Re: [TCML] A new guy with a primary threaded through holes

[Joe Mastroianni <joe@xxxxxxxxxxxxxx>]

To all - this is my first coil, though I have been involved peripherally in building others - many many years ago -( we're talking High School science fair - we used window glass and steel plates to make our capacitors), this is the first I'm doing solo.  Though I tend to build a lot of different things, this is my first foray into High Voltage.  I have have a couple decades generic electronics experience, but those are things like analog synthesizer modules, computer controlled devices, and all things ham radio.   I am getting my TC build information from the web, and the past decade of writings from you kind gentlemen.

----

On the issue of "work hardening" -> Yes, this is absolutely a fact and I suffered from it - though only very slightly.  What I noticed was that  I was not so much rebending the copper with every twist as following it's natural curve, at least on the outer turn.  In fact, my outermost turn was/is about the same diameter as the coil of 50' copper I bought from ACE Hardware.  So feeding it through at least the first turn required no bending. 

Then, as the coil was threaded, the stanchions imparted to it a natural, gentle, spiral bend, and I'm sure this bending not only work hardened the copper, but also added to the friction that impeded the threading process.   

However, the work hardening was never a problem.  I never had to manually bend the tubing.  It always seemed to be naturally threaded/aimed toward the next hole from the process of being forced through the prior holes.   And I can absolutely see how if you took a tool of some form, like a pliers, to manipulate the coil you'd turn it to a kinked, wretched mess.  But I never used anything to coax the coil other than my fingers.

And I am now eating ibuprofen and celebrex daily to get over the pain in my fingers and wrists.  This was not a trivial physical endeavor, and until my coil is complete I honestly don't know if the result was worth the investment in pain.

On the issue of gluing & plastic work ->  I'm hoping I have my plastic species correctly labeled.  This is only the second time in my life I am doing a build with this material, so a lot of trial and error is involved.   I live in the SF Bay area, and I am lucky enough to have three different TAP Plastics storefronts within a 20 minute drive of my home.  I have been getting my materials there.  The 1/2" I used for the stanchions was called "Polycarbonate" by one of the guys at TAP, and Lexan by another.  The cement I used was called "Acrylic" cement, even though I was gluing polycarbonate, they recommended it.   I just presumed that Acrylic was some sort of overarching term for all the stuff I was gluing, because it worked. I did see the stuff called "Weldon" at TAP, but as I was getting good results from the optically clear Acrylic Cement stuff, so I stuck with it.

The underlying 25" disc is a thinner material, probably about 1/8" and is definitely NOT the same stuff as the Lexan.  The so-called Lexan is hard and machinable - just use metal cutting bits/blades at low speeds.  It also stinks to high heaven when you machine it, as it inevitably melts slightly at the point of contact with the cutter.

The disc is a different material that is living hell to machine.  It has a lower melting temp.  If you don't drill on the lowest speed it tends to "weld" the bit into the hole (just think about what happens in metalwork when everything gets too hot - and you have the same thing only at low temps) .  I have had to extract several bits, now.

TAP offers suggestions on their website, and I have spoken to their staff directly. I have tried cutting both materials with a Bosch jig saw, and even on low speeds the non-Lexan stuff melts so badly the cut "heals" behind the blade.  TAP recommends cutting it on a table saw.  They also recommend a router.  I have tried the latter, and it makes an unbelievable mess.  It's not unlike robotically plucking a chicken at high speed, as thin white, feather-size chips fly all over.   I did not want such a mess gumming up my table saw, so I still haven't  tried that, but it probably lends the best cut control.

One other thing - I tried to cut off the top of the holes on one of my test stanchions to make the so-called "C" notches.  That was an unmitigated disaster.  The lexan tended to fracture around the holes using a router (I probably had the router speed too high - but still, it was not good.)  And when I did get one to work I rapidly discovered that Lexan doesn't "give" at all, so unless you have the "C" hole exactly the right size, you can't press fit the tubing.  You might as well be trying to push the copper through a steel groove that's too small.  And is you press too hard, the lexan fractures (at the thin part of the "C" on top). 

All of which gets chalked up to experience.  I think the next time I do this (if there is a next time) I will go with the notches and not the holes. 
   

Best to all,

Joe





>:L or K style "soft" copper tubing work hardens every time it is bent
>slightly, or "skotched" as you call it.
>
>I use 3/4" wide x 1" high x 7-10" long delrin blocks, then machine a series
>of "U-shapes" into the blocks using a ball nose cutter on a milling
>machines.  It's fast, easy, and the copper tubing quickly snaps into place.
>No excessive bending and work hardening of the copper.
>
>Dr. Resonance
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