Drilling out 11mm hole to 13mm?

Some might conclude that he's outsourced "The Medway Handyman" physical business to some lookalike specially selected East Europeans with a cultured Medway accent so he can spend all his time on Usenet as a full time "White Van Man"

Reply to
The Other Mike
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Some twist drill grinding processes actually do thin the webs. I'm afraid I wouldn't tend to bother with that on account of the few drill bits I do actually wear out.

Reply to
Frank Erskine

"Presumably, you were also taught to select the pilot drill be holding it up to the web of the larger drill, to check they were the same size or, at most, marginally larger. "

Haven't heard this advice before and cant quite understand what you mean. Care to expand on this ?

Many thanks

Paul Mc Cann

Reply to
fred

They're no doubt great for small stuff, especially when the main failure mode of such bits is losing them or snapping them.

When you get to 8mm - 10mm though, in steel, quality will out.

Reply to
Andy Dingley

article,

The purpose of the pilot hole is to relieve the load on the larger drill by first removing the material where that drill has no cutting edge; the web between the flutes. It works best if it is no larger than it needs to be to do that, so select the drill by comparing it to the thickness of the web at the tip of the drill.

Colin Bignell

Reply to
Nightjar

LOL! Hoist by his own petard.

Reply to
Man at B&Q

The set goes to 10mm in 0.5mm steps. And I've not had problems with the larger sizes. For normal sorts of things. Including frequently drilling steel. You should try them and save some money. ;-)

Reply to
Dave Plowman (News)

I have two sets.. they drill steel and stainless with ease. So far i have only snapped the 2.5 mm in one set.

Reply to
dennis

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