Baby steps.

[Jan]

So far I've got together:

1) An old buzz box stick welder. It's lasted me for around 16 years and it wasn't anything like new when I bought it. I truly believe you could drive a double decker bus over it and it would still work!

2) Now I've got a used Murex WP17 type TIG torch in what appears to be excellent and hardly used condition. It has a long back cap, unused heat shield & gas lens (a No. 4 I think as there's a smudge of dirt over the number), pristine collet (1.6mm) and collet body and has its own gas valve with around 4 metres of hose. Now I just need a few consumables, some rods and a bottle of pure argon.

I was surprised to see that the power feeds into the gas connector at the machine, so I'll also need a power adaptor and some more hose to go to the gas bottle along with a new set of gauges. However all the ones I can find are 3/8" BSP while the nut on the hose measures closer to 1/2" - unless I'm measuring it incorrectly.

As this is more in the region of an experiment I don't want to start out with a Volkszone bottle even though I have for MIG welding. What's my best bet for gas, regulators, adaptors and consumables?
Thanks in advance old chums (and chumettes).

 

[octo0072000]

pictures Jan would help

 

[Jan]

Can't photograph the buzz box at the moment as it's buried under a load of crap in the shed. There's a small pic of the torch here. My camera's playing silly buggers at the moment and my mobile is on charge.

 

[Paul.]

If it really is an AC transformer welder buzz box, then using it as a base for a tig welder is pretty much a non starter, the minimum you would need is a DC set, which for home use will be an inverter, that would enable you to set up a simple scratch start set up using a valved torch, and would be suitable for mild steel and stainless.

 

[Jan]

I'll have to dig it out and check the output to see if it's AC or DC. Was already thinking along those lines.

 

[Jan]

Just checked it and it's an SIP Powermate 100. The output is pure sine wave AC, so I'm thinking that one of these might change things a bit. At the price what do I have to lose as long as I don't need to crank it up all the way?

Or how about 3 of these in parallel and immersed in oil?

 

[Wallace]

I was in a similar situation a while back, I was given a used BOC TG123V Tig torch which has a 1/4" BSP nut and needed an adaptor to fit the 3/8" BSP Dinze plug. I did not want to buy a 1/4" Dinze plug in case the torch was U/S as 3/8" seems to be the standard size so I bought the correct Dinze plug for my machine and made an adaptor from bits off an old O/A hose and a flowmeter.

 

[Jan]

That torch is virtually identical to the one I've just bought - other than the gas connector and it's a 'Murex'. I'll be getting the other bits 'n' bobs to start using it over the next week or two and see how I go on.

 

[Jan]

Can I assume that the voltage from my MIG welder will be too low to TIG with it?

 

[BrokenBiker]

tig needs a constant current supply, mig gives out constant voltage. 2 totally different processes. There is a video on the welding tips and tricks channel on youtube about scratch starting with a rectified ac buzz box. I would imagine you would need some very hefty diodes and a rather large smoothing cap. He also made a cut out foot pedal so he could break the arc without having to whip the torch away and lose post flow coverage

 

[Jan]

Pretty much what I thought. There's a link in a previous response to this thread to a 100 amp, 1600 volt bridge rectifier that might cut the mustard along with another link to cheaper 50 amp, 600 volt ones. The first one comes with a heat sink, while the smaller ones don't. I was thinking that either (3 of the smaller ones in parallel) might rectify the current adequately. I have plenty of bolts and heat sink compound so that I could use the case as a heat sink, perhaps with a computer heat sink to improve the heat transfer. An enclosed box with a litre of so of transformer oil might be better, but I don't have a source of the oil in such small quantities. Fortunately non-electrolytic caps in ridiculous values and useable sizes are relatively easy (if not cheap) to acquire these days.

 

[Jan]

Just a thought; but wouldn't full wave rectification hold an arc without much, if any, capacitance on the output? That should increase the effective frequency to 100 Hz - close enough to true DC as makes little difference.