"thin metal technique" and diy machines

[gavuk]

I'm quite happy to run beads on thicker material ,but have always used co2 and "thin metal technique" or" triggering" at home on cars.Out of interest how many others just use this technique? how many backstep,or rely on welding oppsite etc....if anyone replies please say what welder and gas you use and if your machine or trigger has been adversely affected by increased starts and stops of these methods to weld car panels .....many thanks Gav

 

[malcolm]

I've used the thin metal technique on thin metal with both the Clarke 155 and the Portamig. The Portamig has a usefully low bottom end and can butt weld 0.8mm on a bench, but for out of position stuff and imperfect prep on 1mm or less I'll use the thin metal technique most of the time. For thicker than 1.2mm I'd always go for continuous welding.

They do reckon stopping and starting puts more load on the machine. None of my machines seem to have suffered as a result. I guess because the technique is used on the lowest voltage settings.

 

[Tupers]

I'd say 80% of the welding we do at work (old cars mostly Minis) is done use the triggering/tack tack tack technique. We use an Oerlikon 2000M (I think) with BOC argon light gas and have had no issues with the reliability of the machine.

When I'm welding I normally weld towards me and go tack, count to 2, tack, count to 2, tack.

 

[gavuk]

Malc not sure where i change technique?,I can def say 2mm or above ,a lot depends on how and where i'm welding i guess .Tupers I use a count as well makes it easier for me ,normally starting the next tack before the last has cooled to black

 

[brookie456]

Malc not sure where i change technique?,I can def say 2mm or above ,a lot depends on how and where i'm welding i guess .Tupers I use a count as well makes it easier for me ,normally starting the next tack before the last has cooled to black

B*gger, innit No easy way

 

[gavuk]

B*gger, innit No easy way

..........any machine issues with the clarkes Iain?.....have you upgraded yet?...

 

[keith19]

I generally have to use the tack, pause, tack technique on thin metal up to about 1.2 mm, both with a Sealey 'Pro' 150 in the past and a Clarke 151 EN at present. But can do short runs down to about 0.8 mm m/s with a bit of backing to take the heat away. All the above with argon/co2 using 0.6 mm wire, and not doing consecutive tacks, but doing them widely spaced apart to reduce heat.

'Proper' pro welders - Murex etc - that I've used in the past give far less bother on thin metal, once you get the settings right.

Flux-cored is more interesting. I can use the tack technique with 0.9 mm f/c wire down to 1.2 mm metal, but have to be careful. Can do same with 0.8 mm f/c wire down to about 1.0 mm metal. Anything below that needs backing, and is touch and go, and only done if I'm lazy and don't want to change the wire, hook up the gas, etc. All with the Clarke 151EN. Still learning as I'm pretty new to flux-cored wire.

Never had any troubles with the contacts burning out through tack work on any of the above welders, probably because the setting is pretty low, as Malcolm says. The Sealey saw several hours of work, sometimes whole days of work, in a week, every week, but eventually had regular wire-feed problems.

But my first ever home welder, a SIP Migmate, did burn it's contacts out after perhaps more than a years ownership, doing tacks on car panel work mostly. (I was restoring a classic at the time, and working on my daily use Mini occasionally). When I took the contact box into the agents for renewal, who should be there but the SIP Rep, who shook his head and said: 'Hah, they all go like that, been doing cars?'
Apparently they had a bit of a reputation for this at the time, 1980-83ish.

 

[philsmin]

I use a pulsing technique on a clarke 90EN and 150TE, both running gasless.

Anything over 2mm I can easily drop the pulsing and just do a straight run, I find the tips last for ages doing pulsing on bodywork (also mainly minis )

 

[schnappi]

Late 90's SIP HandyMIG running 0.8mm flux-cored on 1mm steel. I use the backstep method. I don't think I've had any problems relating to the use of a pulsing technique but at one point I had to replace the the small transformer on the PCB. This was after the machine was stored unused for a few years though, it was working fine when I put it away.

 

[200T]

When I butt-weld thin metal (1mm), I use the 'pilgrim step' (or step back - one tack, next as far as possible away and so on) technique with lots of breaks. The last joining tacks I set after the welds have been ground down to get good penetration. Or I use a higher setting.

I do this mainly to reduce heat distortion as much as possible, which seems to work fine doing it like that.

I'm using a 82% Argon and 18% CO² mix and 0.8mm wire. I've used 100% Argon before, but wasn't happy with that, the welds were smaler and higher which meant more grinding to dress them up. And if I observed it right, penetration is also better with 18% CO².

Regards,
Jan

 

[brookie456]

..........any machine issues with the clarkes Iain?.....have you upgraded yet?...

