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NexStar 8 SE Focuser Knob Question

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#1 JeffreyHorne

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Posted 23 April 2013 - 08:59 AM

Hi all, and thanks in advance for the warm welcome. :grin:

I just received a Fine Focus Knob from ScopeStuff. I was told to get the .775" one from this page.

My scope is about a month old, and I was told that the .775" knob would fit my focuser. I was also told that I'd have to press pretty hard to get it to fit.

Well, I did that, but it just wouldn't fit. I don't think I messed anything up, but I did manage to push the rubber covering of the knob in pretty far (far enough that I can't see the metal shaft of the focuser any more.)

When I turn the focuser all the way in, it comes to a gradual stop (instead of the pronounced stop that it usually has) because the rubber is touching the scope tube. I tried pulling it back out a little bit, but it just won't budge.

I took the scope out to look at the moon, and I could still focus on it just fine.

Any advice? Leave it be? Try to pull the focuser rubber cover out in any specific fashion?

Thanks again!
Jeff

#2 ben2112

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Posted 23 April 2013 - 09:27 AM

You should be able to pull the rubber knob off if you want. So you can pull the on the rubber knob enough to give it more clearance.. Personally, I picked up a set of rubber wheels from the hobby store. It works really well when wearing gloves..

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#3 JeffreyHorne

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Posted 23 April 2013 - 09:32 AM

Thanks for the reply, Ben! I've tried pulling the rubber knob off...it's really hard to get off. I'm afraid I'll mess something up.

Any tips on how to get the thing off?

#4 ben2112

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Posted 23 April 2013 - 09:54 AM

Thanks for the reply, Ben! I've tried pulling the rubber knob off...it's really hard to get off. I'm afraid I'll mess something up.

Any tips on how to get the thing off?


I just slowly pulled and wiggled it until it slid off..

This video show how the knob comes off to replace with a feathertouch.. But as you can see, it just slides off..

https://www.youtube....h?v=nXCBf0JHodQ

#5 hdt

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Posted 23 April 2013 - 09:55 AM

The traditional approach for "inexpensive" focus knobs is either a machined large wheel (like the ScopeStuff thing), or drill a hole in the lid of a jar, and slip over the rubber knob (filling with tape and foam as needed), or, in my case, one of the foam disks from one of my eyepiece bolt cases.

I like Ben's RC wheel approach too.

From the instructions I've read for the Feathertouch focuser, the rubber knob just pulls right off--but it's a hard pull. Kind of like pulling a handlebar grip off of a bicycle handlebar. Bicycle handlebar trick for handlebar grips: Warm soapy water to soften the rubber slightly, then, shove the grips on. When the water dries, the grips grip pretty good on the handlebars.

*Note*: I have never attempted to remove my knob. I've thought about buying the Feathertouch, but didn't. I'd saved up a couple of jar lids, and was about to drill a hole in them, but then, found a foam disk in one of my eyepeice cases. No picture available now; might try to show later.

P.S. A very warm "WELCOME ABOARD" to you!

#6 Tel

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Posted 23 April 2013 - 11:27 AM

Alternatively guys, if that rubber sleeve sticks, a light application of heat delivered by a hair dryer is apparently the traditional method used for its removal. :idea:

Best regards,
Tel

#7 JeffreyHorne

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Posted 23 April 2013 - 11:00 PM

I tried wiggling it, but I'm weary of bending that focuser shaft. I also tried the hair dryer, as Tel suggested, and that really helped. I was able to back it off enough so that the focuser moves smoothly.

So, that focuser ring that I got from ScopeStuff...they sent me the wrong one. I ordered the .775" one, and my receipt says it's the .775" one, but when I compare it to my father's .775" focuser ring, it's clear to see that I was shipped the .770" one.

Thanks, all!






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