Talk Composites - The Forum for Advanced Composites

Can You Make A Two Part Mould Using Putty?

http://www.talkcomposites.com/Topic21365.aspx

By akitcarowner - 6/3/2016 9:00:38 AM

Looking at doing a wheel center cap (Long story short, car stolen recovered and many things missing inc wheel center caps, so why not make them?) whilst a small part will need to be done in a two part mould (due to curves).

So can the putty be used or just stick with csm to make it?

The next question is of course, using wet lay-up and vacuum will that force the carbon into the curves without distorting too much? 

I don't mind running a thin bead of black gel around edges to tidy up and then just put a circle at the bottom, thin bead, then use another piece of carbon for the edge?
By Zebra - 6/13/2016 8:42:05 PM

I use epoxy putty to make two piece molds. It works exceptionally well for what I do. I prefer it to fiberglass any day.

A few things to consider:

It's not amazing at capturing fine detail.

You might need to do some small touch ups on the surface if you don't press it into the pattern in every spot.

The is a much higher chance of the part sticking. Epoxy sticks to epoxy very well. I wet the cf fabric and let it partially cure before laying it in the mold (for the first layer only). It adheres less when partially cured. The flip side to this is that, because it sticks so well, you might not even need to bother with a vacuum for simple parts.

Make sure the epoxy putty is not too thin in any area of the mold or it will snap when you demold. Make sure the edges in particular are thick (like one inch or so)

Make sure the pattern is smooth before using the epoxy putty. If it is textured the putty will stick no matter what mold release you use. 

Add at least a one inch putty border around the edge of the mold so when you separate the two halves with a screw driver, the chips in the surface won't be in the mold cavity

Vaseline is typically enough to allow the mold halves to be seperated.

The putty I use is light and porous. Make sure you seal the surface with something before use. Vaseline is fine for a single use mold. Use something better if it is for multiple parts.