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Replacement for RA slow-motion cable?

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#1 KP0692

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Posted 20 January 2014 - 05:33 PM

Hi guys,

I bought an Orion 130ST Space Probe Newtonian reflector about two months ago and it has been great, but one of the things that has been a nuisance is the RA slow-mo cable. If the tube is pointed at a fairly high altitude to the northwest, it will bump in to the cable and prevent any further movement of the tube in that direction when the mount is polar aligned.

I was wondering if anyone of you have had this issue and have found an alternative to this cable that will allow unrestricted motion in all parts of the sky?

Thanks!

Kyle

#2 Tom and Beth

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Posted 20 January 2014 - 06:29 PM

This?

Or attach a shortie to the other side of the head

#3 KP0692

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Posted 20 January 2014 - 06:44 PM

That is the style of cable that came with my telescope. I'm thinking just a knob that threads in to the mount would be just fine. Any suggestions as to where I can find one?

#4 Mike Lynch

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Posted 20 January 2014 - 07:43 PM

I'm thinking just a knob that threads in to the mount would be just fine.


Does the cable attach to the mount by "threading" into it, as you indicate? Or does it fit over a rotating metal shaft with one flat side?

If that's the case, there would be a set screw on the cable that is tightened against the flat side of the shaft. And you may find a knob at a place like Radio Shack that fits over that shaft and tightens with a set screw in the knob.

That's what I've done for this very purpose!

#5 KP0692

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Posted 20 January 2014 - 08:34 PM

Thanks for the reply, Mike. It goes over a shaft and is fixed by a set screw on the cable.

Here is a picture of the cable attached to my equatorial mount.

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#6 rdandrea

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Posted 20 January 2014 - 08:46 PM

Call Bill Vorce at Telescope Warehouse. See what he has in the way of a cable that isn't on his web site. This is a fairly common part that comes in lots of flavors.

#7 Mike Lynch

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Posted 20 January 2014 - 09:49 PM

It goes over a shaft and is fixed by a set screw on the cable.

Here is a picture of the cable attached to my equatorial mount.


That picture seems to show that a knob by itself might rub against the setting circle, unless the shaft is long enough to allow you to tighten the knob back enough to avoid coming into contact with the setting circle.

If not, you might, indeed, need to search for a similar--but very short--slow motion cable.

#8 KP0692

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Posted 20 January 2014 - 11:34 PM

You are correct that a knob placed directly onto the shaft will bump the RA circle. I'm thinking a shorter cable would fit the ticket.

#9 hottr6

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Posted 21 January 2014 - 08:16 AM

focusknobs.com to the rescue!

#10 Mike Lynch

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Posted 21 January 2014 - 08:37 AM

Heavens above!! There's a knob (and knob dealer!) for all seasons... uh, I mean REASONS!! :lol:

#11 SteveG

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Posted 21 January 2014 - 07:45 PM

The focusknobs are really nice - I was going to recommend them. Orion used to sell similar knobs - I have a brass version of the short one with no stem.

#12 KP0692

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Posted 21 January 2014 - 09:48 PM

Thank you all for the replies! I ended up going with a $3 knob from Radio Shack. Now my telescope is completely unrestricted with respect to it's range of motion.

Clear skies!

Kyle

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#13 Mike Lynch

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Posted 22 January 2014 - 07:52 AM

Great, Kyle!

Glad that knob worked out!

#14 csrlice12

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Posted 22 January 2014 - 08:21 AM

Won't that tend to vibrate a bit more then the older setup when making adjustments? But as long as it settles down quickly.......

#15 KP0692

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Posted 22 January 2014 - 08:44 AM

Smaller diameter knob = more rotations for same RA movement as the bigger knob. So yeah, if I really crank on it the telescope vibrates a lot but if I take it slow it isn't really noticeable. The mount that I have isn't very stable anyways and if there is a good amount of wind there is vibration present.

#16 Sarkikos

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Posted 22 January 2014 - 12:55 PM

focusknobs.com to the rescue!


Nice! This goes on my Favorites.

Thanks,
Mike






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