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Scouseget

Screwdriver Sharpening

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Like many things in horology there seems to be disagreement as to the best way to sharpen screwdrivers.

One point of view is to hollow grind them and the other is to have the sides flat.

I've seen on a few websites and books dead against hollow grinding screwdrivers, but the BHI recommends it and so does the books on clock repair by John Wilding.

Is this just one of the many topics that people need to agree to disagree about, or is it the case that hollow grinding is better for the larger screws on clocks and a flat surface is better for the smaller screws in watches?

This way also makes sense to me as larger screwdrivers used on clocks should not need as much maintenance as the smaller ones used in watches and its much easier to resharpen your watch screwdriver on a diamond hone or oilstone than it is to hollow grind them as this is something you can do at your workbench.

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the hollow grind proceedure is done so that  "the  sides are nearly parallel" at the slot depth and honing gives you only a slite wedge affect at the slot width.  OR  what ever it takes to get a tight fit in the slot.  Not a big deal !    vinn

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In an ideal world you should have both types. Hollow ground ones will be used but when normal force is not sufficient then the flat sided ones take over as it takes greater force before breaking! In reality this only matters if your working on the top drawer movements like Patek etc. to avoid screw slot damage/ marking. 

So if you have means to sharpen screwdrivers both hollow and flat sided... it makes sense to hollow ground the smaller sizes and flat grind the larger ones.

Personally flat sides have worked for me, but I haven't gotten my hands on a Patek  yet!

Anil

 

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This should put your mind at rest. Click on this link.

http://members.iinet.net.au/~fotoplot/sdriver/sdriver.html




That's a really good link for a newly like me OldHippy, thanks. Coincidentally I put an oilstone and jig (plus pegwood and a few other bits) in my virtual basket earlier today with our friends at Cousins, will review the order tomorrow before hitting the pay button.


Sent from my iPad using Tapatalk

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From scouseget posting

"3). I watched a YouTube video yesterday from the AWCI, which stated that not only should a screwdriver be just the right width for the screw slot, it should never bottom out in the slot but rather sit just above it"

Whilst I understand what is being said and why, good luck with that, especially the hollow ground enthusiasts. May get it to work on one screw in one watch but honestly! ?

my test is a bit sort of simple but I found I was doing it without thinking. With the screwdriver of the right size in the slot vertically try to roll it back and forth between thumb and forefinger, if it moves at all "without the screw moving" the driver is not fit, dress or change the bit.

Cheers,

Vic

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54 minutes ago, Vich said:

"3). I watched a YouTube video yesterday from the AWCI, which stated that not only should a screwdriver be just the right width for the screw slot, it should never bottom out in the slot but rather sit just above it"

Whilst I understand what is being said and why, good luck with that, especially the hollow ground enthusiasts. May get it to work on one screw in one watch but honestly! ?

I agree with you. And some cuts are so shallow that unless the driver touches the bottom, no good grip is really possible.

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sharpening a screwdriver on a flat stone makes a wedge,  a wedge will spread the screw slot.  or a wedge shaped driver can snap off half the screw head.  (have you seen any watch screws with half a head?  I have. the screw driver head should reach the bottom of the slot. enough for now,  vinn.

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Hello Vinn,

I agree, the drivers must be sharpened to fit the slot but also finished off by flattenning the sharp end of the "Wedge" so that the flat part is in maximum contact with the bottom of the slot and the sides just about touching. It is a painstaking process that has to be done on each size of screwdriver. 

I have bought Bergeon replacement driver heads rather than do it myself as although I can do it, I am quite lazy ;) though I do "dress my blades" which is not a major bit of work and you usually follow the original design of the blade.  The Bergeon replacements are provided in the condition that I try to emulate when forced into adjusting a driver myself.  Most of my instruction on such matters was gained from a book "PracticaI Watch Repair by "Donald de Carle"      under " Essential Tools" I would never attempt hollow grinding on a small, say .5 mm or any small  screwdriver, quite frankly think that reduction of the metal available would weaken the blade considerably.  In fact to be honest, I have tried hollow grinding only once, on a 2 mm blade under magnification and life is too short. 

Having said all that I honestly believe that it is a personal decision and everyone should do what they want to do, if wrong decisions are made you soon realise and move on. Either way this forum is a great place for a frank friendly exchange of views that for an amateur tinkerer like myself has been really useful.

Cheers,

Vic

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if the screw driver tip does not touch the bottom of the slot,  you are driving a wedge in and might spread or break the screw head. have you ever seen a screw head with one side broken off?  to prevent making a wedge the blade is "hollow ground".  the tip touches the bottom - and  99.5% contact with the sides of the slot.   i hate to see a watch with distorted  screw heads.   use "blueing"  to view the contact.   vin

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I am looking at a vintage screwdriver set on Ebay and am wondering if you can get replacement bits for these; are bit diameters relatively standard, or do you need to determine the diameter and try to match it?

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27 minutes ago, Matt1 said:

I am looking at a vintage screwdriver set on Ebay and am wondering if you can get replacement bits for these; are bit diameters relatively standard, or do you need to determine the diameter and try to match it?

Put the link up and I'll take a look and let you know.

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