Cross threaded screws on CPC 925

[Rumbold2010]

Hi all, just after some hints/tips from you good people. My CPC925 seems to have put together by the Hulk. The 6 screws on the back end of the OTA are just ridiculously tight, so tight Infact that my finderscope is sat with just one attached as the other one cross threaded when trying to loosen it. This issue has reared it's ugly head again as I now want to use an SCT piggyback mount for my camera but as the screws are so tight, I fear these will go the same way. Lots of DIY site suggest ways round a threaded screw head but given the location of them, I'm loathe to involve a drill. Any past experience of the same problem/ hints would be very gratefully recieved.

Don't forget to check your clocks this morning :-)

Many thanks

Andrew

[Merlin66]

Can you post an image of the offending screws?

I've used the C9.25 and the C11 for the past few years and never experienced the same problems....

[NGC 1502]

Hi Andrew. OK, expect you will have read lots of advise on removing overtight screws, most of them involving force, and fully understand your reluctance.

Can you remove the rear section of the scope ? Perhaps that would give access to the inner end of those screws ? If they protrude inside, perhaps you could very carefully

get Mole grips on them ? More force I know, but any scratches would at least be out of sight.

Apologies if this idea is a non-starter - if the offending screws also secure the back end of the scope.

Good luck, Ed.

[JamesF]

Are you sure you mean "cross-threaded"?  I'm struggling to see how you'd cross-thread a screw when removing it.

James

[m.tweedy]

If you have have damaged the head so the screw driver is slipping try using the screw removal tools

http://www.screwfix.com/p/screw-extractor-5-piece-set/18643#

[Peter Drew]

Have you been trying to unscrew the correct ones? those holding the rear cell on to the main tube have internal nuts and are not intended to be removed. The correct ones are those nearest the eyepiece end.  Just checking. 

[steppenwolf]

Are you sure you mean "cross-threaded"?  I'm struggling to see how you'd cross-thread a screw when removing it.

I wondered this too. If you mean that the screw head itself has a destroyed 'cross' then the solution is to re-visit your screwdriver choice. I have found that a screwdriver set with interchangeable bits can help with really tight screws as you can choose the best bit for the screw head in question. If the screwdriver bit cannot hold in the screw head on its own with the screw horizontal then it probably isn't the right profile. Please ignore this if you have actually cross-threaded the screw during extraction.

[Davey-T]

Had a problem with a Meade and drilled it out, not easy as the last bit needs to be done from below with the tube horizontal and grease on the drill to collect swarf, also need to start of dead centre as the screw is steel and the scope ally',  I actually wandered of a bit but tapped the hole out to 5mm, gives bigger stronger fixing and in the case of the Meade got rid of the annoying UNC screws.

Dave

[Rumbold2010]

Hi all, just revisited this post - James is quite right, cross threading is the wrong term. I've damaged the head on the screw so it's just a case of figuring a gentle enough way of encouraging it out. Thanks for all the tips guys :-)

Andrew