Best/Toughest Drill Bit

bowtieman55

bowtieman55

Well-Known Member
Joined
Jan 25, 2006
Location
Edenton, NC
I've got a window regulator that needs repairing and that requires drilling a 1/8" hole into, and bolting together two flat pieces to "reconnect" them. I've broken 2 Titanium Nitride High Speed bits and can't even get a Cobalt bit to start. Thoughts or suggestions for a really bad ass bit that'll start and not break? Thanks.
 
Last edited:
Plasma cutter....how are you breaking a 1/4 drill bit? I would think it would just be a mild steel pin, however if you can drill it then it's probably hard as a coffin nail. If so then you're gonna need carbide.
 
You don't want to use carbide in a hand drill, too brittle and prone to break with uneven loading. If you have the stuff off the car and on a drill press, that's a different story.

What is it that you're actually drilling? Is this something that's been work hardened from stamping? I'm trying to visualize what you're doing.

Whatever it is, you'll be best off using as short of a bit as you can get away with, for the least deflection. Obviously quality matters too.
 
Believe it or not, I've used masonry bits to drill heat hardened broken exhaust manifold bolts out before. It works surprisingly good. Had 2 broke manifold bolts on my old 6.0 diesel. One bit each but it ate into them when all my standard bits wouldn't even nick the surface.
 
Fabrik8 said:
What is it that you're actually drilling? Is this something that's been work hardened from stamping? I'm trying to visualize what you're doing.
Click to expand...

On the window regulator, there are two flat pieces of steel (back to back) that are spot welded from the factory; the factory weld has broken so the window motor doesn't move the window while it's running.
 
Chris_Keziah said:
Plasma cutter....how are you breaking a 1/4 drill bit? I would think it would just be a mild steel pin, however if you can drill it then it's probably hard as a coffin nail. If so then you're gonna need carbide.
Click to expand...

1/8", not 1/4". My bad.
 
The broken weld can be seen in this picture. The two pieces are supposed to overlap and move together; the one in the lower position is controlled by the motor and the upper one controls the up/down of the window.
 

Attachments

  • facebook_1560978228316_resized.jpg
    facebook_1560978228316_resized.jpg
    91.4 KB · Views: 206
In a pinch, might I recommend a small box of self tapping screws? They are sacrificial, short, and you can get a good hold of them with the appropriately sized socket. You would be surprised what a few of those little guys will get through, just give them a good center punch.

If you wanted to head over to Harbor freight or northern tool and grab a set of center drills, that would be ideal.
 
For the amount of work you're going through to drill it (and I assume the goal is to then screw of bolt it) I'd really just ask around and find somebody w/ a welder. It's a 30 second job to do, and it more the right way to do it. I bet there's a half dozen guys here within a 30 minute drive that would do it for you. I sure would. It's doesn't even need to be a fancy or great weld.

Alternative: JB weld or similar.
 


These new hyper step drill bits from Matco seem pretty awesome for harden steel. I seen another video the other day they drilled through a brake rotor like it was butter.
 
Curtis_H said:


These new hyper step drill bits from Matco seem pretty awesome for harden steel. I seen another video the other day they drilled through a brake rotor like it was butter.
Click to expand...


Pricey, but these are what I went with. These drill bits are the cat's tits. Thanks for the head's up, @Curtis_H
 
Generally if your dulling bits your spinning them to fast and not putting enough force behind them unless its something insanely hard.The quality of the bit is normally not the issue. If your dulling a cheap bit youll likely be dulling a quality bit just as quickly. If thats the case, try a cheapy bit with hammer drill spinning it fast. It works often enough that its worth savrificing a couple dollar bit to try. If not get a carbide burr and be done with it.

Sent from my SM-G955U using Tapatalk
 
Back
Top