The parts list is pretty simple -

• 2m of 25×25x3mm Angle Iron
• 2m of 25×15x3mm Angle Iron
• 5m of 3mm steel rod
• 300×300mm steel plate
• 4 x nuts and bolts

This is also a good excuse for me to buy some new tools like a welder!

I did try to scrounge the parts for this but the scrap men have done a pretty thorough job of taking anything not bolted down so I had to buy most of it new.

Step 1

Cut 45 degree  mitre’s in the Angle Iron

Step 2

Heat the bend points and slowly bend the metal.

Step 3

Weld the two corners of the Angle Iron together and weld the steel plate at one end. As you can tell by the picture this is the first time I have ever welded! I would have made the welder myself from microwave transformers but when you can buy them from eBay for £20 it’s not really worth it.

Step 4

Cut the rods to length and weld them on.

Step 5

Grind down all of the nastyness and spray on some high tempreture BBQ paint.

Step 6

Cut the legs to length and cut a notch in to one end so that they can hinge then drill the legs and frame and bolt it all together. I also added some cross bracing to the legs to stableize the whole thing.

And your all done!

UPDATE!

Here it is in action

This project started out because of a need to etch circuit boards and a lack of success doing it the cheap ‘etchant in a tray’ method.

Heated bubble etch tanks were well over my budget and at five liters were also too large. As always eBay came to the rescue by providing three A4 (210 x 297) 6mm sheets of perspex and a 150 watt aquarium heater.

As you can see I divided up one sheet of perspex in to three sections. Two, two inch pieces for the sides of the tank and the remainder for the base. I used a hand held jigsaw to make the cuts, the secret is to use a very fine blade with lots of teeth and when cutting go slow and steady, don’t try to push to much.

Now the messy part starts. Glue the sides all together making sure every things clean and free of burrs first. I initially used normal silicone bathroom sealant but it wouldn’t hold the panels together (probably to smooth) so I had to clean everything up and start again. In the end I used aquarium sealant / glue, used for making fish tanks. Then clamp it all together (you might getaway with elastic bands) and leave it overnight to dry.

The etchant I use is sodium persulphate which works best when heated to between 40 to 50°C which is where the aquarium heater comes in. I had to modify the heater to reach the fish killing temperature needed as it only went up to about 35°. That was as simple as pulling of the temperature selector knob, unscrewing the holder underneath it and cutting off the plastic stop. I picked up a cheap aquarium thermometer (notice a theme here) that handily goes up to 50° so that I could fine tune the temperature.

Now to the bubbly part. I already had an aquarium air pump so I ran a length of pipe (I used medical oxygen hose as it’s a. what I had to hand and 2. allows the hose to be bent without blocking the flow.) to a piece of rigid plastic pipe. I used a hot needle to pierce holes in the pipe and held it down with some suction cups.

If you’re following along at home now is the time to fill it with water and give it a test run. For some reason after a while the bubbles were only coming out of half the pipe, but it’s still enough to keep the etchant moving around so it still does it’s job. (and anyway it was getting late and I was in a rush to etch a board) This is also a good time to adjust the heater to the required range.

Fill with etchant and your done! The capacity is approximately two and a half liters so I had to use five 100g packs of sodium persulphate.

Of coarse if you actually want to be able to use it, you’ll need some way of hanging the board in the etchant. As I only needed to etch a small board I put a couple of plastic cable ties on to a bamboo skewer and bent the bottoms up with the aid of a little heat.

And that’s all there is to it.

Epilogue

Don’t design and make all of this late at night because you’ll forget about silly little things like a lid. Sod it, cling film will do.