Drilling spot welds... Am I missing something?

[atr911]

I hear everybody talking about drilling spot welds... I tried this with some steel bits and had NO luck. Is there a proper technique or drill bit?

Please walk me through this like I was a moron (go ahead and have fun with this one) cause I want to make sure I don't bugger up.

Thank you fella and let the moron flammin' roll!

Adam Roseneck

------------------
1978 911SC 3.0
roseneck@cyberbeach.net

[88 911 targa]

You may have better luck with a spotweld drill bit. Sears may sell them but I know Snap on, Mac etc do sell them. Run by an autobody shop and they will have them. Maybe you can look at one there ( sorry I can't post a picture).

Basically it is a center drill bit with a sharpened circular cutter about 1/4" in diameter. Drill the center of the spot weld withthe drill bit and let the cutter do the rest. Leaves a 1/4" hole where the weld used to be.

Hope this helps some.

[cds72911]

Hi Adam,

There is a special bit that is used for drilling spot welds. It has a flatter bottom than regulat drill bits and sometimes has a centering point. They work well though (a bit pricey).

You should be able to get them at any domestic body shop supply house. Eastwoods has them of course but the price is silly.

Charlie

[don911]

I haven't drilled a spot weld out in a long time but if I remember correctly, I think you use a small hole saw. I think you center punch the spot weld and place the drill bit from the hole saw in the center and drill out around the spot weld. You want to only drill through the first panel. The panel will "pop" out a little as soon as you're through the spot weld. I think I used a special hole saw tool that had a spring so you could push the hole saw down to the panel without having to drill through the panel first.
Does this sound correct to the more experienced spot weld removers?

Don
87 coupe

[88 911 targa]

By the way the best ones I have used were made by blair.

I just looked at the Snap on site, and the ones they sell are more difficult to use, in my opinion. Most body shot supply or auto paint supply stores will have the blair bits in stock. The last one I bought was $30.00.

[john walker's workshop]

spot weld drills leave quite a large hole. it depends on whether you want to save the outer panel. just center a regular sharp bit over the weld and run it thru. drill size should be just large enough to clear the weld. they often have to be seperated by a few wacks with a hammer and sharp chisel anyway.

[atr911]

Okay, but what about lubrications? And what would be the worst dammage taht I could do if I screw up?

Adam Roseneck

------------------
1978 911SC 3.0
roseneck@cyberbeach.net

[john walker's workshop]

just use a high speed drill, no lube. the worst damage would be a car full of holes.

[atr911]

repairable holes right?

[atr911]

repairable holes right?

[dtw]

Hey Adam, hey John...I was just dealing with this problem tonight. The nose section of my car has been previously cobbled up by a PO, so I have been cutting everything apart so I can fabricate new sections.

One thing I noticed Adam, is that the condition of the underlying panel has a lot to do with salvageability. Some of the welds I dealt with tonight came apart easily, but all I found underneath was brown oxide and no steel. Beware of this when tearing things apart; if you will be needing to fabricate new panels, you want the old panels more or less in correct shape to draw patterns from.

I tried the spot-weld drills described above; they took too much metal out for my taste. If the "underneath" panel is still good, there's no need to fill it with holes. I just reverted back to a regular drill bit to chew away the spot welds. Then after weakening the joint with the drill, I put a cold chisel in between the panels and whacked away with a BFH. If you did your homework with the drill, the welds split right apart with a few hammer blows.

Any holes leftover aren't repairable per se, but rather your guides for simulating spot welds on the new panel. Assuming you are using a MIG welder, that is how you replicate factory spot welds. Drill appropriately sized holes in the panel, trial fit and clamp up your joint, then weld in the holes. Magic spot welds. Grind as necessary.

-d



------------------
Dave
1972 911T (E motor) RSR replica project
http://members.nbci.com/dtwinters/garage/