I needed to replace my old propane metal melting furnace, so I thought I'd build a nicer one with some improvements I've always wanted. #casting #metal_melting
Good point regarding flammable/volatile substances that may have been in a drum or cylinder - I met a severely disabled man back when I was a teenager, he used to bring his recumbent tricycle into the bike shop where I worked. He was a farmer until he cut open an empty 44 gallon drum that had had petrol in it. The resulting explosion almost killed him
I have ground old propane tanks open before, the way I did it is to fill them completely with water and grind whilst still full. You then have water/electricity to deal with instead of an explosion risk. Empty tanks/drums are the most dangerous, they always contain fumes that are too rich to burn to start with, but as you cut, air seeps in until it reaches the perfect ratio to explode.
The range of skill’s you’ve developed is impressive, welding, fabrication, machining, electrics, electronics, control engineering and 3D printing! I’m sure there are more…..
Beautiful application of my designs!! I kid. Isn't it amazing how different people around the world can have near exactly similar ideas without ever interacting?? I'll get mine built eventually. Love the video!
Good job, I may do the same one day. I turned one helium bottle into a vacuum chamber, for the cost of 6mm weld on flange (£50). Vacuum chambers that size are normally around £400.
That's interesting, I thought about doing the same with an old butane bottle, I wasn't sure a helium tank would be strong enough. I have a couple of 8" plastic bell jars, but I don't trust them for a full vacuum, they seem very thin.
Nice video! Good advice about grinding cylinders that may have had flammable gasses in them. If you do have cylinders that had LPG in them you can take the valve off (obviously only when empty) then fill them with a hosepipe until overflowing. Tip the water out and then they're suitable to cut. Nice thick steel too. I've only done it for calor style tanks, but I think they're worth a bit more now as empty cylinders.
Thanks! Yes, good tip, this water flushing trick is actually exactly what I suggested on Patreon. Around here at the moment, you can't get a full propane tank without an empty one to exchange. Even then they only have certain sizes available.
Yes, it might seem like a small upgrade but it's one less thing to worry about when wearing all the protective gear and juggling with tongs, skimmers etc. I find it much more convenient to use not having to put something else down to open the lid. 🙂
Neat design andy, I would have added a bit extra height tho so you can add a plinth block, you dont want the burner flame to come in contact with the crucible, otherwise you'll end up spalling the crap out of the crucible and ruining it. A plinth block puts the crucible up above the path of the burner.
Yes, absolutely right about the plinth. I didn't cover it in the video but I did pour a couple from the same refractory material, you can see one in the video thumbnail and you might just be able to make it out from 11:11 in the bottom of the furnace, and later under the crucible (though it's hard to see).
Hi Andy. Well, I've seen a few of these being made, but I wasn't expecting that delightful lid action! Both on and off. Excellent. Your idea? Might well get round to making one of these and your version seems significantly simpler than some others. Thanks for sharing. Regards Mark in the UK
Thanks! Yes, this was an idea I had some time ago, though it's not a huge leap of imagination so I wouldn't be surprised if somebody's thought of it already, I've never actually seen it done this way before though.
What did you base the dimensions on for this furnace? Did you use formulas? How did you size the burner? Did you build or buy the burner, what are the BTU's? How long does it take to melt aluminum?
I built it to take an A10 crucible, though I've never actually needed one that big. I didn't use any formulas, I just built it how I thought was best (though I recall I may have checked how big the hole in the top should be). I made the burner and I've no idea how many BTUs it puts out, it runs on propane at 37mbar, but I'm sure it could be improved. It will melt a crucible of aluminium in about half an hour from cold, but once the furnace is hot maybe 15-20 minutes.
Thanks for publishing this. Curious what the warm-up time is for this furnace - does the thermal mass of the volume of refractory cement cause issues? On other videos I've seen only a skim of refractory used, hence the question.
It seems to get to temperature just as fast as my previous much smaller kiln. Both used my same home made burner. A commercial kiln I used was faster, but I think this is down to my burner design which seems to put out less heat (but also uses less gas).
My furnace at the moment comprises of two thermolite building blocks stuck together and hollowed out lol. Time for an upgrade. What is the capacity of this in aluminium/brass terms?
I actually have a small electric one built from thermolite blocks, it works well, though I did line the cavity with thin firebricks. As for dimensions/capacity: 9:43
@@AndysMachines Thanks. I've never bought a 'proper' crucible. I just use cut up disposable gas bottles. I assume the weight capacity refers to a heavy metal like brass?
Crucible sizes can be confusing, if it's stated in Kg, then it's normally Kgs of brass or copper. If it's ''#' (eg. #6) then it's in lbs of aluminium. Brass weighs approx 3x aluminium.
10:37 what actually causes the lid pipe to spin though? I a level surface you would think simply stepping on a pedal that pushes up under the pipe will just raise the pipe straight up and now swivel off to the side.
@@AndysMachines Interesting, I'm in the middle of making one myself and that has been a trouble spot in the design, in my opinion... I think this is exactly what i was looking for, thanks again.
The metal wire in the lid will expand and contract with heating and cooling, destroying the cast refractory. :( I don't know of a solution unfortunately.
