Welding Tips and Tricks

hi guys
iv been playing around with scratch tig torches over the last week in my spare time ,the problem im having is on stainless steel. the scratch torch is leaving the weld a little grey instead of the usual clean gold/silver finish .
if i use the hf torch (wp26) with 2.4mm tungsten,gas lens with number 8 cup gas flow 7lpm the weld is clean
if i use the scratch start torch (also a wp26) with the same perameters the weld is dirty. iv checked the connections for leaks and there all fine.
could it be the higher volts on the mma mode causing this ? Or has anyone had the same problem.
cheers jay

Hey,

Welcome to the forum.

I have never heard of this problem before, Lots of problems with stainless weld colour but never just between scratch start and hf. Is the hf torch "better' quality than the scratch one? Sometimes cheaper hardware on torches can have less refined features that can effect gas flow. Maybe take the hardware off the hf torch and try it on the other. Other than that Im not sure. Try some mild steel and see if you end up with porosity? You can get a gas flow meter to find out whether your two regulators are putting out the gas rate that they say they are.

http://compare.ebay.com.au/like/4003999 ... eItemTypes

Hope some of this rable helps,

Mick

thanks for the welcome mike

this one is realy confusing me,i tried it on mild steel it welded clean no perosity,the mild steel was alot thicker though. iv tried the torch with the same regulator and hardware.iv not checked the flow rate out the cup !! im gona have to get a peashooter type flow meter to check this.
i think im going to fitt the scratch start torch to the hf settings and try ,that should eliminate a difference in voltage ,il just have to make up a switch to bypass the hf solinoid
like you say it could be a cheap torch and thats why.
also just thought !!!! iv not checked if the back cap is leaking,the seal is new ,just may not be doing its job


cheers jay

Hey Mate,

Hope it works out, Remember it only takes a tiny bit of dusturbance to mess things up , either from a tiny leak, a small sharp edge inside the hard ware that creates turbulance or slightly higher gas flow. That can suck in air from small holes or even the opening of the nozzle.

Mick

Does that machine have a "dig" setting for MMA? That will mess you up with scratch-start TIG if not at "zero", and stainless is where I'd expect to notice it the most.

Some machines (like my Syncrowave at work) have the arc-balance control for HFAC double as the "dig" for MMA (SMAW, for most of us yanks...)

Steve S

Hi Steve

Yea the machine has an arc force control,I sure i had this set at zero. Il take some pics of the welds tomorrow and post them.
Would the arcforce(dig) make a huge differents?

Cheers jay

Hi, Jay,

Arc force shouldn't make a "huge" difference unless turned up pretty good, but it will affect your welding current based on your arc length.

It might take a bit of research, but since your machine HAS arc-force, it might be worth seeing if "zero" actually means "none", or just a minimum setting, like 10% of your amperage setting.

I'm just speculating at this point, but I have a hard time imagining what the difference between the torches would be that would make such a difference in weld quality, other than the ultimate heat the metal sees.

Can you easily set up the torch you use for hf for a brief run of scratch-start to compare the results?

Steve S

hi steve
i checked the different voltages beteen mma and hf tig,there was a difference of 20 volts.
so i set the scratch torch up inplace of the hf torch,and still had the same problem , now this rules out different voltages causing an issue.(i always seem to over complicate problems )
so that leaves a shielding gas issue.
i did 4 short welds ,2 on the right are the scratch torch .

Are those both water-cooled? Air cooled? One of each? I had some issues with hf on water-cooled, but I won't go into it if it doesn't apply.

Assuming it's a gas problem, you need a way to restrict the flow from the cup on your torch (your thumb will do, without the hf to tickle you ), to get a strong positive pressure in the gas line to do a proper soap-bubble test. At normal flow, static pressure in the line is only VERY slightly above atmosphere, while dynamic pressure is low because gas is flowing. This makes a line leak "suck in" rather than "blow out", and can lead to discolored welds (or worse, for a bad leak).

Steve S

Hi steve
The torches are both air cooled .i did the two on the right first so the ones on the left would have been a little cleaner if the material was cooler.
Il pressure check all the fittings and hose.theres only 4 fittings between the torch gas lens and the cylinder so should be easy enough.my guess is its the gas hose crimps.( I'm hoping )

Jay