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Anyone Repair Mounts?

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#1 pdxmoon

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Posted 19 July 2013 - 08:05 PM

Astro Friends:

I have an old Celestron Firstscope 80mm f/11 that came with a very sturdy clamshell type EQ mount.

The RA mechanism slow mo controls froze. In taking it apart I see the teeth are stripped.

I'm not sure if it can, or even should be fixed, but it would fit in a priority mail box and I'd be happy to try. It was a very sturdy mount for me, and before I just use the wooden legs on something else, I thought I'd ask y'all.

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#2 orlyandico

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Posted 20 July 2013 - 01:35 AM

I have several mounts with the teeth screwed like that. Basically you are SOL. The teeth on that gear are made of some pot metal and tend to strip, break, the whole gear cracks, etc. And you can't buy a replacement.

#3 beanerds

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Posted 20 July 2013 - 04:25 AM

If it was me I would look for a used EQ3 , CG4 , mount .
Yes the older EQ2's are a good mount but as already said , the gears are not made of good material , its a
'Zinc Diecast' type that's hard to do any thing with , sorry to say.
Keep an eye out for one of the above 2nd hand , even new a EQ3/CG4 is only $300 ? your OTA is worth it .
Good luck .
Brian.

#4 beanerds

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Posted 20 July 2013 - 04:32 AM

Oh yes I forgot , I have one of these with a single axis drive under my Coranado SolarMax40 , perfect mount for this OTA .
I see that the damage is not central to the gear ? , I shimmed mine out by using a couple of 6mm washers under the holder that holds the 'Worm'. that put the worm in the centre of the gear and made it a whole lot better to set up the backlash and feel during use .
Brian.

#5 Brent Campbell

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Posted 20 July 2013 - 07:21 AM

There are on line companies that sell gears. I just googled and found this one: http://www.arrowgear...tock_gears.html

If you can take the mount apart easily and get the defective gear off, then you may be home free. Another thought is to take the thing to a machine shop. That would be child's play for a talented machinest.

Like the other posters said the problem may be cost. I have a celestron CG-4 that only cost me $125.00. If you choose to repair it you will probably sink more into the mount than its worth.

Oh and pot metal is notorious for corroding like that! My other hobby is O gauge trains and that is a problem for antique trains as well.

#6 orlyandico

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Posted 20 July 2013 - 08:35 AM

That's an EQ-1, EQ-2 at best. Well under $100, even under $50. So really not cost-effective to repair.

I took apart my EQ-1 and removed the pot metal gear, it is doable, but really not worth the effort.

#7 rmollise

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Posted 20 July 2013 - 08:54 AM

These gears are aluminum, usually. "Pot metal" hasn't been used by even the most thrifty Asian manufacturers in decades. ;)

#8 pdxmoon

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Posted 20 July 2013 - 01:07 PM

Thanks. I'll keep my eyes on the lookout for a used CG4. I only have one mount and it would be fun to set up side by side.

I may have a Porta II coming my way and may be able to use the nice wooden tripod legs from this mount on that.

#9 Jon Isaacs

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Posted 20 July 2013 - 09:52 PM

I'm not sure if it can, or even should be fixed, but it would fit in a priority mail box and I'd be happy to try.



Carefully clean up the damage with a thin tapered file. Reassemble it, it might work. If it doesn't, it is still useable if you can keep track of where the damage section is and avoid using it.

Jon

#10 pdxmoon

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Posted 21 July 2013 - 12:45 PM

Trouble is, the entire RA gear is locked frozen; I cannot get it to move at all. It seems to have seized.

#11 orlyandico

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Posted 21 July 2013 - 12:58 PM

if you prise off the thin metal or plastic plate covering the RA axis (where a polar scope would go on a bigger mount) you'll notice that the RA axis is hollow and there's a big nut inside that holds the gear in place.

if you can remove this nut, you can then pull out the entire RA gear. or the nut could be overtightened which is what has seized the RA axis.

again, this is only worth doing if you don't value your time at all. :p

#12 Geo.

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Posted 21 July 2013 - 10:12 PM

There's a CG-3 on ebay now going for $20 or so, looks like a good part source. But in good shape the mount's worth $50 tops, so I wouldn't go too deep.






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