red-hot regardless and would be better if it was contained. Even surrounded by a couple inches of sand in a bucket would be better than bare-doggin it. I've tried it both ways and it makes a difference. If you decide to do this put a cutout lid on the container to contain the sand so you can just dump the charcoal/ash out as needed. Your steel will eventually burn out but not for awhile. Clay flue pipe would work too. I've found that 2-3" diameter x 6-13" long wood turns out best for charcoal as it yields larger chunks. Limb wood is a great source, as dry as possible. Little stuff like chips just turns to fines which is ok for the garden but not so much for fuel. For my charcoal making rig I use a 30gal drum with four 4" triangular holes cut in the side right at the bottom. That let's air in for the burn. Fill it with feedstock chunks right to the top. Put a top layer of kindling on top and light it and dont touch it again. Set 3 bricks on the ground around the drum and set a 55 gallon drum with both ends cut out over the burning drum supported by the bricks. This let's secondary air rise up between the drums and over the top of the fire drum. This is an afterburner and after about 5 minutes of initial smoke, further smoke and gasses will be burned off by it. This will be virtually smokeless. You will have a steady and perfectly consistent flame on the top of the barrel from this afterburner effect for the duration of the burn as long as you dont add anything or otherwise touch it. If you disturb it at all once its burning it will goof the whole thing up, trust me. Once the character of that afterburner flame changes you are done. About an hour or so. Remove the bricks letting the 55 rest on the ground and seal the lid on. Twist the drum into the dirt to cut off all air or shovel dirt around it. Leave it for at least a few hours so it doesn't flash on you. This usually yields about 20% by weight. The main principle of this method is called TLUD top load up draft. Without an afterburner it would produce an intolerable amount of smoke. I know that's more than you asked for. Sorry. Pete
Thanks guys that's a lot of information! Yes I meant a grate for the coals to sit on, but I wish I'd thought of leaving a drain hole before I spent so much time welding the entire bottom shut yesterday lol now I'll have to drill a hole I guess Pete I thought charcoal making took 4 or 5 hours or something but your method sounds quick and easy enough that if it's not raining on Friday I'll give it a shot after work 30 gallon drum aren't really a thing around here but I think I have something that will work
Optional, but not a bad idea eapecially if you are unused to using solid fuel to melt metal. Tuning a charcoal furnace seems to work backwards in some ways if you are used to using a propane or waste oil burner. Getting the tuning wrong can result in having a hole torched in the bottom of your crucible surprisingly fast. The drain in mine worked at least long enough before freezing off to save my tuyere from flooding all the way back into my blower. It came way closer than I liked... So a drain can definitely help, but learning how to tune the air/fuel mixture in one's furnace properly as well as proper care and feeding of crucibles should mean maybe never needing one. For me it made the difference between crucibles lasting years vs weeks. Jeff
Hey guys, I've done a bit since I last posted, I replaced the wood in my barrel with old 1 1/2" boards and had good luck making charcoal on the burn pile at work
So I gave it a go a couple of weeks ago but obviously had the air up way too high and melted my stainless crucible in maybe 20 minutes.. surprisingly fast as tobho mott said: I tried again last weekend but much more slowly with the hair dryer barely running on a dimmer switch and it went much better I only roughed out a slingshot with a rasp as the furnace was heating up so it was rough and uneven, and I put it in a bucket of sand and dropped the bucket a few times to pack it in Especially considering I put not much effort I to it I'm happy with the result: This weekend I'll make a hot wire cutter and try to make some better molds for the next time I'm able to cast. Thanks for all the help guys!
Nice job on the charcoal. It looks like you found a method that works for you. Your drum appears to have taken a beating though! Lol. Make more at every opportunity as supply and storage allow. Running out of fuel will spoil your day. Be mindful of how you handle and store it to prevent it from becoming fines. Once it's peanut size or smaller it will smother your fire and if you dump it on top your fire won't recover. I've found that multitasking, especially when it comes to mold/patternmaking whilst heating up the furnace can turn into a losing game. Standing around watching your metal melt seems like a colossal waste of time but for me anyway, if I'm trying to get other stuff done I end up forgetting important steps or overheating my metal while I'm rushing around trying to fix a broken pattern or goofed up mold at the last minute. There are some pretty good videos on wire cutters on YouTube. A lot of folks here have them too. Mine is just a automotive battery charger and some nichrome wire and alligator clips on the leads. I vary the temperature by changing the clip position on the wire. Nice going! Pete
Here's my hot wire build. http://forums.thehomefoundry.org/index.php?threads/hot-wire-build.132/ That's a good result for your first go with lost foam. The pattern looks like it may have been carved from EPS (the beaded Expanded Poly Styrene). If you buy some XPS/EXPS (the pink or blue Extruded Poly Styrene insulation board from the big box stores) I think you'll find it machines and sands much better than the EPS. The finish will generally improve all the way to 320 grit abrasives but I usually stop with 220. If you coat your foam pattern with a thin layer drywall joint compound, it will reproduce the surface finish and fine details of your pattern exceptionally well yet still breat well enough for the vaporized foam to escape. The non-hardening drywall joint compound thinned with water to an easily brushable consistency works best, and if sealed, can be reused indefinitely. It's also very inexpensive. If you invest some time into shaping and finishing your foam pattern, I think you may be surprised at the quality of result that can be achieved. Some sort of means to vibrate the dry sand mold for enhanced packing is also a good investment. Best, Kelly
Your firrst attempt is recognizable as the desired end result, you should see what abominations mine looked like.
+1. XPS carves and sands out smooth much easier than EPS and leaves no annoying bead texture on the castings. There is nothing worse that trying to smooth out one last spot on an EPS pattern, but pressing a little too hard with the sandpaper and accidentally tearing out a bead of foam! Save that packaging foam for experiments or for sprues, in order to conserve the nicer foam for where finish matters. Some big box stores carry those extruded insulation panels in a few different useful thicknesses, and you can make a LOT of patterns from each big slab. Jeff
Thanks everyone, it actually was xps foam, but i made the mold so last second i just used a coarse wood rasp, if i knew it would turn out so well maybe i'd have taken some time to sand it haha There's a fault halfway up the handle where i must have stopped pouring for a sec, it was hard to see through the smoke so i'll cut it open and see what's inside just out of interest And Pete, everything you wrote is bang on, the other week i dumped all the fines from the bottom of the drum on my fire then cranked up the heat to burn them off and preheat my crucible while i cut some chunks out of a rim, and by the time i checked on things my first crucible was half missing..
