i think ive found my focuser problem?

[tyler_jrb]

Hi, ive been shimming my focuser today to get it central in the tube and well ive had some problems with it for the past few months with the focuser being rough and having a small gap on one side, it wont sit straight in the focuser tube. I have taken the pinion, 4 screws and small metal plate off and with only just noticing there is no gap anymore it sits much better, of course until i put it back together again, I was just wondering if I maybe didn't put it back together correctly last time and if the small metal plate is supposed to be the way it is. I have added some photos the first is of the metal plate itself i believe its keeps tension on the rack and pinion mechanism but it just seems too much of an angle on it as ive seen photos of other similar focusers and they have been at 90 degrees. i can also only tighten the four screws a small amount until its far too tight and rough. I am also wondering if i am putting the plate in the right place and the right way round.

Another problem is that the rack and pinion is very rough almost bumpy racking up and down, i thought this way to do with the damaged pinion but i have replaced that with a new one and it is still the same, the pinion looks fine and all teeth are straight, its the same with the rack that all looks to be fine. the second picture is the way i think the plate goes in, it also has my damaged pinion in it as i haven't greased the other up yet.

any help appreciated.

Thanks, Tyler.b

[EssexMigrant]

Hi Tyler,

Firstly, it might help if we knew which scope this is. Looking at your pics the plate appears to me to be positioned correctly; I'm not certain you can be wrong with it? Is the cover plate just a flat plate? Next question, and very important, is it still greased with proper damping grease? Damping grease is specifically designed for this type of application, and all telescope rack and pinions should have it; it's part of the tuning/adjustment. Ordinary grease such as lithium is no good for this application, for two reasons. Firstly, it's very quickly is squeezed out, leaving the contact surfaces dry. Secondly, and probably more importantly, when the scope is elevated with diagonal, eyepiece etc, the focuser tube needs to stay in position without being locked, and without the tack of damping grease it can't do this. Well it can't do it without the tension being much tighter than it should be. Damping grease is expensive to buy, so assuming that it hasn't been cleaned, leave it. If you need to replace it, use a heavy duty one such as Nyogel PG-448.

Cheers

Max

[tyler_jrb]

Max thankyou for the reply, it was mainly seeming that there was too much tension in the focuser plate. Ive contacted first light optics, my warranty just ran out but even though they have contacted the supplier and are very happy to send me a brand new focuser which i am so very happy with. Wont be able to use it for a couple of days as i need to send the old focuser in but its great i can get another.

Once again much appreciated .

Thanks, tyler.

[EssexMigrant]

Max thankyou for the reply, it was mainly seeming that there was too much tension in the focuser plate. Ive contacted first light optics, my warranty just ran out but even though they have contacted the supplier and are very happy to send me a brand new focuser which i am so very happy with. Wont be able to use it for a couple of days as i need to send the old focuser in but its great i can get another.

Once again much appreciated .

Thanks, tyler.

Good result Tyler!

Max