Upgrading my focuser

[peeceeTal2M]

I'm thinking of upgrading the R & P 1.25" fitted to my 10" Europa with a 2" Crayford. as i understand it i will have to increase the size of hole in the scope tube for the bigger draw tube, can anyone suggest the best way to do this as i don't have a 2" drill / holecutter.

Phill

[ringz]

Phill,

I did this with my 10" Orion scope and it proved to be really easy to do.

Mark the size of the new opening and use a triangular file to file down to the line making a tooth pattern, then file away the teeth with a half round file smoothing the edge to a full circle.

The metal is so thin that it takes no time at all.

I got this method from an ATM mailing list that I used to belong to.

The only problem I had was because the new focuser was low profile and I had to buy an extension tube to bring my eyepieces to focus.

(click to enlarge)

--

Martyn

[Baskii]

Hi Phill,

I've just upgraded to a Crayford on my Europa 200. I used a sheet metal "nibbler" to enlarge the drawtube hole and then smoothed off with a round file. However the nibbler was hard to use because of the limited space and the resulting hole was far from neat. I think that Martyn's advice about using a triangular file is probably spot on and the way I'd do it next time. The metal is soft so filing is no problem, albeit a bit noisy!

During my upgrade I also needed to drill new bolt holes. This should be no problem once you've enlarged the drawtube hole, as you can put the new focuser in to mark the positions of the new bolt holes.

I had the same problem as Martyn with not quite enough outward travel on my new focuser (a Telescope Service dual-speed, similar I think to Martyn's) but have been able to overcome this with a 1.25" - 2" adapter which I needed anyway.

Regards

Alex