Seperating spot-welded panels

[daniboy1_2_3]

Im in the process of replacing the sill, arch and inner arch on a vw corrado. Ive had to use second hand panels from a donor car as much of what i needed isnt available from new. Ive managed to seperate the floor pan from the inner sill although its not the neatest job. Can anybody recommend a chisel set that will help me along with any other tools and techniques that will help me along my way please.

 

[GrahamGKD]

Not had cause to use one myself but people on here often mention spot weld drills which are used to drill out spot welds to allow panels to be broken apart. There are a couple of different types on the market:

http://www.machinemart.co.uk/shop/product/details/cht467-38in-spot-weld-drill/path/spot-welders

Graham.

 

[daniboy1_2_3]

Sorry i wasnt very clear, i have spot weld drill bits but am looking for a good chisel set to minimise damage when seperating the panels and anything else that might help, cheers.

 

[Ginsambo]

Get a couple of different sized spot weld drill bits and drill gently until you notice orange dust or have just passed the first panel in depth. The expensive cobalt ones do last a long time on mild steel panels or buy a box of cheaper ones! Go easy though or you'll go all the way through. Spot weld cutters still leave a nugget that has to be ground down and are hard to locate and are easily damaged - they are a waste of space IMO. You can also get an angles drill head for harder to reach places.

Reveal the spot welds as low/high spots, by scraping off underseal and wire brushing the panel with a grinder or drill.

Only after drilling out the welds, use a chisel! Barbarian!

That way your panel is still usable, you can repair, clean up the seams and plug weld up again, maybe adding a few extra plugs. Use a chisel from word go and you are left with a bent up sardine can and a lot of extra work repairing the panel. I only use chisels in a scrap yard on vehicles fitted with an LPG when I'm cutting off more than I need and can cut down later with a disc.

If the panel isn't lifting on its own, your spot weld bits aren't centred in the weld, or they are too small - maybe try using an 8mm bit, rather than a 6mm. I just use the widest, cheapest carpenters chisel I can find to separate, hitting it flat side up - but as said the panel should just fall off if your drilling is carefully centred.

 

[rkde]

I only use a dormor drill bit (spot weld drill) I go slightly larger than the weld by about 2mm which always separates its self. If I just want it apart I use an air chisel which will do the job in seconds but does not leave you with a good finish. A long time ago I used to use an old wood chisel as it was thin enough and didn't need to do much, wrong tool for the job but did what it had too

 

[GrahamGKD]

Sorry i wasnt very clear, i have spot weld drill bits but am looking for a good chisel set to minimise damage when seperating the panels and anything else that might help, cheers.

Sounds like you need a broad but fairly thin chisel to slide between the panels and separate them without distorting them too much? Something along the lines of a bolster chisel but probably not so thick? My dad used to make such thinks from (I'm pretty sure) an old circular saw blade from a big saw.
Graham.

 

[welshpug]

draper do a chisel for this purpose.

 

[daniboy1_2_3]

Thanks for all the advice. I have drilled the spot welds out but have deformed the panel in a few places and drilled right through. Like you say its difficult to see them all sometimes and if a small portion of one is left it can make quite a mess seperating them. Im using an 8mm drill bit.
The area that needs repairing is pretty bad and im having to replace a section of floor pan where it meets the inner sill and sill. Ill also have to put a repair piece in for the inner sill before putting the outer sill back in place.
Drilling right through isnt a problem as it will need holes in it so i can weld it back together again. Im hopeing it will straighten out ok together with some welds and it will look decent. Its the first time i have tackled such a big job so maybe i could post up some pictures if anybody would mind guiding me through it? I most definately want to do it myself and this is the only way to learn properly, unfortunately im learning that mistakes are very costly in time and money so advice is what i need.
Ill have a look for that draper chisel.

 

[eil]

As Welshpug says you can buy them, http://www.justoffbase.co.uk/Flat-Chisel-for-Spot-Weld-Cutting-Sealey-AK570 but I have always used old wood chisels as there is always some knacked ones lying about.

 

[ghound]

I find using the plasma cutter just the job and quick, but i'm replacing with new panels and welding the old spot welds back in, and finishing them off with a flap disc.

 

[droopsnoot]

I use an old paint scraper. It's an old but good one, where the flat metal blade goes through the wooden handle so when you hit it with a hammer, you're hitting the end of the blade, not the handle. That said, the wood split ages ago so now it's just the blade. But that's exactly what I use it for - drill out the spot weld, insert between the two panels, and hit until the panels break apart. Sometimes (as they've been together for 30+ years) just removing the spot welds still doesn't make the panels drop apart.

 

[Sean]

I use an old paint scraper.

X 2

sometimes a wood chisel too, I find that any cold chisel is too chunky and distorts the panel

the other technique is to cut the old panel that the panel you want is attached to, then just grip the flange with pliers and roll the strip of waste off like an old FrayBentos tin

but then im usually doing 2cvs, they are as thick as FrayBentos tins

Sean

 

[badersbus]

I have used a flat 2 inch bolster chisel for years to separate panels when the spot welds have been drilled out.
A little trick i learned from a knarly old panel beater years ago, is grind another cutting edge down one side of the chisel blade. You can then tap the normal cutting edge into the seam , and then knock it sideways along the seam. That way you don;t need to keep putting the chisel in and out !!