Nikon Labophot Overhaul: dealing with glued part

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samw
Posts: 2
Joined: Fri Nov 19, 2021 8:46 pm

Nikon Labophot Overhaul: dealing with glued part

#1 Post by samw » Fri Nov 19, 2021 9:16 pm

Hi all,

I'm overhauling a Nikon Labophot whose grease has turned very gummy. I almost have everything apart, but I'm stuck at removing the the coarse focus bearing, part 106 in the repair manual, page 15 of the pdf (page 22, according to the printed page numbers, due to missing pages). The manual says to immerse the assembly in alcohol (to dissolve the adhesive on the part, I assume). A few questions:
  • Can that be right? The bearing is still in the pillar of the scope arm at this point. I'll need to dunk the whole bottom end of the arm in several inches of alcohol to get the bearing submerged. (Possible, but annoying!)
  • Any idea if isopropyl alcohol will do the job? The manual says the adhesive is "#350". Not very informative.
  • Alternatively, I could apply heat to soften the glue. But I don't know if that would actually work, and I'd hate to damage anything (though that seems unlikely; I can be pretty precise with the heat).
  • How can I get torque on this part? It looks like the bearing is supposed to be taken off with a pin wrench. I'm assuming a fair amount of torque will be required to break the adhesive. But I'd rather not buy a tool I'll only use once. Also, the outside diameter is finely threaded for a mating part, so man-handling it with a wrench seems like a bad idea.

I don't really expect anyone to have direct experience with this exact situation/scope, but any advice from more experienced people would be appreciated.

Thanks!

-- Sam

PeteM
Posts: 2989
Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Nikon Labophot Overhaul: dealing with glued part

#2 Post by PeteM » Fri Nov 19, 2021 10:27 pm

Perhaps a drop of a solvent (ligher fluid?) followed by a drop for two of instrument oil could lube this part in place? Most lube problems I've seen with this era Nikons have been in the many-toothed spur gears and the often-broken pinion gear that moves them.

My recollection is that the main shaft can be removed from either end.

samw
Posts: 2
Joined: Fri Nov 19, 2021 8:46 pm

Re: Nikon Labophot Overhaul: dealing with glued part

#3 Post by samw » Sat Nov 20, 2021 3:38 am

Huh. I think I may be misunderstanding what parts are still in this thing.
left side
center
right side

The big black disk on the left side doesn't show up in the diagram of parts in the manual. I thought it was the left-side coarse focus bearing, part 106, but maybe it's not? Maybe it's pictured in one of the missing pages, and the coarse focus bearing is behind/inside it. Looking through the hole in this black disk, I can see the shaft 109, but not anything else attached to its end. I took this to mean the black disk was the bearing, but perhaps its not.

So maybe the shaft is actually free, but the glue-like grease is holding it in. I've done my best to pull the gear on the right side out (to bring the shaft with it), but there isn't a lot to hold on to, and I'm afraid of damaging the gear.

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