Making a key

[Smokedaddy]

Looking for suggestions how I 'might' be able to make a key (wrench) for a microscope turret. The only way I could measure it was by using a gum eraser pushed in the bore. Best I could measure it across the hexagon flat was 0.050". I don't have a wire EDM machine and wouldn't know how to operate it if I did. I figured some of you might conjure up a way to make something to go into the bore to fit that Hexagonal stub.

[Joel]

My first thought - .050 is a common hex key size. Take a piece of stock (maybe O-1), drill it a bit larger than the width of the flats (and deeper than you need) and broach it with a short stub of hex key with the end carefully filed to a shallow vee. The key would need to be short and pressed straight (I would try doing it in the lathe with the tailstock drill chuck), and it might take more than one try, IDK. Add a knurled knob or a short T handle.
If the screw is easy to turn and doesn't need to be moved often, aluminum might be ok and would be easier to broach.

A .050 hex socket might have the correct hex already broached into it, in which case, all you would have to do is remove the key and turn down the OD to fit the recess.
If it wasn't in such a small recess, you would have more easy options.

[Smokedaddy]

Thanks, I just found this which might work.

[wierdscience]

Ha! Just fixing to post the same thing, probably the easiest.

[Joel]

Jeez, I'm a dumbass. If there is a hex key, then obviously there is a matching size hex cap screw/set screw...

Added - A set screw might give you a bit more to work with and is more likely to be found locally and in small quantity.

https://www.amazon.com/Socket-Screws-Stainless-Wrench-Length/dp/B072MBL3MC

[Smokedaddy]

... no worries, I feel the same way Joel.

[Noitoen]

Make a slightly tapered hex and hammer it into a piece of pipe to make a tubular wrench or what you may call it.

[Beazld]

Depending on where the microscope is made, could be metric. Here’s a list of inch and metric smaller size wrenches.

https://handtoolessentials.com/blog/tools/allen-wrench-sizes-hex-keys-chart-metric-sae/

[old mart]

I'm with Smokedaddy on this, try and get an 0-80 UNF socket head cap screw. It should have a 0.050" hex recess in it. The od could be turned down if required. Hold the threaded end securely in a pin vise and if the fit is not too slack, it should work.

[mattthemuppet]

that looks like a high end compound scope. What's the make and model? I may be able to get you some info from a couple of reps I know if it's an Olympus or Nikon.

I would be pretty surprised if it's an imperial fastener - science in the US has been metric for decades, so it'd have to be way old to use imperial.

[Noitoen]

You can see Nikon under the cover. 2,5mm set screw has 1,295 mm across the flats according to ISO 4026

[Corbettprime]

Somewhere in the shop is a set of jewelers screwdriver s that had quite a few teeny tiny nut drivers. Never had a need for them, so I have no idea where they are, so I can't go measure them. But that might give you an idea where to start.Just went over MC, look under jewelers screwdrivers, external hex, about 5 buck each, metric or inch.

[Mcgyver]

If you can find an existing, by all means, but if not, you can do a good job of it with some light forging. Drill a hole, tap in a hardened bit of the shape you want, bring it up to heat and tap around it.

Here's some shots of how - one of two sets of nut drivers I made. Why make nut drivers? Its a model engineering thing, you need special sizes for scale hex bolts (imperial and BA) and you need thin walls to fit in tight quarters.

[ptjw7uk]

Ebay has a set
https://www.ebay.co.uk/itm/56PCs-Pre...QAAOSwy3JcCD5h

or US site

https://www.ebay.com/itm/KINDLOV-112...l8AAOSwIchessp u

[Paul Alciatore]

I also would bet it is metric.

They make tool sets that include small hex drivers. I have one with about five or more of them, probably starting at about 1mm or less. I bet one of them would fit.

https://www.bing.com/images/search?q=small+metric+tool+set&qpvt=small+metric+tool+set&FORM=IGRE