On Monday 4. May 2015 19.00.22 Luke Kenneth Casson Leighton wrote:
right. ok, the plan is as follows:
- phase 1: get 3d printed parts working (as +ves)
- phase 2: split all parts into two -ves
- each 1/2 part will be subtracted from a "block"
- this "block" will fit inside a metal container
- the two 1/2 -ve parts will be fitted inside the metal container
- low-viscosity injection mold plastic will be used to create a prototype
part
You're braver than I thought. ;-)
phase 3:
- the two 1/2 -ve parts will be printed out on flash-thermal resin (on a
DLP) * the two 1/2 -ve parts will then be flash-cast to metal.
- the resultant 1/2 *METAL* parts will then be used for *production*
injection molding.
the reason for using high-accuracy thermal resin to cast the molds in metal is that - i hope - they will be much more accurate, so will not require polishing.
if they *do* require polishing (i.e. not look good enough) then what i will do instead is investigate some casting methods that give the cast parts a "sandy surface" look, meaning that any blemishes simply won't show up as significant.
I think Bunnie had some interesting/amusing things to say about surface blemishes when they were making the moulds for Novena:
https://www.crowdsupply.com/kosagi/novena/updates/1330
$USD 20k on polished injection molds when they're only going to last 2 to 3 thousand units before they wear out due to abrasion - it's silly. there has to be a better way.
A while back, I became interested in these matters and surfed around looking at UK-based companies offering injection moulding services. Maybe I should dig some of those links out and see if there are any collaborative opportunities. Interestingly, I think one of them was actually publicly-owned (by a local council) and was technically a non-profit.
Paul