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Dennis
14-03-2011, 06:09 AM
The problem with drilling and shaping acrylic is that if the tools get hot, the acrylic will melt and jam them. It is fine to use normal twist drills, but run your machine quite slowly and use a few drops of lubricant. For holes bigger than say 2.0 mm in diameter it is worth drilling in incremental steps as cracking can also be a problem.

For sawing try to find blades meant for wood, with very spaced out teeth and use some beeswax, or Burr Life. I spend my holiday money at Aki, a Spanish DIY supermarket, where they have really gap-toothed blades. Spiral saw blades from Proxxon stockists also work well, but you need to concentrate hard to cut a straight line.

If trimming with burrs, use the biggest and coarsest possible. Dental technicians work a lot with acrylic and one of their supplier is Chaperlain and Jacobs. Below I have shown acrylic burrs meant for this and also mounted pink stones. Files need to be as coarse as possible so as to bite well.
For polishing use emery compound on calico wheels, followed by ‘Vonax’ on a fluffy cotton one. A green Scotchbrite wheel for the pendant drill, or polishing lathe, gives a good satin finish.

Below are some of the tools used and some gift ideas for docking glasses, cut from display blocks. You need a good vacuum for cleaning up afterwards. Dennis.

ps_bond
14-03-2011, 08:48 AM
I've had relatively good results cutting acrylic with wax saw blades (also spiral!); they're coarse, though and need a moderate amount of cleanup afterwards. Similarly, I've been advised to use a wax file in shaping acrylic (and cleaning up after spiral saw cuts); I'm less sure about that one so far.

Dennis
14-03-2011, 10:06 AM
Yes, you're right about coarse files, Peter. I have inherited something called a Bastard File. My father used to smirk when he said that and they are no longer listed.
There are some coarse half round files at iron mongers though which could work better than wax files. Dennis.

ps_bond
14-03-2011, 10:21 AM
Axminster still sell them in bastard cut (along with second & smooth); I've got a 4" bastard cut that I use for less-than-subtle silver removal - while the 12" is really only useful for ripping large amounts of steel off things. I wondered about some of the wood rasps, but I think the teeth would leave too much marking - dreadnought files are pretty good on hard plastics though. That said, most of those tend to be quite large, so less useful in jewellery.

WitchfordSilver
29-06-2011, 09:49 PM
They were my favourite files at school; it was the only time you could shout who’s got the bastard without getting a clip around the ear.

Water torches can be used to flame polish the sides I think.