Drill Sharpening again

[VicParticipant @vic]

I have been giving this topic some thought recently and had initially decided to use a collet block and ER collets. I then dismissed the idea in favour of using a collet Chuck in a shop made fixture. Chuck now ordered plus a few more collets to fill the gaps in my set. I then happened upon this site, which I must admit I’d seen before. Lots of very useful information. What quite surprised me was the persistence of using an angle down approach. One guy has decided to do it differently, albeit using a standard grinder. The author does say that “point up gives better visibility” which was my first thought. I’m hoping to built something much simpler for use on my belt grinder and will also be using a point up setup. If the belt grinder doesn’t work I’ll try something else but I’m still inclined (pun intended) to go point up if possible.

https://gadgetbuilder.com/DrillSharp.html#Facet4_Completions

There are also plans out there for at least one of these machines if anyone is interested.

[VicParticipant @vic]

Here’s a YouTube Video of one of these types of machine.

[Clive FosterParticipant @clivefoster55965]

Angle down means that the point is thrust away from the grinding wheel should any sort of hang up, or grossly excessive feed, occur.

Angle up means that any hang up tends to pull the point into the wheel further increasing the stress on it.

Given the inherent brittleness of grinding wheels such increase in stress is generally considered a bad thing as it could lead to the wheel shedding pieces or even exploding. Neither being a pleasant prospect when standing close by. Best grinding practice requires you to be aware of any chance of over stressing the wheel in any way and arranging things to  minimise any chances of such things happening.

Quite a few old time practices are safe only when the wheel is driven by a lightly tensioned belt drive so anything approaching a hang up stalls the wheel. Something to be aware of when scouring historical works. Modern direct off the motor drives are unforgiving. Doesn’t help that most double ended grinders are objectively significantly over-powered for pure grinding duties as the makers, rightly, assume that they may well be used to drive wire wheels or polishing mops which do need the power. Its important to use wheels designed for double ended grinders as these are more robust than those intended purely for tool grinding.

One thing that worries me about amateur designed drill sharpeners and similar fixtures is that the drill, or other tool, is invariably held rigidly. My Clarkson drill sharpening attachment has a spring loaded pin pushing the spindle out against an internal stop. This allows about 1/8″, 3 mm, push back if you overload things. Not a perfect safety measure but it does help. Yes I have been grateful for that in a couple of brain fade moments when inadvertently dialing in too much feed. Subsequently I realised my initial set up procedure was bad leaving openings for such errors. So i changed my methods, hopefully closing the loopholes.

Geometrically point down should be easier to make stable but I doubt if the forces involved in grinding are sufficient to make brute stability an issue. Damping against vibration is the main reason why grinders tend to be big and heavy.

Clive

[JourneymanParticipant @journeyman]

There is an article on Woody’s Workshop that has an update to the Gadget Builder drill sharpener. This converts many of the parts to 3D prints thus removing a lot of the machining in the original. I think this has been mentioned in the Forums before. The article includes the necessary STL files for the prints.

Article may be found here – 3D Printed Four Facet Sharpener

An interesting update

John

[Clive Foster]

On Clive Foster Said:

Angle down means that the point is thrust away from the grinding wheel should any sort of hang up, or grossly excessive feed, occur.

Angle up means that any hang up tends to pull the point into the wheel further increasing the stress on it.

Given the inherent brittleness of grinding wheels such increase in stress is generally considered a bad thing as it could lead to the wheel shedding pieces or even exploding. Neither being a pleasant prospect when standing close by. Best grinding practice requires you to be aware of any chance of over stressing the wheel in any way and arranging things to  minimise any chances of such things happening.

Quite a few old time practices are safe only when the wheel is driven by a lightly tensioned belt drive so anything approaching a hang up stalls the wheel. Something to be aware of when scouring historical works. Modern direct off the motor drives are unforgiving. Doesn’t help that most double ended grinders are objectively significantly over-powered for pure grinding duties as the makers, rightly, assume that they may well be used to drive wire wheels or polishing mops which do need the power. Its important to use wheels designed for double ended grinders as these are more robust than those intended purely for tool grinding.

