Perfectly ground Twist Drills every time.

I recently got some good drills from the relative of a long gone British Aerospace engineer who did stuff like gyroscopes and tooling for surgeons

His drills all have a tiny land ground at the point to extend the drilling point workzone

That's called point thinning. Very common because as a drill reduces in length the central web gets thicker for strength.

I never knew that John.

I got one of the Holzmann drill bit sharpeners mentioned today and have been playing with it this afternoon. Seems a solidly built unit and the "plastic" bits are thick and hard rather than flimsy. There is a video on the German parent website here .

I am not sure about the angles it produces though, the first grind, I'll call it cutting looks too shallow to me and the clearance angle grind which is done second barely touches the back of the cutting edge.

First picture shows after the main grind of the cutting edge...

And after the clearance angle has been ground

Not sure whether to return it or not.

Andy

Hi Andy,

I also bought one in the end, very pleased with it, but before you grind the clearance angle, you need to reset the drill position in the holder again.

HTH

Edited By Chris Shelton on 13/05/2015 16:49:14

Hi Chris,

That certainly takes more off but neither the instructions or the video mention resetting the bit between grinds, the video clearly shows doing one then the other all in one camera shot. It doesn't look right to me :-

Hi Andy

Not sure how to put youtube links on the forum, but if you look at the tradetools tv review of a re-badged version of the drill sharpener, he states you should reset the drill after sharpening.

Chris

Thanks Chris, so it does, link here , now that is annoying, 2 sets of contradicting instructions for what appears to be the same device. I feel more inclined to believe the manufacturer though.

Andy

I would have said from the second pic the drill has been thinned too much. The cutting edge looks to have gone in the center.

I've got a Holzmann myself and I've noticed it's quite sensitive to hand feed variation which can give an off center grind effect if you don't take care.

It shouldn't need resetting for the second grind unless the second grinding station is set too high.

All I have done is regrind on the same setting if it looks off and that seems to fix it.

Can someone tell me is the content from the earlier part of this thread [presumably by Graham Meek] that has been redacted without acknowledgement viewable somewhere?

I've read a lot about Spiralux and Picador drill grinding jigs on this forum and have recently acquired one of each [they look about forty years old at least but are BNIB]. I'm getting pleasing results with the jigs, but would like to refine my understanding of drill sharpening further, and then possibly refine my jigs and technique.

Quick answer is yes but it will need some digging to find it all. I will have a look but others may be quicker. Just Googled 'Drill sharpening Graham Meek', plenty there to start with.

Tony

Edited By Tony Pratt 1 on 10/11/2022 17:55:34

Bill

… not sure if the van Royen document would help … but here is something to point you in the right general direction [the original hyperlink being useless now]

MichaelG.

.

.

Edit: __ this might be quicker: https://www.model-engineer.co.uk/forums/postings.asp?th=140032

Edited By Michael Gilligan on 10/11/2022 18:32:32

Thanks, Tony, I've Googled this aplenty, but I'm not seeing the "nice work" by Graham referred to by Michael in this thread's opening post, nor the "practical demonstration" referred to by Clive, which presumably illustrates "the improved drill clamp arrangements" summed up by Thor as "advice on improving the jig". I've seen one photo in a later thread on this forum showing Graham Meek's jig set up next to a Clarke grinder, but nothing I could interpret as a practical demonstration.

The following thread too has frustratingly been purged of images and possibly text as well:

https://www.modelenginemaker.com/index.php/topic,3788.0.html

There's clearly some reason for the removal of previously visible material from both forums, but I can only guess what that reason might be.

EtA:

Thanks, Michael, for the Van Royen reference, which has enabled me to find this:

https://www.model-engineer.co.uk/forums/postings.asp?th=140032

The related Graham Meek content is presumably now pay-per-view only in some form.

Edited By Bill Phinn on 10/11/2022 18:37:21

It's been completely removed from the system so not even pay as you go.

Though if you know where to look it can be found on the net.

Curiouser and curiouser.

Edited By Frances IoM on 10/11/2022 19:44:24

I have pointed Bill to where he can find the puff of smoke that he was looking for, so all is not lost

Please could you point me there too?

Edited By Frances IoM on 10/11/2022 21:49:57