(First post!) Finding the TIG useless for cars....

[Darkcat]

Hi all
First post on here, so be gentle!!

Ive had a decent TIG set for a while now, and its great for tidy welds and chassis building, however ive recently had to do a bit of body work on one of my cars, and found it near-on useless for welding patches on. (either cant form a pool or just blows through, or melts the edge of the piece im attaching back before ive got a pool)

Am i just doing it wrong? or is it basically useless for sheet steel work?

The set im using is a Thermalarc 175 TE (HT start etc)

 

[gavuk]

It can be done but its not as easy as mig or gas for bodywork,for the reasons you mention..If the tig is all you have available you need to ensure patches are really good fit idealy touching,i'm reluctant to say overlapping unless its a get you through a couple of mot's ....tack and tap...only attempt to weld in when its touching or you can bridge the gap ...best of luck ....but i'd mig it

 

[langy]

I do body panels all the time but the metal needs to be clean, clean clean.
A pedal helps a lot, gaps will make it much harder so no gaps.
I use a 1mm tungsten and 1mm rod which makes the job a breeze.

 

[carl0s]

Hmmm.

I have a butchered hole in my RX7's firewall where the clutch master cylinder goes through.. I was hoping to weld a plate over the butchered hole (I used a carbide burr on the end of a drill to enlarge the hole, so that I could affix the master cyl directly to the back of the pedal.. i.e. inboard).

Is this going to be difficult for me, a learner TIG welder, then? I have access to a MIG set but everytime I've tried to use it it's gone horribly wrong, and besides, I bought and started learning TIG!

The firewall might be thicker than other panels?? In the back of my mind I am worried that it might be a double-skin.. is that likely? It's been a while since I 'modified' it.

 

[hotrodder]

Am i just doing it wrong? or is it basically useless for sheet steel work?

Sorry, it's you TIG is often the process of choice when stuff gets thin/fiddly.
Coachwork... not so much in most circles as there's not much point in using TIG unless tackling the job in much the same way as an 'old skool' master panelbeater would with oxyfuel- the extra distortion from a higher heat input welding process isn't really an issue as welds are dressed out with hammers and dollies (dealing with distortion at the same time) and metalfinished. Quite different techniques compared to bodywork with MIG where distortion is typically something to be terrified about, overlapping spot welds are used to keep it to a minimum before grinding the (relatively) large amount of excess weld away and reaching for the plod [/tongue in cheek]

As Langy said you NEED 1.0mm diameter or thinner wire really, 1.0mm tungsten is optional/personal preference. I don't bother with anything smaller than a 1.6mm BUT grind 'em to a much finer point than i would when thicker material. Fairly obviously you need to be comfortable welding sub 1mm thick sheet/tube out of position i.e. not sat at a bench with the part sitting on a huge heatsink under excellent lighting conditions. Fit up is important regardless of welding process as welds shrink i.e. welding over gaps = more weld metal = more shrinkage (distortion). As said, it's also a LOT easier if the fit up is spot on

 

[outofthefire]

Would a piece of ally or coper behind the joint help, I dont have any experience of tiging thin stuff but its what I sometimes do when I have to mig thin steel.

 

[langy]

Hmmm.

I have a butchered hole in my RX7's firewall where the clutch master cylinder goes through.. I was hoping to weld a plate over the butchered hole (I used a carbide burr on the end of a drill to enlarge the hole, so that I could affix the master cyl directly to the back of the pedal.. i.e. inboard).

Is this going to be difficult for me, a learner TIG welder, then? I have access to a MIG set but everytime I've tried to use it it's gone horribly wrong, and besides, I bought and started learning TIG!

The firewall might be thicker than other panels?? In the back of my mind I am worried that it might be a double-skin.. is that likely? It's been a while since I 'modified' it.

If your a learner with TIG I would MIG it, Personally i would fit the filler piece in not over the top.

.

 

[Basil]

Another thing with TIG on sheet metal is to keep the arc length SMALL. A long arc wanders around and melts things.

 

[ronan]

I use tig for very thin metal and its the job , the thing is if you are having trouble with the two edges of joint melting back is to have the rod ready to go in and make a puddle or have the rod sitting between the plates.