I am replacing the cowl panels on my 53 F-100. I bought a Blair Spot weld cutter. It has replaceable cutters and they state they could last for "1000's" of spot welds. My problem is that I have broken 3 cutters, and they are double sided, on just the one panel. What am I doing wrong?
I am using my 18v Dewalt drill, first I used it on the lower speed, then thought it needed to be faster, bumped it up to the higher speed. I am also using lubricant on the tips, but they just seem to catch and break.
If I have to go back to the shop again today, I'll feel like a total doofus.

Any advise would be appreciated!

 

Are you trying to cut all the way thru both panels? It's only supposed to cut thru one panel around the spot weld.

 

No, just cutting the top panel. Some spots are rusted and it does go all the way through, but for the most part, just the top panel.

 

I have had the same thing happen. Sometimes the cutters are just too hard and break off easily. I've gotten some that last a long time and some that lasted barely one panel. The hardness of these bits seems to be inconsistent.

You can extend the life of them if you make sure that you center punch each spot weld before drilling. Make these punch marks deep so the pin won't bounce out. Also try to keep the cutters level with the panel. This is hard to do. They always seem to cut one side of the spot weld more than the other. This causes the bit to jam into the hole, and it rips the teeth off of them.

If you aren't drilling completely around the weld (If you are hitting any of the spot weld itself) slow down a whole lot. The welded metal is very hard and will destroy these cutters. Sometimes you can't avoid cutting through the weld but it's hard on the bits. They make larger bits that you can try, to avoid cutting through the weld.

The most difficult thing about using these bits is that you have to go slow with less pressure than you want to use. They really rip off the metal, and I always tend to want to get those welds out fast, so I break the cutters by pusshing too hard and drilling too fast. Slow down, and use less pressure and you will break less of the cutters.
I've opted to just break a bunch of the cutters and go fast. The cutters aren't all that expensive, and I ussually have a limited amount of time to get things done.

I've seen people use step bits for this instead. Has any one had better luck with them?

 

Step bits work, but they leave a bigger hole in the bottom panel......

 

Thanks guys-

I am probably pushing way too hard. I'll ease up and see how that goes.
Thanks again

 

i use a 1/8" bit first, it seems to give the pin a place to rest so it doesnt jump around. the cutters are quite brittle, ive found with less pressure they last a little bit longer

good luck....

 

Use a 1/8" drill bit and make a pilot hole first, then use a different drill. (I love my Dewalt 18v drills to, but they seem to break off drill bits alot) Use a slow speed and dont apply a lot of pressure.

 

I am not a pro welder but I know the weld itself is much harder than the metal around it. Also it might be a good idea to lightly grind the spot weld area before you start the drilling process.