Re: ATM Junkyard Aluminizer :)

[ATM@antiquaries.com]

Congratulations!

Tungsten wire is very flexible until you heat it the first time. I 
used to wind a spiral spring-like coil, leaving two legs. The legs 
were connected tot he high-amp terminals and small loops of pure Al 
hung on the coil, which was horizontal. Tungsten is soluble in molten 
Al so the wire would get very thin where the Al was. I remember 
getting about 2-3 burns on a filament.

Best to try to have the mirror vertical so if some Al falls off it 
won't damage surface.

You can run a high-voltage electrode into the chamber and watch the 
plasma as the vacuum gets better. Great fun! I suspect, too, that 
there is some ion cleaning of the surfaces if you do this.

Anyway, congratulations again!

Frank Manasek




>Greetings All,
>
>Despite the following difficulties, I actually built a functioning
>Aluminizer for less than a Grand!
>
>#1 Penning Gauge is dead, used to work, but not when I needed it.  (I think
>I can fix it, but I've had good luck "Driving Blind")
>
>#2 I need to optimize the tungsten evaporator,
>     I'm using tungsten Tig rods, and they work, but I need to build a better
>system of holding them in place, as well as making a JIG to heat and bend
>them into shape.  I've been using pliers and a blow torch, and it works but
>it could be much better!  Also, can anyone give advice on an optimal
>evaporator layout?  My chamber is a little short (12" diameter X 12" tall)
>by the time I put a 10" full thickness mirror in there, the distance
>between mirror and filament is only ~10".  I did a before and after on a 10
>inch I did today, and my coating did remove some of the correction (as
>expected). Fortunately the mirror was slightly over corrected to start with
>so the coating actually helped in this case.  I was thinking that perhaps
>having 3 evaporative point sources off set by some radius from the center
>may help, but I'm not sure how to calculate the effect.
>
>#3 I MUST add a shutter, I put a 1/4" pit into a mirror today when a blob of
>aluminum fell off the tungsten wire and onto the mirror during filament
>startup.  Most disappointing!  I think I may have run the tungsten a little
>too hot during start up, or loaded up with too much AL  The odd part is the
>blob landed several inches off center of the mirror / filament  (Murphy's
>law?)
>
>The good news is I'm getting excellent adhesion, only a couple small pin
>holes, decent coverage, no oil back streaming problems, and its LOTS easier
>than silvering!
>
>If interested you can see my contraption on link #19 from my webpage
>
>Take Care,
>James Lerch
>http://lerch.no-ip.com/atm (My Bino-Scope Construction Site)