# DIY plastic and ceramic parts molding and casting



## PStechPaul (May 1, 2012)

I'm putting together an order at www.mcmaster.com for some mechanical parts and I happened to check out what they have available for parts molding and casting. Some of the products I was interested in are:

http://www.mcmaster.com/#casting-compounds/=l3jfw9

I was mostly looking at:

Urethane, 25 cubic inches, 1 pound, $32
Machineable epoxy, 40 cubic inches, 2.7 pounds, $62
Urethane foam, 216 cubic inches, 1 pound, $60
Silicone, 22 cubic inches, 1 pound, $58
High strength Alumina ceramic, 3000F, 38 cubic inches, 4 pounds, $53
Silica, 2700F, 62 cubic inches, 4 pounds, $53

It may be possible to cast metal parts by using Silicon Carbide (2700F) for the mold and Silicon Bronze (1780F) for the parts. 

Here are some videos about the foam and urethane casting:





 




 
There are probably many applications for this in the DIY EV world.


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## Carl55 (Jun 9, 2012)

My first attempt at posting a link. You might want to check out this guy.


http://www.youtube.com/watch?v=IYZOTt9zTv0


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## PStechPaul (May 1, 2012)

That was quite interesting. There is a trick to embedding video. Use just the identifier string, select it, and click on the YouTube icon, which will wrap the code tags around it. About like this:

[YOU TUBE]IYZOTt9zTv0[/YOU TUBE]

If you remove the spaces between YOU and TUBE it will display as embedded. Thanks for the link.


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## Salty9 (Jul 13, 2009)

Have you considered DIY lost wax casting? http://www.cnczone.com/forums/casti..._diy_casting_questions_lost_wax_aluminum.html

Google "DIY lost wax casting" for more info.


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## TigerNut (Dec 18, 2009)

PStechPaul said:


> I'm putting together an order at www.mcmaster.com for some mechanical parts ...
> 
> 
> 
> There are probably many applications for this in the DIY EV world.


Very cool video. However, where he shows mixing stuff in Dixie cups, you might want to use something else like polypropylene cups that are actually meant for mixing resins. The Dixie cups are made of waxed paper. When you use a stirring tool, you can scrape bits of wax from the sides or bottom of the container and those pieces will contaminate the part you're casting. In the worst case, the wax can cause the resin to not set properly and ruin your work.

I did a lost-wax sterling silver casting about 35 years ago in school... very cool. We made the wax positive of the part we wanted, added sprues for filling and venting, and then set that into a plaster mold. The wax was evaporated out in a kiln. The casting process itself required a centrifugal spring-loaded crucible that mated to the mold (or more accurately, the mold is made to fit the centrifuge). Then the silver was melted (with flux) using an oxy-acetylene torch, poured into the crucible, and then the spring is released to spin the assembly and force the metal into the mold.

I think the trick with aluminum would be to avoid contamination of the alloy as it melts. You need to have an appropriate crucible and flux. Heating will also be somewhat tricky... an induction heater would be a great tool but tricky to fixture above or in the centrifuge.


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## Salty9 (Jul 13, 2009)

I had a "senior moment" when I posted the lost wax suggestion. I intended to suggest lost foam casting where the foam is burnt out by the hot metal being cast.


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## dragonsgate (May 19, 2012)

TigerNut said:


> Very cool video. However, where he shows mixing stuff in Dixie cups, you might want to use something else like polypropylene cups that are actually meant for mixing resins. The Dixie cups are made of waxed paper. When you use a stirring tool, you can scrape bits of wax from the sides or bottom of the container and those pieces will contaminate the part you're casting. In the worst case, the wax can cause the resin to not set properly and ruin your work.
> 
> I did a lost-wax sterling silver casting about 35 years ago in school... very cool. We made the wax positive of the part we wanted, added sprues for filling and venting, and then set that into a plaster mold. The wax was evaporated out in a kiln. The casting process itself required a centrifugal spring-loaded crucible that mated to the mold (or more accurately, the mold is made to fit the centrifuge). Then the silver was melted (with flux) using an oxy-acetylene torch, poured into the crucible, and then the spring is released to spin the assembly and force the metal into the mold.
> 
> I think the trick with aluminum would be to avoid contamination of the alloy as it melts. You need to have an appropriate crucible and flux. Heating will also be somewhat tricky... an induction heater would be a great tool but tricky to fixture above or in the centrifuge.


Oils and waxes can retard resin curing to a point of not hardening and staying sticky. Two part mixes should be measured accurately or the piece can get to brittle if to much hardener is used or stay soft if not enough is used. This is a simple explanation. As for lost wax moisture or residue wax in the mold cavity will flash back when the molten metal hits it and leave a hole in the casting. A special casting investment is used for lost wax casting. Regular plaster or plaster of Paris will explode. If done right you can get some fine detail with either resin or spin casting.


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## hamsterpower (Oct 13, 2009)

There is a very interesting and detailed thread about DIY casting aluminium over on VWvortex. http://forums.vwvortex.com/showthread.php?4662626-The-complete-guide-on-casting-parts


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## Ziggythewiz (May 16, 2010)

hamsterpower said:


> There is a very interesting and detailed thread about DIY casting aluminium over on VWvortex. http://forums.vwvortex.com/showthread.php?4662626-The-complete-guide-on-casting-parts


Thanks...someday I shall put that to good use...


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## Coley (Jul 26, 2007)

I have been casting parts for just about anything for over 30 years.

I have cast new door handles for the inside of my YUGO as they were plastic and broken.
I use Petro-Bond sand casting, rubber mold spin casting, plaster casting and now a lot of no-bake castings of Chevy and Packard parts.

An example of my castings is this one on ebay 360570267666
I cast mostly ZA alloy, as that is what most of the parts I reproduce were made of originally.

Your pattern is the part that needs the best detail put into it.


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