Huh... I thought standard threading on a mic clip was 5/8", 27 turns per inch. Many stands have a 3/8" top, which requires an adapter to work with a std mic clip, like this:
soundslive.co.uk/product~name~Microphone-Clip-Thread-Adaptor~ID~5521.asp
Dunno if this is old news to you. Never seen metric clips. A lot of new mics (esp Sennheiser) come with one of these adapters, so if thats what you need it might be sitting in your shop or in a mic box somewhere.

5/8"-27 is the US standard. Euro standard used to be 3/8". Light stands have a different size/pitch yet. Camera mounts could be 1/4", 3/8" or custom BS. I do have some ancient metal stands that have crazy sizes with original reducers to 5/8". I think these are Atlas but god help me if I lose the top piece because unless I get better at a lathe than I currently am, I'll just be chucking those in the bin. Regardless of size and thread pitch, the worst are the plastic mic clips. So easy for these to get AFU. I don't even bother to use 'em in order to prevent inevitable slaughter and mutilation.

We have plastic mic clips :( oh well. Dynamics can survive a 5' fall onto carpet, I'm sure.

OK it seems that these are actually 3/8" and 5/8" and not some wildly inaccurate number of mm.

I've just had to use tape to attach a larger clip onto this tiny little annoying stand - the stand itself is good with a heavy base, and has like a compressed gas lift on it. It's cool, but with no adapter, grr.

Score 1 for ductape!

AKG and Sennheiser, being European companies, almost always include the 3/8" - 5/8" threaded adaptor bushing. If you lived closer I'd send you a crate full of them.

i live in buffalo...