Re: Advice on Primary

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "James Robinson" <james.robinson@xxxxxxxxx>

Hi,

It all sounds like doom and gloom for winding the copper through holes, 
however I did it that way, and it wasn't too difficult. I roughly formed 
the tubing into a spiral on the floor, and i mean pretty rough spiral of 
about the right dimensions not worrying about getting the spiral anywhere 
near exact.  Then I started feeding on the formers from the outside of the 
spiral, innermost hole on the former first, doing this one former at a 
time. Then I distributed the formers to their approximate positions around 
the outer turn, so the pipe is through one hole of each former.  Then comes 
the hard part (more time consuming than hard); go around the spiral, moving 
each former an inch or two in the right direction thus "screwing" the 
formers onto the pipe.  Do this one former at a time in the same direction 
as the coil is wound. Eventually the first former will get to the outer end 
of the pipe, which is then threaded through the second hole and so on. It 
does get quite tight toward the middle, as more holes are threaded, i 
started having to tap the formers gently with a small block of wood. As the 
formers go round they force the pipe into a near perfect spiral.

I used some machine oil to lubricate the holes, constantly re-applying 
through the process  - but perhaps a silicone lube might work better - 
anything that won't attack the plastic.


If you absolutely must join do it as others have suggested with some kind 
of soldered "dowel" and make sure that it is completely deburred smooth 
join - I would do thius before you start to wind.  I would calculate the 
total required length before you start to wind and cut to length (do the 
maths 3 times b4 - cutting too short would be a nightmare!) You should be 
able to find the equation for the length of a spiral on the web.


points to note -

* keep formers approximately evenly spaced throughout the process
* make sure the holes aren't too tighter fit
* lubricate throughout the process
* keep it slow - an inch or two at a time is fine - any more and i suspect 
you may find yourself in a pickle.
* wind with the formers 'loose' i.e. not joined to the base board and fix 
once complete.
* calculate the pipe length before you start and cut to size.


It does take time (it took me about 3 hours sitting in front of the TV with 
a glass of wine!) but the results look very good.



I would like to post some photos - is there anywhere I can do that anyone??

James Robinson


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, February 23, 2005 12:00 AM
Subject: Advice on Primary


> Original poster: "Medina, Benjamin (UMR-Student)" <bamxbb@xxxxxxx>
>
> Hello,
>
> I know this topic has already been discussed but I am still having doubts 
> when it comes to the winding of the copper tubing through the holes or 
> notches of the supports. So if someone could clear this up for me that 
> would be very much appreciated.
>
> As of now this is what I plan on using:
>
> 1. A 50ft roll of 1/4" OD refrigeration copper tubing.
> 2. A 3/4" thick sheet of plywood as the base.
> 3. 5 supports in an L shape cut out from a cutting board I got at WAL-MART 
> fixed to the plywood base with screws (similar to the image below).
>
>
> http://hot-streamer.com/temp/Medinaimage001.jpg
>
>
> At first I thought of fixing the supports to the base and winding the 
> tubing through the holes, but now I am realizing it will be a PAIN!! 
> Therefore, should I slide in the supports, starting at the center and work 
> my way outside, through the entire roll of tubing? Or should I start at 
> the ends and work my way inside?
>
> Some people prefer holes in the supports; others prefer notches. I am not 
> sure about this. I am thinking that the notches might bend the tubing if 
> one is not careful when doing this. Any suggestions?
>
> Say I want 15 turns. While winding the tubing, let's say I run out of 
> tubing on the 11th turn. Is it okay to solder another continuous piece of 
> tubing to the original, to complete the 15 turns or not? I guess, what I 
> am asking is if I need a continuous roll of tubing or not? Will this 
> affect the coupling and/or the overall performance of the TC?
>
> Another thing I noticed is the fact that the tubing is double wounded, 
> making it even more tedious to work with it. A guy at Home Depot suggested 
> to unroll the tubing on the floor and then wind it on/through the 
> supports. Any suggestions?
>
> I appreciate your time. Thanks for the help.
>
> Regards,
>
> Benjamin Medina
> Rolla, Missouri.