Manual Drilling - Breaking Bits

[automan]

A 2.5mm drill is just shy of 1/16" inch which is as small as most people go. They are susceptible to bending and breaking, especially when drilling metal with a hand drill. Drilling metal requires more drill pressure which leads to breakage. Drilling cast iron castings can be especially tricky as there are often hard spots or voids within the casting.

When drilling with a small drill, watch the drill bit to avoid bending the drill. The nature of a hand drill puts the force off center which will naturally cause a bending moment. This can be reduced by using your other hand to apply force directly in line with the drill while the hand on the trigger is mostly controlling the motor.

Hand drills, especially the battery operated kind, are lacking in rpm which makes it difficult for drilling with small drills. The drill will tend to take a bigger chip which is more likely to cause a jam and breakage. One has to go easy and let the drill do its cutting-at its own pace.

shy of .1"

 

[RaisedByWolves]

I was drilling the 2nd of five 2.5mm holes in in 7x16 LMS lathe bed to mount the rack, and broke off the bit as it punched through. I was using a piece of 1/4” square stock set on the ways shoulder to keep me from going too far, with the drill bit all the way into the battery-powered drill, but when it punched through, I must have lost true and - snap.

Any suggestions on how to do it better with a manual drill? No drill press handy… Ten new bits will arrive from Amazon tomorrow. Fortunately, I could push out the broken bit in the hole as I had flooded with Tap Magic while drilling.

BRET

Here’s part of your problem.

I understand why you think this is a good idea, but it’s not. You’re putting direct pressure on the flutes of the drill chucking it up that far and severely limiting its ability to flex.

Chuck it up normal and you will be better off as the drill will be free to flex over its entirety of the flutes rather than being constrained.

 

[automan]

Here’s part of your problem.

I understand why you think this is a good idea, but it’s not. You’re putting direct pressure on the flutes of the drill chucking it up that far and severely limiting its ability to flex.

Chuck it up normal and you will be better off as the drill will be free to flex over its entirety of the flutes rather than being constrained.

Good point wolfie!

 

[automan]

Full carbides 6" long at 9/32" dia. do ok if fast and let it flex(a bit).

I did 1000's of S.S. catalyst shells for t-cuples fast and long.
cliff

 

[MaverickNH]

Here’s part of your problem.

I understand why you think this is a good idea, but it’s not. You’re putting direct pressure on the flutes of the drill chucking it up that far and severely limiting its ability to flex.

Chuck it up normal and you will be better off as the drill will be free to flex over its entirety of the flutes rather than being constrained.

Good learning there, thanks!

BRET