[Coco] molding info

[Mark J. Blair]

> On Oct 29, 2014, at 15:47 , Josh Harper via Coco <coco at maltedmedia.com> wrote:
> does any one know what is involved in reverse engineering a computer case or other case parts to make new molds of the original item  just wondering what it would take and if it could be done  

I've done some design of injection-molded parts at work, and had them manufactured in small quantities by ProtoMold:

  http://www.protolabs.com/protomold

You would need to have appropriate 3D CAD software, with support for things like adding draft angles. Tools like SolidWorks are industry standards; I used Cobalt from Ashlar-Vellum.

You would also need to understand how to design moldable shapes, which isn't trivial. I managed to learn everything I needed from the excellent tutorial information provided by ProtoMold. I'm an electrical engineer, with interest in mechanical design but no formal training in the field.

At that point, it would be a matter of sitting down with the item to be reproduced and some tools like calipers, angle and radius gauges, etc., and recreating a solid model of it, making sure that the model can be manufactured within your molding manufacturer's design rules. As an example, down near the bottom of this page are some renderings of solid models I recreated of an old piece of WW2 military gear (but I've made no attempt to fabricate it):

  http://www.nf6x.net/2011/12/ft-505-pack-mount-for-the-scr-619/

Unfortunately, even with the fairly recent arrival of quick-turn low-cost injection molding services like ProtoMold, tooling is still pretty expensive. For example, I designed a little two-piece box about the size of a small matchbox, with each half moldable in a straight-pull mold with no side actions. Tooling cost around $10k for the two molds needed.

I don't think there's any profitable or even break-even business model for making new molds for CoCo items, given my guesstimate of the total size of the CoCo collector community. I don't see it happening unless some wealthy person felt like dumping $10k or more on tooling for a personal project and then letting others buy the plastics without trying to cover the tooling costs.

I could design things like custom cartridge plastics myself (and I'd enjoy doing it), but it'd never happen unless I won the lottery and could afford to dump tens of thousands on silly personal projects.

I have used ProtoMold's sister company FirstCut for personal projects, though (as well as stuff at work). $10k for mold tooling is too expensive for me, but a hundred bucks or so for a one-off milled aluminum thingie every now and then is do-able.

  http://www.protolabs.com/firstcut

It appears that they've added some other services/processes since the last time I've used them that might be applicable for small custom projects. I think that there are also numerous services that provide 3D-printing, but I've never done anything with those additive processes so far.

-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/