UNC & UNF thread

[RT65CB-SWL]

Hi all,

I need to replace some bolts on my OTA's. (see below).

1. Meade ETX105 - thread 6-32 - replace the ones on the back (joins the plastic flipmirror/

visual back assembly to the main OTA).

2. Celestron C6/SCT - thread 8-32 - I am going to add a RDF finder as well as the 6x30 finder.

(the 'spare' or 'blanking' button cap bolts/screws supplied with the OTA are not long enough).

3. TeleVue Ranger - thread 10-32 - to mount the 'QwikPoint' block on the OTA. (the supplied

socket cap bolts/screws are not long enough either!)

None of these manufacturers has stated whether they use UNC or UNF thread! and nothing

in the user guide/manual(s) that I can see or on the websites!

OK! I know is 'UNC' is 'coarse' & 'UNF' is 'fine' but that is about it. It is at that point where I am

confused as should I use 'UNC' or 'UNF' thread.

[JamesF]

To the best of my knowledge...

6-32 is UNC

8-32 is UNC

10-32 is UNF (10-24 would be UNC)

James

[JamesF]

FWIW, the first number specifies the major diameter of the thread, but below 1/4" the diameters are specified by numbers rather than measured sizes. The second number is the number of threads per inch. For #6 and #8 diameter threads, 32 tpi is coarse. For #10 diameter threads, 32 tpi is fine.

James

[RT65CB-SWL]

Thank You JamesF - now to order/purchase some "...super trooper beams..." (ahem!)

super 'douper' stainless steel socket cap bolt/screws.

[Uplooker]

Hi Philip,

I have been there. have a look at this thread:-

Ian

[RT65CB-SWL]

Ordered socket cap & button head screws (as above) on Wednesday (3 July) from Westfield Fastners (www.westfieldfastners.co.uk) - delivered by snail mail (er! Royal Mail) on Friday (5 July)