Thanx for help on toggle switches - here's a compiled list

Steve Caple wrote:


In some cases that might be true. It would depend on the oil and plastic involved. I've read several comments, studies, or 'papers' on this subject, and there's little agreement. Whether the oil CAUSES the cracks seems undecided. That it WORSENS existing cracks seems certain.
Dan Mitchell ===========
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On Tue, 04 Oct 2005 15:50:08 -0000, pv+ snipped-for-privacy@pobox.com (Paul Vader) wrote:

Water has zero lubricity. That's what the KoolMist is for Peanut oil works great without injuring the acrylic when you are drilling. Acrylic should always be drilled at slow speed. Peanut oil also works very well as a tapping lubricant. Froggy,
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Froggy @ thepond..com wrote:

Hi Froggy:
I've not tried the peanut oil, so I won't comment on that.
I disagree that water has "zero lubricity" ... certainly it's not in the same league as most oils, but it can substantially reduce friction. It can even be used as a lubricant in bearings, in various ways. If a rubber sleeve or pad is inserted in the bearing, water serves well as a lunricant. Indeed, such bearings were used in some boat propeller shafts. When cutting plastic, it serves mainly as a coolant, preventing the plastic from melting. It also serves as a barrier film to prevent the soft plastic from sticking to the cutting tool, and does reduce friction.
Friction is a complex issue, and usually comes down to some form of surface welding on a microscopic scale. Most ANY film between the surfaces reduces this adhesion, and reduces friction.
Dan Mitchell ===========
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[ ... ]

I used to center punch plexiglass, then I heard you couldn't center punch it. I kept on center punching it, and still do when I need to drill a hole. What ever the problem with center punching is, I seem to have missed it.
Most of the stuff I've used comes with a sheet of paper stuck to each side. Mark on the paper, cut, drill, etc., then take the paper off when everything else is finished.
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You have a more gentle hand with the punch than I do I guess. Generally, it will crack or star the surface. If you're expanding the hole that might not be a big problem.

The paper is good for avoiding scratches too. Window plexiglass will scratch if you look at it funny. *
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Vince Guarna said the following on 10/1/2005 4:54 PM:

There are special bits for drilling plexiglass. They have a much more "pointy" end that doesn't take such a big bite out of the plastic. Drill slowly. Low pressure and slow speed. Also, if you're careful you can use a propane torch to smooth the drill holes and the edges. Experiment a bit with some scrap. Heating the edge and moving all the time you will se it turn clear and smooth. Takes all sharp edges off without sanding and smooths scratches. Tapping holes for screws is the same as drilling. Slow is the key to preventing breakage.
Kirk
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'Captain' Kirk DeHaan wrote:

When I worked in a machine shop, I used alcohol when working Plexiglas. It helped to float the chips out of the way, especially when tapping...
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