Ultra thin screwdriver

Hi folks,

I am looking for a flat screwdriver with an exceptionally thin blade, for use on clock mechanisms. The blade needs to be at least 3/16" long, but no more than 25/1000" thick. Does anyone know of a source for such a screwdriver? UK sources are preferred, if anyone knows of them.

I know I can try grinding my own, but I'm not convinced I can do it neatly.

Follow-ups set to rec.crafts.metalworking.

Many thanks,

Chris Tidy

Use a thin rod and grind it on both sides. Your guide will be whether the end is at a right angle? Then smooth/finish the end.

Wiha

I think the problem with trying to grind something this thin using a bench grinder is that it'll get wedged between the grinding wheel and rest.

Chris

You mean a feeler gauge? I don't think one would be strong enough.

Chris

You're letting your name get to you.

It doesn't have to be tidy, it just has to _work_.

By 3/16" long you mean it fits a 3/16" diameter screw head?

I have a set of "precision screwdrivers" from Radio Shack (US), the largest one is 9/64" x 0.025 or so. You ought to be able to grind this freehand on a wheel -- just hold some 3/16" rod straight down to get a nice radiused cut on each end. I'd be tempted to grind it to a knife edge, then go straight in until I'd achieved my desired thickness.

Thanks for the link. Unfortunately 4 x 0.80 mm is too short and too thick.

Chris

Brownell's Magna-Tip bit # 180-2 Brownell's pn 080-180-225AB

.180 wide, .025 thick

Bill

Whooops!! Kind of missed the "at least 3/16" long.

Brownells 080-210-225AB .210 wide, .025 thick. Heck--they make .025 bits clear out to .360 wide. Even go down to .020 thick. Lots of skinny slots on old guns!!

No, I mean the actual length of the blade is 3/16".

I just don't want something which is a bad fit in the slot, and which may damage the screw heads. That's a good idea to grind it to a knife edge first. It might help to get a neat shape.

I guess I could try making one from a piece of drill rod, but it might need quenching, I'm not sure. Or I could just start with a screwdriver.

Chris

I think I may have found a solution:

Best wishes,

Chris

I find it helps a lot to get the thickness even -- wedge shaped screwdrivers are a pain.

If I need a one-off screwdriver I often start with music wire from a hobby shop. If you don't let it get hot it stays pretty hard.

But quenching your own drill rod is undeniably more manly.

Cheers, Bill. Thanks for the source!

Chris

Grind the end of a 1/32-1/16" Allen wrench, hex key in Europe. Use the side of the wheel.

The length from handle to tip, or the length of the parallel surfaces to go into the slot in the screw head? 3/16" is awfully short from handle to tip. 4.76mm total length.

Except that this will leave the blade tapered, so it will be particularly thin at the bottom of the slot, and likely to twist and cam out of the slot.

Grind on the top of the wheel (wheel coming towards you), allowing the wheel surface to produce nearly parallel surfaces at the tip. Put something soft and large on it (soft wood like pine will do) so if it digs in from a slight misalignment, it won't have a small end to be driven into your body.

If you want a non-slip tip, make the final grinding at right angles to the shank so the grinding marks will act as a gripping surface.

Don't get it that hot and quench. This will make it harder, more brittle, and more likely to break off in the slot. Just grind gently -- keep it fairly cool, and the default temper of drill rod should be very good for your purpose.

Note that it is standard practice for gunsmiths to make individual screwdrivers to precisely fit the screw slots in individual guns, so it is not difficult to do. And an old clock mechanism sounds like something which should get similar care -- especially since screw slots and screwdriver blades were not standardized during the times when some of these were made.

I've made specialized ones to fit the screw slots on English made concertinas. I used a Dremel grinding stone in a Unimat lathe to give a small enough radius for the purpose. I also used an index head mounted in the cross-slide to allow making the curve on both sides the same -- take pass with the longitudinal feed, rotate 180 degrees on the index head, make the same pass on the other side of the blade, then measure to determine how much to take off on the next pass to precisely fit the screw slot.

Good Luck, DoN.

watch supply companies sell sets of jewler's screwdrivers for this purpose- start there - get the best you can - they are reasonably inexpensive - my set has a dozen sizes, each with replaceable blades

It's very easy to do "neatly" from a bit of drillrod (silver steel to you) if you have access to a vertical mill. It can certainly be done by hand with a Dremel but that does take a bit of patience and skill.

Check UK sources for gunsmith screwdrivers, if there are any.

You might even find something at Farnham's.

I know it's not what you want to hear, but I ground one from a very small Allen key, took only seconds to do. And I'm by no means a good engineer (ie not time-served)

Ideally, use a T handled Allen key to produce a really nice little screwdriver. Works well for me.

Karen

If you can't be a good example, then you'll just have to be a horrible warning.' Catherine Aird

When you say 3/16 long I assume that you mean 3/16 a wide tip. Take a 3/16 dia screwdriver. Slide an appropriate drill stop onto blade. With your off hand grinder "off", Put the blade to the wheel with the tip near tangential and the shank resting againstthe tool rest. Tighten the drill stopjust resting under the tool rest. Run the grinder and grind each side of the tip until .025 or less achieved. Now grind or stone the tip face until .025 or to fit screw.

All takes less time than writing this or reading rec.crafts.metalworking.

Richard