Ball bearing housing required for William Optics DDG focuser.

[S.A.M]

Hello SGL people,

Hopefully somebody will be able to point me in the right direction in getting a replacement component for my William Optics DDG Focuser?  Recently my 80 mm WO Zenithstar II ED Doublet fell off a table, (oops I hear) and I have done some damage to the focusing mechanics, as when I turn the focusing knobs in or out it feels rough in operation?  I did ask a question about getting a diagram of the focusing mechanism earlier in SGL and was successful, hence I have been able to break the focusing mechanism into component parts and after going over the kit and found the roughness to come from the bearing housing (pictures attached).  Without buying a complete new DDG focuser, does anybody know where I could get a new or good working bearing housing from please?

Thank you for looking.

Peter

[Davey-T]

Is it just the stainless steel bit you need ? there are folks who will make you one, probably not cheap though.

http://www.get-it-made.co.uk/

Dave

[S.A.M]

Probably do not need the SS part, think the problem is to do with the (brass?) spindle part as when I turn it it still feels rough.

[Davey-T]

These people make stuff

http://www.get-it-made.co.uk/

Dave

[S.A.M]

Thanks Dave,

Will have a look at them.

Peter

[Dave In Vermont]

Perhaps it just needs to be adjusted. And maybe some good quality grease applied to the bearings and the 'bearing-race' they run in. The fall may have just knocked the mechanism so it's running tight. I'd just loosen this and re-set it so they turn smoothly, which some grease would be good for facilitating.

But I can't be sure without actually inspecting the part. But I'm also a bicycle-mechanic who builds custom-bicycles for folks, so I'd have it down in less than a minute. Either fixed, or pronounced DOA (Dead On Arrival). So this tells me it's a straight-foreward job that any good mechanic should be able to do for you.

I'm sure you can get it working right (maybe even better than new) in short-order!

Dave

[Waldemar]

PTFE grease works wonders in cases like this...

[Physopto]

You may get away with a clean and grease. But you said it fell off a table. If the fault was noticed straight after that then there is a good chance that the bearing housing has been Brinelled. That means the balls have permanently damaged the housing that they run in by hammering small depressions into it. If that is the case it will need replacing. Hope that isn't the case but be prepared.

Derek

[Dave In Vermont]

Brinelling (pitting) the races is possible, but it would need a bit of weight to do this - just look and see where the ball-bearings are riding. If the race has a number of small dents on the surface, it's pitted and won't be as smooth as it could be. It should still work alright. It's a focuser, not part of a turbine spinning at 20,000rpm in a jet-engine.

I thought I was the only perfectionist here!

"I am easy to satisfy. I will always settle for the very best there is!" - Oscar Wilde

er...

Dave

[Physopto]

Hi Dave,

The bearings are under some weight as setup to give the required frictional drive. Any fall can very easily produce Brinelling because of the point loading. Any shock of that nature will have the potential to indent the housing. The W.O. Housing quality is not the best to start with and I doubt that the races are properly hardened if at all. A friend of mine has one and his is just the same. They are not built to Feathertouch standards for sure. There again even a Feathertouch dropped could be damaged, depends upon how hard the fall was. Even leaving a bearing unused and stationary can cause Brinelling just from stationary loading. I have seen it many times. 

Derek

[Waldemar]

" I thought I was the only perfectionist here!  "  hahahaha that is a joke, no...? 

[S.A.M]

Thank you all for the replies, I have cleaned all the old grease out and then air blasted the housing to remove any white spirit left?  Applied new grease and it works better than it did, not up the smooth standard but much better than the rough handling I had before.  I suspect the bearing have had a knock as for one turn I could feel the roughness three times, ie the three bearings inside the housing.

Peter