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THE AM BULLETIN BOARD => Technical Forum => Topic started by: W7SOE on March 10, 2009, 12:56:53 AM



Title: Fimo!
Post by: W7SOE on March 10, 2009, 12:56:53 AM
I am going to wind a new tank coil myself.  I have seen this done with epoxy used as the "rib" material.

Has anyone ever tried to use Fimo before?

(Femo is a polymer craft clay that gets hard when baked)
http://en.wikipedia.org/wiki/Fimo

Wonder what the HV properties are....

Plus I can have pink tank coil ribs.  ;-P



Rich


Title: Re: Fimo!
Post by: KL7OF on March 10, 2009, 08:03:49 AM
give some cured Fimo a ride in the microwave oven.....pretty good test for RF properties


Title: Re: Fimo!
Post by: W7SOE on March 10, 2009, 04:45:39 PM
I think that must be THE Rf test!

Come to think of it, that epoxy putty that you knead to mix might be better.

rich


Title: Re: Fimo!
Post by: KL7OF on March 10, 2009, 05:12:10 PM
I have used hot glue ...or wind your coil out of tubing that needs no support


Title: Re: Fimo!
Post by: W7SOE on March 10, 2009, 06:27:49 PM
Tubing will take up too much space.

I have tested a bit of Fimo on a small coil (Sculpey actually, different brand) and it works great!  Gets hard but still flexible.  Haven't been able to break it.

Can't detect any conductivity.  (HV untested)

Rich


Title: Re: Fimo!
Post by: W7SOE on March 12, 2009, 12:26:02 PM
Wound a nice straight 2" coil, about 30 ft of 12 gauge.  Managed to get it off the form ok and laid down two ribs of Fimo.

Popped it in the oven. 

What does metal do when heated?  It expands! 

Watched the whole thing spin and destroy itself as the metal heated and the coil gave it self about five more turns!   :o

Had to laugh!

Will try again with the no-bake epoxy putty method.

Thanks for indulging my goofy threads.

Rich


Title: Re: Fimo!
Post by: W3SLK on March 12, 2009, 08:19:18 PM
Rich, I rebuilt a B&W 850A by using acrylic dissolved in acetone. I used a flat piece under the coil and spread the dissolved stuff on top with a short cropped brush. It worked quite well. My only problem was that the evaporation rate of the acetone caused many minute bubbles through out the paste after it dried out. However it was still strong. Something else I thought about trying was winding a coil on a form with some synthetic and applying a current through the wire just enough to heat and soften the stuff around the wire. Then turn off the power source and let it set.
GUD Luck OM.
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