Mods to Orion GX 250

[D Wright]

I have been using the bad weather to do some mods to my standard scope. First thing was the focuser which was bad so I replaced it with a 2" dual speed Crayford. Next thing was the collimation screws which were just M8 bolts. I replaced these with plastic handled adjustment screws to make collimation easier. The next thing was the mirror cell, the older Orions have a solid cast 10mm thick plate for the mirror cell which prevents cooling of the mirror so I took the mirror and cell out and removed the mirror and cut 3 50mm diameter holes in the plate and fitted 3 12V cooling fans. After this I repainted the mirror cell and all other fittings on the scope gloss black. I then turn my thoughts to a 12V power supply, as I already needed a supply for the controller I decided to make a power supply box from a waterproof junction box with 2.1mm plugs and sockets with a 12V in and 3 12V out sockets. One powers the handset, one the fans and i have a spare for dew heaters in the future. For the input I can run it from a car or leisure battery or a power tank. The only thing left to do was make cables to connect it all and test it. I hooked it up to the car battery and everything works fine.

I have included some before and after photos.

[NGC 1502]

Good job !!    My early model OO 10" Dob had a similar primary cell with only one small central ventilation hole that gave overlong cooldown ( now sorted ).

Does yours have the 6mm thick full diameter secondary support ?   Fortunately mine was fitted with the later thin 4 vane spider.

Do you use your scope on the pavement as shown in the pics ?

Cheers, Ed.

[Stu]

Nice job. I had an SX250 which I always intended to refurbish but never quite got round to it. I did get the base machined out and fitted springs and thumb wheels to improve the collimation. I plan to use this in a suitcase dob project at some point in the next 30 years [emoji6][emoji6]

[D Wright]

Yes my scope has the 2 thick secondary supports this is a job for the future, to either replace them or thin them down. I don't use the scope on the pavement, only put it there for photos. Luckily where I go to observe there is a small strip of tarmac so it is nice and stable. If using it on grass I try to put it on bricks or some other solid support. I am going to get some anti vibration pads which should make it easier. I wanted to get the plate machined similar to the photos above but it was going to cost too much on a limited budget. Also the small aluminium plate is glued to the back of the mirror and I am not sure how to get it off without damaging the mirror. That assembly above looks so good but I think what I managed at home will do the job.

[Stu]

Yes my scope has the 2 thick secondary supports this is a job for the future, to either replace them or thin them down. I don't use the scope on the pavement, only put it there for photos. Luckily where I go to observe there is a small strip of tarmac so it is nice and stable. If using it on grass I try to put it on bricks or some other solid support. I am going to get some anti vibration pads which should make it easier. I wanted to get the plate machined similar to the photos above but it was going to cost too much on a limited budget. Also the small aluminium plate is glued to the back of the mirror and I am not sure how to get it off without damaging the mirror. That assembly above looks so good but I think what I managed at home will do the job.

Yes, for a budget point of view you've done a great job, and a very sensible one. The machining was quite expensive but I was getting a number of bits done at the same time so just did it. Financially it didn't really make sense but I did not want to throw it away

[Moonshane]

I like the black paint. What did you use?

[D Wright]

It was  Finnigans black gloss smoothrite