Drilling Out SUPER Hardened Screw

[Patricia Brown]

In cleaning up my newly acquired '72 cowl-back body, I came across some little (1" wide, 1/2" tall) flat "tabs", about 6 or 8 of them, screwed across the top of the windshield frame. Do these have something to do with supporting the glass?

Anyway, most of them unscrewed but a few which were stripped and I had to drill them out. I'm down to one remaining, stubborn screw which refuses to be drilled out. I am using cobalt bits (the hardest my local hardware store carries) and they won't touch it. It's dulled 3 of them now. I know nothing is wrong with the bits because they went through the other screws like butter (even after being dulled). It sits and spins on the screw and won't even throw any slivers. I finally used a cut-off wheel on my Dremel and was able to take the head off and remove the "tab", but the screw's shank is still stuck in there. Is there any way to remove such a super-hardened screw? Do they make drill bits harder than cobalt, and where can I get one?

Thanks! Patricia

[Larry Kelly]

Re: Drilling Out SUPER Hardened Screw

I have had good sucess with carbide ball end mills. They are expensive though.

[Gene M.]

Re: Drilling Out SUPER Hardened Screw

If you use solid carbide drill bits, they are a lot less expensive than end mills. Tool and die shops in your area may sell you one. Another place I found them was E-bay.

[Billy Olson]

Re: Drilling Out SUPER Hardened Screw

Make sure you aren't fighting a piece of broken drill bit (been there done that!!!). Since the others drilled out easily, it is odd that the last one would not. Good Luck!

Billy

[Terry F.]

Re: Drilling Out SUPER Hardened Screw

Thats what I was thinking. I think sumthins up! Doesn't sound right to me.

Terry

[Terry F.]

Re: Drilling Out SUPER Hardened Screw

Try to anticipate problems like that when working around sheetmetal screws and old car frames. Give the screws a tap with a punch and hammer then soak them with penetrating solvent, etc. If you can apply heat, use heat also. If you can grab it with pointed visegrips, that may work also. Most of all, take your time and soak stuff that won't come out easy. If something gives you the slightest trouble, stop and soak it and tap it. All it take is a little vibration sometimes.

Sounds like a broken drill bit to me. No screw is that hard. You would have to try real hard to find something like that.

Terry

[Dick G.]

Re: Drilling Out SUPER Hardened Screw

I am not familiar with this fastener or part, but like Terry stated use heat; from a small propane torch will work. If you are able to clamp on a vice grip, concentrate the heat to the outside only. Then carefully spray on some penetrating fluid WD-40 type. It will only smoke. The penetrating oil will suck into the fastener and srew right out. Now if this is not fruitful get your wire feed welder out and weld onto the head of the fastener only. Build up a tower of new weld on top of the fastener only. With heat from the welding still hot, screw that sucker out. This has always worked for me except for some body-mount bolts due to access and of course the removal of exhaust manifold studs,etc.. Have Fun and always be safe. Dick Gutman

[Gordon Peterson #4961]

Re: Drilling Out SUPER Hardened Screw

This is probably overkill for this problem, but here's an experience I had with a broken tap - talk about hardened. I was chasing the threads on my bare block when a 1/4-20 tap snapped off in one of the timing cover holes. It broke off flush. I bought one of those tap extractors that has the fingers that run down the tap's flutes - absolutely hopeless! Frantic, I talked to my machinist buddy. He set the block up on a "tap buster" which is a precise electric welder designed to vaporaze a broken tap right in the hole leaving the original threads intact. It took less than ten minutes to do (fascinating to watch) and I was back to chasing the threads on that hole again. CAREFULLY! So, the message here may be to talk to a GOOD machine shop. Sometimes they can do wonders.
Pete

[Jon #40768]

Re: Drilling Out SUPER Hardened Screw

I do not have any experiance with a tap blaster, but it might be the same as an edm machine. The edm will work in a similar maner.

Jon

[Patricia Brown]

Re: Drilling Out SUPER Hardened Screw

Thanks for all the ideas. No, it's definately not a broken drill bit in there; all the bits I've used on it are not broken, just dulled. Also, all the drilling did was make a very shallow dip in the head of the screw that is now shiny. Out of desperation, I was able to cut the head off with my Dremel's cut off wheel. However, the shank is still stuck in there.

I'm interested in finding a carbide drill bit. We have no good machine shops around here (my own, dreadful experiences!) and I'm not aware of any machine supply house. However, can someone recommend a company on the 'net?

Thanks! And I WISH I had a MIG welder and knew how to use it! Someday...

Patricia

[Larry Kelly]

Re: Drilling Out SUPER Hardened Screw

Dewalt makes carbide drill bits (as do others). I think they are available at Lowes, Home Depot, ACE Hardware etc. Most tool suppliers on the net want a minimum order. It will take a fair abount of pressure to get it started but once it get through the hardened part, it will cut like butter. Be careful, carbide is very brittle and will snap.

[Patricia Brown]

Re: Drilling Out SUPER Hardened Screw

Thank you, Larry. I didn't realize Lowes, etc. would have them. Interestingly, I could not see that Grizzley sold them, and they cater to machine supply. Anyway, I'll give Lowes a check. Thank you!

Patricia

[Patricia Brown]

Re: Drilling Out SUPER Hardened Screw

Have you guys run into hardened screws like this? I'm rather surprised a cobalt bit would be dulled by a screw that doesn't even appear to be rusted. Also, strangely, I wonder why the philip's head would get buggered by a screwdriver, yet a cobalt bit can't drill it! Our local Lowes and Home Depot had cobalt but not carbide bits. I guess it's down to somewhere on the 'net.

Patricia

[Patricia Brown]

Re: Drilling Out SUPER Hardened Screw

Ahhhh. I found the coolest website! It's called Drill Bit City. Man, do they have it all! They even sell re-sharpened carbide drills at about half the cost of new. I just placed an order, so I'll be really curious how they do on this stubborn screw!

Patricia

[Gerard Q.]

Re: Drilling Out SUPER Hardened Screw

Are you sure your not drilling in reverse. I'm only saying this because I'm guility of doing it.