TIG welder advice

[dhalse001]

Hi guys,

A mate pointed this post out to me, and I've read it, and would like to add my 5 cents worth.

Welders
I bought a chinese welder off Ebay and a plasma cutter at the same time from Import1989 calling himself MyToolstation. I looked long and hard, and considered shops etc (who seemed to me to be just importing chinese welders and adding a good sized mark-up on them. In hindsight I might have been wrong). I paid £650 for both WSME200 Tig (AC/DC) and a Cut50 plasma. However, after about the first use the Tig stopped working properly...! I tried to return it but funny how he didn't want to know. I got Ebay involved and I'm on my 3rd welder with this guy (now 7 months later) and this one has had an issue occasionally (seems to have a solenoid switching problem, then static goes away after a few days and I'm away again). He won't answer emails, Ebay messages, text messages, mobile calls... I guess alarm bells should have rung when I picked it up from a warehouse full of Chinese imports, but the guy there was Turkish and couldn't understand simple English, and I managed to gather from him that he'd never done any welding before...! The plasma cutter has an occasional intermittent issue too (air doesn't stop sometimes even though you've realeased the trigger)!

Whinging aside, both these problems are intermittent and infrequent, and I get some good use out of them.

Ok - so - for anyone who has similar issues: I've stumbled across a guy called Mike, who runs Plasmapart.com. He is very knowledgeable and has the plans for these welders and was very willing to help me out. He said that they import their welders and do some mods on them to improve them (and plasma cutters too), as the Chinese didn't quite get the electronics right. He was very helpful, and if I need a new welder or repairs, I'll be going to him (it was a relief to find someone who could help)!

Gas
I went with Adams gas for a while (till Sunday just gone). They're good, friendly and rent free. However, 9L pure Argon at 137 bar filled for 57.60 is expensive, and I'm just finishing my third. I'll start another reply... this is going nuts due length...

[dhalse001]

Ok... so gas.

I had my flowmeter up too high. It's best to sort that out quickly! I was up at 14L/min, now I'm on 8L/min and feeling better.

However, I shopped around and the discounts for buying bulk argon are MASSIVE. I've just bought (rent free contract) pure argon 30L for £105.60 from Barnet-Welding. One of the key factors was that they're filling to 200 bar (and yes 200/137 is about a third more gas). I mentioned this to Adams and they hope to do a 20L tank soon, and potentially at 200bar. (Pickup / delivery / deposits aside)

Gas Type
Ok. Not being content, I bought a small Mig welder... I'm doing a bit of stainless at the moment so did some reading on gas. Mig they recommend an Argon/CO2 mix. But that is because usually you're welding mild steel. I read more as I know that the price of a mix including some CO2 is significantly lower than pure argon. The catch is, you need pure Argon to weld stainless. CO2 is 'active' believe it or not (see Metal Active Gas welding), and stainless can 'pick-up' some of the carbon if exposed to it... That's bad and you can read why somewhere who'll explain it better than me.

They say that the CO2 (not referring to stainless) helps with the weld puddle flow and you can produce nicer welds, and that it will 'penetrate' the metal further allowing you to weld thicker steels (say > 10 or 15mm). Argon has less penetration and hence the weld pools sit 'higher'.

Pickling Paste
It's expensive stuff - the cheapest I managed was a little over 40 quid including delivery from Wasp supplies. It won't fix 'coking' that another reader referred to earlier. How do I know... well, I never thought of purging, or considered the effect on the other side when I was inadvertently wrecking my stainless HLT...! So I tried pickling paste but to no avail.

I'll post some pics for fun. But in the next post as this is moaning about length again.

[dhalse001]

Tig weld 3mm x 70mm stainless box steel. No filler rod.
http://www.flickr.com/photos/dhalse001/ ... hotostream
Coking on the inside. Maybe amps too high as molten bubbles coming through, but oxidising/coking and then they started to rust.
http://www.flickr.com/photos/dhalse001/ ... otostream/
Plasma cutting a circle by freehand.
http://www.flickr.com/photos/dhalse001/ ... otostream/
1"BSP (33mm) blanking plugs, o-rings from the USA, and couplers, all stainless 316. Add a 32mm holesaw (master cobalt), and you've got a 50 quid solution for the 3 welds I stuffed up that 'coked' and now I have a weldless solution (after cutting out 32 mm holes around the coking. Yes it was that bad... please stop laughing).
http://www.flickr.com/photos/dhalse001/ ... otostream/
Plasma cutting 3mm box. If I built a guide (ie wasn't so impatient), I imagine I could get it straight. It cuts quickly and easily. I've done 12mm thickness cuts previously but it's supposed to go above 18mm.
http://www.flickr.com/photos/dhalse001/ ... otostream/
Cut50 Plasma cutter
http://www.flickr.com/photos/dhalse001/ ... otostream/
WSME200. Note also that the earth clamp plugs into the +ve terminal (opposite of a stick welder). Is it just because it's Chinese?... apparently its not just mine, but most of these tig welders.
http://www.flickr.com/photos/dhalse001/ ... otostream/

[dhalse001]

Pics in links above.

