04 Gluing acrylic (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 9 Sep 2003 17:29:54 -0400
From: B2 <bensonbd@xxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: 04 Gluing acrylic

> > I am searching for a good method of gluing a stack of two or three
> > acrylic disks, to make an electrostatic machine with embedded sectors
> > in the disks. Imagine a Wimshurst machine with the sectors inside the
> > disks, accessed only through small buttons.
> > I tried so far two methods:

Hi Antonio:

Acetone works for me.  Getting the bubbles out takes a lot of practice.
Clean both surfaces scrupulously with isopropyl alcohol (reagent grade
ethanol if oven stress relieved).  Bond strength gets better the longer the
acetone is in contact with the acrylic.  Practice a lot on scraps before
attempting the big pieces.  You may have to "soak" the inner discs in the
acetone to get enough surface penetration for a good bond.  A good bond is
present when the stack appears optically as one disk with no or very few
bubbles.  Weights may be required to get the bubbles out.  Bonding is almost
instantaneous.  You only get one chance to do it right!

Another method is to heat the assembled acrylic pieces together in an oven
just below the melting point.  They must be lying on an absolutely flat and
level surface.  Use weights on the top piece.  This requires great skill to
be done successfully.

Another method is to hold them together with many nylon screws.  Use RTV to
insulate the holes.

Another way is to use a compression hub with two halves that screw together
and tighten the center part together.  Can be as simple as a piece of half
threaded rod, two nuts, two lock washers, and two fender washers.

There are other methods using lasers, microwaves, induction (dielectric)
heating, or ultrasonic welding, but I am not familiar with them.

Cheers,

Barry