One thing that worries me about amateur designed drill sharpeners and similar fixtures is that the drill, or other tool, is invariably held rigidly. My Clarkson drill sharpening attachment has a spring loaded pin pushing the spindle out against an internal stop. This allows about 1/8″, 3 mm, push back if you overload things. Not a perfect safety measure but it does help. Yes I have been grateful for that in a couple of brain fade moments when inadvertently dialing in too much feed. Subsequently I realised my initial set up procedure was bad leaving openings for such errors. So i changed my methods, hopefully closing the loopholes.

Geometrically point down should be easier to make stable but I doubt if the forces involved in grinding are sufficient to make brute stability an issue. Damping against vibration is the main reason why grinders tend to be big and heavy.

Clive

As I said in my post, I’m hoping to use a belt grinder. Which is incidentally Bi directional. If this doesn’t yield the results I’m after then I’ve been eyeing up a Diamond coated aluminium wheel.

“Angle up means that any hang up tends to pull the point into the wheel further increasing the stress on it.”

Surely that depends on wheel rotation and which side of it is being used?

[VicParticipant @vic]

Another nice little grinding setup.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, Vic … Michel Uphoff looks like a man to watch !

MichaelG.

[Clive FosterParticipant @clivefoster55965]

Vic

Conventionally grinding wheels, abrasive belts et al run downcutting with the abrasive passing downwards over the material being worked. Obviously for material support and also to avoid chucking grinding debris up into the air where not only does its spread even more freely than when its driven down but also seriously increases the likelihood of breathing in dust. Grinding and sharpening can be a messy business at the best of times. My machines have proper built in vacuum collectors but the abrasive working area still gets messy. So glad that I made a doorless room to contain the mess. But I have much more space than most folk.

Worst point about running in the unconventional, upwards, direction for just one thing is the very high probability of making a mistake when you forget it goes the opposite way. OK with a fixed set up tho’.

Abrasive belts aren’t very good at drill sharpening. Sort of OK if the edge is fully intact and just blunt but they don’t deal well with point damage.

Clive

[Michael Gilligan]

On Michael Gilligan Said:

Thanks, Vic … Michel Uphoff looks like a man to watch !

MichaelG.

That “Tiny Tool Grinder” looks great. I hope he eventually has those plans drafted, I’d be interested.

One of the problems (for me) is the amount of bench space some of these grinding setups take. I could just about find room for one of those on my bench.

[VicParticipant @vic]

I found the disc he’s using. I’d prefer something a bit finer though.

[Chris CrewParticipant @chriscrew66644]

I never knew that sharpening a twist drill could ever be such a big deal and generate so much angst. Dear me, most of the old timers I knew did it free-hand on a pedestal grinder, although that was a skill I never mastered hence my use of a simple jig.

[Howard LewisParticipant @howardlewis46836]

Many of the old timers were old and very skilled. My turning instructor could grind a drill quite accurately by hnad. But he had spent 40 years perfecting his art!

A good drill grinding fixture is a HUGE asset.

I would not not expect to get good results from an abrasive belt, because of the lack of precision.

(In my book, that is like using a 6 inch rule to produce an airtight fit)

The ultimate seems to be four facet grinding, but this requires a very good jig, or a cutter grinder, such as a Wordem, or Stent. The ultimate is either a Quorm or a professional cutter grinder.

You can buy simple gauges which will measure to see if the lips are equal length. (If they bare not forget any hope of accurately sized holes. The clearance angles, fo most purposes do not need to be within a degree or two, but materials such as brass need more care, lest they “grab”.

HTH

Howard

[Grindstone CowboyParticipant @grindstonecowboy]

I’ve found when sharpening things with a belt sander and using a rest to support them (like a lathe tool, for instance), the joint in the belt tends to round over the edge a little. I guess they are ok if the belt is travelling towards the edge (so the edge is the last thing to touch the belt), as it would be if sharpening a knife.

Rob

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