It probably will, but after the first couple of firings it will probably have moved around as much as it ever will. The whole lid will expand and contract in use and without the wire or something else to retain the refractory it would just fall out pretty fast. Furnaces do wear and need maintenance of course, but this one has lasted very well so far, I think the combination of ceramic fibre and refractory helps cushion the refractory from movement of the steel parts.
Similar design to one we had, yours is just a touch smaller. But I have got to say, dont work with aluminum or other molten metal over concrete, if it spill it can spall and splatted molten metal everywhere. Work on dirt, grass, sand, even plywood will work.
Yes, that's a good point, concrete is not the best surface to work over. I do have a large metal tray I usually fill with sand and put everything on that, furnace, moulding boxes etc... But it's a little small for this furnace and looks really cluttered on video.
I don't upload anything anywhere other than Patreon (and RU-vid). Nowadays I don't charge for any plans, they are free (but you're welcome to make a contribution!). I think this was one of my last projects where anything was behind a paywall. All the information you really need is in the video anyway.
2½ years of fairly regular use later and a lot of the 'heat proof' paint has come off the lid (mostly on the side that swings over the top) but the refractory lining has not cracked or degraded in any way.
I have cut many propane tanks up in the past, but I'm wary about showing potentially dangerous things on RU-vid. The safe way to do it is to remove the valve and flush the tank with water, filling it completely so there is no space for any gas to remain. Some people will tell you that even this is not enough, that the steel of the tank can absorb the gas and emit enough of it over time to create an explosive mixture. I think that's a myth, but if you're going to grind open cylinders of flammable gas, please make yourself aware of all the dangers and how to mitigate them, and remember I told you not to! (Do what I say, not what I do! 😁)
Actually it was a metal cutting bandsaw that I converted into a power hacksaw. I got fed up with how quickly it went through blades. It cuts at about half the speed now, but is ultra reliable and blades are cheap and quick to change.
@@AndysMachines I saw that it was a motorized hacksaw and when you mentioned David Gingery as the source for your foundry design I thought maybe you used his design for a motorized hacksaw. Gingery says the same thing about his saw as you did about yours. The blades are way more affordable. I like his books very much. His brother (I believe it was his brother and not David himself) has written a book about making crucibles. I liked your RU-vid very much. Very well produced and your foundry is a great design.
Thanks! I have quite a few books in the 'workshop practice series' but the crucible furnace one is the only Gingery book I own. I know he did a whole series on building a workshop from scrap (shaper, lathe, milling machine etc.) and a number of people on RU-vid have built his lathe.
I've never used it, but I suppose it can't hurt. If you get the higher temperature refractory (comes in different grades) and perhaps use a thicker layer than I did, maybe >50mm, it should last a good long time. You might get some hot spots in the furnace, eg. directly in front of the burner, the paint might help here.
The castable refractory is at least 25mm thick (probably more as the ceramic wool compacted a little under the pressure). I did use the higher temperature 1600°C stuff, which is also apparently good for filling small gaps, so hopefully it will hold up well. After 4 fairly long uses so far it still looks brand new, we'll see how it holds up!
So... I am confused, but only because it's counterintuitive to think that your solution to a rather specific problem only people like me, the extremely lazy but let's call it an overwhelming need for efficiency, would encounter. I'm so lazy, ehhh I really want it to be so efficient that when I step on the pedal the lid lifts and if closed it will lift and open automatically, but also if it's open then when the pedal is depressed, then it will lift, and close automatically. My level of laziness, ehhh need for efficiency, is great that I can't be bothered to try to figure out the rocket surgery involved in order to add springs, and doodads, into the turboencabulator so I don't have to touch the lid , ehhhh so my furnace is closer to autonomous, I mean, so I search RU-vid for videos... Honestly before seeing this video I didn't even know I needed the hands free lid, or that I could possibly be any more lazy, I mean, my furnace could even be more efficient, but I found this video. Now, I have this need that requires fulfilling, and there's a plan to success, but then.... Wait.... I must've missed something, and while that's not unusual with my laziness, uhh.... quest for efficiency, but how does it own when it's closed, but then it closes when it's opened, all with the same action. I'm confused.... Footage isn't doctored.... No forced perspective, it funny angles to hide slopes.... No obvious green screen with support staff dressed in fireproof green material... No perpetual motion machine claims.... Or flat earther community member evidence either.... And no blatant usage of black magic or sorcery.... .... No!? There's no way! It couldn't be so simple, could it? You're telling me it's as simple as just shaping the slot of the motion guide rod slot? Just shaping the slot to suggest the motion needed, in whatever position it's in, and that's it!? Let this be a lesson to everyone! Never stop, never give up! I'm my relentless search for efficiency, screw it.... I'm my search for lazy, I've found someone might have done it already, so always double check so you didn't waste your time, you might even learn something along the way! And that something might even be how to improve upon your laziness, making you more efficient. Queue heartwarming score, and..... "The more you know......." Shooting star gif Fade to black...... And..... FIN! Wow! that felt good! Was it good!? Loljk
