Re: ATM Amateur Anodizing?

[andydtg@phoenix.net]

Dave Sleeter wrote:

>Here's a question that should be of interest to lots of ATMs. Is there a 
>way that amateurs can color and anodize their own aluminum? Anyone with a 
>lathe can make telescope parts out of aluminum, but getting them black 
>anodized is always a problem. The process isn't expensive, but the 
>minimum setup charge of $50 to $100 makes in impractical to have just one 
>or two parts done. If anyone knows a way that ATMs could anodize their 
>own parts in their own workshops, this would be of great help.

There was a thread on this a few months ago, no quick/easy answers. 
I've been experimenting with anodizing in my spare time. The
process itsef is *real* simple but can get messy:

- the anodizing itself consists of immersing the part in a dilute bath
  of H2SO4 (battery acid, available at your car parts store). The part
  is connected to the + side of a dc power supply. The - side is connected
  to a lead plate of comparable area to the part also immersed in the
  tank but *not* touching the part. I tried a heavy duty 12v battery
  charger & found there's not enough voltage to get a thick enough 
  coating. I'm building a 50-150v variable supply. The anodizing
  itself is transparent. It takes several minutes to get a coating.

- Dyeing is the real problem. It's also simple, just soak the anodized
  part in a *hot* bath of dye until the color is what you want, then boil it 
  in clean water for several minutes to seal the dye & flush out the acid.
  I've tried some of the 'Rit' mineral dyes (Walmart) without much
  luck. The commercial black dye can be bought but the minimum 
  quantities are *ridiculous*, I was quoted $500 for a several lifetimes
  supply of the black stuff. 

If anyone knows a source for small amounts of anodizing dye, please
post! I'll report results on these experiments as I get them.



 

 
Andy Saulietis / DTG Alt-Az-Fp Drive Systems
HDPE Worm Gears, Custom designs & Machine work
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax
e-mail: andydtg@phoenix.net