Fine Jeweller's Screwdrivers that won't chew up tiny slot–head countersunk BA screws?

[Chris55000]

Hi!

I'm having a nightmare of a time removing many tiny countersunk–head 6BA and 8BA screws in a CDU130 being dismantled for spares that simply chew up when I try my screwdrivers on them, none of which are the best quality, and are too wide for the screw slots, or simply ride up out the slot sides and chew the head up!

Worse, the original screws were nearly all "loctited" into either captive nuts or threaded bosses and you can't hold them with a nut–spinner!

Can anybody recommend a good quality Jeweller's Screwdriver Set that won't chew up tiny BA screws wholesale on the second CDU130 I want to repair please?

Chris Williams

PS!

Two of the 8BA screws screw into threaded holes in the wafer bosses of the battery/mains and charge switch so if they get mangled the whole switch assembly is rendered useless if they can't be extracted in one piece – the switch is only a tiny thing with wafers the size of a 2p piece!

[Cruisin Marine]

I find the bigger the selection of screwdrivers you have the more chance of the things you attack surviving.
For smaller work Spiralux and Richmond always work well for me, and the older red RS screwdrivers, and old BT footprint if you can get them that small.
None I mentioned are jewellers SD's though.

[Nickthedentist]

Wiha Picofinish are good but affordable. I have two of some sizes, one of which I've customised by grinding tbe blade thinner so that it fits narrower slots; this works better than using a smaller size which wouldn't be as wide as the slot.

But you cant expect miracles... if the screws are seized or the heads chewed, even a good screwdriver won't necessarily succeed.

[broadgage]

I have a couple of sets of RS own brand jewelers screwdrivers, and they seem fine after many years of light use.

Badly stuck very small screws can sometimes be freed by extreme cold.
Make a tiny ring shaped dam out of blue tack around the screw, and with plastic tweezers drop a few grains of dry ice onto the head of the screw.

Alternatively a few drops of liquid propane will produce a similar cooling effect.GREAT RISK OF FIRE. OUTDOORS ONLY.

Hopefully the screw will shrink and become easier to remove. Work quickly before either the screw warms up or surroundings cool down.

[emeritus]

I think the blades of current screwdrivers are designed for metric screw slots. The only screwdriver I had that was a perfect fit for the smaller BA screws was an old wooden handled one inherited from my late father that must be pre-war. I have since carefuly reduced the blade thickness of a modern one to fit the old screws. The same problem arises with old Nettlefolds slotted brass woodscrews.

No experience on how to deal with stuff like Loctite, but I would try lighter fluid in the first instance, followed by the various solvents I have to hand: methlyene chloride, methy ethyl ketone, acetone, and cellulose thinners.

N.b. in an emergency, old bicycle spokes can be re-purposed as small screwdrivers by grinding an end to a blade. They can also be used to make spade bits for drilling wood by first hammering the end flat and then grinding edges. Spokes are made of high quality steel.

[Herald1360]

Shifting Loctited screws can be expedited by heating the screw head with a soldering iron provided the screws don't go into bushes in thermoplastic!

[G6Tanuki]

Another useful trick for loosening Loctited screws is to give them a good whack! I've got a toffee-hammer and an old screwdriver - one of the type where the metal part runs right the way through the handle to a 'mushroom' on the top - which I keep for this purpose.

[Remember to remove all the valves etc from the chassis before trying this].

When repairing things like cameras where any damage to a screw slot is not wanted I file a cheap "jewellers" screwdriver to fit very snugly. I must have about four sets filed for different cameras.

[emeritus]

The edges of the blades of screwdrivers that have seen a lot of use, tend to become rounded-off, and can then cam out under high force. A freshly-sharpened edge will provide better grip.

[Bufo Bill]

I'm not that experienced in electronics repairs but I have come across my fair share of the type of screw I call "TLB's" Tricky Little Bounders, and this is gold dust, just what I needed. Thanks to those who have posted, and good luck Chris!

[Chris55000]

Hi!

I did eventually get the switch removed – only slight snag was, one of the heads sheared off leaving the remains of the screw in the switch plate front boss with very little chance of getting it out!

I did eventually locate another switch of identical construction on eBay but it was of
4P 5W type rather than the 4T 4W of the original!

The Oscilloscope concerned has now been completely dismantled and all the bits packed in a cardboard box for use as spare parts, as I have two more to try and make one good one out of for future sale with handbook when I finally finish writing it!

Chris Williams