Etching Tank

I've been busy on non-ham activities the last few weeks so I haven't progressed many projects. I'm re-organising the workshop and trying to throw out some equipment surplus to requirements. My wife calls it junk!

I had a few SCSI tape drives lying around and as I opened one up to recover the controller board it occurred to me I could make a tank agitator for etching. In the past I had used an aquarium bubbler with an air stone. I stopped using this because it generated a plume of etchant that stained nearby objects. I moved on to putting the pcb in a zip lock back and manually rocking it while it sat in a dish.

This works well but if I could automate the rocking and heat it at the same time things would be better. I'm blessed with a working stove and hot plates in the workshop, but don't tell the wife or I might be expected to move into the workshop for good.

So there when I opened the SCSI drive was a great big cog used to load the tape. It took all of 5 minutes to work out there was a lug underneath the cog I had to chop off so it could rotate continuously and wire up a plug pack to the motor. A few more minutes to work out how to attach the rotating cog to the etchant bath and I was done. I used a bolt onto a pop stick, or small piece of wood found in frozen ice sweets, and a piece of string from the wood to a peg on the dish.

With the hotplate turned on and the motor running things went smoothly. The only issue is the dish tends to walk around the surface of the hot plate. I'm going to fix that by running the cord over an arm and pulley perhaps 50cm above the etchant tank. That way the lifting on the tank will be vertical instead of including a side to side motion as well.

The current arrangement looks like this before I make the arm and pulley:

A very temporary proof of concept. Which just goes to show that one man's junk can contain his treasure.

Regards
Richard VK6TT