"Using 3D printed rapid prototypes as "greens" or masters?" Topic

I know some companies are doing this now – but isn't there a problem with the vulcanization temperature?

Good question. I suspect not as much as there is with "green stuff". IIRC the plastic in RP machines is ABS

Yes…we are using rapid prototyping for our upcoming War Rocket models (slated for release in October 2009). Generally, the rapid prototyped models are very fragile and break very easily during vulcanization. In addition, solvents from the RP resin leach from the models during vulcanization and result in an incomplete curing of the vulcanizable silicone molds. Our method to overcome this is to have the RP resin parts cast in bronze though lost wax casting at a jeweler's foundry. The parts are much stronger and can be buffed and polished to a high shine before molding. It's a lot of extra steps compared to traditional sculpting, but the precision and symmetry is worth it! Here's more info:

link

Matt Beauchamp
Hydra Miniatures
hydraminiatures.com

You can also make an RTV mold and a resin copy of it, then use that as the master for vulcanization.

Some RP materials can inhibit the cure of the RTV, but the type we use does not. If the kind you are using does inhibit Platinum or Tin cure RTV's then you can switch to a Urethane RTV.

When I worked for GW we made resins copies of every new model (since about 2002) and used those as the masters for vulcanizing the green master molds, that way if somehting happened to the original we had an RTV mold and resin copies to fall back on.

There are a number of resins available that can withstand up to 350-400 F temperatures, but they can be a bit pricey, $200-$300 per gallon, and you also have to post cure the parts in an oven between 1-2 hours for the components to set properly.

Very interesting info, Mechanical Horizon

This may only work for me, but I have had a lot of luck vulcanizing alumilite resins. I did do th above oven curing trick.

One advantage of having a bronze master is the ability of polish the surface of the model. Even with high-rez printng, there is a noticable texture from the printing process. foe example, I purchased a few B5 spaceships and the printing texture was very prominent and distracting--how many coats of primer will it take to make them smooth?

I suppose I could sand the printed RP master before moldmaking, but they are so fragile I'd be afraid of breaking it. The printing technology is changing rapidly and will only get better so these steps may be eliminated in the future. In fact, a few companies are experimenting with 3D metal printing. However, the bronze master has been the only method that yields high quality results for us.

Matt Beauchamp
Hydra Miniatures

Depends on the print. If you are using Solidscape prints, they are basically wax, and very delicate.

Prints from Invision HR and related machines are plastic, and with some pre-treatment, can be molded directly through the use of Niceme green based low-temp vulcanizing silicone mold rubber.

Wet sand the part if it is printed in plastic.

A coat of polene will keep it from inhibiting the RTV cure – platinum or tin.

I'd try the Nicem green on the lowest temp. I have some printed stuff, I just haven't had the chance (or money) to buy some Nicem Green to try.

I used printed masters to make RTV tools at the company I just got laid off from. We went through 24+ 55 gallon drums of rubber last year (when business was still good), and I've seen all kinds of parts and cure problems.

you take the wax like proto copy clean it up then have a master made with it using investment casting this master can be cast in all types of medals but I think silver is the easiest to cast and then to work with.

Ninja Magic send the RPs for investment casting in silver. The silver gets cleaned up (if needed) and becomes the master for the molds. (Ninja Magic does the rapid prototyping for Ad Astra Games as well as its own line.)

I need someone who can make masters for me from the RP original as well as do the production casting. I emailed Jeff Valent Studios but never got a response.

I have several prototyping machines (12 different types). It really depends on what you are trying to do with the model. The real trick is to choose an rp process that will give you what you need. We have systems that print in wax they work really well for metal casting masters either spin or drop. If you have questions feel free to ask me at etackett AT cox DOT net. Someone was talking about terrain models in another thread. We usually CNC foam spray silicone then back with FRP or plaster bandages. The biggest thing you can do to make sure you get a good cast without inhibition is barrier coat the models use an acrylic clear coat like Krylon. The wax moels coming out of prototype machines are not truly WAX be carefull of projet technology the wax support will actually leech out of the master model.

Cheers,

e-