Large O-rings for big newts

[Prador]

Random one here.

I've been after a third tube ring for my 250pds to enable easier ota rotation when mounted. Has anybody fitted a large o-ring (or two) to stop the ota from slipping through the rings when loosened?

260-280mm o-rings are cheap on Amazon but wondering if they actually grip the tube sufficiently. I'd rather not find out the hard way 😮

Many thanks

[Captain Scarlet]

I fitted a 239-something o-ring to my 200p, but not to prevent slippage, rather to try to stiffen up the tube near the focuser, as collimation was changing as I changed altitude.

i wouldn’t worry about sufficient grip, I’d worry more about crushing or buckling the tube.

see pic below...

cheers, Magnus 

Edited March 8, 2020 by Captain Magenta

[CraigT82]

12 minutes ago, Prador said:

Random one here.

I've been after a third tube ring for my 250pds to enable easier ota rotation when mounted. Has anybody fitted a large o-ring (or two) to stop the ota from slipping through the rings when loosened?

260-280mm o-rings are cheap on Amazon but wondering if they actually grip the tube sufficiently. I'd rather not find out the hard way 😮

Many thanks

If you're talking about rubber o rings, not sure... but they're cheap enough to try and find out! 

[Prador]

1 minute ago, CraigT82 said:

If you're talking about rubber o rings, not sure... but they're cheap enough to try and find out! 

Yep a big nitrile rubber ring around 260-270mm so a snug fit.

They're only a fiver so worth a shot. I would've got the tube ring on astroboot but the postage is too high.

[omo]

Try a jubilee clip inside some silicone or rubber hose (tube protector), would work as a rotator, used the same on a dob as a bumper:

 

 

[1parsec]

How about making your own using o-ring cord. 
It's available in many sections. Cut to length and a dot of super glue to join.  Cheaper too !
https://simplybearings.co.uk/shop/Seals-O-Ring-Cord/c19_4549/index.html?page=1