Let’s talk about Drill bits, specifically twist drills.

[Clive FosterParticipant @clivefoster55965]

My experience is that sharp, really sharp, adequately solves 90% of drilling problems. Assuming decent quality drills to start with of course. Most of the economy ranges are really for hand drill and the rougher end of pillar drill jobs so wider tolerance bands are fine. You might get a nice one, you might not. Generally the expectation is that such will be broken or bent before blunt becomes an issue.Often the pretty TiN coated ones turn out to have only a thin crust of hard material under the make-up so sharpening isn't possible. Not necessarily a bad thing if the drill is also less brittle. I've seen such cheapies pushed so hard by big guy in a hurry that they are significantly bent and survive.

Even with a conventional point bumping a sharp drill into the work a few times will get you a clean start. But you will have to re-sharpen more often.

Given that both Andrew and I have Clarkson drill sharpeners its interesting to see how different our drill practices are.

Andrew finds that by the time his drills need sharpening they are often in poor enough overall shape that new replacements are appropriate.

Given that the default state of my Clarkson T&C grinder is with the drill sharpener set up any drill whose sharpness is even the slightest bit debatable gets mounted and restored to proper condition. As it's about a minute, on a slow day, between a beady eyed "Hmmn" on picking up the drill to putting something sharp enough to shave with into the machine chuck I see no reason to accept anything beyond the most minor wear. After 10, maybe 20 holes in steel you can feel that the drill has lost its best edge. Still perfectly good for, probably, 'undreds more holes but ….

Clive

[SillyOldDufferModerator @sillyoldduffer]

Posted by Mick B1 on 13/12/2022 11:07:28:

Yes, learning the bench grinder to sharpen drills, and make and resharpen HSS turning tools and form tools of all types, is time excellently well-spent that repays itself for ever.

…

Hate to disagree, but in industry as opposed to hobby work, that idea is a 'Dark Pattern'. That is, a practice that seems correct, but actually has negative consequences.

Industrial workers cost money and their output pays their wages. A worker who stops to regrind drills isn't productive, so he's potentially wasting money.

The firm should balance the cost of the worker and lost production against the money saved by sharpening blunt drills. It's usually better to minimise downtime by swapping new drills for blunt ones, and to only send big drills off for resharpening.

Resharpening in-house is an option, but the owner has to consider the cost of the machine, the space it takes up, and paying someone to drive it. And a machine that isn't busy resharpening most of the time is unlikely to be paying it's way. Thus it's often cheaper to outsource than to own a drill-sharpening machine.

Assuming it's sensible to resharpen drills and other failures to tackle cost efficiency partly explains why so many British engineering firms went bust, even though everyone in them was working hard and thought they were doing a good job. Dark patterns are nasty because they often go unnoticed for decades…

Dave

Edited By SillyOldDuffer on 13/12/2022 17:25:28

[Ramon WilsonParticipant @ramonwilson3]

Posted by SillyOldDuffer on 13/12/2022 17:25:05:

Posted by Mick B1 on 13/12/2022 11:07:28:

Yes, learning the bench grinder to sharpen drills, and make and resharpen HSS turning tools and form tools of all types, is time excellently well-spent that repays itself for ever.

…

Hate to disagree, but in industry as opposed to hobby work, that idea is a 'Dark Pattern'. That is, a practice that seems correct, but actually has negative consequences.

Industrial workers cost money and their output pays their wages. A worker who stops to regrind drills isn't productive, so he's potentially wasting money.

The firm should balance the cost of the worker and lost production against the money saved by sharpening blunt drills. It's usually better to minimise downtime by swapping new drills for blunt ones, and to only send big drills off for resharpening.

Resharpening in-house is an option, but the owner has to consider the cost of the machine, the space it takes up, and paying someone to drive it. And a machine that isn't busy resharpening most of the time is unlikely to be paying it's way. Thus it's often cheaper to outsource than to own a drill-sharpening machine.

Assuming it's sensible to resharpen drills and other failures to tackle cost efficiency partly explains why so many British engineering firms went bust, even though everyone in them was working hard and thought they were doing a good job. Dark patterns are nasty because they often go unnoticed for decades…

Dave

Edited By SillyOldDuffer on 13/12/2022 17:25:28

Yes Dave but that hardly applies in the home workshop. If you take that literally then you either need the means to sharpen to a finished degree – for the most part which isn't necessary – or have new drills for every time one gets blunt.

Sorry mate but can't agree with that principle from a home perspective at all.

That may be fine in highly commercial enterprises but in the myriad of support jobbing shops – without CNC machines – not really a viable proposition. Not many without CNC these days I grant you, but then how long have they been round in comparison to previous machining practices.

For the last couple of days I've been making small 'castings' from solid for the valve lay shaft on the marine engine all drilled with hand ground drills and milled with cutters that have had hand ground radii on them.

As Mick says learn something worthwhile and it stays with you for life.

Best – Tug

[Mick B1Participant @mickb1]

Posted by SillyOldDuffer on 13/12/2022 17:25:05:

Posted by Mick B1 on 13/12/2022 11:07:28:

Yes, learning the bench grinder to sharpen drills, and make and resharpen HSS turning tools and form tools of all types, is time excellently well-spent that repays itself for ever.

…

Hate to disagree, but in industry as opposed to hobby work, that idea is a 'Dark Pattern'. That is, a practice that seems correct, but actually has negative consequences.

Industrial workers cost money and their output pays their wages. A worker who stops to regrind drills isn't productive, so he's potentially wasting money.

The firm should balance the cost of the worker and lost production against the money saved by sharpening blunt drills. It's usually better to minimise downtime by swapping new drills for blunt ones, and to only send big drills off for resharpening.

Resharpening in-house is an option, but the owner has to consider the cost of the machine, the space it takes up, and paying someone to drive it. And a machine that isn't busy resharpening most of the time is unlikely to be paying it's way. Thus it's often cheaper to outsource than to own a drill-sharpening machine.

Assuming it's sensible to resharpen drills and other failures to tackle cost efficiency partly explains why so many British engineering firms went bust, even though everyone in them was working hard and thought they were doing a good job. Dark patterns are nasty because they often go unnoticed for decades…

Dave

Edited By SillyOldDuffer on 13/12/2022 17:25:28

Yeah, yeah, yeah… bin there, done that … it depends on the industry and the type of work. In a repetition shop putting out a steady range of products in a cost-competitive market, of course you wouldn't train operators to sharpen drills, and any who took extra time to do so might lose a piecework element of their pay.

You might have a tooling department to sharpen them along with milling cutters in batches if the cost/benefit sums were right.

In toolroom and instrument shops where the variety of work is very wide and specially adapted tools are often needed on an ad-hoc basis, long lead-times are often saved if you have people who can knife-and-fork a suitable tool capable of delivering the required dimension.

Industry ain't where most of us are – it's a hobby done for fun, so we don't always plan in detail and we're often faced with something we have to make in order to do the work in front of us. So we're much closer to the working environment in the previous paragraph.

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