new focuser

[shaunster]

Ive just bought a skywatcher dual speed crayford for my lxd55 schmidt newtonian and the drawtube is slightly larger than the hole on the tube!

Has anyone enlarged their hole before, it would seem easy but time consuming using a metal file or something? its only about 2mm out

[NGC 1502]

Hi, well you could file it out, but the problem is, what happens to all the metal filings ? Ideally, the tube needs to have the optics removed before you begin. Also, schmidt newts are harder to collimate than standard newts when you get it all back together again. I suppose you could get back to your focuser supplier to see if they have an alternative. I would be very reluctant to strip out all the optics on your S.N. but you may be braver than me !! Ed.

[shaunster]

well its easy to remove the corrector plate, just have to mark it up so it goes back exact same way then re-colimate which took about 5 mins last time i did it to replace the finderscope bracket.

then i could block the tube to ensure no fillings get onto the main mirror as the other end will be open anyway.

I think its doable without ruining the optics, but its time consuming thats for sure

i guess there is no easy way, other than buying a moonlight + fixing kits but thats 3x more expensive and i still have to remove the corrector anyway

[NGC 1502]

Hi, Well perhaps you do have a way forward then. If the secondary is attached to the corrector plate then that gets all of the optics out of the working area. Also if you keep the tube tilted with the main mirror higher, as well blocking the tube, then as you say, it's doable. Hope you are successful, Ed.

[step_hen]

I have had the corrector plate and main mirror removed from mine without problems. I did notice that the allen bolts on mine where different sizes for the mirror unit than the corrector plate though! As you say, just mark up their original positions and once put back together collimate as normal. I wouldnt want to have the optics any where near it while using a file!

Stephen

[shaunster]

Thanks all, think ill do it next time i am free