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Regrinding cross head screwdriver tips?

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bugbear650230/06/2016 10:04:52
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I'm primarily a woodworker, but since woodworking tools are made from metal, I end up doing small scale metal work, normally with hand processes.

I have had great success over the years regrinding lovely old straight blade screwdrivers - it's well worth it, since some of the handles are either comfortable, beautiful or both.

But I have some car-boot Pozi and Phillips screwdrivers, of very good quality, where the ends are a little burred up, but still with plenty of good metal left.

I would like to grind these so the tips are near-perfect again.

My absurd sharpening/grinding jig should hold the required angles to good tolerance

http://www.woodworkinfo.site88.net/tour.html#sharpening_jig

Does anyone know the specifications of Pozi and Phillips (size 2 in both, primarily) ?

BugBear

Edited By bugbear6502 on 30/06/2016 10:06:24

Edited By bugbear6502 on 30/06/2016 10:06:53

Michael Gilligan30/06/2016 10:21:32
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You should find detailed descriptions of the shapes in the relevant Patents.

... Sorry, I'm on the 'bus at present, so can't really do it for you.

Look on 'espacenet' advanced search:

MichaelG.

Ajohnw30/06/2016 10:59:39
3631 forum posts
160 photos

It might be worth going for JIS on the Phillips ones. It's a slight modification to reduce the cam out. I have a set and they always come out if it's a difficult screw. I'm not convinced that the socket in the screw is any different but they make a hell of a difference when I am working on microscopes and I hear on other Japanese products. I assume that the design allows them to tighten the screws more or leaves more tolerance on power driver torque settings. That's the trouble with these designs they were never really intended for hand held screw drivers.

I often feel that a slot head and truly hard hollow ground blade is a lot better as far as screwdrivers are concerned, These days though all tend to be made with air hardening toffee what ever style they are. The correct temper for blades is rather close to the one for cold chisels used for chiselling steel.

John

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bugbear650230/06/2016 11:00:51
77 forum posts
6 photos

I have found the Pozidriv patent; it's US2474994 (A).

BugBear (off to find Phillips)

bugbear650230/06/2016 11:02:18
77 forum posts
6 photos

Philips - US2046839 (A)

BugBear

MW30/06/2016 11:15:39
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how would you grind the extremely thin cross section on a pozi-drive, just out of curiosity?

JasonB30/06/2016 11:20:28
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Carefully!

Thank god for hex bitssmiley

Edited By JasonB on 30/06/2016 11:21:11

MW30/06/2016 11:24:28
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:P i thought maybe they forged the shape on a die like a drop forge?

Michael W

bugbear650230/06/2016 11:35:25
77 forum posts
6 photos

I'm not planning on grinding a "new shape". That would be "quite difficult".

I just want to grind-back the prexisting cruciform shape the sharpen up the burred leading edges.

phil_grind.jpg

As per the red (lipstick?!) on the right picture.

BugBear

Ady130/06/2016 11:39:13
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3871 forum posts
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I recently got one of those Lidl angle grinders and fitted it to a stand I had previously purchased at Lidl, this gives it good stability when in use. A 1mm stainless cutting disc means that it can do those really fiddly grinding jobs very easily compared to a standard fat grinding stone

I've not done a lot on it but I prefer using it for my HSS touch up jobs now

Jon Gibbs30/06/2016 11:43:27
739 forum posts

+1 for Jason's comments.

I've got magnetic hex socket handles in various lengths and buy new good quality hex bits (Wiha or Wera) when they get worn.

bugbear650230/06/2016 11:48:06
77 forum posts
6 photos

I feel the love for hex bits, and use them a lot (most of the time, TBH)

But sometimes, when a screw head is deeply recessed in a hole, a hex bit holder is too large, and you need a simple screwdriver.

And a bit of luck at a recent car boor turned up a lovely Spiralux ratchet screwdriver, PZ2, with a burred tip - the primary motivator for this thread.

BugBear

MW30/06/2016 11:57:05
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2051 forum posts
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Definitely a much more rigid way to tighten things up with a hex or square, little chance of it rounding out/off 

They've all got their place though, even all the security lock types. Anyone used a lenz spanner before? one of the more unusual ones. 

Michael W

Edited By Michael Walters on 30/06/2016 11:59:25

JasonB30/06/2016 12:00:36
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Bugbear, you can't just regrind those red edges. If you look at the image you posted the thickness of the 4 "lobes" gets thicker dute to them being hollow ground hence the curved surface.

Pozi will be even harder as there is the extra bit of metal between the 4 main lobes

Get youself some long reach hex recess bits for deep screwheads

Michael I meant 1/4" hex bits which you just chuck away when worn and use a new one not hex or Square/Robertson drive

 

Edited By JasonB on 30/06/2016 12:06:23

bugbear650230/06/2016 12:02:58
77 forum posts
6 photos

>>Bugbear, you can't just regrind those red edges.

I certainly can't grind them "much".

And I can grind Pozi even less.

But a little may be enough.

BugBear

Edited By bugbear6502 on 30/06/2016 12:03:19

JasonB30/06/2016 12:04:49
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But then they are shorter and don't fit as far into the screw for a given size bit and you end up risking chewing up the screw.

MW30/06/2016 12:23:37
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oh, i see, kinda like a carbide tip.

Michael W

JasonB30/06/2016 12:33:33
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I think it would need a larhe dia grinding wheel like this to go between each lobe first and then grind the red areas toi get it back to original size.

Don't you have a hex holder for your Yankee?

I seldom use the Yankee now but it does have the advantage of the battery not going flat so is always in the toolbox if neededwink

grinder.jpg

Howard Lewis04/07/2016 16:49:29
3633 forum posts
2 photos

A set of Hex drivers is pretty cheap, so why not just junk the worn ones, and buy a new set?

(They should be at least more accurate than you can regrind them).

Again, the female drivers are pretty cheap, and can certainly be used in a pistol drill, and probably easily modified to fit in a Yankee pump screwdriver.

Howard

JasonB04/07/2016 17:13:46
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No need to modify a holder to fit a Yankee as you can buy then ready to fit

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