Saved the pennies and got the Portamig, don't regret it at all. The Clarke's are good machines, especially for the price, but the Portamig is so easy to set up, and the results are out of line with my abilities Will post a thread when the workshop goes on line leccy-wise, (hopefully in +/- 2 weeks).

 

[mm289]

Quick question on thin metal technique.

Using a 100EN with 0.6 and Argon C95 on 1.0mm sheet/car bodywork

Not a problem with tacks and small runs, reasonably succesfull at " 1 Min" and 3.2 wire speed.

Just the penetration doesn't seem to be great bizarrely - if I do short tacks I get a nice weld on one side but just the heat ring on the other, longer tacks and it burns through.

Is this normal or do I need more practice

Cheers,

MM

 

[gavuk]

Just the penetration doesn't seem to be great bizarrely - if I do short tacks I get a nice weld on one side but just the heat ring on the other, longer tacks and it burns through.


MM

Are you welding joints or on top of a sheet?....have you tried the next increase in power?...timing is crucial,try counting in your head whilst pulling the trigger

 

[mm289]

Butt welding joints. There isn't a lot of sensitivity in power on the 100, so the next step up is great for 1.3mm but blows through on 1.0mm

Played around with wire speed and just about there, but it is a knife edge between burn through and penetration,more often than not get a really nice weld on the one side but no real ridge on the underneath.

MM

 

[keith19]

MM, what kind of joint are you doing on 1 mil? Just noticed you posted butt joints. Have you got the metal touching? you don't want any gap at all at that thickness, remember. You are using quite thin steel, and if doing non-crucial stuff like car panels, so long as the weld has penetrated enough so that it cannot be levered apart, that is quite enough.

You don't need to see bulging penetration on the other side to get a strong enough weld on thin metal - the difference between heat marks and blowing through is quite small on metal that thin, and some welding machines do not have the fineness of settings to get the output just right. So we have to compensate as Gavuk says, by technique. Holding the torch slightly nearer or farther away, counting how long we are holding the trigger for the tack, putting a sheet of something underneath to take excess heat away, subtly altering the angle of the torch, etc. All this comes from experience of your own machine.
Keep at it, practice makes it easier - eventually.

 

[mm289]

Thanks guys,

the weld seems plenty strong enough, its just when i grind back the underside (opposite to the weld) you can still see a very fine line where the two panels join i.e. the weld pool hasn't penetrated right through.

The inital repairs have been on a sill which I have been welding from the top for ease, this will be inside the sill and unseen, the bottom will be on the visible side (if you crawled under the vehicle) and I was trying to get this side to be an invisible repair - if you see what i mean

So when I move onto butt welding a repair onto the side panel, I guess I should weld from the outside (visible side) so when I grind down it is to solid metal?

Cheers,

MM

 

[keith19]

Yes, that's correct, it looks better to weld from the side that will be seen, so far as MOT repairs go anyway. The MOT testers like to see a bit of weld, but this does make us a lot of more uncomfortable work at times!

You can try clamping or jacking some copper or brass sheet under the joint to be welded from the inside, then upping the power a bit as you weld from on top, or hold the tacks a bit longer. This lets the metal melt but not collapse, so it looks more like a properly welded joint from underneath. Takes a bit of getting right, but often worth a try if it's easy to weld from on top, and difficult to weld from underneath. Sometimes these sort of tricks aren't possible, and then it's a case of getting the vehicle as high as you can to be able to weld as easily as possible underneath, sideways is easier if at all possible.

 

[weseeyou]

sorry if this seems like a dumb question but why couldn't a joggler be used to form an overlapping joint and then use a plug weld technique ? the weld would be easier, stronger and there would be less grinding needed plus there would be less risk of panel distortion or blowthrough surely?

 

[Country Joe]

sorry if this seems like a dumb question but why couldn't a joggler be used to form an overlapping joint and then use a plug weld technique ? the weld would be easier, stronger and there would be less grinding needed plus there would be less risk of panel distortion or blowthrough surely?

In a joggled joint, the overlap creates a moisture trap between the layers, giving rise to later corrosion.
Butt welding, where just the very edges are joined, would prevent this from happening.

Regards,
CJ

 

[weseeyou]

In a joggled joint, the overlap creates a moisture trap between the layers, giving rise to later corrosion.
Butt welding, where just the very edges are joined, would prevent this from happening.

Regards,
CJ

in my experience all welded joints rust unless access can be got to both sides and the metal is cleaned up primed and top coated . With closed box sections like sills you'll always get continued rust from within the sill because the other side of the weld has had the primer blown off it and is exposed .

With a joggled joint at least you have less likelyhood of blowing through and a stronger joint with less panel distortion and less post filla and grinding required Where possible I like to plug weld a joggled joint which allows the joint to be pre-filled with a mastic sealant that gives the joint half a chance.