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Re: No secondary coil form/former



>EDHARRIS-at-MPS.OHIO-STATE.EDU wrote:
> 	Don't use any form! I was playing around this weekend and found that I
> could wind a coil of magnet wire on a waxed paper coated PVC form. The PVC was
> slitted up/down one side to allow it to collapse when I was ready. I wound a
> 8"long 4" diameter coil and coated it with 2 coats of Celluose Nitrate based
> laquer ( that's all I had), let dry for 1 day, then collapsed the PVC form. So
> now I've got a fairly rigid free standing coil with no former material save a
> bit of waxed paper which was "glued" to the inside. The coil is very stiff but
> could easily be crushed - it could support a light aluminum toroid but I'd use
> a thin stiff internal support for much more weight.

I have had exactly the same idea - except that I'd use polyester-resin
for the coating as there are antiadhesives for polyester.. One could
easily coat the "halved" pvc-pipe with the antiadhesive and apply
a few layers of polyester-resin on top of this - after that one would
wind the coil and add a few more layer of polyester.. After this one
could just remove the pvc-pipe or what ever "mould" one uses.. 

It might actually be logical to add a few layers of PE or waxed paper on top
of the pvc and add the antiadhesive on top of this as otherwise it might
be difficult to remove the pvc-pieces.. The layers of PE or waxed paper
can easily be removed as they wil not be "glued" to the inside.. 

It's great to know that someone actually tried this..

The great question is whether this kind of a coil-form is electrically
strong enough - or how thick should the walls of resin really be? 

Yours,

  Kristian Ukkonen