How to make miniature square wrenches

[Leitzcycler]

I recently bought a phase contrast condenser for my Orthoplan. There were no centering wrenches with it so I had to think how to resolve this problem in my workshop. As my solution might have wider interest, I present my results here.

The starting point is to find metal tube of appropriate diameter. The ideal inner diameter should be slightly smaller than the diameter of the centering screw head. In this case the diameter of the condenser phase plate centering screw is 1.5 mm. I found stainless steel tube from my storage which was good enough. It was originally the inlet tube of an old gas chromatograph which I dismantled years ago. If you don’t have a gas chromatograph or you don’t want to dismantle yours, you might find brass tube in a hobby craft shop. It should also work though is more soft.

Then you need a nail with square profile near the wanted diameter. Using a file, tune approximately 5 – 10mm length of the nail top to match the diameter of the centering screw head. Then cut the tube to get a piece of appropriate length and using a hammer tap the top of the nail into the tube. Then tap the tube with a hammer evenly from each side (the head with the nail inside) to mold the tube profile. Then take the nail off. Now the profile of the tube head should be square, more or less.

Finally, you attach thumbwheels to the opposite head of your wrench tube. I have plenty of thumbwheels of various shapes and sizes dismantled from old lab instruments and machines in my storage. I drilled a small hole through a thumbwheel and the tube inside and used a small nail as a rivet to fix the thumbwheel permanently to the wrench. The rivet is fixed by tapping using a hammer.

As you can see, these simple centering wrenches fit perfectly and there is no need for the complex and expensive construction of the original Leitz centering devices with cardan joints presented here http://www.microscopy-uk.org.uk/mag/img ... es7rev.pdf

[MichaelG.]

Nicely done ... but you might find it easier to adapt watch keys.

MichaelG.

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According to Walsh’s ebay listings for Star Keys:

No. 3 (1.65mm)
No. 5 (1.50mm)
No. 7 (1.30mm)
No. 9 (1.15mm)
No. 11 (1.00mm)

[Leitzcycler]

Thanks for the good idea! I never come to think about that. However, maybe this was of more fun. At least it was free.

[Hobbyst46]

... However, maybe this was of more fun. At least it was free.

And nicely creative and inspiring ! these old microscopes make one feel a MacGyver...

[MichaelG.]

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A quick update ...
Here is a more useful list of common Watch Key sizes, also from H.J. Walsh

0.95mm - Swiss 12, Old English 00
1.00mm - Swiss 11, Old English 0
1.05mm - Swiss 10, Old English 1
1.15mm - Swiss 9, Old English 2
1.20mm - Swiss 8, Old English 3
1.30mm - Swiss 7, Old English 4
1.40mm - Swiss 6, Old English 5
1.50mm - Swiss 5, Old English 6
1.60mm - Swiss 4, Old English 7
1.65mm - Swiss 3, Old English 8
1.75mm - Swiss 2, Old English 9
1.80mm - Swiss 1, Old English 10
1.90mm - Swiss 0, Old English 11
2.00mm - Swiss 00, Old English 12

... Contrary lot aren’t we !?

MichaelG.

[Leitzcycler]

So far so good.. However, the outer diameter is also limited in this particular case.

[MichaelG.]

So far so good.. However, the outer diameter is also limited in this particular case.

Have no doubt that I admire your solution !

I simply listed the key sizes for convenient reference.

MichaelG.

[Leitzcycler]

Everything is just fine . Thanks for the valuable list! I probably would have bought a couple of these if I was aware of these are available. And if these would be too thick, it is always possible to refine them to appropriate diameter.

[Roldorf]

Everyone want's to 'Buy' these days. Where has skill and innovation gone?
Well done for giving something that was sitting in a box and likely to end up in landfill, a second life.
Congratulations on your innovative skills we should all try harder, after all that's what brought us down from the trees.

[Hobbyst46]

Everyone want's to 'Buy' these days. Where has skill and innovation gone?
Well done for giving something that was sitting in a box and likely to end up in landfill, a second life.
Congratulations on your innovative skills we should all try harder, after all that's what brought us down from the trees.

Well presented !

[MichaelG.]

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On the same general theme ...
I posted this link recently, in another topic:
http://www.smsi.org/publications/mn199808.pdf

It’s worth looking at the article by John Gustav Delly [pp21-24]
... and noting the prices he mentions [in 1998 ]

MichaelG.

[Rorschach]

This is a great idea! Unfortunately I don't have spare thumbwheels to use. So I might opt for the watch key solution. So Orthoplan Zernike condenser needs a 1,5mm diameter wrench. I wonder if there would be enough knowledge around here to put together a simple diameter database for these for various makes and models? I think that would be useful for many as the asking prices for these condenser wrenches are ridiculous (even roughly 100 euros for a pair!).

Well, a database was a bit pompous when in reality all that would be needed is a thread where the first post contains the list and is edited each time a new entry arrives

[MichaelG.]

Recycling tip for the day:

If you don’t happen to have a ready supply of salvaged ‘knurled knobs’
… have a look at the caps on toothpaste tubes and those on tomato purée

MichaelG.