[TCML] Preparing acrylic coil form
bert.hickman at aquila.net
Sat May 3 07:57:05 MDT 2008
Hi Scot and all,
Just a minor quibble - Lexan is polycarbonate (PC), while acrylic is a
different material, polymethylmethacrylate (PMMA). Both are excellent
dielectrics, and both can make great performing (and great looking) coil
However, coilers may want to use caution when using some solvents on
polycarbonate or PMMA - try out on a scrap piece first. Lexan tends to
be more sensitive to solvent damage than PMMA. Some solvents, such as
alcohols, trichloroethane ("trike"), or acetone, can cause immediate
crazing (a network of small surface cracks), especially on curved
surfaces where the material retains internal fabrication stresses.
Many years ago, a coiler reported that he had tried cleaning his brand
new Lexan coil form with isopropyl alcohol in preparation to winding.
The form rapidly began developing a network of surface cracks (crazing),
and the spider web of cracks began spreading before his eyes. They
simultaneously grew deeper, and the form disintegrated into small
fragments in a just matter of minutes.
> Hey Matthew....
> Acrylic (Lexan, polycarbonate plastics) are/is an awesome choice for a
> secondary form. Some things you may want to consider when using it is to
> make sure you clean the winding area with some type of cleaner like
> Windex to remove any source of sweat, salt residuse while handling it. I
> personally dont agree with the application of solvents, sanding or using
> harsh chemicals on the tube. I have found that applying a thin coat of (
> comes in many names) "Tool Coat"( Tool Grip comes to mind) its clear and
> has a rubbery finish when dry, but I have used it in a manner as when I
> am winding the wire on the tube to spray a light coat as the wire goes
> on to the tube it helps bond the wire to the tube and "seems" to add ito
> the insulative properties of the winding. Once the winding is completed,
> I apply another final layer of the spray to the secondary to complete
> the process. It makes for a resiliant "flexible" coat and is more
> resistant to cracking than Behr 50 ( if you can find it, its good stuff
> but becomes very brittle a few years later)...
> cleaning with a solvent, sanding and drying falls under the prep for PVC
> in retrospect... clean it, spray it lightly, apply wire, recoat it....
> but take your time :)
> Scot D
> Mark Lock wrote:
>> Hi all.
>> I've been slowly building my first TC for a while now and I've recently
>> acquired my coil form, a nice piece of acrylic. My question is what do I
>> need to do to prepare it for winding? I've read that it should be cleaned
>> with a solvent, sanded, dried and varnished among others, but is that all
>> My transformer is 12KV 30mA if that's any indication of how much
>> is required.
>> Thanks for your help, this mailing is awesome.
>> Tesla mailing list
>> Tesla at www.pupman.com
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