Step one for stiff rack and pinion?

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Doppler9000
Posts: 110
Joined: Thu Oct 13, 2011 3:56 pm

Step one for stiff rack and pinion?

Post by Doppler9000 »

Hello,

I got an Nikon XY stage and one of the axes is stiff. The unit seems clean, without heavy use, so what is the first step to take to smooth out the motion?

TIA

PeteM
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Location: West Coast, USA

Re: Step one for stiff rack and pinion?

Post by PeteM »

Could be several things. The likeliest, in my experience, is congealed grease inside the focus knob tube.

There are also adjustments for how tight the rack fits to the pinion and how tight the ball or roller bearing gibs fit.

These aren't hard to disassemble, clean, lightly grease, and reassemble. You'll want to take your time, though, beginning by removing the focusing knobs and seeing if they are tight (the inner one especially) and disassembling those if so.

Doppler9000
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Joined: Thu Oct 13, 2011 3:56 pm

Re: Step one for stiff rack and pinion?

Post by Doppler9000 »

Thank you, Pete.

On this stage, the inner knob seems good, the outer is the stiff one.

Are you aware of a parts diagram, or should I just go slowly?
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ray_parkhurst
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Re: Step one for stiff rack and pinion?

Post by ray_parkhurst »

My first move is always adding a small amount of penetrating oil to see if that will free the mechanism sufficiently. I use TriFlow. I've saved many such mechanisms that way, and rarely do I need to pull them apart after careful application. Make sure you start with the knob itself, as that is often the problem rather than the rack and pinion or whatever mechanism is used. Shafts are often neglected and don't have the same grease as the other moving parts, and may respond very well to oiling.

Doppler9000
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Re: Step one for stiff rack and pinion?

Post by Doppler9000 »

Ray - where do I add the penetrating oil to lubricate the knobs?
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PeteM
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Re: Step one for stiff rack and pinion?

Post by PeteM »

I'm not aware of a parts diagram. Just keep track of how things come apart - snapping a photo or two the first time can be useful.

ray_parkhurst
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Re: Step one for stiff rack and pinion?

Post by ray_parkhurst »

Doppler9000 wrote:
Wed Nov 29, 2023 10:12 pm
Ray - where do I add the penetrating oil to lubricate the knobs?
I'm not 100% sure, but most likely if you remove the nut that holds the lower knob in place, it will expose the bearing surfaces.

Doppler9000
Posts: 110
Joined: Thu Oct 13, 2011 3:56 pm

Re: Step one for stiff rack and pinion?

Post by Doppler9000 »

Waiting on the TriFlow, but designed and printed a wrench in the meantime.
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lothman
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Re: Step one for stiff rack and pinion?

Post by lothman »

if it is sticky grease this should become better with temperature, so put it in the oven to 50°C and see if it runs smooth. Sometimes it helps if you move it warmed up several times but stickyness will come back. Best would be to clean and replace the old grease instead of thinning the old grease with something like WD40.

Doppler9000
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Re: Step one for stiff rack and pinion?

Post by Doppler9000 »

I think I will take the opportunity to learn.

Is an adjustable spanner wrench the right tool for the next stage? (Nut put back for safety)

If so, what are the good ones? The Thorlabs unit looks pretty good.
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ray_parkhurst
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Re: Step one for stiff rack and pinion?

Post by ray_parkhurst »

Doppler9000 wrote:
Sat Dec 02, 2023 8:04 am
I think I will take the opportunity to learn.

Is an adjustable spanner wrench the right tool for the next stage? (Nut put back for safety)

If so, what are the good ones? The Thorlabs unit looks pretty good.
I'm not sure what actually rotates in the pic shown. I'd recommend seeing if you can identify the bearing surfaces, and apply a bit of oil to their outer edges.

If you can't figure out where to add the oil, then you may need to remove the nut. If you don't have a proper spanner, you might just try a heavy pair of needle nose pliers, but be careful they don't slip. The nut appears to be for adjustment, so is probably not very tight.

Doppler9000
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Joined: Thu Oct 13, 2011 3:56 pm

Re: Step one for stiff rack and pinion?

Post by Doppler9000 »

I decided to bail on taking the mechanism apart, since the axis wasn’t *that* stiff. I decided to just clean the bearing tracks, using TriFlow, microfiber, and a bamboo skewer, which worked well.

ray_parkhurst
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Re: Step one for stiff rack and pinion?

Post by ray_parkhurst »

Doppler9000 wrote:
Sat Dec 02, 2023 11:16 am
I decided to bail on taking the mechanism apart, since the axis wasn’t *that* stiff. I decided to just clean the bearing tracks, using TriFlow, microfiber, and a bamboo skewer, which worked well.
Excellent! TriFlow is a superb lubricant for this work.

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