Drilling rusted screws

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Pevehouse

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Hello all, got a project I’m helping my nephew with and I’m running into a problem. We are installing a new convertible top on his mustang and there’s several small screws that are going to need to be drilled out. They are about a number 5 or 6 sheet metal type screw, the heads used to be torx bit heads but rust has gotten the best of them hence the drilling. Problem I’m having is I’m killing drill bits trying to get through these little boogers. I will go through 1 or 2 ok but then on the third the bit is so dull it will not cut. Wondering if it’s the rust that’s getting me and if there’s any suggestions on bit types and material I should be using. Thanks in advance for any help you guys can offer
 
A sharp HHS or Cobalt bit should do the job. A left hand bit would probably be better in that once the head is penetrated it will likely unscrew. There are several listings for left hand drills on eBay
 
Some of the socket head screws (Torx or hex) have the head hardened to help keep them from stripping out. They can be hard to drill. Use a name brand quality drill bit, preferably left hand, either cobalt or carbide. Carbide can chip easy while trying to start into a rough hole.
 
If they've got rust, then the rust IS damaging the drill bit.

Best is to A, dig the rust out with a pick as well as you can, B, drill slow and dry. If you've got lefties, smoke 'em if you've got 'em. Otherwise, whatever you've got, it's too small to get great results out of a lefty anyhow. The drill will break before it gets enough torque to unscrew "stuck" threads. Although a lot of times it's the washer face under the head that's really stuck, and a "sheet metal type" screw doesn't get "that" stuck anyhow...

Not sure where you're working on that convertible top, but if it's not ill advisable (and it may be just that...), but if you can, stick a straight punch inside the damaged torx head, and thwack it with a hamer a couple of times. (respectfully, choose the hammer and the effort level according to what's under that screw....). That shock, driving it in like a nail- Well, it won't drive in, but that shock can loosen stuck threads AND stuck washer faces under the head...

After those thoughts- Welcome to auto repair. This stuff was designed to be worked on until the warranty is up. After that, of course you still can, but the onus is on you, as the vehicle was never built to last forever... Start gently, and escalate slowly, and think several steps down the road at EVERY opportunity. You "want" this way to work, but where does it leave you if it doesn't.... 99 percent of these battles are about self restraint and persistence. The rest of the battle, with small screws, is a ten pack of decent drill bits when you'd usually just keep a couple at most on hand. They need not be that fancy. Just suitable for the minimal drilling you'd be doing in the material. It's the rust that kills 'em moreso than the metal. There's no screws on that car that you can't drill with the cheapest of drill bits, PROVIDED they've got a good tip on them.
There's another tip I suppose- Before going into a screw extraction, briefly test your brand new drills on "something". Make sure the point is good, center is good, both sides cut.... That'll wreck your day, and keeping centered on a screw stump is enough fun, you don't need the cross wind from "misbehaving" drill points
 
@Jake M not sure why dry? I would stick with HSS, and just sharpen the bits. I just broke a Carbide burr and it pisses me off how delicate they can be. Same with carbide drill bits... BUT masonry bits are tough, so if you have a sharp masonry bit go for it. I was able to drill out a broken drill bit an oops bad memory it was a hss drill bit, followed by a carbide to drill the hss drill bit out, and that broke, so I used the masonry bit.
 
woodchucker said:
@Jake M not sure why dry?
Click to expand...

I'm not sure I can fully answer that. Rust and oil making a grinding paste? I doubt it's that but it's the best I've got. 30 years of repairing cars, trucks, machines, equipment, here in the salt belt... Don't oil when you're drilling through built up rust, your drill bits last better, so you bollix up the holes less. And once youn hit metal, it's also low speed, low depth, low demand drilling, so it's not needed. If you wanted to core out a hole down the middle of a long bolt, fresh metal, deep holes, that's different (maybe), but in a very small, shallow thing like this, where it's tough to get enough tool pressure on the best of days- Well, after the rust is gone it probably wouldn't hurt (although this is a convertible top...), but it's just not a demanding hole. It's really the "drilling through rust" part though that goes better without oil. After that, it's just clean metal, normal hand drilling judgement would apply.
 
Sometimes with stripped Torx screws, it is possible to get the tip of a screw extractor in there and just turn it out. Penetrating oil, like PB Blaster, helps too.
 
Welcome to hell. I've been there. The screw gets welded in place by the rust and is pretty much part of the panel.
Cobalt drills might work
 
Jake M said:
If they've got rust, then the rust IS damaging the drill bit.

Best is to A, dig the rust out with a pick as well as you can, B, drill slow and dry. If you've got lefties, smoke 'em if you've got 'em. Otherwise, whatever you've got, it's too small to get great results out of a lefty anyhow. The drill will break before it gets enough torque to unscrew "stuck" threads. Although a lot of times it's the washer face under the head that's really stuck, and a "sheet metal type" screw doesn't get "that" stuck anyhow...

Not sure where you're working on that convertible top, but if it's not ill advisable (and it may be just that...), but if you can, stick a straight punch inside the damaged torx head, and thwack it with a hamer a couple of times. (respectfully, choose the hammer and the effort level according to what's under that screw....). That shock, driving it in like a nail- Well, it won't drive in, but that shock can loosen stuck threads AND stuck washer faces under the head...

After those thoughts- Welcome to auto repair. This stuff was designed to be worked on until the warranty is up. After that, of course you still can, but the onus is on you, as the vehicle was never built to last forever... Start gently, and escalate slowly, and think several steps down the road at EVERY opportunity. You "want" this way to work, but where does it leave you if it doesn't.... 99 percent of these battles are about self restraint and persistence. The rest of the battle, with small screws, is a ten pack of decent drill bits when you'd usually just keep a couple at most on hand. They need not be that fancy. Just suitable for the minimal drilling you'd be doing in the material. It's the rust that kills 'em moreso than the metal. There's no screws on that car that you can't drill with the cheapest of drill bits, PROVIDED they've got a good tip on them.
There's another tip I suppose- Before going into a screw extraction, briefly test your brand new drills on "something". Make sure the point is good, center is good, both sides cut.... That'll wreck your day, and keeping centered on a screw stump is enough fun, you don't need the cross wind from "misbehaving" drill points
Click to expand...
Curious to know why you think rust would affect a drill bit.

It’s just a decomposed layer of the base metal that is less than paper thin.
 
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