Nikon Bellows Repair

[Roderick JenkinsParticipant @roderickjenkins93242]

I inherited these Nikon PB6 macro bellows some years ago and although they have seen very little use, the nylon(?) bearings have all fractured at a stress raising corner. I drew up replacements in Fusion 360

Several prototypes were printed and a few iterations required to get the rack and pinion to engage properly – all 3 were subtly different

Works now though

PLA is probably not the ideal material for a bearing (nor, it seems, is nylon!) but it slides ok.

This repair alone has probably justified the cost of the printer.

Cheers,

Rod

edited for typos (as usual )

Edited By Roderick Jenkins on 08/05/2018 12:46:32

[Roderick JenkinsParticipant @roderickjenkins93242]

[ZebethyalParticipant @zebethyal]

I'll have to check mine to see if it is suffering from the same issue.

if it is, would you be willing to share the files, either Fusion or STL?

PLA can work OK as a bearing, many printers use it directly for sliding on stainless rods.

[Michael GilliganParticipant @michaelgilligan61133]

Excellent job, Rod

It will be interesting to see how long the PLA lasts … but obviously you now have the ability to produce spares 'just in time'

Out of interest: Is there evidence of fillers in the original black plastic items?

… If so, some idea of the particle size & shape would be interesting.

I seem to recall that the Olympus equivalent used Nylon [or similar] of 'natural' colour.

MichaelG.

.

P.S. … I'm currently having a 'materials' problem with the rubber eyecups on a pair of otherwise wonderful Nikon microscope eyepieces: Hopefully we are not witnessing a trend.

[Jeff DaymanParticipant @jeffdayman43397]

.

P.S. … I'm currently having a 'materials' problem with the rubber eyecups on a pair of otherwise wonderful Nikon microscope eyepieces: Hopefully we are not witnessing a trend.

Is the eyecup material problem related to gumminess / decomposition of the material, or is it getting brittle and cracking, or is it something else?

A few years ago eyecups would likely be made in silicone rubber, either compression moulded or made by liquid silicone injection moulding process. This material is chemically nearly inert when cured and will maintain mechanical properties for many years. I have some silicone rubber parts made 35 years ago that feel and work exactly the same now as then.

Due to cost pressure in the components marketplace many such silicone parts are now made with injected moulded TPV and TPE thermoplastic elastomers, and have been for ten years or so now. Some grades of these materials behave similar to silicone rubber.These materials are far less stable and much more reactive with solvents and contaminants like cosmetics alcohols skin oils and detergents than silicone, but are cheaper than silicone rubber.This results in parts that LOOK like they always have from known brands but the performance of the parts may not be same as earlier products from same manufacturer. Driving vendors to lower costs often eventually means they have to source cheaper raw materials that may not meet all specs.

[Michael GilliganParticipant @michaelgilligan61133]

Jeff,

Thanks for responding

And my apologies to Rod for hi-jacking the thread so soon

The eyepieces are a recently purchase secondhand pair of Nikon CFW 12.5x / 16, in focussing mounts.

Technically; although they are very well-matched, I think they are two 'individuals' from different production runs … the lettering is subtly different, and one rubber eyecup is more flexible.

The stiffer of the two eyecups has a couple of small splits in the edge; and seems likely to deteriorate further, in the near future.

A web search finds plenty of examples of CFW eyepieces with worse eyecups; so I'm pretty sure the problem is endemic. The rubber appears NOT to be Silicone.

To date, I have found nothing that looks like a viable replacement, and I am very interested in making my own, in Silicone Rubber [preferably black] … If you have any advice, I would be most grateful if you could send me a personal message.

MichaelG.

[Roderick JenkinsParticipant @roderickjenkins93242]

Meanwhile, back at the bellows

The issue with the plastic inserts appears to be a known problem. Not sure that this is a modern trend – these bellows must be at least 35 years old. I've put the the STL files in my Dropbox here

I can't see any obvious signs of reinforcing filler at the fracture surfaces.

Seeing as we're digressing – I've got a Nikkor 55mm macro lens but the grease from the focusing helixes has found its way onto the diaphragm causing the blades to stick together.

I took my courage in both hands, together with a small screwdriver, and took the thing apart and cleaned it. Again, this is a known problem and there is much guidance on the net.

I think I might try my hand at some focus stacking.

Rod

[Neil WyattModerator @neilwyatt]

Cleaning of cameras can be done – I managed to resurrect the multi-leaf shutter of my Yashicamat using clutch cleaner

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Roderick Jenkins on 08/05/2018 21:02:13:

I think I might try my hand at some focus stacking.

.

Zerene Stacker is excellent, Rod

MichaelG.

.

http://zerenesystems.com/cms/stacker

Edited By Michael Gilligan on 08/05/2018 21:32:52

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Roderick Jenkins on 08/05/2018 21:02:13:

Meanwhile, back at the bellows

The issue with the plastic inserts appears to be a known problem. Not sure that this is a modern trend – these bellows must be at least 35 years old. I've put the the STL files in my Dropbox

I can't see any obvious signs of reinforcing filler at the fracture surfaces.

.

Thanks for checking, Rod

I was actually thinking of filler as a problem, rather than reinforcement … Unless the chosen plastic is inherently black, it would presumably be pigmented.

MichaelG.

[Jeff DaymanParticipant @jeffdayman43397]

Michael G – PM sent.

[ZebethyalParticipant @zebethyal]

Many thanks for the STL files.

Hopefully I won't need them, but if I do, you will have saved me the design time.

Thanks once again

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