Skywatcher dovetail bolts UK

[AshleyThompson]

Hi Guys,

I'm a bit confused about what bolts i'm looking for and what to ask for in the UK. I think they're meant to be 1/4" UNC but here in the U.K. they seem to all be called M5/M6 etc, but nothing seems to fit. Any help is really appreciated.

 

Thanks

[skybadger]

They should be M6 for a chinese or japanese made mount. Different thread size. Its Metric 6mm and has a pitch of 1.0mm.

M

[AshleyThompson]

46 minutes ago, skybadger said:

They should be M6 for a chinese or japanese made mount. Different thread size. Its Metric 6mm and has a pitch of 1.0mm.

M

I've tried that and I'm afraid they don't work. M6 screws in a tiny bit but then stops and is impossible to turn.  This is the dovetail by the way: https://www.firstlightoptics.com/skywatcher-mounts/skywatcher-dovetail-mounting-plates.html

[Cornelius Varley]

9 minutes ago, AshleyThompson said:

I've tried that and I'm afraid they don't work. M6 screws in a tiny bit but then stops and is impossible to turn.  This is the dovetail by the way: https://www.firstlightoptics.com/skywatcher-mounts/skywatcher-dovetail-mounting-plates.html

They will 1/4"-20 tpi UNC bolts. If you have no luck with a local bolt supplier, you can purchase them on ebay.

[skybadger]

ah ok. in which case they really are 1/4"x20 threads per inch Whitworth or Unified Coarse. You can get them from ebay here <http://www.ebay.co.uk/itm/1-4-5-16-3-8-7-16-1-2-034-UNC-Fully-Threaded-Hexagon-Set-Screws-Bolts-Zinc-Plated-/161708830520>for example for set screws and here <http://www.ebay.co.uk/itm/UNC-CAP-SCREWS-A2-STAINLESS-STEEL-ALLEN-KEY-BOLTS-8-10-1-4-5-16-3-8-7-16-1-2-034-UNC-/360625314824> for cap/Allen screws. Watch out for bolts with no threads...

M

 

 

[AshleyThompson]

Thanks a bunch guys, just ordered them from eBay.

[Geoff_L]

1 hour ago, Cornelius Varley said:

They will 1/4"-20 tpi UNC bolts. If you have no luck with a local bolt supplier, you can purchase them on ebay.

I second that. The smaller dovetail was supplied in white with my EQ5 and the thread in the middle is standard 'domestic' tripod thread (i.e. 1/4" - 20 tpi whitform). While UNC has a different thread angle (60° instead of 55°) the tapped hole is 'sloppy' enough that 1/4" UNC will fit. FWIW, I recently bought some 1/4" UNC cap screws and also some double-male-ended tripod adapters (see attached photo) from Amazon UK fairly cheaply. The double-ended adapters let me fit a ball head and DSLR onto the EQ5 for wide-field, tracked astrophotos.