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Sunshine

Advice Regarding My Dob

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I was wondering if dob owners  with similar dob’s could weigh in on something.  The mirror box cradles on my dob rest on what seems to be nylon pads, the cradles themselves have what seems to be an aluminum strap that rests on these nylon pads. 
When using the scope, I guess the nylon wears away at the aluminum, this creates a nasty powder which ends up covering the aluminum straps and inevitably smears on my clothes when handling the mirror box, is this wear normal?. For two surfaces which shouldn’t produce too much friction, it certainly seems as though something is wearing away too quickly no?. I use a very small amount of petroleum jelly one in a while on the strap to keep movements smooth, just a thin film.

 

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Edited by Sunshine

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Aluminium is covered with a thin oxide as it corrodes very quickly in air and that could well be what is rubbing off as you rotate the unit on the guides. That oxide may well have become embedded in the blocks (teflon perhaps) and that'll set up a friction surface that will continue to grind against the aluminium surface, compounding the effect. Probably not going to be easy to sort without removing a layer off the bearing edge of the block or replacing them, but someone else that has similar may be able to advise better.

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I have similar pads on my dob bearings but what bears agaist them is a smooth black laminate rather than metal sheet. I don't get the dust issue. The laminate surfaces used on my dob ar similar to those on top of kitchen worksurfaces I think.

 

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Maybe I should give the nylon pads a light sanding with a fine paper to expose a fresh layer? 

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8 minutes ago, Sunshine said:

Maybe I should give the nylon pads a light sanding with a fine paper to expose a fresh layer? 

might not help for long as you'll create a roughened surface and the oxide can bed in easier. Perhaps cover the metal with a laminate (or replace with) would be a better long-term fix. I doubt coating the metal with epoxy or lacquer or similar would work as it'd be hard to get an even layer that would last so not sure if there's a quick fix there either. Stainless steel maybe?

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Hi Sunshine, don`t waste anymore time, youi have a couple of choices ,remove alminium,carefully, and replace with a strip of laminate,having sanded the remains of any adhesive, or sand the aluminium and cover with laminate,then trim to correct width,Repace "Nylon blocks" with  virgin teflon. Try  this company for bits "

http://www.scopestuff.com/#ATM Stuff

Regards

Mike

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7 minutes ago, Demon Barber said:

Hi Sunshine, don`t waste anymore time, youi have a couple of choices ,remove alminium,carefully, and replace with a strip of laminate,having sanded the remains of any adhesive, or sand the aluminium and cover with laminate,then trim to correct width,Repace "Nylon blocks" with  virgin teflon. Try  this company for bits "

http://www.scopestuff.com/#ATM Stuff

Regards

Mike

Thanks, I realize now I mentioned those were Nylon, they are in fact Teflon, whether they're "virgin" Teflon as opposed to "sullied" Teflon, I could not say lol.

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