Saturday, 17 November 2012

Bubble etch tank complete

All the ebay ordered parts have arrived, and so I've assembled the etch tank. It all went together as planned in the last post - the only tricky detail was cutting some plastic strips to cover the hole where the semi-circular stand holder was removed from the inside of the frame.
Etch tank bubbles at 51 degrees
On the right is the aquarium air pump. This is connected to the air curtain, cut to length and sitting at the bottom of the tank. A right-angled connector for the air curtain was made from a scrap of polyethylene (aka, blue plastic chopping board) and the barb from a garden irrigation tube joiner. And a bit of hot-melt glue.

The multimeter is showing the temperature (Celsius) of the water in the tank, via the thermocouple in the tank top centre.

The water is heated by that white stick sitting vertically in the left of the tank - this is the heater - just two 30 ohm resistors in series, encased in heatshrink tubing.

The heater seems pretty effective. At 0.75A of current, I was able to raise the water temperature from 22 to 52 degrees in about 15 minutes, so it should be more than capable of maintaining the temperature of the etching solution, if it starts at the correct temperature. I'm driving the heater from an adjustable bench supply, so I'll adjust the current to find the equilibrium point is (or near enough).

Now, all I need is a project to etch...

Total cost

2"FORMAT" 6x8" photo frames$6.00
1Small tube of silicone sealant$8.50
1Aquarium air pump (incl delivery)$6.58
12 metre length of air tubing (incl delivery)$2.45
130cm air curtain (incl delivery)$1.96
230 ohm, 6 Watt wirewound resistors$3.68
1Length of heatshrink tubing-
1Length wire for heater-
Total:     $29.17