Screw size for focuser.

[paul mc c]

Hello all, would any one know what size of screws i would need to attach this focuser to a scope.

I have the Agena Astro adaptor to fit my c80ed but im not sure of the screws.

Thanks Paul.

[Louis D]

If it's a GSO focuser, they're M4 sized.

[paul mc c]

1 minute ago, Louis D said:

If it's a GSO focuser, they're M4 sized.

Its labeled Astro-tech,but they look identical,thank you, M4 is the width isn't that right ?,would you know what length i need.

[Louis D]

1 hour ago, paul mc c said:

Its labeled Astro-tech,but they look identical,thank you, M4 is the width isn't that right ?,would you know what length i need.

M4 is the width and thread pitch combined (technically, M4-0.70).  Length?  Probably no more than 5mm assuming thin wall tubing for the refractor.  Just measure the thickness of the scope's tubing and the depth of the threads in the focuser (thickness of the focuser flange) and add them together.  It's probably okay to go a few millimeters beyond that.  You just don't want long screw tips protruding into the light path.  I'd also get stainless steel screws to avoid corrosion issues.

[paul mc c]

Nice one,didn't have my thinking cap on,thank you for that.

Paul