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Help cleaning out plug welds

K

K-Dog

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Millersville Maryland
I do collision repair.

I am wondering if anyone here has any bright ideas or knows of a way to quickly clean the paint and e-coat out of the holes in a plug weld on a new sheet metal panel. I can easily clean the top surface. No big deal, but getting the second sheet metal clean enough for welding, not so much.

20160504_153007_zpswlczugzk.jpg


Right now I am just scratching it with a pick tool and that can be time consuming and tedious.

I tried sticking a die grinder bit in there but that thins too much metal. I don't know if a wire brush bit for my Dremel would be aggressive enough to remove e-coat. :dunno:

I am out of ideas.
 
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laneyracing

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Spot blaster works great, with the rubber boot so the sand doesn't get everywhere, they do a good job on this or cleaning small pinholes in welds when prepping for filler or primer
 

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C

ChevyEFI

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Can you explain where a new panel would be inaccessible at some point during the repair? I am stuck in my mind of a qtr. panel that's been removed such that the old welds are removed and can't picture your dilemna.
 
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HMCFab9

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Grind it before you put the top panel on for the last time. I've done it that way for years.
The other option is a die grinder with a bit that's just sharp enough to get the paint off.
 
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1930

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Remove the paint first with your grinder, you have access, spray a weld thru primer and burn it in or if you want to do it your way than hit it with a waffle disk, 97% of the paint will be removed and the rest will burn off.
 
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MoonRise

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Go read the MP&C thread in the Fabrication section.

IIRC, he shows a tool he modified just for that purpose. Pretty much a 'flat' tip modification to a drill bit IIRC.
 
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OP
K

K-Dog

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ChevyEFI said:
Can you explain where a new panel would be inaccessible at some point during the repair? I am stuck in my mind of a qtr. panel that's been removed such that the old welds are removed and can't picture your dilemna.
Click to expand...

Its not so much about access. You can see in the photo I posted there are two brand new pieces of sheet metal screwed and clamped together. ( one is a tail light pocket and the other is a rear body panel on a mercedes benz.
A few people have said just grind it off the vehicle. I want to disturb the factory e-coat as little as possible. The factory e-coat is superior to any weld-thru on the market.

Daves69 said:
Grind a drill bit flat and use it to scratch the paint.
Click to expand...

MoonRise said:
OK, made me curious about Robert's (from the MP&C thread I referenced in my last post) tool to clean up the underlying sheet in prep for a plug/rosette weld.

Yup, a modified drill bit of the appropriate diameter. Reshape the tip and turn the bit into a sort of end mill shape.

http://garagejournal.com/forum/showthread.php?t=182565&page=9

Post # 178.

:beer:
Click to expand...

Yeah I am liking this idea. I have a few dozen spare and broken bits I could surly modify. Make it dull enough that it just scratches the e-coat and doesn't move much metal.
Thanks for the input !! :thumbup:
 
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K

K-Dog

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Mohawk Dave said:
Rivet shaver would work 100% perfect.
Click to expand...

I never knew there was such a thing.
Those are pretty neat.
I don't know about my purposes because they might be too aggressive. I am often working with very thin metal, and poking through would really ****. :(

That said I might look into a few of those rivet shavers for,,, well shaving rivets I guess.

Thanks. :thumbup:
 
B

bmwpowere36m3

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Always just ground with a die-grinder prior to final assembly… can mark hole with paint pen to keep "damage" to minimum. In the scheme of things, it won't matter.
 
H

HMCFab9

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[QUOTE
A few people have said just grind it off the vehicle. I want to disturb the factory e-coat as little as possible. The factory e-coat is superior to any weld-thru on the market.:[/QUOTE]

You're going to burn any coating off when you spotweld anyway, so grinding it a little isn't going to hurt it. (a weld thru coating still burns off by the weld)
 
B

bmwpowere36m3

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HMCFab9 said:
[QUOTE
A few people have said just grind it off the vehicle. I want to disturb the factory e-coat as little as possible. The factory e-coat is superior to any weld-thru on the market.:
Click to expand...

You're going to burn any coating off when you spotweld anyway, so grinding it a little isn't going to hurt it. (a weld thru coating still burns off by the weld)[/QUOTE]

+1

I was going to mention that... in the end, their will be areas that won't be protected. Unless you dip the chassis in a bath of e-coat... it'll never be as "good" as the factory. However good enough for the foreseeable future.
 
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Mastermind

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Ypsilanti, MI
I have a spot weld bit that the little tip snapped off first time I used it, put it in a cordless drill and just touch it in there.
Think dent fix/astro style,not rotobroach. like a flat tip drill bit as mentioned.
 
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