[littleCNCjohn]

I recently made a rubber candle mold by using my 3-axis Taig milling machine to machine a 4"X4"X6” block of pine to the desired shape of the candle. I then poured liquid urethane on it, allowed the urethane to set, and removed the pine model so that the cavity could be filled with wax to make a candle. The problem is that the grains of the pine left an impression in the urethane that transfers over to the candles! Does anyone have a suggestion of an alternative material that is inexpensive and is easy to machine? Thanks,

John

[inventor83]

acrylic?

[Rolf_K]

John, I would think you would want to seal your wooden model with several coats of lacquer and sanding in-between. Not until you have a high-gloss finish will the job be done.

I recently made a rubber candle mold by using my 3-axis Taig milling machine to machine a 4"X4"X6” block of pine to the desired shape of the candle. I then poured liquid urethane on it, allowed the urethane to set, and removed the pine model so that the cavity could be filled with wax to make a candle. The problem is that the grains of the pine left an impression in the urethane that transfers over to the candles! Does anyone have a suggestion of an alternative material that is inexpensive and is easy to machine? Thanks,




John

[rowbare]

This might work for you. I have never tried it though. FMSC - RenShape Modeling and Styling Boards

Just noticed they offer a sample kit: FMSC - Machinable Media Sample Kit

bob

[JEST]

I recently had occasion to make a wooden mold for casting. My original was cut in machinable wax. However, the caster destroyed it (another adventure)

Here are some of the things I experienced.

Pine is going to cause grain issues. Next time, I would recommend using a hard wood (oak, birch...). I had success using birch plywood (scrap pieces in the garage)

Shellac works VERY well for sanding/sealing. I also found that the clear coat for the "fake stone" paint works quite well.

I found urethane and lacquer both took too long to harden, and "felt" sticky even after a week of curing. This was a surprise as I am a fan of lacquer finishing wood projects!

The images are, rough cut, sealed/sanded, coated in graphite dust (release agent), original wax cut.

[awerby]

Go with machinable wax. It has no grain, it's cheaper by volume than Renshape, and you can melt down any chunks of it that are left over or no longer necessary for your projects, cast new blocks, and carve more parts. It releases from rubber better than anything else you can carve, with no extra coatings required: MachinableWax.com (But keep it away from Jest's caster...)

Andrew Werby
www.computersculpture.com

[littleCNCjohn]

Thanks everyone for the great input! Last night I took my file back to the model and found that it only touched on the grains, so they probably swelled when I painted it with lacquer.. now I know to repeatedly file and shellac, and to go with hard wood. I looked into machinable wax some and plan to try using that next (FMSC sells machinable wax too). If you’re curious here are some pictures of candles made from the two molds that didn’t turn out so well. Thanks again,

John