A while ago I bought a cheapish welder on eBay. Its a Rossi CT620iS. Its a multi function unit that does stick welding, DC TIG welding (no aluminum) and plasma cutting. The whole mess uses cheap standard parts that can be ordered freely on eBay from the usual places. The various torches have model numbers on them too.
Stick welding is straight forward. Buy a packet of sticks, hook up the ‘earth’ clamp, put a stick in the tongs and start covering everything in smoke, spatter and slag. Fun stuff.
TIG and plasma cutting require a bottle of Argon and compressed air respectively. The flow of gas is controlled in the welder by an electrically operated tap (solenoid valve). On this welder both gasses go into the same gas intake on the back bottom right. This does present some plumbing problems which I have solved like this:
This is a flammable gas free zone. I would absolutely not proceed like this with acetylene, propane, butane etc. However, I thought that for routing compressed air in through the regulator and moisture trap at the top (air goes in from my compressor at the left) compressed air fittings would suffice.
I also decided to use these fittings downstream from the Argon flow regulator that is screwed into the ‘swap and go’ Argon bottle. I have not found documentation to say this is ‘OK’ but I am happy with it unless someone tells me its dangerous somehow. I’d certainly not run bottle pressures through such fittings though.
As an aside, Argon is by far the most abundant gas in Earth’s atmosphere after Oxygen and Nitrogen. It is 20 times more abundant than Carbon dioxide which is the next most common gas. Oxygen, in second place, is 20 times more abundant than Argon.
As you can see, I am currently set up for Argon. The air regulator at the top is not connected at either the inlet or the outlet in the picture. To change I need to unplug the Argon and plug in the hose hanging down from the air regulator at the top. I then need to connect my air compressor at the top left.
I recently discovered the ‘ear clamps’ you can see on the hoses. These are excellent. I crimp them shut with some nail pulling pincers. There are of course proper tools… The clamps are single use but have no sharp bits sticking out of them and are, for want of a better term, ‘sprung shut’. If the hose under them compresses they can take up some of the space created. Screw clamps don’t seem to do this to nearly the same degree. I remove the ear clamps with a grinder by grinding at an ear until I am through.
There is also some glue lined heat shrink over some of the clamps. This is to provide strain relief and wear resistance. The outlet of the compressed air regulator at the top is an example.
A final word on Argon. It is a noble gas like Helium (and is therefore not chemically reactive) but much heavier. Being heavier I believe it is even more likely than helium to cause asphyxiation if inhaled because it settles in the bottom of the lungs. I am careful not breath Argon and I use it in a ventilated area.
As always, this is an account of what I did and not a ‘how to’ guide.
Benjamin's Bench 