Sharpened drill bits don't last 5 seconds.

[atikovi]

Thought I would tap for a smaller bolt.

 

[MJD1]

Why not drill a hole next to it and avoid the frustration
Use a thick backing washer and move on.

 

[atikovi]

Can't get to the back side.

 

[American Locomotive]

You don't want to use a smaller bolt for a seat. If you crash, the seat will break off and you 'll be sad.

You're already most of the way through the bolt. Just get a fresh bit, push very hard at a slow speed with plenty of oil and take your time.

Then step up the size progressively until you have the bolt out.

 

[dutchgray]

Some heat may help loosen it, then get a very large punch and the biggest hammer you can wield one handed and belt that bolt a couple times. The try an easy out or hammer a torx bit into what you have drilled and try to tighten a little first, then undo, but do not break them off in there under any circumstances.

Otherwise you will just have to finish drilling it out, decent bit and lots of pressure, you will have to rig something up to get some leverage on the drill.

 

[ItsNemo]

Thought I would tap for a smaller bolt.

I will repeat...what makes you think a bolt you can barely drill out will let you tap new threads in it?

Also, not safe.

 

[Fcvapor05]

What???? I own a machine shop. Drills are HSS, and you can get them red hot, and it won't change the hardness.
Drill doctors are junk. Learn to sharpen by hand. Also most people don't follow the correct procedures and drill to fast or with not enough or too much down pressure.

I'm a metallurgist. You will absolutely change the properties of high speed steel if you get it red hot and let it cool in air.

You'd be right that a bit that's gotten that hot will still make holes in mild steel and most aluminum alloys without issue.

Sharpening drill bits is hard- for most people that don't work in a machine shop and don't do it all the time. If you know what you're doing, its possible to do it right pretty much every time.

But if you're on garage journal asking questions about why your drill doctor doesn't work, chances are that you don't have years of experience sharpening bits and you're going to ruin a lot of bits learning how.

 

[Skin]

Would a solid carbide bit be next? Can they be used in a hand drill?

Absolutely not. As stated subtly on page 1 they don't last. More specifically what happens is it shatters almost instantaneously. Carbide, like diamond, is immensely hard and cannot hold up to vibration or being bent along its vertical axis. The feed angle cannot change while drilling and the chuck and work piece need to be perfectly ridged. In a hand drill you will literally snap it in about 10 seconds. Hopefully before it lodges itself in the hole because then pray to the gods you can shatter it as if you cant the only way to remove tungsten is to use a wonderful device called a Metal Disintegration Machine.

The best bits I've found are sold by Mcmaster Carr under the coated cobalt section and are Guhring FireX bits (TiAISiN coated cobalt). The Matco Hyper-Steps are suppose to be excellent as well and they have new cobalt versions too.

If it were me though and I were chewing up a lot of bits I usually switch over to small carbide burrs.

 

[didit]

There are a few different methods you can use to remove that broken bolt. You already have it drilled deep enough for using an easy out. Before using an easy out it would help to alternately heat it up with a torch and then sparingly apply a 50/50 mixture of ATF & acetone. At the molecular level, this mixture will be thin enough to penetrate and break the friction bond. Then use the easy out. Repeat if nessesary.

If that doesn't work then as already suggested, center a nut over it and weld the nut to the broken stud. Apply the ATF/acetone mixture again and back the nut & stud out.

Be careful not to start a fire. Good luck!

 

[jimmyin3D]

Have you tried using the Irwin Hanson spline head extractors?

If you have alrdy drilled a hole into the bolt then the spline heads will grab it and can be backed out. They work great for applications like this.





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[atikovi]

Drilled some more. Enlarged the hole some more until up to the threads. Punched out the remains with a air hammer. Cleaned up the threads with a tap. Seat back in.

 

[M635_Guy]

FWIW, I find the Project Farm "channel" videos on YouTube really interesting. He's got one on drill bit sharpeners and one on drill bits.

 

[bwringer]

I just love a happy ending!

 

[Indiana Dave]

Did you end up buying different drill bits? Using a hand drill, obviously?
I've got a broken bolt, and have broken a drill bit, another dril bit, and an easy out off in the same broken bolt.

Drilled some more. Enlarged the hole some more until up to the threads. Punched out the remains with a air hammer. Cleaned up the threads with a tap. Seat back in.

 

[tonyciambrone]

The best bits I've found are sold by Mcmaster Carr under the coated cobalt section and are Guhring FireX bits (TiAISiN coated cobalt). The Matco Hyper-Steps are suppose to be excellent as well and they have new cobalt versions too.

If it were me though and I were chewing up a lot of bits I usually switch over to small carbide burrs.

Yea buddy. Guhring makes some quality tooling. And I second carbide burr and a die grinder. take a little bit with the burr, wipe it with some oil, blow the bore out with air, take a little bit more repeat.

And yeah if you snap a cobalt or carbide drill in there you're gonna have a bad time

 

[zendriver]

I'm a metallurgist. You will absolutely change the properties of high speed steel if you get it red hot and let it cool in air.

You'd be right that a bit that's gotten that hot will still make holes in mild steel and most aluminum alloys without issue.

Sharpening drill bits is hard- for most people that don't work in a machine shop and don't do it all the time. If you know what you're doing, its possible to do it right pretty much every time.

But if you're on garage journal asking questions about why your drill doctor doesn't work, chances are that you don't have years of experience sharpening bits and you're going to ruin a lot of bits learning how.

It's not hard sharpening drill bits on a DD at all, if one follows the 3 step directions.


I have no problems with sharpened bits on metal.

The DD sharpening stone has contact with the bit edge about a half-second each pass, so a user would really have to crank the piss out of it, to get a bit hot, maybe it happens. If so, the user did not follow the simple directions.

When I worked in a metal shop 30 years ago, all bit were resharpened by machine, because they wanted them resharpened accurately.

Agree many bit problems come from improper drilling.