ordering mold from Shapeways

I posted this first to for sale - forum, but this forum fits better..
Hi!

I ended up trying to mold the mendel plastic parts. I draw a mold and uploaded it to shapeways.com for ordering. Would there be any interest in this mold, if it ends ups a successfull way to produce mendel? The price will be about 27$ which you can, hopefully, use to produce all 6 corner vertexes? If this is successfull, I will make molds for the other parts as well.

You can see it in [www.shapeways.com]
Please, do not yet order it, unless you want to be an alfa tester. I have not yet tested it by myself.

I prepared the mold by importing the stl file from the reprap file system. Then I cut it to half (cannot mold a part with crossing holes. You need to be able to remove the piece from the mold..).
I build up a 2mm thick walls. The inner side is slightly sloped to make the removing easier.

My plan is either to order a packet of polymorph and mold it from that (Shapeways White & Strong can handle temperature up to 70 degrees) , or just by some resin and use it. I will inform you when I have some results.

Anyone have any experience on this subject? I think I need some releasing agent to be able to release the piece from the mold.
I'm considering honey wax (melting point 65 degrees), parafin (40-60 degrees) or stearin (72 degrees). So the polymorph melts at 60 degrees, the mold can stand up to 80 degrees (shapeways has updated the temp), Which releasing agent should I use? Should the agent be liquid (will it get mixed with polymorph) or solid when the mold is made?
My plan is first to melt the releasing agent (honey wax) and let it solidify to the mold. Then melt the polynmorph and let it cool down somewhere between 65 and 60.
Fill in the mold and let it cool down. Release the piece (hopefully it can be released..)
If I use parafin, it would be melted while polymorph is frozen, maybe the piece would be easier to release? Or would the parafin just mix up with the polymorph and spoil the piece?

----------------------
Sebastianbailard already suggested using vaseline as relesing agent.

I've never done anything but silicone molds, they use a simple spray to release from the molds. I think it's technical name is Dichloromonofluoroethane
Dimethylmethane Butane. Here's the name brand I used, but I don't think it actually matters the brand.

See also, cooking type oil sprays like "Pam", mineral oil, or purpose-made spray-on 'Mold Release' agents like the one ManDrake recommended.

Every sculpture supply shop will have something, e.g.
[www.arizonasculpture.com]

They buy it from the same suppliers who manufacture moldmaking supplies.
Here is smooth-on's release agent selection:
[www.smooth-on.com]

Hi!

I got my mold and this seems to be possile way to get the plastic parts, Of course, if you can have the printed versions, get them. Or if you have a cnc mill, mill them. If you don't, this is one way.

At first, shortly how to get the parts:
1. get the mold and polymorph
2. grease mold with vaseline (petroleum grease?). Actually I changed my car's bearing a short time ago, so I had some axel bearing grease. I suppose it is mostly vaseline. Use as thin level as possible, but carefully put it everywere inside the mold.
3. Fill the mold with polymorph granulates
4. Put some water on the bottom of a pot. I filled somewhere 1,5 - 2 cm.
5. Carefully heat the water up to ~75 degrees (Celsius). Put the mold in the water
6. Wait. Be patient. Use an accurate temperature meter. Turn on the cooking plate as necessary to keep the heat up.
7. When the granulates has melted and are clear, add some more. Heat more, and add the granulates as necessary until the mold is filled with clear polymorph. You need to add them a few times.
8. Take the mold out, push a screw or two on the polymorph.
9. Coold the mold down. I put it on the freezer. Be patient and let it cool down until it is all white.
10. Use tongs to get the piece out of the mold. This is why you need to push the screws on the piece ;-). It does not get out very easily, but using decent force, you can do it. After you get the piece out, you can take the screw out.

Repeat this 12 times...

This is not very fast way of making them, it takes something around 1/2 to 1 hour to make one half. Most of the times you are waiting for the mold to cool down.

Here is the longer story:
First I tried without any releasing agent. This was a bad idea. The polymorph got stuck to the mold, I had hard time to get it out.
Secondly I tried WD40. Did not work, could not take the mold out. However, by heating the mold up, I got the polymorph easily out of the mold.
Thirdly I tried Olive oil. Worked quit much like WD40.
I did not want to use vaseline in the beginning, because I quessed it would leave some marks on the molded piece. I had no more ideas, so I did it with the car axle bearing grease. After adding the screw, it turned out to be working. However, it is still not very easy to release the part. There is some marks on the piece, but they are not as bad I was afraid of and certainly they does not affect the usability.

Future: I will first make the corner vertexes for myself (maybe this weekend) and maybe start the wiki pages (can someone point out where I should link it?). I think I could make the mold walls somehow thinner, so it might be easier to remove the piece. The material is quite flexible, but 2mm walls in the current mold does not blend too much. Thinning the walls makes it also cheaper :-)

After that I will continue making the molds for the other parts as well.

Here are also some pictures.

For strength, I would like to see solid webs joining each pair of the opposing
rods.