Carl,
Years ago we had the same problem with loose turns when we wound our big coils. What we did to resolve the problem was to pre-heat the spool of wire by placing it in a box overnight with a 100w "incandescent" light bulb. Then we spooled the wire out of the box and directly onto the coil form with a good drag for a tight wrap and never had another problem.
The other trick is to lay down a thin coat of your coating compound directly in front of your winding so the coil gets wound wet. This technique and a custom machined comb worked great for large space-wound coils.
Hope this helps.
Regards,
BrianB
> On May 8, 2014, at 10:08 PM, "Carl" <cn8@xxxxxxx> wrote:
>
> Has anyone had problems with unequal thermal expansion of copper and PVC causing loose turns? We wound a coil into epoxy at about 11:00 this morning, and at 5:00 we had a bunch of loose turns. (Slow setting epoxy.) We put it in a dry sauna and they tightened back up, and it made the epoxy set faster. We had a similar problem on another coil, too. The coefficient of expansion of copper is 9.3 in/in degree F while PVC pipe is 28 9.3 in/in degree F. Maybe it would be best to wind it cold.
>
> ---Carl
>
>
>
>
>
> -----Original Message----- From: Kenneth Luo
> Sent: Thursday, May 08, 2014 6:24 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Request for a NST
>
> Hi everyone,
>
> Thanks for the offers, but the first two people I emailed already replied
> back, and one of them happened to be within 90 min. driving time so I just
> drove over there today and picked up the supplies I needed. I got 6 OBITs,
> so with any luck at least two of them will be properly working and I can
> get started.
>
> Kenneth
>
>
>
>
>> On Wed, May 7, 2014 at 10:15 AM, <imie13@xxxxxxxxxxx> wrote:
>>
>> If you are in the Chicago, IL area I have something of interest.
>>
>> ----- Original Message -----From: Andrew Robinson <arobinson@xxxxxxxxxxxx>To:
>> Tesla Coil Mailing List <tesla@xxxxxxxxxx>Sent: Wed, 07 May 2014 03:38:01
>> -0000 (UTC)Subject: Re: [TCML] Request for a NST
>>
>> On 5/6/2014 12:04 PM, Kenneth Luo wrote:> Is anyone still offering to sell
>> some spare NSTs / OBITs for a small SGTC> project?>> John Howson and Miles
>> Waldron already offered, but when I tried contacting> them a few days ago
>> they didn't respond. (To be fair, I only replied back> to them several days
>> after their offer).>> Thanks,> KennethI also have a few older style 15/30s
>> and maybe some 12/30s. I might be able to ship, but it can get expensive
>> for those heavy things. Contact me off list if
>> interested._______________________________________________Tesla mailing
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