Thread: Commercial casting project

So Ive decided to give epoxy a go instead of PR. Because I have to hand sand everything I'm spending hours cleaning up the crappy finish on the PR. Despite my master been high gloss and the moulds been good, the finish requires a lot of wet and dry. I'f I ever end up selling anything I'll be paying myself $ 1.50 /hr . I did a small test with epoxy and can basically polish straight out of the mould with decent results. No doubt a quick wet and dry with 1200 first would be better but time is money.

I believe epoxy shrinks a lot less,if at all and sticks real well,not tried it myself but what I have read about it would suggest that cheers ~ John

So far so good. More expensive but if it saves me hours of sanding and finishing its money well spent. Plus its so non toxic to be around compared to PR, which is pleasing the wife no end. The PR was on the nose. I didnt notice it through my respirator but the wife sure did. And no blinding death hardener

Cheers,

Alex.

Loving the epoxy, sort of. Temperature is vital to cure time. I poured late yesterday arvo and this morning the items were super flexy, not tacky though. Prized them out of the moulds and left them in the sun all day and they hardened up fine. Good thing they were only bangles for my niece.Its a lot softer than PR and takes machine really well. I tried the router on some PR and it spat a big piece at me where as the epoxy cuts like butter.

Nothing quite like breaking new ground hehe, I think the hardness of acrylics is why they make durable pens,but does have its own problems Epoxy has its place in pen making ,mainly casting and bonding dissimilar materials like worthless woods etc , keep this up and you will soon have it down pat a lot of what we do is trial and error ,you take an idea look for a starting point and info up to that point ,then go for it , some failures to be expected in the course of such endeavors ,but as they say, "Nothing ventured-Nothing gained " cheers ~ John

A lot of useless bits of expensive prototypes sitting on the bench at the moment Make a master, make a few changes to it, re mould it as a new master, make changes, re mould it etc...... its the bloody pinkysil thats the killer cost wise. My kingdom for cheaper pinkysil

Cheers, Alex.

Nah! what you want is one of those new fangled 3D printers that builds things from the ground up in fine layers hehe ,could be a programming learning curve though ,similar to 4 axis CNC routers another dark art to dodge could you perhaps use a mock up of your molds with something like cheap cutting boards ,screwed together then if neccessary sealed with hot melt glue ? that way you could dismantle the mold for modifications till you are happy with the results cheers ~ John

Oh God, technology overload. I'm sure things were manufactured before CNC and 3D were around. Hmmmm, maybe get some clay

Hmmm ~ they used to use sand for making molds of pretty high standard hehe ! but maybe plaster of paris molds while in the development stages could cut costs cheers ~ John

Geez John I dunno. I'm messy at the best of times, plaster could be a disaster

Cheers,

Alex

Plasticine works ok for moulds. You can mould it warm, you can cool it and carve with chisel, gouge and knife.

You can also push it over half an item, vaseline the layer and then plasticine the top layer. Then cool and pull apart, gives you a 2 part mould.
(Better to use plasticine for half and cast a mould over it with silicone or pinky. When thats hardened up, remove plasticine, turn over and cast second side of mould.

But plasticine mould only work once as you need to pick it apart after casting.

But if you get one end result you like you can pinksil or silicone cast that as your final mould.

I'd be tempted in using plasticine and casting with plaster until I got the preferred shape. Then seal plaster prior to using the plaster cast for molding the silicon, which in turn is used to mold the resin.

Thanks for the advice guys - looks like more research. I have received advice to avoid 2 part molds where ever possible but sometimes there is no choice I guess

Hi all. Well things are progressing nicely ( and expensively) so far. It looks like I will have something to patent ( fingers crossed). Anyway, I was wondering if anyones knows of a wet sanding machine suitable for finishing the PR/epoxy. Since I'm not using a lathe I'm finding the finishing takes too much time from a $$$ / hour per piece perspective. Even with epoxy which is giving me better results from the mould. I'm moving back towards the PR as the visual appearance is far superior to epoxy I think. Can PR be injection moulded ? Just thinking from a mass production perspective

Cheers,

Alex.