Collapsible 10" dob hard to collapse

[brian.bozo (Brian)]

Hi all

I've been absent for a few years, thinking I knew enough to get me by, but I've volunteered to do a "service" on a friends collapsible 10" dob.
She says that it's always been difficult to extend and collapse the tube. I've stripped the tubes out, thoroughly cleaned them as well as the locking sleeves and adjustable ball bearing locks.
It's still jerky when being extended and collapsed, but only marginally better. The teflon sleeves through which the tubes run is slightly scored, but I'm guessing this is normal, considering dust might settle on the shoulders of the sleeve.
I'm loathe to lubricate anything in case dust/dirt might stick to the lube.
Help please.

[mental4astro (Alexander)]

Hi Brian,

Use a high quality car wax ONLY on the tubes. This is the same trick as done on the laminate bearings of dobs. Clean them only with metho. Don't use any other cleaners or solvements as these can leave residue. Also clean the clamps the tubes slide through with metho.

Don't use some cheap and nasty car wax product. These contain nasty solvents, and don't have the same properties as the good stuff. The Turtle Wax that comes in a tub is perfect. Yes it costs a little more than the cheap stuff, but it is a better product for the scope, and your car too! Apply it to the tubes and wipe it off. Only the tubes. This will help reduce the binding your friend is currently experiencing especially if the tubes are scratched.

The tubes should be cleaned occasionally to prevent scratching. Dirt won't stick as you fear to these waxed tubes. Have your friend clean and re-wax the tubes say once a year. If things are very dusty, then do this a bit more regularly. And if you have a scope that uses Teflon in its bearings, you should also clean and wax the surfaces the Teflon slides over as described above at least once a year. DON'T wax the Teflon. Teflon is used because of its unique physical properties - only clean the Teflon pads with metho to maintain the physical properties of it. The quality of the action will be restored to as good as new and reduce binding, gittering, and backlash, and make using the scope not only easier but much more enjoyable as you are not needing to wrestle with it. You should not be needing to use any strong force to move the scope.

Alex.

[Sconesbie (Scott)]

Thanks Alexander. I'm having the same things happen with my dob. It shudders a bit when I expand or collapse it and whilst it isn't an issue for me I'd prefer them to run smoothly.

[brian.bozo (Brian)]

Thanks Alexander
As mentioned, I stripped the tubes and clamps that the tubes slide through. I'd thoroughly cleaned ALL parts with metho, used a quality car wax to polish the tubes.....all exactly as you described......much better than it was but still gittery on the down slide. Pulling up is perfect.
After stripping down several times and trying different wet and dry lubricants, I started from scratch and cleaned everything down again and reassembled it all. I used a dry base lube on the tubes. It's probably the best it's going to get. Smooth lift, slightly gittery on the drop.
When I examined the guides that the tubes slide through, I note that the teflon sleeves are very slightly scored, meaning that the tubes have been forced up and down for a long time, and is the principal cause of the problem.
I'm trying to find somewhere that I can source new sleeves for the guides.
There's nothing on the net about spares, that I can find.
I'll contact the makers and see if they can help. Their advice for remedying the tube problem was...
"Dust and grim can build up on all the bearing surfaces. We recommend cleaning these off and removing any dirt or debris from the bearing surfaces. "
Really?? Who'd have thought it was that simple?
Thanks again for the reply, Alexander. My friend is very pleased with the way the scope is working, but I'd like it to be better. I'll try the turtle wax to see if it makes an improvement. I'll let you know.