Un-picking spot welds

[GTVeloce]

Can anyone tell me the best method to remove this small panel? It is in the engine bay and used to hold the coil but is just in the way now and I want to remove it without making an awful mess if possible! Preferably the method doesn't require an oxy set as I don't have one...

Thanks

[agent86]

You can buy a spot weld drill bit that is just like a holesaw but with the specific size for the welds eg a normal drill bit with a circular saw around the shaft. It cuts a neat circle around the weld and the panel should come free. Should be available at Repco or similar shops.
Cheers Mark

[colcol]

Or you could use a double ended panel drill, so called, because panel beaters use them to drill out spot welds, it is a drill bit with a cutting edge on either end, and when they go blunt they are thrown away, measure the approximate diameter of the spot weld and buy a panel drill to suit, common size is 5mm or 3/16 inch, available at engineering supply shops such as Blackwoods or some panel beating supply shops, centre pop the centre of the spot weld, so the drill doesn't wander and drill thru the attached panel, until you break thru to the parent panel, you don't need to drill thru the parent panel, just drill out the weld, then depending on access, you can put a screwdriver or cold chisel behind the attached panel and lever it off, knock the burrs and sharp edges of the parent panel, so you don't continuously cut yourself, and paint the parent panel in your favourite color, so it doesn't rust, have fun, Colin.

[Beatle]

Or you can grind a standard drill into a spotweld drill bit (not easy).  The idea is that the top panel is cut away leaving the underneath panel with little or no hole through.  This then gives you a base against which to start the weld when you fit a replacement, or refit the original panel.

[colcol]

Hey Paul, that drill you have is called a sheetmetal drill, it cuts the outside of the weld, cuts a perfect circle and doesn't leave a burr, i use them quite a bit, and doesn't leave a lot of cutting chips, the only problem is grinding one up, they are not easy to make, particulary if you have rubbish eyes like mine, you need a good centre pop mark, otherwise the drill bit will grab and rip the drill out of your hand, Colin.

[Duk]

Hey Colin, that drill you described is 'called a centre drill'. It's used for drilling holes for live and dead centre's ina  lathe tailstock. Or when tuning between centre's.
Also good to help drill holes accurately. Even with a centre punch mark, drills can be bastards for wandering. By first starting with a centre drill which is more rigid for its diameter than a normal drill, an accurate pilot hole can be started.

[scott.venables]

Hey Colin, that drill you described is 'called a centre drill'. It's used for drilling holes for live and dead centre's ina  lathe tailstock. Or when tuning between centre's.
Also good to help drill holes accurately. Even with a centre punch mark, drills can be bastards for wandering. By first starting with a centre drill which is more rigid for its diameter than a normal drill, an accurate pilot hole can be started.

True, but the aim with drilling out spot welds is not to drill through the panel to which the part has been spot welded.

Scott

[colcol]

Mr. Duck, a centre drill would be no good for this, as it will drill out the centre of the parent metal, which you don't want, a panel drill will work ok, just don't drill thru the parent metal, just drill thru the attached panel and lever it off, a sheetmetal drill is like a flat bottom drill with a 'spike' in the centre for a guide and to make the drill stable, also called a trappaning drill as it trapans or cuts the outside of the circle, and when you cut thru, it leaves a 'pip' or little washer, Colin.

[Beatle]

The drill in the pic I posted is almost a 'shetmetal drill' except that it doesn't have a cutter edge out at the extremity.  So instead of cutting through the top sheet and around the spot weld to leave a nib, it kinda mills the whole spotweld down to the base sheet, leaving only a small hole in that base sheet of metal.

HINT:  For the amatuers among us, when you go to plug weld the sheet back in place using a MIG, you can use a small sheet of copper to back up the base sheet, especially if the base sheet is holed.  This stabilises the weld so it doesn't drop through.  Just remove the copper as soon as the trigger is released.

[colcol]

Or another completely different way if you have good access, would be to use a angle grinder slowly, so you don't burn off all the paint, and put some sort of shield around it, so you don't end up with little bits of molten metal all over the paintwork and glass AND your glasses, Colin.