Problem with drill bit

[qquake2k]

I'm having a weird problem with one drill bit. The chuck keeps loosening when I use it. It's a 12.5mm brad point bit, reduced shank. I'm using it in a full size drill press with a 5/8" chuck, tightened with a key. This morning I had to tighten it several times as I drilled 2" into an acrylic blank. This doesn't happen with any other bits, not even a 9/16" brad point, or a 10.5mm bit from the same manufacturer. Any ideas?

 

[Dalboy]

Very strange do you tighten using all three points on the chuck or do you just tighten with the one usually the nearest to you. Try putting the chuck key in each hole on the chuck and just give them a tighten

 

[bassethound]

Very odd, I always do what Derek said with the key and never had one get loose!

 

[woodhacker]

As Derek says. have you checked the reduced shank to see of it is true (could have a slight taper to it)

 

[Penpal]

I never could take to these drills preferring drill point ones but I feel for you its painful when this happens. If there is the slightest bit of oil or grease around a drill when you receive it this can cause this problem. I wash my new drills and clean out the chuck regularly another thought some acrylic can be slippery and not set fully. Good luck.

 

[chas_41_uk]

As already suggested

 

[Penpal]

I noticed on occasions chucking stepped shaft drills to be sure I dont go past the shoulder I keep a finger nail on the step when chucking or texta at the step to prevent mischucking.

Peter.

 

[Bill Mooney]

As Derek says. have you checked the reduced shank to see of it is true (could have a slight taper to it)

I agree. It could have a slight taper on the shank.

 

[qquake2k]

I've never heard of tightening the chuck in each of the three holes, but I'll try that next time. I also measured the shank to make sure it's not tapered. Right at the shoulder, it measures 0.437". But right above that, and all the way to the end of the cut down shank, it measures 0.434". Next time, I'll make sure to leave a gap between the shoulder and shank when I chuck it up.

 

[wm460]

I've never heard of tightening the chuck in each of the three holes, ]/SIZE]

We were tought that in metal work class at school, especially on the metal lathe chuck.

 

[qquake2k]

I took a metal shop class in school, but it's been so long ago, I don't remember what we were taught about using the drill press.

 

[21William]

It sounds like the reduced shank hasn't been machined very well. You'll have to buy a new one. Try a different make.

 

[Grump]

It sounds like the reduced shank hasn't been machined very well. You'll have to buy a new one. Try a different make.

Waste your money if you like, all it would do is put it in a vice or chuck and grind the bugger to parallel and square init?

 

[silver]

Waste your money if you like, all it would do is put it in a vice or chuck and grind the bugger to parallel and square init?

It sounds like the reduced shank hasn't been machined very well. You'll have to buy a new one. Try a different make.

I agree with Grump, I would stick it in my wood lathe chuck and spin it up and use a bastard file to square it up. Doesn't need to spin too fast and don't push down too hard, keep a constant pressure.

Otherwise I would put in the metal lathe and square it up. If you don't have one then I sure there is someone around you that will have one.

 

[loftyhermes]

Why not cut off the reduced bit and/or just use what's let of the shank?

 

[21William]

Why not cut off the reduced bit and/or just use what's let of the shank?

His drill chuck may not accept a bit that big.

 

[Dalboy]

His drill chuck may not accept a bit that big.

It should do as the OP has a 5/8" chuck

 

[21William]

It should do as the OP has a 5/8" chuck

Quite right, I missed that!

I'd wonder why he bought a reduced shank bit but the discount shop near me has lots like that. I guess they're for power drills with 10mm chucks.

 

[Penpal]

Nought wrong with reduced shanks I have turned down so many on the lathe never had a wink of bother and as has been said using power drills with smaller chucks saved me so much grief.

Peter.

 

[wm460]

You didn't buy your drills from PSI, I got some that even with out the reduced shank they are wonky as buggery.