Holding drill bits

Is holding a regular drill bit beyond the plain part of the the shank a bad idea? Sometimes I might want to make a shallow small diameter hole - say a 1/16" drill to a depth of 1/4". My inclination is to hold the drill with just enough exposed to make the necessary depth, to increase rigidity and stop the bit wandering. Whenever I do this I make sure I don't over-tighten the chuck, but it somehow feels wrong putting pressure on the flutes (although it hasn't caused any problems... yet!).

What's your opinion? What about reamers and end mills, where the cutting surface is on the edge?

I was always told to only hold by teh plain shank.

If you want a short hole get some stub drills.

Put the drill in a split brass ring 'collet'. Just thinking of a drill held by its flutes is like scratching fingernails down a blackboard......

I thought about that but when I saw a double-ended one I thought there's no way to avoid holding that by the flutes as well as the plain shank!

Do you mean a 'split bush' type thing? I don't have any fingernails left, I chewed them all off after nervously tightening a chuck on the flutes of a drill bit :D

What are you using to drill these small holes with ? If its a drill press without an adjustable stop, adjust the table for depth with the spindle fully down. If its a hand drill, use a common pen, and cut the forward part of the barrel to length, then put a couple of drops of super glue or shrink tube it in place.

yes, split bush. But why don't you start with a centre drill anyway then the long drill doesn't matter.

I would have thought the concentricity of the drill would suffer if you held it by the flutes in a regular 3-jaw drill chuck. A collet might be OK (though I wouldn't use an expensive one) or as suggested a split bush which would emulate one.

With the double ended drills the flutes are short and the one inside the chuck is (mostly) beyond the jaws. They are a favourite with roofing contractors here, tin roofs abound.

Ian S C

Shorten the bit then re-sharpen?

Or if you just want to mark the depth to drill on the bit then a little brightly coloured heatshrink or even tape or crimped thin wall tube etc

Hi

I do it quite often using an ER collet in the mill. I'm sure I read somewhere that this was one of the benefits of using ER collets for holding drills as you get a more rigid setup, and don't necessarily need to use a centre drill first. It also helps if you have restricted height between quill and table. It may or may not be wrong but it works for me, wouldn't do it out of choice with a drill chuck though.

I saw the price of Guhring spotting drills in the MSC flyer yesterday!

I have, probably from one of those 1001 mini-drill accessory sets, about half a dozen small stub length drills with 90-degree ends (not true spotting drills that only have about 1/3 turn of flute) and they do the job admirably.

Neil

If you shorten a twistdrill and then resharpen you will need to thin the chisel edge as it gets thicker the shorter the drill becomes . If the drill is sharp ( as it should be ) there is no need to hold it close to the end as it will not wander provided it is started truly just let the drill do the work , do not apply too much pressure . One other point , drill shanks are soft , the flutes are hardened and thus could possibly shatter if used whilst gripped in a chuck .

Jeff

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I would have thought gripping a drill bit by the spiral flutes would increase the probability of snapping them considerably.

If this should happen I cannot think of a better way to gouge and ruin the gripping parts of a chuck or collet.

Nick

OK thanks all for the input, I'll stick to holding by shank only in future :D

This is simple once one thinks about it. Why would manufacturers provide every drill bit with a plain shank? Is it just for somewhere to mark its size? Is it so it can be stored in a nice box with holes for each drill size? Is it so they can make it easier? Or is there (an)other reason(s)?

I doubt HSS is any tougher at one end or the other, just much thicker section at the plain end? So more likely to shatter at the flutes?

Not true. The shanks are left soft. Very useful on taper shank drills with knackered tapers as you can turn them down to a parallel shank.

David

By gripping them by the flutes?

Roger

Done quite a few reducing jobs myself just gripping on flutes. I used to use split bushes but too timely of late.

Self centreing 3 jaw chucks are so plentiful nowadays its easy to keep a not so good one aside for similar sorts of jobs I suppose. I was lucky to get my hands on a freeby 6 jaw self centreing chuck ( Ex Brierly Drill grinder ), which i keep aside for similar.

Don't think i have ever felt the need to grip on flutes for drilling though, plenty other alternatives as mentioned.

But dont loose track of the fact that as mentioned flutes are used for gripping on for grinding purposes as per on the Brierly's.