Plastic molding on a budget?

**rotarypower101** · 12-27-2005, 02:59 AM

Has anyone done any research on making plastic parts from scratch?
Barring the difficult facts of producing a mold, are there any ways to mold plastics on a budget?

I know a lot of the basics of real plastics molding and have a extensive section in a text, ie worm screw hydraulic machines and feeder pellets elaborate heated molds, but I am wondering if there are any ways for the small guys to be able to mold plastics?

Has anyone found any great ways to make plastic parts if a sufficient mold were available?

Any thought or research people would like to share on the topic?

I remember going to a car expo where a guy had some moldable plastics www.plastexnw.com but it seems they either went out of business or changed their name.

I also just read a thread on vacuum forming, but i dont think that is exactly what i am looking for.

Any ideas on the topic?

**shotgunefx** · 12-27-2005, 03:48 AM

Depends on what you're trying to make.

My knowledge is far from extensive, just know from my own searching.

Most plastic interior parts you see is done with RIM (reactive injection molding). No cheap way to do it. Well there is (thousands vs hundreds of thousands), but I have a feeling the cheap way isn't cheap enough.

Thermoplastics require a ton of heat and pressure and the molds too are expensive. And any complex part with molding, there's a good chance even if you could make one cheap, would get stuck in the mold due to undercuts etc if not perfectly made.

There used to be a material called Friendly Plastic I used years and years ago. Basically pellets that became workable in hotwater and dried rock hard. Was cool stuff, but looking for it last year, I don't know if you can get it and apparently it doesn't last. Plus cars get pretty hot.

There are vinyls and polyurethanes you could get that are pretty rigid (or can be) that are easily moldable. There are used extensively in movies. Here is one place to get them. Wether it would hold up in a harsh auto environment? Dunno.

update
Oh yeah, you can always use lathes and what not to mill plastic depending on the part.

**BLOWNZO6_pc** · 12-27-2005, 09:25 PM

This is what I do for a living.. Custom Plastic Injection molding.

There are a few ways to make plastic parts.

The catch is you have to have CAD data to do it.

I have designed a couple of different monitor solutions, etc. They are about $200 to have one made. The material they use is similar to Nylon or ABS.

I have also drawn up a dash plate for the Corvette and it would not be THAT bad if you sell them for about $200 each and could sell about 50 of them. That would be enough for you to sell them and break even on the tooling.

To make a long story short.. there is not a cheap way to mass produce them. Anything low volume is going to be expensive. But the SLA or quick prototypes is not a bad way to make some one or two off plastic things.

**mushin** · 12-27-2005, 11:34 PM

I remember seeing an intriguing tutorial on DIY vacuum forming a while back linked from Hack a Day. Basically the jist was oven -> mold + shopvac, and the results were quite impressive. Never did get around to trying it though. You can probably find it (or similar) with a bit of google magic.

**shotgunefx** · 12-27-2005, 11:39 PM

Originally Posted by mushin

I remember seeing an intriguing tutorial on DIY vacuum forming a while back linked from Hack a Day. Basically the jist was oven -> mold + shopvac, and the results were quite impressive. Never did get around to trying it though. You can probably find it (or similar) with a bit of google magic.

I did some experimenting with that and it worked great for the test parts.

Though I need to make a better frame to hold the plastic.

Here's a little mount I made for my dreamgear keyboard.

**antimatter** · 12-28-2005, 01:11 AM

anyone care to post that link?

**pRoFiT** · 12-28-2005, 01:46 AM

How about this build you own plastic vacuum forming table.

http://www.hhhh.org/~joeboy/resource...cuumtable.html

Side note: The company I slave for has an SLA machine. Really neet. It builds a plastic model from a CAD file (STL) one layer at a time out of this plastic liquid. when the laser beam hits it it hardens the plastic. Accurate to about 4 thousands of an inch. Maybe even better then that. Ive made tons of parts with it. Once you sand and paint it you cant even tell its an SLA part.

p.s. SLA = stereo lithography, CAD = Computer-adied design For the noobs

**remarque** · 12-28-2005, 11:08 AM

You can make the plastic part out of plastor, then use Castomold from www.usplastics.com and pour it over the mold. Once the Castomold has set simply remove the your plastor mold pour some Castolite in the mold from www.usplastics.com let that harden and you have a plastic part. You buy dye for the Castolite to make your part any color. Castomold is $19.17 for a quart and Castolite is $17.35 for quart. That to me was the simpliest and cheapest way to make plastic parts.

**mushin** · 12-28-2005, 12:43 PM

Here's the site I was talking about. Had it bookmarked on my work machine

http://www.halloweenfear.com/vacuumformintro.html

edit: hmm, reading through it it looks a bit different then I remember it... I recall them going through the making of a stormtrooper helmet, maybe that was a different site. Oh well. The site's pretty detailed anyway.

**rotarypower101** · 12-28-2005, 08:48 PM

Originally Posted by remarque

You can make the plastic part out of plastor, then use Castomold from www.usplastics.com and pour it over the mold. Once the Castomold has set simply remove the your plastor mold pour some Castolite in the mold from www.usplastics.com let that harden and you have a plastic part. You buy dye for the Castolite to make your part any color. Castomold is $19.17 for a quart and Castolite is $17.35 for quart. That to me was the simpliest and cheapest way to make plastic parts.

WOW that looks like it may have some potential.

Have you seen any parts that were made from this material?

I usually have the means to get a rough shape by making a mold, and then work from there, but it is very difficult to cut a part from a strait billet at times, and impractical!

I wonder what the structural and thermal properties of this material is compared to std. Plastics?