Drill chucks

[MuzzerParticipant @muzzer]

Posted by jason udall on 20/02/2014 16:43:24:
Just has a thought..on the subject of shank vs drill size…
How do boring heads get on?..
Or fly cutters..
Hole saws
..

Boring bars and fly cutters can't hold a candle to a solid piece of HSS or carbide – they are considerably less rigid. When a well maintained twist drill is working near its capacity, it's producing 2 continuous spirals of almost full width swarf. You'd only try to reproduce that rate of metal removal with a boring bar or fly cutter once even if it had the same cutting edge length. Hole saws have no means of swarf clearance, so you have to use a series of micro pecks to clear the swarf (dust!). Even during a peck, the rate of metal removal is pretty modest.

The main reason I use a pilot hole is to ensure it starts centrally and to avoid the central core of the drill needing to cut. Although they are designed to drill without one, they need a greater force to advance the drill without a pilot.

I have had issues with keyed chucks slipping but not with keyless (apart from cordless drills). That's presumably because the keyless chucks are inherently self-tightening.

[Ian S CParticipant @iansc]

Called into the local second hand shop today, a fresh few tools arrived over the last few days, one thing was a 3/4" Dormer drill, with a 3/4" shank, $NZ4, I might think about it, but I would have to take it down to 5/8" shank dia.

Ian S C

[Author]

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