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CGE leg clamp screw anyone seen this before?

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#1 phanf4

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Posted 24 August 2009 - 12:42 PM

One of my CGE Tripod leg lock screw seams to have broken. I guess "seams" is a bad term. What is strange is it looks like a screw with a sping like metel wrapped around the screw to make the bolt????? Has anyone replaced one of these before. Would I need to go through the phone tag game with celestron or is there a quicker solution.

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#2 AlanT

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Posted 24 August 2009 - 01:50 PM

Hmmm... not sure, but it looks like a Helicoil thread insert was installed in the leg casting, stuck to the lock screw, and came out with the lock screw when it was loosened. If you're not familiar with thread inserts, here's a link showing some types: http://www.helicoil.in/helicoil.htm

If it is a thread insert issue, then it might be repaired pretty easily, maybe even reusing the coil that's now on the screw. If you know a machinist/mechanic they could probably fix it for you.

al

#3 phanf4

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Posted 24 August 2009 - 02:25 PM

I think you were right. It does look like its the insert the screw goes into. This does not look like it will be easy to get it back in without "unspringing" while putting it back in. Thanks for the help.

#4 Luigi

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Posted 25 August 2009 - 07:58 AM

Was the coil insert in the leg or in the knob. The bolt in the knob looks to have a hex socket on its end as if for use screwing it into the knob. It's common to use inserts in plastic to increase thread strength.

#5 Eddgie

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Posted 25 August 2009 - 08:43 AM

So, would the phanf4 be a model E or model J?

Yes, it is a helical insert. At some point the leg was probably repaired. I checked my own CGE and inserts were not present in any of the legs, so this is something to do with your particular sample.

My guess is that whoever did the repair did not put a drop of locking compound on the insert when they put it into the leg.

You can probably get a replacement at a local hardware store.

The replacement will have a little tab on the end that is used to drive it into the hole, and that tab will have to be broken off after insertion becuase it will obstruct the hole keeping the knob from going in. This can be done usually with a long nose pliers after the coil is inserted to the proper dept. Use a needle nose pliers to turn the coil in, then snap it off. It will be pretty self evident when you find the proper coil size.

Have the RIO leave the light on for you!

#6 mclewis1

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Posted 25 August 2009 - 09:02 AM

I had a look at my CGE purchased in 2007 and it does have an insert in the leg. I assume the other two legs are the same. It's not easy to see but there is definately a "step" at the entrance of the threads and if you run your fingernail around the edge of this step you can find the beginning of the Helicoil (regularly tapped threads don't have either the step or that pronounced edge defining the beginning of the threads).

Clearly either the original hole/thread was done wrong or they couldn't get T handle knobs with the larger diameter thread so after the legs were manufactured they were modified with a Helicoil like insert (likely much cheaper than throwing out a whole run of legs).

#7 AlanT

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Posted 25 August 2009 - 09:44 AM

I looked closely at my CGE tripod (new a year ago) and it has thread inserts in the leg clamps by design. The leg clamps are probably cast aluminum and the inserts are a good thing in this application.

If your equipment is still under warranty you'll have to think through that stuff. However, if left on your own, I think it would be a relatively easy fix for a machinist familiar with inserts (and who might already have the insertion tools). Inserts are occasionally used in auto engine repairs and you might even find an auto parts place that has inserts & tools available. I'd think the size (internal thread is 3/8-16) would be pretty common.

al

#8 mclewis1

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Posted 25 August 2009 - 02:57 PM

Al, Good point about the casting ... it could indeed be that the coil is simply added for strength. Perhaps Celestron started seeing a few mounts coming in for repair of that knob that tightens the legs and made a line change to the mount.

#9 Eddgie

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Posted 25 August 2009 - 09:56 PM

My CGE is probably 5 or 6 years old and doesn't have the inserts. The screws go directly into the casting, so maybe this is a running evolutionary upgrade.

At any rate, it doesn't sound hard to fix.






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