Re: acrylic; motors

[Nathanael Henderson <jude@pconline.com>]

> material I had lying around, to the curved surface of the drum. I went
> through 3 pieces. They have a tendency to crack suddenly while they're
> under tension from being wrapped, and I do things like drill holes in them.
> It seems I remember talk of using heat to curve some window material. Was
> it acrylic? How much heat? Can anyone give me a quick hint or two about how
> to do this?

     Hmmm....   Acrylic is a thermoplastic, and if you can heat it to
about 260F or so it bends quite nicely (and permenantly.)    The
conventional method would be an oven to form a sheet.   I haven't tried it
myself, but what I'd do is place the sheet in your oven at perhaps 350F or
so, with the sheet resting on perhaps some wooden dowels.  Watchi it until
it starts to sag, then yank it out and toss it onto the curved
surface of the barrel, pressing down on it to bend it.  You won't get a
perfect fit, but it'd be a lot closer than a flat sheet.  :-)   Keep the
oven cracked--acrylic releases flameable gasses when heated.   (It'll
smell a little unpleasent.)   Experiment with strips of scrap plastic
ti get the feel of the process before trying for the final product.   Be
carefull with the hot plastic--it can give a nasty burn, and cools slowly.
If overheated, acrylic will form bubbles in it as tiny ammounts of
moisture in the plastic vaporize.

> I've seen discussion here of electic motors sealed in oil to keep water
> pressure out, but I never paid much attention, because it didn't apply much
> to me. But now I'm wondering a couple of basic things: (1) So is oil like
> water then -- not very compressible(2)

    Liquids are, by definition, not compressible.

> Does this work with just any motor?

    Assuming it's sealed to contain the oil.  :-)   There WILL be a loss
of efficiency since the motor can't turn as easily through oil as it would
through air.

> Why doesn't the oil short out bare electrical parts, like brushes or
> whatever? Is oil not conductive?

    Bingo, non-conductive.  Or rather, not conductive ENOUGH.   Get a
cheap multimeter and give it a try.


'Than