Finally had a chance to do another melt and convert some of my long-standing collection of aluminum scrap into muffins. I learned a lot. What did not go well The new lid holder piece kinda didn't work out that well. Given that the refractory body/lid didn't fit that well to start, this metal rim made it even worse. I ended up entirely plugging the top vent and had to live with a lot of heat escaping in the cracks. Also, the metal handles get cookin' hot, probably gonna wrap them. Starting it, again, took a good 15m of the following Find bbq lighter (10m) Discover it's broken/useless Get propane torch, manage to light it with the oxy torch sparker It goes out, light it again Set cardboard on fire, place inside furnace Start propane on low, turn on fan, it goes out Do propane torch/cardboard dance again Start propane on high, it immediately goes out Propane/cardboard dance Propane on low, turn on air, it goes out Propane/cardboard dance Propane on high, pull air nozzle back, pointing 1/4 at the opening Slowly move air back into place, close lid It took about 1.5hrs to come up to temperature, running at full tilt (20psi), so the previous comments about needing 30psi are dead on. Also, probably not pushing enough air. My diy squirrel cage fan doesn't push enough air I think the other part of why it took so long was that, to begin, I had a lot of air, not a lot of metal in the crucible. I now recall reading that you should start with at least a few ingots/big chunks/fill the thing with tiny pieces, cuz it facilitates heat transfer Melting stuff with paint on it is a terrible idea and you should just not do that. At the end of the 5hr melt I stank of burning paint (even I insisted I shower immediately) My bandsaw blade snapped in two while attempting to 'save time' My dross skimming tools are way too short - gloves got smoking several times, got to re-enact FlappyBird The scrap (like computer hard drive chassis) generated a large amount of dross My two year-old suddenly scooting around on his little motorcycle while I had a full crucible about to poor was the most stressful thing I have done in a while. You can't really be understood wearing a respirator, standing next to a roaring propane furnace, by a little guy wanting to show off his bike moves. What went well I managed to make at least 40lbs of muffins before I ran out of time Did not set driveway on fire (grass got slightly on-fire-ey) Crucible lifter/pourer worked really well now that I've welded the pouring bit on properly. I got rid of a lot of awkward aluminum scrap I've been tripping over for months It's satisfying to turn "garbage" back into raw material Very glad I have a respirator (P100 filters) and use it. I should really get new filters on that guy. Got a decent workout via hacksaw, lifting, hammering, sweating Dang the inside gets hot - got to re-enact FlappyBird The outside remained quite cool, relatively - it was only warm, I could touch it with a bare hand. Once I got into the routine, melting/pouring was a lot less terrifying (plus I had a face shield this time) My neighbour commented on the stink when he came over to see what the noise was all about, but after assuring him that I will not be doing any more melts with paint/plastic, he laughed, thought it was pretty cool. I am glad to have cool neighbours. What will I do differently in future Fabricate something better for dross skimming Figure out a better solution for the lid (again) Clean the scrap as best I can before melting (time invested here = happier neighbours, less air pollution and stank) Children get to stay inside during furnace operations (it sounds reaaaaalllly obvious in hindsight, lol) Build/source a better fan Charge the crucible ahead of time with solid/bits of stuff Don't even bother looking for a bbq lighter Yup, there ya go. If this hasn't been helpful, perhaps at least you got a laugh out of it. Edit: Oh right, pictures.
A longer skimmer handle and upgrading my leather gloves to high temperature aluminized gloves made a huge difference for me, I used to have to keep extra gloves handy for when I'd have to toss the smoking hot first pair. Before I thought of that I got a little blister on my pinkie once for putting them back on too soon thinking they'd cooled down enough... Nice muffins! Jeff
Ahh.. good times. Every pour is a learning experience. Some good, some bad. I usually learn more when I dork something up. I was about to pull my crucible full of bronze recently when my wife comes outta of the house to take the dog for a car ride. When I asked her to please not leave me alone while I did this, I got the stink eye. Better safe than sorry. I had to learn that short skimmer sucks the hard way too. Same for a picking tool to lower ingots into the furnace. Tobho taught me a simple easy fix for that one.
Sounds like you had a blast. Good that things didn't get outta hand. I use a 12" long skimmer but I take the crucible out of the furnace first. To light my furnace, I light up a small sliver of fatwood, lean it against the plinth, and slowly turn on the propane. I'm curious about something. My furnace runs at 2.0 psi propane, no forced air, and melts 6 lbs. of aluminum in 45 min easy. The furnace barrel is 8" dia. and 11 inches high. I generally use less than 2 lbs. of propane per session. Why does your unit with higher propane pressure, forced air take so long to heat up?
I shall address in order. Tobho: I never got quite to that point, but if I start doing this on a regular basis, most likely will be upgrading that route. When I inquired at a local welding (gas) supply shop, they had nothing 'suitable for foundry work' (their words), so it'd have to be something off Amazon. I still have a pretty tight budget, so I'll deal with smoky hot gloves for now. Jason: Haha, yeah, bronze is in my scary zone. Worth the hasslin'. And dude...what are you, clickbaity-with-no-clicky?? Get rid of your utensil problems with this one easy fix! What simple easy fix?! Al Puddle: HAHAHA. GET IT?! I did do some skimming with the crucible out as a result of the tiny skimmer. Good tip on lighting, will keep that in mind. Regarding the melt timing, furnace barrel is ~12" dia, 14-16" high, A10 crucible. Hotface wall is ~3/4" thick, lid is ~1.5", base is 1.5", made of pure 3000F castable refractory. However as an experiment (and because budget), I'm using play sand as an insulator. It works quite well, but I suspect it adds a huge thermal mass right around the furnace barrel, so while the outside stays pretty cool, the sand ~1" around the hotface is probly pretty scorching hot. As I mentioned above, how I charged the crucible also a factor. How long I waited before opening the lid to check. How much heat is escaping due to janky design. You get the picture. Long story short, gonna make modifications for next time and try again. Propane is pretty cheap, thankfully. I think I went through ~10lbs over 5 hours, but did not measure before/after. (that's something else I need, a bathroom scale)
hah... clicky click.... Visit harbor freight and buy a set of cheap lines man pliers. Weld two long reigns to the head of it and then grind the inside of the handle for grabbing stuff. Play with them a bit and then bend to suit your needs. These are about 40" long and can pick up half a 15lb ingot with no trouble.
f Melt time has a lot to do with flame temperature, the more excess combustion air you have the cooler the flame is. i fire with just enough excess air to provide about a 2500 flame temp, a couple of the earlier comments about not being able to keep the flame after lighting sounds like way to much air or air velocity. fuel usage has to do with orifice size and feed pressure, i use low pressure natural gas and can melt brass and bronze. With proper orificing and a properly insulated furnace i could reach iron temps. Art b
My next rig is going to be natural gas, no question about it. My wife always says, you stink like jet fuel and oil when I come back in after a melt. Plus I think it's given me a headache or two. Jury is still out on that one.
