[TCML] Preparing acrylic coil form

[Bert Hickman]

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 
forms.

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.

Bert

bunnykiller wrote:
> 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 
> piping...
> 
> 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
>> necessary?
>> My transformer is 12KV 30mA if that's any indication of how much 
>> insulation
>> is required.
>>
>> Thanks for your help, this mailing is awesome.
>> Matthew.
>> _______________________________________________
>> Tesla mailing list
>> Tesla at www.pupman.com
>> http://www.pupman.com/mailman/listinfo/tesla
>>
>>  
>>
> 
> 
> _______________________________________________
> Tesla mailing list
> Tesla at www.pupman.com
> http://www.pupman.com/mailman/listinfo/tesla
>