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I need the size of the grub screws used by Miraphone in their rear rotor caps.

I am certain that if it's metric, it is an M4, but all I have access to is M4x0.7, which has threads that are visibly coarser than the Miraphone part. Could these be M4 x 0.5?

Does anyone know for certain what the nominal size of this grub screw is?

This is one of those unfortunate ASAP requests.

TIA for any help.

Could they be UNF 8-36 threads????????

I apologize that this answer does not mention a metric size, but - out of the wild blue - have you tested SAE 8-36 or 8-32 ?

If you are willing to explore these possibilities, since you claim its courser I believe I would try 8-32 first, as 8-36 is nearly the same as the metric thread which you claim is too fine.

Again, I apologize for the "have you made sure that it's plugged in" type of question.

EDIT:
... Apparently, we were simultaneously posting.

Would you like me to go out to the shop and see if American 8-32 sousaphone tension screw screws into one of those? If it's urgent, I will.

Probably in 3 or 4 hours, Christian will be at work. And you can call him on Facebook and ask.

The M4x0.7 is coarser than the Miraphone screw. The Miraphone screw has the finer threads. I was wondering whether M4x0.5 (fine threads - and hard to source) might be the answer, and whether 8-36 might be an okay sub, but it sounds like 8-36 and M4x0.7 are about the same.

I will email Eva tomorrow. Thanks, though!

Yeah, I should have read more carefully and should have waited a few more minutes until I was more awake...

8-40 ?

https://www.ebay.com/itm/256194884908

If you want to ask Christian on Facebook Messenger audio or video conferencing, I believe they will be open at 3:00 a.m. our time.