Thread: drill sharpening guides.

good info thanks for posting

Thanks Soundman,

I used to have all that info from my apprenticeship, but I missplaced it years ago.

Thanks, Soundman. Very comprehensive. Saved in my "Tools" folder. Here's a dissertation I found on drill point geometry; more than you ever wanted to know.

http://www.mmsonline.com/articles/068901.html

Joe

Thanks Soundman,
much appreciated.

I am gaining an ever increasing pile of drill bits from my local trash'n'treasure market (@ 50c to $1 each), some of em perfect, or with a touch of surface rust, some of them... well, potentially good sacrificial practice material for learning how to hand sharpen- and then a whole lot somewhere inbetween, chipped or dull, that need a quick resharpen.

Cheers.

Thanks Soundman and Joe.

Good info on the drill geometry.

Cheers
Pops

Thanks Soundman, and thanks joe.

I usually buy a new 4.5mm drill bit on my way to work each monday. Had today off, and decided to try out the great info that you have provided. Tried both methods from step 9, but my problem was that I could not maintain the same angle on each point angle.

I know secret to good sharpening skills is practice and more practice, to refine technique. but not wanting to spend hours refining skills, I thought there has to be an easier way. So I come up with the following (no idea if it has been done before)

Attachment 51674

What I come up with was a piece of angle aluminium, bolted to a hinge. Which is screwed to a block of wood. Secured to the bench. The aluminium guide is set to the required angle. Then you proceed with the instructions that Soundman gave, using the second method of step 9.

Works well (on large bits), I need to modify to whole setup to accomidate smaller bits. Was thinking of a small gate hinge, and a smaller piece of angle aluminium. This will enable me to get closer to the grinding wheel with smaller bits.


Cheers Scott

Doc, your grinder has a tool rest with a groove in it for sharpening drill bits.

Tools

Here's a drill bit speed chart for a range of bit types:

http://australianwoodsmith.com.au/pd...speedchart.pdf

The way I was taught and most people I know sharpen free hand you do not use the rest.
The secret to getting a reliable angle is muscle memory and standing the right way.
stand straight in fron to the grinder with your elbows tucked into your sides.

you controll most of the process with the right hand and turn the drill with the left... mostly from the wrist.
Both hands and the wrist stay in the same place and you turn the drill by the stub with your left hand.
repeatability of the angle isn't the hard bit, grinding the cutting edge in the correct part of the rotation is.

A grove in the grinder rest in my opinion is pointless, a scribed line at the correct angle on the rest on the other hand can be very helpfull.
As can a white square of card with a "T" in fine pencil or ink mounted on the barrel of the grinder.
so you grind as best you can the line the shaft of the drill up with the leg of the 'T'...by twidling with your left whilst holding it still with the right you can then compare the ground angle and the length of the ground edge.
bothe the angles and the length of the ground edge should be identical.

the next examination is straight on down the point ... this will show you if your geometry is correct.

all these observations are best done in the grinding stance with the grinding grip....you can the go straight back to the wheel and correct any variation.
you have maintained your stance and grip so it should be easier to return to the wheel at the correct presentation.
If you can handle a skew chisel this should be an absolute doddle.

cheers

Touche' Soundman!

I grip the toolrest from underneath with my LH middle and ring finger and hold the drill by one flute between my LH thumb and forefinger, I then stand at the angle I want on the cutting edge of the drill from the front of the grinder, then grab the stub of the drill with my RH and using a slight "twist and drop" technique that matches the twist of the drill and back relief for the cutting edge, take steady and smooth swipes against the grinding stone.

I was taught and without practice forgot it.

For twist drills over about 6mm I just use one of those cheap jigs aimed at the side of the grind wheel. For under that size, I throw them away.

Originally Posted by rsser

I was taught and without practice forgot it.

For twist drills over about 6mm I just use one of those cheap jigs aimed at the side of the grind wheel. For under that size, I throw them away.

Don't throw them away Ern, I can use them or even resharpen them for you

Here Here........ if you can't or are too lazy to sharpen drills don't throw them away....... stick em in a tin and post em to someone who can.

I have to admit I dont try sharpening anything smaller than 1/8 unless I can avoid it.

I most certainly sharpen 3/16........ when I get to a riveting session I'll go thru 3 or 4 drills in a day.....In aluminium you need realy sharp drills.

cheers

Reminds me of a green builder I once worked for. He had to drill some 10mm holes in a universal beam, and he was cussing about having gone through four bits already, and he was about to go off to the hardware to buy another half a dozen to get the job done.
He felt like a bit of an idiot when I picked up his bits and sharpened them all on my belt sander in a couple of minutes.
I scored a couple of his bits for showing him that trick.