Cheers,
Dave.

[Kev888]

Crikey - what a lot!!

Thanks for all the masses of info - its reassuring that I seem to be on the right track. Good to see the pictures on coking too - I got a second flow meter for back purging so its good to know its definately needed. I just need some time now - to talk to local gas suppliers and practice more.

Cheers
Kev

[froggi]

TIG - Gas flow on flow meter IIRC should be around 8ltr pmin and will vary on metal welded and whether back purging is used

For MIG - I almost always used Argoshield (I think - been a while and many pints have passed my lips).... BOC sell it and you'll more than likely pay a premium on it. CO2 does assist with the weld pool to some degree also and as rightly said, this is on Mild Steel (MS in future).... SS shielding gas is as rightly stated, Argon.

Keep the faith Kev and the skills will come ... Keep asking questions of those in the know and practice, practice, practice !!!

[Matho]

to weld stainless most literature that I have read suggests using a argon/helium and some with co2 mixed in as well like this

http://www.boconline.co.uk/products/pro ... /index.asp

I have MIG welded thin stainless with pure argon and with co2, the argon mix was hard to get good penetration and seemed to be cold, the co2 was alot hotter weld with good penetration but on really thin stuff it would blow through. I wouldn't mind trying an argon heluim mix but I'm not going to rent a bottle just to play around with it. I just thought I would share my experience with different gasses, it was a big difference so if your having trouble with getting a good weld maybe try a different gas mix

cheers steve

[froggi]

+1 to Steve... Now that brought something back to the front of memory re the helium addition but you are now starting to go into the realms of silly costs re shielding gas ... well at least here in the UK

[Kev888]

Interesting - I'd not come across helium being used, thanks!

I guess it would be quite expensive to use helium for my larger pots at the mo - knowing me i'll have to grind all the welds back quite a bit anyway so perhaps its a bit too subtle for my current level of expertise! Maybe its something I could consider in the future when I'm more skilled and for any smaller pipes that are easier to fill/purge or which I can't get into and for critical jobs like FVs

Cheers
Kev

[dhalse001]

Looks like MyToolStation or Import1989 is now calling himself Ipad-Mypad.

Buyer beware, or Buyer Buy Again!!!

Amazing how if you get shut down or if things don't work according to plan, you can change name on Ebay and carry on as if you're someone else!!!

D.

[testtube]

I've been welding an aluminium bonnet.. Did it with a mig.. I blame it on the pigeons.. Could have done with a tig.

As far as I have been told, thin stainless, any tig will do as long as you have the right rods and gas.

[Kev888]

Last night I made an elbow-shaped bottom drain and welded it onto a tank - eventually. Its 'much' harder than I'd imagined, welding awkwardly shaped real-world things rather than nicely set up small or test pieces on the work bench... Many breaks for re-grinding the tungsten and about a decade grinding my dodgy welds smooth again afterwards - huge respect to people that can do this well!!

I seem to have got there finally, pending the leak test anyway, and only poked myself in the face with a hot welding rod once. Though I think I may need shares in dremel grinding disks, they're dropping like flies when grinding the internal welds (I can use an angle grinder externally).. Perhaps theres a better tool for the job, and thats just around the lip of tubes - I've no idea how I'd make an internally inaccessible butt-weld sanitary.

Does anyone know of a good/better way to grind smooth stainless welds inside tubes - say 3/4" nominal bore?

Cheers
Kev

[gnutz2]

Hi Kev, are you referring to the burn through (all the fluffy stuff) on the inside of the pipe?

As far as i'm aware the only way to avoid this is to back purge the tube your welding, basically tape one end of the pipe closed and fix a pipe in the other end with a bung (like a rubber cork for an air lock) or some people use rubber gloves which also act as an indicator as to when the pipes full of argon, fill the tube with argon and begin welding. This should give you a nice clean weld on the inside.

The other option would be to turn the heat down so you dont burn through, afterall your not after any real strength in the welds just a watertight seal.

HTH

[Kev888]

Ah I see, many thanks!

Its my ineptitude thats the problem really - getting the penetration right; sometimes I get globs of metal on the inside when I accidentally overdo it (especially on thin stuff when it saggs or burns through). From what you say though, I suspect perhaps I'm purposely trying too hard not to leave any crevices as well, and going too far for that reason. I'll try being lighter on the 'umph' dial - it may help reduce the distortion I'm getting too.

I'm back-flushing with argon - when I remember to switch the valve on for my back-flush feed anyway; remembering to turn it on/off seems to be something of a mental block at the mo. The other one is that I seem completely incapable of picking the torch up without accidentally pressing the damn trigger at least once.. At least I found a local supplier of argon so its not quite so financially annoying now.

Cheers
Kev

[gnutz2]

Are you using a foot pedal? They can be tricky when starting out.

Also if you have pulse function, use it. Especially on thin guage pipe.