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

[3DTOPO]

These guys don't seem to have very high standards for their castings. If one of mine came out that poorly, I wouldn't be celebrating; I'd melt it down and try again. Burning the PLA inside the sand mold evidently disrupted the surface significantly, so any crisp detail was lost. I just hope nobody watches this video and hurts themselves badly trying to do it themselves.

For staters they are sand castings - which will never quite have the same detail as investment castings. You are incorrect about any crisp detail being lost - many of the original print lines are evident and you can't expect to do any better than that from a 3D print.

Next, these casts are straight out of the sand - no touch up work at all was done to them. It only takes very minor work to sand things into shape.

Finally, where they came out a little rough it was only because the sand wasn't adequately packed tight enough - but a little learning is to be expected with a whole new technique. These are literally the first casts as we learned the new process. We didn't think of it at the time, but all we needed to do is flip the sand mold over and repack the sand from the other end.

And we take safety very seriously! I pour in a full fire proof proximity suit (with full head protection), we pour in a dry sand box, the molten metal is never lifted above waist level, the building is adequately ventilated, we use proper tools, etc. and so on.

[awerby]

For staters they are sand castings - which will never quite have the same detail as investment castings. You are incorrect about any crisp detail being lost - many of the original print lines are evident and you can't expect to do any better than that from a 3D print.

[If you were setting out to demonstrate the utility of this process for creating small detailed castings like the one you attempted, you have not succeeded. This process might be okay for rough castings, but since there's no way to introduce a core, it's not going to work too well for most of them either. Solid lumps cast poorly, and some of the problems in that one might be due to shrinkage porosity. If you try it again, use a chill and see if it works any better.]

Next, these casts are straight out of the sand - no touch up work at all was done to them. It only takes very minor work to sand things into shape.

[As someone who's done my share of that "minor work", I'd say melt it down and start over.]

Finally, where they came out a little rough it was only because the sand wasn't adequately packed tight enough - but a little learning is to be expected with a whole new technique. These are literally the first casts as we learned the new process. We didn't think of it at the time, but all we needed to do is flip the sand mold over and repack the sand from the other end.

[I think the process, such as it is, would be improved a lot if you used a refractory coating on the part before packing it in the sand. People who do the similar lost-foam process with aluminum use dry-wall compound, but there are lots of better ones that might stand up to hotter metals.]

And we take safety very seriously! I pour in a full fire proof proximity suit (with full head protection), we pour in a dry sand box, the molten metal is never lifted above waist level, the building is adequately ventilated, we use proper tools, etc. and so on.

[Yes, I noticed that. (Nice induction furnace, by the way! Is that home-made?). But I worry about the people who watch You-tube videos and go out to try this at home, in t-shirts and tennis shoes, with the kids all crowding around. You could shake off that "bottle rocket" explosion you got on your first attempt, but it might be a life-changing event for them (and not in a good way).]

[3DTOPO]

[Yes, I noticed that. (Nice induction furnace, by the way! Is that home-made?). But I worry about the people who watch You-tube videos and go out to try this at home, in t-shirts and tennis shoes, with the kids all crowding around. You could shake off that "bottle rocket" explosion you got on your first attempt, but it might be a life-changing event for them (and not in a good way).]

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

[awerby]

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

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

[3DTOPO]

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.

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.

[3DTOPO]

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

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.

[awerby]

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.

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

[3DTOPO]

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

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...

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.

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

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.

[Ama-fessional Molder]

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

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

[3DTOPO]

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

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.