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C8 RA Knob has play.......

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#1 Night Surfer

Night Surfer

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Posted 04 April 2005 - 02:31 PM

Hi...
I have a Classic Orange C8 I got about a month ago. There were a few stars out last night (1st time in 3 weeks!) and I decided to do a star collimation test (passed :)). I noticed that the RA adjustment knob has somewhere between a 1/4 and 1/2 turn "slop" or "play" to it.
Is this normal?
Can it be adjusted??
Thx,
-NS-

#2 garyc11

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Posted 04 April 2005 - 03:11 PM

is it the knob itself? if the ra and dec knob are the same switch them and see if the slop goes away if so order some new knobs.

#3 Night Surfer

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Posted 04 April 2005 - 04:16 PM

I will check tonight when I get home, but I am farly certain that it is not just the knob. I can hear it "catching" inside as I move it from either end of the slop.

#4 Digital Don

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Posted 05 April 2005 - 12:24 AM

Hi NS,

The R.A. knob on the older C-8s is connected to a shaft containing a small pinion gear. The pinion drives a larger gear that moves the scope in R.A when you turn the knob.

If you can truly turn the knob 1/2 turn before it engages, and you're sure the set screw on the knob is properly tightened, it's possible that the pinion is loose on the shaft.

But, checking requires a major tear down. So, before doing anything, be sure the clutch itself is also properly adjusted. I don't believe there is a way to actually adjust the mesh of spur and pinion gears, but if the pinion is loose, you could probably super-glue it. Actually, my best advice is to take a look at a similar scope owned by a buddy. That will give you a reference point.

Keep in mind that there is some play in all these type C-8s RA knobs.

Good luck,

Don :usa:

#5 Night Surfer

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Posted 10 April 2005 - 01:29 PM

well...ahem.....turns out it was just the set screw after all.
Embarassed but relieved :o

#6 Digital Don

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Posted 11 April 2005 - 12:45 AM

Hey, all's well that ends well :o

Don :usa:


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