Mold Making, Casting

[Daniel Markovich]

A client asked if I could make molds with my laser engraver and I did not know how to answer the question. The idea would be to find a material to engrave away an image deep enough then use it as a mold to pour different rubbers and plastics. Has this ever been done? Any suggestions? Thanks everyone!

[Chuck Stone]

I do it the other way .. use the engraver to carve a master, then make the mold
from that. But it depends on what you're going to pour. I make little tiny things
so it works out fine for me.. depth of less than 1/8" is fine for the laser, but
more than that and you'll likely need to find another way. (CNC router perhaps?)

[Daniel Markovich]

That makes sense, I am just exploring possibilities and ideas people throw at me. Thanks!

[Rodne Gold]

I do spin casting masters, make em out of acrylic and then they get put into a mould , vulcanised to harden the rubber *the heat destroys the acrylic master but the mould is perfect* , the high temp rubber moulds are used to spin cast low melting point metals, Works a treat.

[rich shepard]

I've engraved some in acrylic for mud flaps for model trucks. These were in 1/24 scale and he cast then is a rubber compound of some type. He sent me the photo of the prototype and i worked from it.

rich

[Rodne Gold]

Biggest problem with trying to actually engrave the mould is that you have little control of depth and the engraved surface is VERY rough in most cases , acrylic would work for anything that is under about 150 degrees C
You can actually engrave high temp mould rubber - RTV (room temperature vulcanising) silicon , works similar to rubber stamp material in terms of settings and speeds , but you still have the issues with depth control and mould surface roughness.
We did some work for a dental technician , he actually wanted to use wax to pour into a set of moulds and then use the lost wax casting process to cast em in gold , he polished out the surfaces after casting so surface roughness wasnt an issue , these were EXTREMELY small items as they were used as tooth decorations. We used 6mm Acrylic and engraved em very shallowly , did multiple "polishing" passes to try minimise the laser engraving roughness. A polishing pass runs over the entire graphic slightly out of focus at high speed and low poer , just enough to sort of "melt" the ridges the laser leaves.

[George D Gabert]

Last year there were several discusions of making candy molds. You might want to do a search as several good ideas and a place showing casting materials were shown.

GDG