Jeshua Lacock Presents Lost Shell Sand Casting for PLA 3D Printed Models

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Originally Posted by 3DTOPO

It is an informational video of what we do here. We go out of our way to discourage others from trying it at home.

How many of these people that you have in mind, just happen to have an induction furnace laying around that is able to melt a pot full of copper at a flip of a switch?

I could only hope that if someone owns *any* type of professional industrial equipment, that they know how to use it properly and safely before attempting to even turn it on.

Note that I spend 5-minutes going over basic metal safety in this video:
Lost PLA 3D Print to Metal Casting; Complete

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While you can go hotter with an induction furnace, even people who have put together a home-made melting furnace (like the one in your other video) can do themselves a lot of damage, although I wouldn't exactly describe it as professional industrial equipment. I did watch that video, and I appreciated the safety information you provided in it, which is more than one typically sees on You-tube. You should tell people who watch the other one to watch that one before attempting to duplicate your feats of metal-casting. If you'd used the plaster-sand investment instead of straight sand, that little figurine would have come out better. But like I said, a refractory coating could help a lot.

Andrew Werby
Juxtamorph.com

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Originally Posted by 3DTOPO

It is an informational video of what we do here. We go out of our way to discourage others from trying it at home.

How many of these people that you have in mind, just happen to have an induction furnace laying around that is able to melt a pot full of copper at a flip of a switch?

I could only hope that if someone owns *any* type of professional industrial equipment, that they know how to use it properly and safely before attempting to even turn it on.

Note that I spend 5-minutes going over basic metal safety in this video:
Lost PLA 3D Print to Metal Casting; Complete

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To be fair, you can build an induction furnace with not much more work than this casting process takes.

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Originally Posted by awerby

While you can go hotter with an induction furnace, even people who have put together a home-made melting furnace (like the one in your other video) can do themselves a lot of damage, although I wouldn't exactly describe it as professional industrial equipment. I did watch that video, and I appreciated the safety information you provided in it, which is more than one typically sees on You-tube. You should tell people who watch the other one to watch that one before attempting to duplicate your feats of metal-casting. If you'd used the plaster-sand investment instead of straight sand, that little figurine would have come out better. But like I said, a refractory coating could help a lot.

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My point is there is a lot more to it than someone just seeing a video like this and duplicating my efforts. They are going to have set out to make a whole foundry. It can't just be copied on a whim.

Of course I can get finer detail with investment casting. The point of this method is it provides "good-enough" results for many many things and is much simpler, faster and less expensive.

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Originally Posted by Ama-fessional Molder

To be fair, you can build an induction furnace with not much more work than this casting process takes.

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A 15KW or more powerful one? I would like to see that!

I've only see toy sized ones "easily" made. The amount of hardware alone needed to build a 15KW induction furnace is anything but trivial.

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Originally Posted by awerby

You should tell people who watch the other one to watch that one before attempting to duplicate your feats of metal-casting.

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Actually - I won't tell anyone to duplicate my efforts - that isn't the purpose of the video. The description for the video reads in part: "WARNING: This is for informational purposes only. Fire, molten metal, high power and high temperatures are potentially extremely dangerous."

I'm not saying, "Yeah you can do just like me even if you don't know what you are doing or have any of the right tools" - quite the opposite.

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Originally Posted by 3DTOPO

Actually - I won't tell anyone to duplicate my efforts - that isn't the purpose of the video. The description for the video reads in part: "WARNING: This is for informational purposes only. Fire, molten metal, high power and high temperatures are potentially extremely dangerous."

I'm not saying, "Yeah you can do just like me even if you don't know what you are doing or have any of the right tools" - quite the opposite.

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Nobody pays any attention to those warnings; it's like all those toys that come with tags saying "this is not a toy - not for use by anyone under the age of 18" that the toy company lawyers attach in an attempt to avoid the strict laws governing children's toys, or the ubiquitous warnings on every building in California telling people that something in there might do them harm: http://www.latimes.com/health/la-he-...v02-story.html . I thought the safety info in your original video was actually quite good - telling people not to do this on concrete, advising them to make sure anything they stick in the pot was pre-heated - this is important stuff.

But I've heard from lots of people on various forums who saw a few YouTube videos about casting metal in the backyard and were totally clueless about the dangers involved - there's a lot of enthusiasm for melting scrap metal in tin cans and flower pots and pouring it in molds made from who knows what. All I'm saying is that you should append the "lost shell" video to the other one, which has the safety info, rather than distributing it separately. There are a lot of characters out there jostling for their Darwin awards...

How's that deep-Z CNC router working for you? Have you worked out the 4th and 5th axes yet?

Andrew Werby
Juxtamorph.com

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Originally Posted by 3DTOPO

A 15KW or more powerful one? I would like to see that!

I've only see toy sized ones "easily" made. The amount of hardware alone needed to build a 15KW induction furnace is anything but trivial.

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15kw really isn't that hard. The hard part is powering it. You need around 80 amps, assuming a normal inefficiency (likely that the efficiency would be much higher than 80%, haven't done the math) of 230v single phase power. A single sub panel in a well equipped home can handle that and the lights in the shop without significant issue.

