Casting a joint

[VF-1James]

Hey all, it's been a while sine I've posted.

I have been devoting my time to trying to create my own custom characters in 1/6 scale for the last few months, but have run into a few problems. I'm using a Medicom RAH 301 Kai body as my base (customized from a few different figures), but as is the problem with most Medicom figures, the shoulder joints keep breaking. Realizing that the joint will break no matter how many times I buy a new figure to replace it, the obvious solution is that the joint needs to be made from a stronger material. I have learned basic resin casting, but I don't think it's enough to withstand the pressure from moving the arm at the shoulder.

That said, I believe metal is the answer here. However, metal casting is currently beyond my skill set, so I've decided that I need the help of a recaster for this. If anybody has any recommendations about whom I should contact, please let me know. Macross World has always been one of the most intelligent, helpful forums out there, which is a rare exception to most places on the net. In this situation, I'm proud to belong. Thanks guys.

[Evil Bones]

have you thought of using a simple sand cast to make your mold & cast the part.

you can also buy metal casting kits via the net.

Laters & good luck, EVIL

[jardann]

These are just some suggestions, I have only attempted metal casting one time before. Someone else will hopefully have more accurate information.

You could try using plaster or plasticine clay like Fimo to make the mold. I think either of those, once cured, could hold up to the heat of metal casting.

The problem I think you will find though is that most of the metals used for hobby casting are relatively soft also. Depending on the way the joint is shaped and works, the metal might just bend or break too. I think the stronger metals will require a much higher melting point so that may open up some more things to take into consideration.

It sounds tome like a strong vinyl would be ideal for your situation. But I don't know nuthin' about dealing wtih that.

Definitely look for other advice though because I could be totally off base here. Hopefully someone with more experience can chime in and help you out.

Good luck with the project!

Edited September 20, 2008 by jardann

[AcroRay]

I'm not speaking from first-hand experience here, but have considered this:

You might consider working in a material available at auto parts stores called "J.B. WELD", its a metal impregnated resin putty that - when cured - is as strong as metal and can be sanded & treated like metal as well. I've known people who have patched engine blocks or rebuilt broken or incomplete engine parts, pins & plates with it. One would think the results would be workable for a toy or hobby project.

I'd speculate that if you could make some sort of two part mold in Fimo, plaster or some other rigid material then you could push JB Weld into the mold, allow it to cure, then break the mold away and work with the JB Weld casting like you would any other metal part.

Personally, I haven't had any reason to try it myself, but the idea occurred to me a couple of times when I've encountered the JB Weld stuff.

[VF-1James]

I'm not speaking from first-hand experience here, but have considered this:

You might consider working in a material available at auto parts stores called "J.B. WELD", its a metal impregnated resin putty that - when cured - is as strong as metal and can be sanded & treated like metal as well. I've known people who have patched engine blocks or rebuilt broken or incomplete engine parts, pins & plates with it. One would think the results would be workable for a toy or hobby project.

I'd speculate that if you could make some sort of two part mold in Fimo, plaster or some other rigid material then you could push JB Weld into the mold, allow it to cure, then break the mold away and work with the JB Weld casting like you would any other metal part.

Personally, I haven't had any reason to try it myself, but the idea occurred to me a couple of times when I've encountered the JB Weld stuff.

Wow, thanks AcroRay! This stuff might be the key to this project. It seems easy to work with, and it has the strength I need for the part. I'm going to try it.

[AcroRay]

Cool! Please let us know the results. If you have trouble finding the J.B. Weld, let me know and I can get you some at a shop local to me.

[big F]

I too know people who have used JB weld to fix up stuff its like bondo with metal in, quite strong.

[VF-1James]

I've ordered 2 different versions of it from the net (one regular, one a quick set version), so we'll see how this stuff works when it arrives. I was also thinking it sounded a lot like bondo, Big F.

I was wondering if anybody knows the properties of this stuff. Because I want to cast a part, I'm wondering if a silicone mold is going to work or not. This stuff seems to bond to almost anything- that's what it was designed to do. I'm not a chemist, but I imagine that silicone will work. Will definitely run a test on silicone that has been set first, before I run off and spend the time making a mold box for the part.

[nightmareB4macross]

I've ordered 2 different versions of it from the net (one regular, one a quick set version), so we'll see how this stuff works when it arrives. I was also thinking it sounded a lot like bondo, Big F.

I was wondering if anybody knows the properties of this stuff. Because I want to cast a part, I'm wondering if a silicone mold is going to work or not. This stuff seems to bond to almost anything- that's what it was designed to do. I'm not a chemist, but I imagine that silicone will work. Will definitely run a test on silicone that has been set first, before I run off and spend the time making a mold box for the part.

If you're planning on casting a part, use a silicone mold. Try encasing metal inside your re-casted part to make it stronger. JB Weld epoxy putty is pretty strong but it really is more for repairing/patching parts and/or creating new parts to be machined, not really for pouring into small molds.

Of the two versions you've selected: The slow curing type is the way to go since you're developing your skills to create parts. The quick cure (only 5 minutes to set) is for quick forming or really rough parts that you will be honing after the alloted amount to set the epoxy has passed.

Remember to use gloves when working with this stuff.

***How about showing us a pic of what you wish to recast?

[MechTech]

I haven't seen the part, but I'm guessing the JB weld is thick. If so, you can make a "squash mold." Instead of pouring the compound into the mold, you fill the two halves to overflow with the compound and squash them together (being careful to maintain shape). I've done it several time with various parts that didn't want to mold the regular way.

If you think you'll have to go metal, your silicone molds will work for that too! Silicone is usually good up to 400 degrees F on the average (results may vary ). - MT

[VF-1James]

Thanks for the advice guys. I got the quick weld in the mail on Friday, and did an experiment with it. When set, it still seems far too brittle at such a small size. What I'm now thinking is that instead of worrying about making this part, I could possibly take the piece to a machine shop and they could make it for me. From what I've read, I could get the part made from either plastic or metal.

Does anyone have experience using machine shops?