Top Hole Screws

JohnD

JohnD

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I am looking for a tool that can be used on these. They have a flat surface with two holes drilled in the top, and are often found on binoculars. The screws are too tight to be undone with a lens wrench.

$_57.JPG


the one in the picture looks like it also has a tiny grubscrew to prevent it coming loose, this is not usual.
 
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You may have to buy a set of 'Security Bits' but these things - I think - are called Spanner Bits.....they are metric and popular sizes are 4, 6, 8 and 10 mm.
John :)
 
I keep meaning to get some of the right bits myself! Couple of drills with the right size shank, and a small adjustable spanner usually does the trick.
 
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To my eternal shame I have attacked these with spring dividers before - with the points ground down of course! For such a crime I should be fed white water and Trefolux sandwiches for 4 days :eek:
John :)
 
The last time I wanted one was to dismantle the micrometer adjustment on a Chinese microscope a couple of years back.
The drill thing is no better than the dividers really. IIRC I looked at the dividers. . . I'll pass on the sandwiches though. I'll just starve thanks. The smell of that stuff!
It's the old story though, what do you do when you (occasionally) come across one of these? Order the right tool and wait, or "get on with it" (aka bodge):D Also there's the thing about forgetting what you've got. Now this may be an age thing (I'm not that old though!), but occasionally I find tools in the back of the garage cupboard, which I bought for a one off job, and have (at least more or less) forgotten about.
 
thanks!

I found some on snake eye spanners on fleabay, but in smaller sizes. They seem to be on US sites, and sized #1, #2, #3, #4


I just measured the bins I am working on today, and the pin spacing seems to be 7mm, 10mm and 15mm. The pin size is very small, looks like it might be 1mm and 2mm. However they are British and very old, so it might still be an imperial size

Still can't find any big enough.

I have found a "pin wrench" as used on angle grinders, but the pins are much too big.
 
Happens all the time Dave....never mind forgetting what I've got, its forgetting what I originally bought it for :eek:
John :)
 
Burnerman said:
You may have to buy a set of 'Security Bits' but these things - I think - are called Spanner Bits.....they are metric and popular sizes are 4, 6, 8 and 10 mm.
John :)
Click to expand...

Is that the pin spacing? Where do you get them?
 
John (Burnerman) I know the feeling! I've been having a bit of a sort out. (Ha!) I've got one of those office cupboards, which is very handy for keeping important things in. Which then get pushed to the back, and ten years later. . . :)

JohnD I'm certainly no expert on old instruments, but once you get away from bulk manufactured stuff, you often find funny things like metric theads and sizes on quite old equipment. And indeed vice-versa. I've got a feeling that it might have been done to be awkward, or it might have been done because the machines used were metric.

I looked when I had the microscope apart, and as you say, the bits you want were mostly available in the US, although IIRC, I found somewhere that did them over here. I've just looked and it looks as if I didn't bookmark the site. Again IIRC I wasn't convinced that the sizes the US sites were offering would fit the microscope. It's a while back though. I was going to make some bits. . .

At the end of the day, my method didn't butcher the heads of the bolts, and as I can't see me doing the job again, it was good enough.
 
JohnD said:
Burnerman said:
You may have to buy a set of 'Security Bits' but these things - I think - are called Spanner Bits.....they are metric and popular sizes are 4, 6, 8 and 10 mm.
John :)
Click to expand...

Is that the pin spacing? Where do you get them?
Click to expand...
I have a set from Screwfix, I think.....plenty on ebay or amazon though. (The tri wing bits will come in handy if you go to work for Boeing :LOL:)
John :)
 
I will keep looking, but the head size and hole spacing are much bigger than those.

And the pin size is very small.
 
thanks!

I have tried a watch opener, it will not quite go small enough. On mine, the metal pegs with the small spikes that go into the holes are changeable, and not steel, but a soft black-painted alloy, or possibly whittled out of carrots. Watch opener bits are mostly square or rectangular rather than the small round pins I need. Of my set of about 20 watch bits, only the very smallest will fit the hole in the largest of the three nuts, but the tool will not go small enough to fit both holes at the same time.

I have seen a thing called a Clock Wrench, but it is intended for rectangular notches, not round pin-holes
 
D

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