Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Parts ideas...comments please!
Date: Sep 25, 9:07 am
Poster: Richard Hull

On Sep 25, 9:07 am, Richard Hull wrote:

>I am thinking about revising my earlier (and more uneducated) ideas of a cylindrical fusor and going with a spherical one. I have located some potential parts sources and want some feedback about the suitability of these ideas.
>8" 1/8" thick SS-type 304 hemispheres, $61.70 each from http://www.jgbraun.com/balls.html. (I don't know about the properties of different SS's, maybe one of the more knowledgeable machinist-types could understand if this is suitable)By the way, I also saw the reference to Richard Hull's machinist.

I did all my own machine work and welding on Fusor III (shown on new fusor video). I used large SS 316 high pressure flanges found at a scrap yard.
($20.00) I have only a 6" lathe so I used my milling machine to work the flat blank off flanges into something that would work with the 6" hemispheres. (rotary table). Many manhours went inot cobbling that up. It works with indium seals and only marginally. GET THE RIGHT STUFF UP FRONT!

I figure I got fusor III up and running with OK, but marginal sealing, and if I figured just machine time at only $5.00 labor, I could have bought about 10 of the proper 8" conflat flanges!!!! (I only needed two)

You really should TIG weld or get it done for you. It is cleaner and more reliable. With brazing or silver soldering the parts will warp due to the required high temps. As they cool, the forces can easily crack the softer brazing alloy and leave you with warpped mating surfaces.

I also have a helium leak detector which I am restoring, although fusor III was not tested with one. I did take each half, as finished, and checked for gross leaks with acetone and did find two very small leaks which I touched up with the TIG system.

Fusor IV is a 6" system and I purchased the 8" Conflat flanges for that one fairly cheap (~$250 for both). I don't regret it either. Nothing seals like a conflat!

Fusor V will be a 10" fusor and I have already bought the official 12" conflats for it (Duniway) and am out about $700.00 for those two items. Go Conflat on any serious system over 6". By that time you are really serious anyway. (see the Zambelli system).

Hint, Stay small and the prices for pro stuff will follow suit.

Richard Hull