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Flat blade screwdrivers

Discussion in 'd.i.y.' started by Tony L, Feb 1, 2019.

  1. Tony L

    Tony L Administrator

    I’m seeking some vocabulary here. I notice many vintage slotted screws have very narrow width slots and typical modern screwdrivers of the appropriate size are just too fat to fit/work. As such there must be a term for the correct screwdriver that I don’t know/can’t as yet google up!

    I may not be explaining this especially well... what I mean is if we have a screw head that looks like (|) where the ‘I’ is the slot, it is easy to find a screwdriver with a blade the height of the ‘I’, but when I do it is too fat (left/right in this orientation) to fit the slot. The sort of machine screws I mean can be found in say old GPO bakelite phones, Avometers, Japanese microscopes etc etc. There must be an older sharper type of screwdriver for this use that has a name? Basically a type of screwdriver that hasn’t had the end ground down flat the way modern ones have. Any ideas?
  2. Snufkin

    Snufkin pfm Member

  3. James

    James Lord of the Erg\o/s

    I'd just get a screwdriver with the right blade width and grind the bevels on a whetstone or abrasive paper (on a flat surface) until the desired blade thinness is achieved.
    YNWOAN, Hempknight and andy831 like this.
  4. Rug Doc

    Rug Doc pfm Member

  5. awkwardbydesign

    awkwardbydesign Officially Awesome

    Ooh, that looks useful. Thanks.
  6. martin clark

    martin clark pinko bodger

    +1 for this

    I actually keep motley old small knackered/cheap screw or torx drivers, purely for this sort of temporary use/regrind - usually the kind that have failed by chipping because they were cheap & 'glass-hard', rather than reasonably tempered. Which is also easy to correct with a small torch/flame if you wish...
  7. Vinny

    Vinny pfm Member

    The screwdrivers that you are after are usually known as expensive.
    Try Kennedy
  8. cctaylor

    cctaylor pfm Member

    Whatever you do don't do what my father used to do. He would take a grinder to the tip of a screwdriver leaving a wedge which would cog out the blade if you applied any pressure.

    He was a model engineer and I thought he should have known better.

    What you need to do grind at a shallow angle, similar to the blade as made. Try not to overheat the blade.
  9. bugbear

    bugbear pfm Member

    Grinding it the answer - you can't buy them.

    Either low angle on a flat abrasive, or hollow grind on a fine wheel.

    Since car-boot screwdriver cost pennies, you can have many attempts before you're out of pocket.

  10. Paul R

    Paul R pfm Member

  11. Tony L

    Tony L Administrator

    Thanks, the Canford one looks like it may well be the one for phones etc, though annoyingly they have a £35 min order, so I’ll likely keep an eye on ebay for an old GPO one.

    I’m still convinced there must be a formal term for the class of screwdriver I’m looking for as the world is still full of the screws and modern screwdrivers really don’t fit them correctly. This isn’t just a UK thing, it applies to Swiss, German, Japanese etc kit of past eras too. The item that prompted the thread is a lovely 1950s or early-60s vintage K series Olympus microscope. It is beautiful condition, but the focussing mech is clogged up with nasty old stale sticky grease so it needs stripping down and cleaning out. I just know that anything but *exactly* the correct screwdriver will just ruin the painted machine screws, so I’m not going to even attempt it until I source one. I’m sure back when it (or Avometers, 301s, TD-124s etc) were made no one had to grind the wrong screwdrivers down to make them fit, so these things must exist!
  12. timH

    timH Senior Moment Member

  13. timH

    timH Senior Moment Member

  14. snowman_al

    snowman_al pfm Member

    Tony I think the term you are looking for is 'Precision Screwdriver'.
    There are proper optical instrument sets, but they are expensive.
    timH that is a brilliant idea.

    Grinding or stoning blades is ok but you go through the hardening on today's efforts. So twist the end if you find a tight screw...
    Most important thing is that the blade fits the full length of the slot so you 'load' the whole head and not a small section which leads to twisting out marks.

    My Granddad was a tool maker - ''use the right tool for the job'', yes Granddad.
  15. kennyh

    kennyh pfm Member

    Which screws in particular Tony so I can have a look now for you?
  16. Tony L

    Tony L Administrator

    Thanks folks, some interesting suggestions. Here’s a pic of some typical vintage screws:


    It is the type of screwdriver I’m interested in, once I know what it is called I’ll buy several/a set of different sizes. Note how narrow the slots are, no modern screwdriver of that with would ever fit. In this case the situation is exponentially harder as the machine screws are painted, so even the slightest slip would ruin the piece irreparably. I’m actually trying to avoid disassembly and working at it with a light oil and heat (its currently sitting on the radiator!) This has got the course focus moving pretty well, though the fine is still jammed soid.

    Anyway, this is just one example of many. I come across this type of screw head (though not painted) very regularly, so would very much like a nice set of the correct drivers. They are the reason people make such a god-awful mess of restoring Garrards, TD-124s etc. Admittedly I’m so OCD that I *have* to replace any screws with chewed heads, I just can not stand that kind of ham-fistedness!

    The gun screwdrivers may well be a good candidate, I imagine they may have many screws of a similar vintage nature and of sizes that are of use to me (I never need anything big). Unfortunately I don’t understand inches well enough to interpret the stated sizes!
  17. kennyh

    kennyh pfm Member

    Quality flat blade blade screw drivers are always slimmer at the "doing" end than the crap now sold under names like blue dot and all that.

    Without going to silly Snap on prices look at the Teng sets and also Sudorf, the latter set I bought recently from a tool van at our local garage and they will have no problem with the screws in your pic, beautifully slim blades......as do Teng.

    There are Teng sets for sale on Amazon and Ebay now, zoom in on a set and you'll see the thinness of the blades.
  18. kennyh

    kennyh pfm Member

    Here's a pic of one of the Teng's. I've just put a micrometer on it and at it's point it is less than .5mm/20 thou.

    To get slimmer I reckon you are in to modelling tools and Watch stuff. That gets any GPO screw out.

  19. Mike P

    Mike P pfm Member

    Most fasteners are made to DIN or ISO standard dimensions these days. Is it possible that screws on old kit may predate these standards?

    I have some old Stanley screwdrivers inherited from my grandfather which are good quality (correct temper etc) and have nice slim heads.

    I think car boot sales would be a good source of ild screwdrivers.
  20. JemHayward

    JemHayward pfm Member

    Optical screwdrivers rarely come in sizes over 3mm width, and the blades are almost knife like - I know, I shoved several through my fingers over the years. They are remarkably expensive, or maybe 'domestic' screwdrivers are remarkably cheap. Screwdrivers with thin blades need to be made from harder materials, and so tend to be quite expensive. The trend towards fatter slots is probably cost saving, as softer materials can then be used.
    TimF likes this.

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