Then, you need at least 1 awg power cable to handle the current draw, which isn't an issue since you should have the sub panel within a couple yards of the device. I would just be safe and buy 0 gauge, because it is more commonly available and not really any more expensive. So that gives you a pretty good safety factor on the power supply.

After that, you need a variable frequency drive of some manner. This can be purchased outright if you have the coin, or built if you have the knowledge. The mechanics of which I am not entirely clear on, though I do understand how to do it at a much lower current/voltage. I think it involves suitable capacitance. I could research further if I intended to build one, but if I recall my electrical courses correctly you would ideally do so in parallel.

From there, you have your work coil. You would use some solid copper and plenty of applied muscle to wind it.

Stick a nice crucible in the middle, and there you go. If you want to get really fancy, you can liquid cool the work coil.

It isn't really a matter of it being difficult, the problem is one of scale. 15kw is hard to obtain for a home user, but certainly possible.

I suspect I could build one with reasonable safety devices, liquid cooled coil, appropriate power (including professional installation of the sub panel) and have it running for maybe 3k USD.


BUUUTTT that's all theory. I have had enough practice on projects of that scope to know that there are always unseen obstacles that slow things down. That's the part where many home users cut corners, do something dangerous, and kill themselves.

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Originally Posted by Ama-fessional Molder

It isn't really a matter of it being difficult, the problem is one of scale. 15kw is hard to obtain for a home user, but certainly possible.

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Actually swashing around 700 amps in the primary coil and many thousands of amps in the secondary (work) coil at 30-85 thousand times a second at 230 V input without blowing up is quite technologically demanding.

There is a reason modern induction generators weren't invented until the late 60s early 70s.

Just 15KW needs a fairly massive DC transformer, a massive water-cooled capacitor bank (totally deadly if mis-touched), a massive toroid, water cooled work coil, big fat water cooled insulated-gate bipolar transistor (IGBT) and a well designed control card.

Unless you can show me a web page with schematics and proof of working induction generator over 5kW, I think I have made my point. The biggest I am aware of is ~5KW and was designed by my friend Tim Williams - who went on to design induction generators for Radyne.

Besides purchasing all the hardware, it will take weeks (if not months) of someones time to build the circuit boards, order and assemble all the parts and just hope that it all works. The project is easily on the same level as a thesis project.

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Originally Posted by Ama-fessional Molder

I suspect I could build one with reasonable safety devices, liquid cooled coil, appropriate power (including professional installation of the sub panel) and have it running for maybe 3k USD.

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Or - you can buy one brand new for around $1k. Sealed in an enclosure and working with instructions.

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Originally Posted by awerby

Nobody pays any attention to those warnings; it's like all those toys that come with tags saying "this is not a toy - not for use by anyone under the age of 18" that the toy company lawyers attach in an attempt to avoid the strict laws governing children's toys, or the ubiquitous warnings on every building in California telling people that something in there might do them harm: http://www.latimes.com/health/la-he-pro-con2-2009nov02-story.html . I thought the safety info in your original video was actually quite good - telling people not to do this on concrete, advising them to make sure anything they stick in the pot was pre-heated - this is important stuff. But

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Originally Posted by awerby

I've heard from lots of people on various forums who saw a few YouTube videos about casting metal in the backyard and were totally clueless about the dangers involved - there's a lot of enthusiasm for melting scrap metal in tin cans and flower pots and pouring it in molds made from who knows what. All I'm saying is that you should append the "lost shell" video to the other one, which has the safety info, rather than distributing it separately. There are a lot of characters out there jostling for their Darwin awards...

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Well if people are going to ignore the warnings there, people are going to ignore them elsewhere too I suppose.


The point I have been trying to make, is, I wasn’t like look just stick something dangerous in a microwave (or something everyone has at home). Like: “gee-whiz folks - look how easy it is to be stupid! - you can be just as dumb as me if you want to” - and there are no end of those sort of videos that actually exist on Youtube.


The whole process takes special gear, and with that usually comes special know-how and respect - in my experience at least.


That said, the video does absolutely already link to the older video.

I am also considering making a basic foundry set up and safety video as well.

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Originally Posted by awerby

How's that deep-Z CNC router working for you? Have you worked out the 4th and 5th axes yet?

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It has about 2.5 feet of useable Z and the machine works really well. I have a 4th axis going now. Haven’t really had the need for 5-axis but when I have the time I look forward to building one.


I am also finishing up a 4-axis metal lathe/mill combo conversion as well.

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Originally Posted by 3DTOPO

I am also considering making a basic foundry set up and safety video as well.

[That would be great; it's sorely needed on YouTube. Append it to any foundry-related videos you put out; it could save lives.]





It has about 2.5 feet of useable Z and the machine works really well. I have a 4th axis going now. Haven’t really had the need for 5-axis but when I have the time I look forward to building one.


I am also finishing up a 4-axis metal lathe/mill combo conversion as well.

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What sorts of things are you making with that router? What materials does it cut?