TIG Shrinking

[Wendelspanswick]

Has anyone experimented with panel shrinking using TIG as a heat source?
I have watched the videos of guys using shrinking discs on steel and aluminium panels, they use the disc to generate heat through friction and then rapidly cool with compressed air or wet sponges to contract the excess material.
I know you can use Oxy/Acetylene to do the same but I gave up my bottles years ago.
I have a couple of places that I need to shrink on the aluminium bodywork of the Austin special and I was going to trial using the TIG to generate localised heat and then cool with compressed air, just wondering if I would be better off using DC rather than AC so I don't etch the panel?

 

[zx9]

I don't know, I would have thought it would be too localised but I am looking forward to hearing others experiances before I experiment on the Rangie's front wings.

 

[Wendelspanswick]

I was thinking of pre-balling a 3.2mm tungsten, minimum frequency and experimenting with a low set maximum current for a given time.

 

[500e]

Never thought of it but sounds feasible,always used O\a never had a go with the discs either.
Keep us informed you can experiment on scrap any pics of 7

 

[Paul.]

Tig can be used as a heat source but its take a bit of practice to avoid melting the job, use DC, grind the electrode like a crayon rather than a sharp point, turn the gas up and use a big ceramic, amps will need to be fairly low for sheet and keep a wide arc so that you get a flame effect, keep the arc moving to avoid burning through, it can very quickly go wrong. well worth practicing on scrap first.

 

[chevy2]

I've used tig as a heat source several times when i've been too lazy to drag the oxy/acet into the garage,
what i've done with steel is too keep a big arc gap from the material and always keep the torch moving,
it does still damage the material surface a bit,
Also done it on AC and keep the frequency on minimum,
my machine goes down to 20 i think,
once again keep the torch moving with a large gap and unlike DC on steel if you keep the amps low the material surface remains relatively undamaged.

 

[Wendelspanswick]

Never thought of it but sounds feasible,always used O\a never had a go with the discs either.
Keep us informed you can experiment on scrap any pics of 7

Not much progress on the 7, did all the floor panels, a reinforcing bulkhead in the tail and the nearside bonnet skirt over Christmas but most of my spare time, which is not much at the present, is spent on building the barn.

 

[Wendelspanswick]

Cheers for that, I will have a play at the weekend and report back.

 

[Paul.]

Just re read your post and noticed its ally you are working on, in that probably best to use AC and suffer a bit of surface damage, it does work I've done it many times but ally is more difficult than steel because of the lack of colour change, if it goes shiny you've melted it.

 

[chevy2]

Just re read your post and noticed its ally you are working on, in that probably best to use AC and suffer a bit of surface damage, it does work I've done it many times but ally is more difficult than steel because of the lack of colour change, if it goes shiny you've melted it.

I simply keep the torch moving all the time with a lowish heat to keep it just below when a shiney pool shows,
that should be enough heat to enable shrinking back.

 

[langy]

I just use a sanding disc mounted backwards in a grinder

 

[500e]

Do you mean soft disc with backing pad ?

 

[Tigman]

you could try a stripe off disk ! i was having the vinyl letters off the van and it got hot and the big panels moved about a bit might do it ?

 

[langy]

Do you mean soft disc with backing pad ?

Yes, all you need is friction

 

[markyb]

Hi mate could you post some pics of the areas you have problems with .Cheers.