Homebrew PCBs

----- Original Message ----- 
From: "Len Warner" <yahoo@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, November 19, 2006 11:26 AM
Subject: [Homebrew_PCBs] Re: Ultrasonic etching tank?


> At 2:25 pm ((PST)) Fri Nov 17, 2006, Christopher Hart wrote:
>>On Friday 17 November 2006 11:32, Leon Heller wrote:
>>[snip]
>> > Why not use continous agitation for the larger boards by rocking the
>> > container? They will only take about 10 minutes.
>>That would require me watching the boards constantly. I frequently have 
>>many
>>projects going at once, and I just work on another while waiting for the
>>boards to etch.
>
> There used to be a photographic darkroom aid for print-making which
> rocked the dish to create wave motion to ensure even developing or
> thorough fixing.
>
> It should be a trivial exercise for most of us to rig up something similar
> using a snail cam driven by a geared mains synchronous motor or a
> barbecue spit motor.

There used to be a design for something like that in the ARRL Handbook, 
using a small motor and eccentric cam, with the etchant kept warm with a 
heat lamp. Manual rocking in a larger container half-filled with hot water 
works very well and only takes a few minutes.

Leon