Vixen dovetail threads

[bosun21]

Does anyone know what size of screw fits in the threaded holes on the underside of the green Skywatcher Vixen dovetail?. Just got my new EQ mount and wanted to fit a safety stop. Trying to get used to my scope pointing up while in the home position. In my minds eye I keep seeing it sliding down and crashing on the floor 🙀. 

[900SL]

I don't know about that specific model but I keep a few M6 and 1/4"-20tpi bolts handy, they seem to be the standards

[bosun21]

4 hours ago, 900SL said:

I don't know about that specific model but I keep a few M6 and 1/4"-20tpi bolts handy, they seem to be the standards

Thanks for that. I had an inkling that it was M6. I’ll order a few.👍

[Louis D]

I don't know about European models, but the ones sold in the US have 1/4"-20 threaded holes, the same as the tripod thread on cameras.

[RT65CB-SWL]

 

...if 'Yes!' then they are 1/4"-20 threaded holes, as mentioned above by @Louis D

Here in GB/UK 🇬🇧 they are called 1/4" BSW or 1/4" Whitworth. I would not use M6.

Edited March 18, 2022 by Philip R

[bosun21]

1 hour ago, Philip R said:

 

...if 'Yes!' then they are 1/4"-20 threaded holes, as mentioned above by @Louis D

Here in GB/UK 🇬🇧 they are called 1/4" BSW or 1/4" Whitworth. I would not use M6.

It’s these ones 

[RT65CB-SWL]

Yes... they would be the 1/4"-20, 1/4" BSW or 1/4" Whitworth.

The only metric thread that I know of that is 'compatible' with its imperial equivalent is... M10 = 3/8"

[teoria_del_big_bang]

If you can it's really well worth getting some M6 and some 1/4 -20 screws, they become very useful items in astro gear as you will find yourself using both at some stage, some manufacturers use metric and some imperial, generally any through holes (non-threaded) in dovetails and so on will take either.
Also a good tip is to keep them in separate boxes because they look very similar and to keep a 5mm and a 3/16 " allen keys close to hand as you will need different keys for metric and imperial screws.

I bought these recently, quite cheap and very useful.
5mm T Key
3/16" T Key.

Steve

Edited April 5, 2022 by teoria_del_big_bang

[Stephenstargazer]

On 18/03/2022 at 18:18, Philip R said:

Here in GB/UK 🇬🇧 they are called 1/4" BSW or 1/4" Whitworth.

Sorry, but this is a common misconception, often repeated  - the equivalent to US 1/4" 20 tpi is a 1/4" UNC in UK parlance. Which is not a problem as UNC are stocked by most fastener companies.

BSW and Whitworth are a different thread entirely. You would get a shock and disappointment if you ordered some of those!

Edited March 30, 2022 by Stephenstargazer

[bosun21]

7 minutes ago, Stephenstargazer said:

Sorry, but this is a common misconception, often repeated  - the equivalent to US 1/4" 20 tpi is a 1/4" UNC in UK parlance.

BSW and Whitworth are a different thread entirely. You would get a shock and disappointment if you ordered some of those!

I just ended up buying a bunch of 1/4” 20’s from Amazon and they fitted perfectly.

[Carbon Brush]

It will all get much easier when we can all stick to the one standard.

Off topic I realise. When making or modifying any astronomy parts, I always tap with metric threads.
It makes buying parts and having the tools to hand so much easier.