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Old June 18th 15, 08:03 PM posted to rec.crafts.metalworking
Tim Wescott[_6_] Tim Wescott[_6_] is offline
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Posts: 223
Default Materials for making a mold

On Thu, 18 Jun 2015 12:56:52 -0500, F. George McDuffee wrote:

On Tue, 16 Jun 2015 19:25:47 -0500, Tim Wescott
wrote:

I'm working on a project that may well end up having a case made of
fiberglass. As I'm working on a 3D model that will use mostly to make
pretty PDFs for my fiberglass guy and my customer, It occurs to me that
I could just make a 3D model of a mold and send it to a machine shop.

A 1.25 x 12 x 48 inch piece of 6061 costs $430 from Online Metals. Is
that pretty much what I would expect to pay for materials from a machine
shop? Is there any material that's significantly cheaper, that can be
tossed into a CNC mill and made into something mold like, and then hand-
polished to a high shine?

========================
After reading the replies to this post, I have some questions:

(1) What is your projected volume?


A few dozen a year.

(2) Why fiberglass? How about alternatives such as vacuum formed
thermoplastic?


First, it's the devil I know, and I know it'll be strong enough (I want
the thing to easily survive a drop from table height onto concrete).
Second, I have a strong personal tie with the vendor.

Vacuum-formed thermoplastic is certainly a contender, but I think that by
the time I get all the other properties I want, given my anticipated
production volumes, that I wouldn't be happy.

(3) Did you get quotes from enclosure/case vendors? The size/shape
appears close to a gun case.


A hinged case isn't a good starting point, I don't think. I've been down
this sort of road before, and I just don't see finding a case that'll
meet my needs that isn't custom-made.

(Enclosures are a bitch. With the exception of PC builds I have yet to
do an electronics project where the cost of a nice-looking case didn't
exceed the cost of the stuff inside it.)

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com