primary hold down's

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: primary hold down's
From: Tesla List <tesla-at-stic-dot-net>
Date: Sat, 7 Mar 1998 17:23:03 -0600
Approved: tesla-at-stic-dot-net

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From:  Chuck Curran [SMTP:ccurran-at-execpc-dot-com]
Sent:  Saturday, March 07, 1998 6:47 AM
To:  Tesla List
Subject:  Re: primary hold down's

Walt:

A very effective technique for holding the tubing into place is a by-product
of how you actually cut the notch itself.  Specifically, several years ago
someone on the list mentioned an idea that I have found to work very well.
Instead of cutting the notch so that it is 180 degrees of a circle, place
the center point below the edge of the form so that you end up with
something like 240 degrees of the circle.  I actually offset the center
point 1/16" and with 5/8" tube it worked well.  The tube then snaps into
place and stays quite well.  If you have access to a Bridgeport mill this is
real easy to do.  You could also drill the series of holes and then cut off
a portion of the form edge and drilled holes, to leave most of the hole/arc
in the form.  I have also done this with 3/8" tube with good success.  When
I make the next primary, which will be next month, I will probably offset
the center point somewhat more than 1/16".  Sometimes the 3/8" tube primary
would pop out of position when I was working on tap points.  I ended up
drilling a 45 degree cross hole underneath each notch on my bigger primary
and using a small nylon ty-wrap to really lock it into place.  That is
bullet proof , but the next one I will try with simply a deeper notch.

Chuck Curran


-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: 'Tesla List' <tesla-at-pupman-dot-com>
Date: Saturday, March 07, 1998 1:31 AM
Subject: primary hold down's


>
>----------
>From:  Walt Kulpa [SMTP:gwkulpa-at-earthlink-dot-net]
>Sent:  Friday, March 06, 1998 12:27 PM
>To:  tesla-at-pupman-dot-com
>Subject:  primary hold down's
>
>Hi, I'm working on the form for my 1/4" refigerator tubing primary.
>I'm planning on using 1/4" polycarb for the support fins. I've got the
>calculations made on where to notch the plasitc in order to create a
>nice uniform  30degree slope and 15 degree rise with 1/4" spacing
>between turns, but what I don't have is, what can i do for holding the
>tubing into the notches? I don't want to just let it lay there, do I?
>I'm not so sure that adehesive is a good idea, is it? How is holding the
>tubing into the plastic commonly done?
>Thanks, Walt Kulpa
>
>