I've finally perfected the PCB etching process with my new magnetic stirrer/hot-plate combo that I picked up from Ebay. I can now completely etch a 6"x6" 1 oz. double sided PCB in about 12 minutes. Previously, it was taking 30-40 minutes.
After attempting to etch a board with a large magnetic stir bar and getting FeCl all over, I decided to modify my pyrex baking dish with some standoffs to keep the PCB off the bottom and allow room for the magnetic stir bar.
I picked up these squished marbles from a craft store for $2 and then using pure silicone sealant, I glued them to the bottom of the pyrex dish.
These are the perfect shape and size for this application and they come in a variety of colors to satisfy even the most demanding home-built PCB hobbyist!
After using a larger stir bar, I realized that it was way too much stirring action and wasn't really necessary. So, I picked up a 1/2" x 1/8" stirbar and it works just great.
This little gem was picked up from Ebay for $20. It was auctioned as a broken unit, but after opening it up, I found that a screw had worked itself loose and was lodged in the cooling fan. I removed the screw, and re-installed it in it's proper hole, and the unit fired right up and works great. Score!
The hot-plate feature is highly recommended. This unit will bring a baking dish of water to near boiling temperature in roughly 15 minutes. I'm guessing that I run the FeCl at around 150-175 degrees F. I wasn't sure where the toner would start to melt at, so this seems to be a safe range.
This is the first stir bar that I tried. It was much too powerful with this bar.