Replacement nuts for EQ5 dual axis motors

[Prikka]

Hi,

Sorry for my rudimentary question. I'm sure that the answer lies somewhere in the web, but I somehow I've missed it.

I bought my EQ5 few years ago with optional dual axis motor drive kit. Somehow I managed to lose one of manual coupling nuts used for engaging motor drive. I've tried to find replacement nuts, but it seems that thread used in these nuts is not the most common (or at least not the most common used here in Finland). Does anyone happen to know which thread standard is used in these nuts?

Regards,

Prikka

[JamesF]

A picture of where the missing part is from might help. I'm not sure I understand which bit you mean.

James

[Prikka]

Part that I've lost can be seen in attached picture, it is the knurled part on top of the pinion.

[Oily]

I'll check what the thread is when I go to the shed

[Oily]

Right just checked,it is indeed a strange thread,not M8 x 1.25 nor 5/16 unf nor 5/16 unc?Maybe it's a thread like BSF/BA or Whitworth?

[JamesF]

I don't have a set of thread gauges, but looking at it the three you've suggested would be the only ones that spring to mind as possible. I have thought it unlikely they'd be a British standard. All of the other threads I've come across on astronomy gear have been metric or UNF/UNC. Perhaps it's meant to be one of those threads, but not very accurately cut. Wouldn't be the first time I've seen that

James

[Oily]

Well I tried all of the above thread restorers I have and not went on properly,maybe it is a 'badly cut thread'?

[JamesF]

I've just been out to the workshop and I can't find anything that fits either

James

[Prikka]

Thank you both for your help.

The remaining coupling screws to both axis without any problems so it seems unlikely that there's something wrong with the thread (Unless all parts are threaded using the same sub-standard tools). I managed to get hold of few nuts with metric, UNC and UNF threads, but as you've already said, these won't fit.

I know a hardware store where they can probably tell which thread standard is used in these parts. The only problem is that I live quite far from that HW store, but I guess I just have to pay them a visit.