amatuer question on spot welds

[BA.]

I've got 2 new quarter panels installed, and I'm happy with the work there and the tubs and other welding from the same shop.

They had asked if I wanted to grind down the spot welds myself or have them do it. We kind of agreed that it was something I could do myself.

Now that I'm doing it, I find myself questioning how much to grind without sacrificing the weld strength! Specifically, I'm lookin at the wheel lip and the sail-panel for both the drip rail area and rear window area.

Can I grind them all flat/flush with their surrounding metal or is that hurting the weld strength too much?


Thanks!

[parsonsj]

I need more information. Is this a true spot weld, or is it the MIG equivalent (drill a hole in one panel then weld the edges of the hole to the panel behind it)? If it's the second case you can grind it flat but not deeper than the original sheetmetal. If there is a slight divot left after that grinding, you'll need to fill it with body filler.

jp

[baz67]

I second what JP says. You want it flush or you may have issues with later bodywork.

[mikey]

Ditto use a roloc disc on a die grinder takes awhile but it onky grinds a small area with minimal heat buildup. 24 grit works really well you will use a few discs though.

[BA.]

Thanks for the replies guys.

I didn't realize the possibility of two ways of spot welding. Makes sense though. Damnedest part is that I do not know what method was used. I may need to give the guy a call tomorrow and find out.

In the mean-time, I figured I'd post up some pics for you guys and others, and future reference.

On the wheel-house area, I've already ground some down there, but on the rear window area, I haven't touched them yet.

[Matt@RFR]

Those are MIG welded.

If they were done by an actual spot welding machine, there would be nothing or very little to grind down.

And for future reference, it's not the process that's used, it's whether or not it was done correctly that determines if you can grind flush or not.

[parsonsj]

it's not the process that's used, it's whether or not it was done correctly that determines if you can grind flush or not.

Good to know.

My take is that real spot welds (as opposed to the MIG rosette welds commonly called spot welds) don't need grinding, and probably shouldn't be since there is no filler metal added that might be a candidate to grind away. In other words, any grinding will be removing base panel metal. I've never ground one, anyway.

I was answering the MIG question because I do have some experience with that, and there is often a thick hump of filler material that ought to be ground away (like we see in the pics above) to make the panel joint more linear in response to vibration and such.

jp

[Matt@RFR]

Some spot welders put enough pressure on the tongs to buldge the HAZ alittle, and the hand held ones can have enough pressure put on them by the operator to sink or raise the weld area. Those are the only reasons I'm aware of that would require a spot weld to be finished in any way.

This is what I've read anyway. I walked by a spot welder once. That's the extent of my experience with one, and I plan on keeping it that way.

[parsonsj]

I walked by a spot welder once

Me, I saw one in a catalog once.

jp

[ahowudoin]

how about a picture of the quarter to sail panel

[BA.]

well I've learned a few things today! This is a good day.

Sorry for my misunderstanding of "spot weld" in the initial post, ....didn't mean to confuse anyone.

I'll grind these spots down a bit being careful not to go below panel level.
Thanks for the education and tips.

[Ricoch3T]

Me, I saw one in a catalog once.

jp

I've used one