10 replies to this topic

[HUBBA.HUBBA]

Are they worth it or just use a HSS 6mm drill bit for getting the outer sill spot welds out.

[MiddletoM]

i used them for restoring my car but for my dads i never bothered buying new ones, i just drilled straight through with a normal drill bit knowing i could weld through one of the holes to the solid new panel. Alternatively i used a grinding wheel to ground the spots 90% down then used pliers to peel the metal off.

[GraemeC]

A standard drill will damage/cut the inner panel before it has removed the spot weld from the outer panel.

This will leave a hole behind, whereas a spot weld drill will leave a (pretty much) untouched metal surface behind.

[slidehammer]

Spot weld drills are well worth buying. The ones to get are the ones that look like a standard twist drill with a flat top and a center point to self center. Don't waste your money on the ones like small hole cutters they are rubbish. The twist bit type can be resharpened with care. They are usually cobalt tipped steel for longer life. It means with luck and care you can split seams leaving the panel underneath largely untouched ready for welding the replacement panel to.

[DeadSquare]

Are they worth it or just use a HSS 6mm drill bit for getting the outer sill spot welds out.

 

If you ever get the chance to use a three flute spot weld drill, you will know the answer.

[sonikk4]

A standard drill will damage/cut the inner panel before it has removed the spot weld from the outer panel.

This will leave a hole behind, whereas a spot weld drill will leave a (pretty much) untouched metal surface behind.

 

Not strictly true as use a 1/4" Cobalt drill bit to drill out spot welds but ensure i do not go through both layers of metal. All of my restos have been done with this method and its down to the tooling you have and how you use it.

 

Also having a decent quality thing scraper to split the welds is paramount.

[Harry L]

I like a spot weld bit as you can easily remove welded panels without leaving a trace on the original panel. 

 

An example is when cutting out the inner wings of my VTEC project, I managed to drill out the front part and leave the (recently painted) front panel perfectly intact.

[Daz1968]

I bought a few dormer cobalt spot weld drills and they were invaluable when doing my project, just don’t buy cheap drills as they are useless. 

[steeley]

Good quality cobalt butterfly spots weld bits will last for a long time and do a great job, isolate all the welds so you can see them clearly before you start
I used the same one for doing whole front end both sills and boot floor with no problem, don’t buy the cheap gold ones they don’t last

[DeadSquare]

As no one else has, I'll mentioned the obvious, that having located the spot weld, mark its middle with a center punch.

[sonscar]

I have not had anything good enough to drill out spotwelds.On the rare occasion I have I used a shallow ground drill.I was tempted by the holecutter type,it was useless.Steve..