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cpc800: a known tripod design/equipment flaw?

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#1 rdl800

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Posted 01 March 2013 - 07:16 PM

I've had the cpc800 since April 2010. I would say that due to poor weather/light pollution, it has gotten moderate use in the time since I've received it. I am so careful with it in every regard, you can easily say it's overkill. Overall I couldn't be happier with the scope; I would buy the same scope if I had to do it all over again.

However, before winter I noticed a hairline fracture in one of the 'leg spreader clamps' on the tripod. I called Celestron and with no problem -- and no charge -- they sent me a replacement. Luckily they sent two replacements instead (maybe by mistake), because now (I thought) I would have a spare in case another clamp failed.

I didn't immediately change the broken clamp because I didn't believe it was affecting the stability of the scope, so I put it off... Here's where the concern comes in. .. When I decided to work on the tripod yesterday and replace the broken clamp, I discovered there was ANOTHER one that was cracked -- this time all the way through. Very strange because, as I said before, I am obsessively careful with it.

Considering the fact that I am extremely careful with my scope, the clamps I'm sure will continue to be a problem. They are made of plastic, by the way.

If there are other cpc owners who have had this problem, or can give input/info on this that i don't have, i would appreciate it.

Thanks,
Rob

#2 Steve Daniel

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Posted 01 March 2013 - 11:14 PM

I have the same scope. I don't see any cracks in mine. Where exactly were yours cracked? Now I'm paranoid...

#3 Bob Griffiths

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Posted 02 March 2013 - 09:11 AM

No not at all ..however I sure have with several other tripod leg clamps on several different tripods..

Plastic ...cold weather...and over tightening will crack these things time after time...

My CPC is pier mounted so I do ot use the tripod but I'm willing to bet that at least one of mine would have been broken because frankly sometimes I think I;m hulk hogan when it comes to applying a little pressure tightening things

Bob G.

#4 rdl800

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Posted 02 March 2013 - 09:27 AM

Steve,
The crack is right in the middle -- the thinnest part of the clamp.

I took a pic of the damage minutes ago with the hope of posting the photo, but it seems you have to jump through hoops to get an image in the post. I either forgot, or cloudynights made it more difficult than it has to be (not in the mood to fool with it on a Saturday morn).

But I guess I would be concerned too if I were you. Like I said, I treat this thing with kid-gloves when I use it.

Bob is lucky enough to be using an alternative, but he makes a great point: if the clamps are too tight that might have caused the problem. Which also means that loosening up the clamps a bit might prevent it from happening again.

Thanks for the suggestion Bob. i've yet to dismantle the tripod to fix it (snow on the ground -- no rush), but will definitely take your advice when I tighten the clamps.

thanks for the replies,
Rob

#5 Footbag

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Posted 02 March 2013 - 01:32 PM

I found the tripod clamps and all of the parts to be terribly designed. I didn't ever notice the clamps cracking or breaking which is curious because I've had to use a hammer to loosen them in the past. But I had problem with all of the fasteners.

Originally they worked fine, but just a couple of nights in the grass and the dew rusted them all up. I then started keeping WD40 in my astro-toolbag. I really hate using it, because I figure it could easily contaminate everything. But on more then one occasion, I was literally stuck, unable to level my setup until I did some late night repairs.

#6 Koen Dierckens

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Posted 05 March 2013 - 10:20 AM

I've read several times that the cracks are caused when spreading/folding the legs during setup the wrong way, causing too much stress on the clamps.

The only correct way to setup the tripod is to turn it upside down, fully push the legs apart/together and then turn it back on its legs. This will avoid all undesired stress on the clamps that will cause the cracks.

Flip the tripod upside down on some soft underground outside (grass, eg) or a pillow/styrofoam pad when you're inside in order not to damage the floor or the center pin that helps you finding the center spot of the tripod plate.

I guess that also shoving the tripod with the scope mounted on it might cause the clamps to crack. So always disassemble the scope if you're unable to lift the assembly if you want to move it.

#7 Agatheron

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Posted 05 March 2013 - 12:34 PM

One of mine broke, but it didn't seem to change the performance of the tripod at all. However, Celestron sent me a new part after I contacted tech support and sent them a picture of it. I've not had problems with the other two... at least not yet. I'll have to check mine for cracks...

#8 rdl800

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Posted 06 March 2013 - 02:46 PM

Koen,
I was happy to read your post regarding the folding/closing of the tripod. I always thought the same thing, and I'm glad I have another opinion to confirm what I always suspected.

It really does seem that it is EASY to put stress on the tripod legs/clamps when closing them -- especially if they are closed awkwardly.

R.

#9 carver2011

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Posted 07 March 2013 - 01:24 PM

rdl800,
Sorry to hear about your tripod problem. I don't own one, but in seeing them in the field, I feel they are a fine scope package, and a lot of scope for the money. I agree with Koen's assessment of how to open the tripod to reduce the stress on the brackets. But, if there are enough cases of the brackets cracking, then it may very well be a design flaw. As I said, it's a lot of scope for the money, but a better designed bracket, or stronger material, may be in order.
Regards
Ed

#10 Brian Risley

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Posted 07 March 2013 - 11:42 PM

I have not located the part you say is plastic and cracking. Everything I feel on mine is metal. A picture from anyone who knows exactly what he is talking about would be greatly appreciated.
Brian

#11 zippeee

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Posted 08 March 2013 - 12:28 AM

My wife cracked the spreader clamp on our tripod the first week we had it. At the beginning she had a hard time because of the bulk and would often collapse the legs unevenly. I couldn't really care less and would never hold it against her. Two years of flawless operation since.

Posted Image

I'm a materials engineer and I work in machining. There is a very obvious stress riser in the design. These types of plastic components are typically investment or die cast with inexpensive materials. I was thinking about making some new ones out of a more resilient plastic but because it's been working fine . . . meh, I have better things to do.

#12 rdl800

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Posted 08 March 2013 - 08:37 AM

Zippeee,

the damage your picture shows looks exactly like my (two) cracked clamps.

This was the purpose of why I originally posted: to see if others were having similar or identical problems with their clamps/tripod.

Your post confirms a design flaw. But, like you said, the overall quality of the scope outweighs what I see to be a relatively small problem -- but a problem nonetheless.

great post and info. Thanks for posting.

Rob

#13 jerwin

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Posted 01 May 2013 - 11:09 AM

My CPC1100 tripod just cracked last night, and I recall reading this post a while back. My crack looks just like Zippeee's picture. I'm way out of warranty, does anyone know where to pick up this part. There has to be a bone yard of Celestron parts somewhere in the US, right?

I just put a ticket in with Celestron, but I figured I'd see if anyone on CN has found a good Celestron parts warehouse.

Thanks,
Jim

#14 jerwin

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Posted 06 May 2013 - 04:32 PM

Just an update, I found potentially a good parts resource. He's a CN sponsor

http://www.astronomy...o.parts.outlet/

However I received a message back from celestron that said "We are sending you one as a courtesy if available."

Not sure how long it will take me to know if one is available, but that was pretty nice of them none the less.

clear skies,
Jim






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