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Subject: Re: [Homebrew_PCBs] Pump for sray etching

From: Adam Seychell <adam_seychell@...>
Date: 2003-11-23

I mentioned the nozzle types I'm using in one of my earlier
replies.
What you propose sounds interesting. Just a quick warning,
try not spend a lots of money on an idea in case you end up
scraping it and starting again :) I've leaned this the hard
way.
I think one of the most difficult tasks building a spray
etcher is configuring the nozzles and spray patters so you
get uniform etching. I'm sure the spray etching equipment
manufactures spent lots on R+D to get this right.

Adam


mpdickens wrote:

> --- Adam Seychell <adam_seychell@...> wrote:
>
>
>>What was the voltage and current during
>>your test ?
>
>
> I set the pump up in a configuration I was told was
> the most common in an RV (At least, most RV's here in
> the US):
>
> 12 Volts
> 5.5 AMPS (The pump is rated up to 7.0 amps)
>
> Question:
>
> What are the dimensions and specifications of the
> nozzles that you are using. I've settled on using
> quanitity-6 180 degree fan nozzles (Three for the
> front of a pcb and three for the back of a pcb.
> Further, I think I'm going to use quantity-2,
> windshield wiper motors to rotate the nozzles back and
> forth. This will afford me multiple speeds of 180
> degree back and forth rotation without having to do a
> stepper motor. Also, I've found a portable plastic
> sink that I'm going to use as the enclosure that
> houses the spray machine. I going to build a door that
> fits on the top of the sink that will have a lexan
> window for viewing. The drain in the bottom of the
> sink will be connected to a gasoline can (Firmly
> attached, but quickly and easily removable). The
> etchant will be pumped from the gasoline can into the
> enclosure and then allowed to drain back into a
> gasoline can (For easy maintenace). So, basically,
> during the etching process, the etchant will circulate
> between the gasoline can and the enclosure via the
> pump. Modularizing the etchant allows for a couple of
> features/benefits:
>
> 1.) I can filter the etchant as it etches (Less wear
> on the pump) so that viscosity stays realively
> constant.
>
> 2.) Regenerating etchant and/or changing out etchant
> is easy.
>
> 3.) I can easily wash the pump out with h20 following
> use without diluting/contaiminating the etchant.
>
> 4.) I can wash the board in the machine prior to
> removal.
>
> 5.) breaking down the etching machine is easy: The
> etchant is self contained and easily storable.
>
>
> Best regards
>
>
> Marvin Dickens
>
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