Vickers/Watson microscope focus creep

ChrisR · Post by **ChrisR** » Tue Sep 08, 2009 11:42 am

Edit - It was sold to me a "Vickers" but Watson, Barnet is the only name on it.

I'm experimenting with a part-microscope I bought for very little. It's a Microsystem 70. It seems to be quite strongly & stiffly built.

It has just 1.2mm of fine focus, but it's easily adjustable to a micron.

A problem I'm having is focus "creep". The stage drops. Other than taking the focus mechanism apart to find a way to stiffen it, is there a technique to avoid it? I've tried starting with the rack low and going higher, so gravity might take up the backlash (free play) but still, it drops.

I've ventured a little way into its knobs, but wonder if anyone has a manual for this scope?

When I've learned from this one, I'll move to an Olympus CH I have, which art least has a friction knob.

It isn't much movement. I was watching the striations on a moth scale, successively in focus, wondering if I could catch each one with a flash.
I tried shouting at it, but it must be deaf, it's pretty old.

elf · Post by **elf** » Wed Sep 09, 2009 12:38 pm

Sounds like you just need to add an intervalometer for fully automated stacks

How far will it drop? Is it just a couple of microns or will it continue to drop to the bottom?

You could try removing some weight from the moving parts.

ChrisR · Post by **ChrisR** » Wed Sep 09, 2009 1:16 pm

Yes, that did occur to me. I can just set the camera to take some large number of pics. One day I'l get something automated, I hope, but getting anything is two steps forwards and one back.

I'm not sure how far it drops because as soon as it's gone a few microns everything's fuzzy. I suppose it stops but you can't see it moving.

Weight - apart from pulling the other wing off the moth,,,,,,

Time to get my knobs off I think. If the worst happens I can always play with the ball bearings

elf · Post by **elf** » Wed Sep 09, 2009 1:24 pm

ChrisR wrote: Weight - apart from pulling the other wing off the moth,,,,,,

I was thinking more along the lines of drilling lightening holes (that is holes that will lighten it not holes that will let lightening in) in it.

Can you post an image or two of it?

rjlittlefield · Post by **rjlittlefield** » Wed Sep 09, 2009 3:51 pm

Stages are designed to not creep, when properly lubed and adjusted and with no weight added.

Unless significant weight has been added for specimen holding, it sounds like this one has a lube or adjustment problem.

But exactly what that might be, I have no idea since I haven't even read about that type scope.

If you're really interested in tweaking it up, I recommend to ask for manuals and advice in the Yahoo Microscope group. They have more people and resources than photomacrography.net does in that area.

Alternatively, a bit of bodging to push a soft pad against the outside of the fine focus knob should take care of the problem.

Or do you mean that the stage drops even when the fine focus knob is prevented from turning?

--Rik

ChrisR · Post by **ChrisR** » Wed Sep 09, 2009 4:04 pm

Thanks Rik I'll see if I can find it!
The way it works is that the fine focus lifts the stage, coarse rack, pinion and both sets of concentric knobs, all as one. The fine focus spindle is finely threaded but further "in" than I've managed to get so far.
When the stage drops by itself, it doesn't necessarily turn the knob.
Only one ball bearing on the floor - I measured it in case I lost it again, 1/32nd", so I was lucky to find it!

Harold Gough · Post by **Harold Gough** » Wed Sep 09, 2009 11:16 pm

ChrisR wrote:Only one ball bearing on the floor - I measured it in case I lost it again, 1/32nd", so I was lucky to find it!

Carpet fluff on the ball bearings should slow the creep!

Harold

Charles Krebs · Post by **Charles Krebs** » Thu Sep 10, 2009 9:46 am

When the stage drops by itself, it doesn't necessarily turn the knob.

That sounds odd. But then there were a variety of ways these things were made over the years.

You might want to try posting your problem on the Yahoo microscope group. Sometimes you'll find someone that knows exactly what the problem is with a specific older microscope. At least I would give it a shot before doing surgery. It's always a bit dicey to take one of these things apart with nothing to guide you.
(You always do a better job on the second one, once you've discovered the proper way to do it without breaking any parts! )

ChrisR · Post by **ChrisR** » Thu Sep 10, 2009 11:29 am

Thanks. I submitted a post there, but it has to pass the censor before display. SO who's been telling tales??

rjlittlefield · Post by **rjlittlefield** » Thu Sep 10, 2009 12:00 pm

ChrisR wrote:I submitted a post there, but it has to pass the censor before display. SO who's been telling tales??

Fear not -- it's a standard practice to keep the spammers away. I had to pass the gatekeeper too, on my first posting there.

--Rik

elf · Post by **elf** » Thu Sep 10, 2009 12:41 pm

ChrisR wrote:Thanks. I submitted a post there

If you don't get an answer, I have a nice array of drills and milling machine bits so just send it to me and I will be happy to make it lighter

Gary W Brown · Post by **Gary W Brown** » Sun Sep 13, 2009 5:59 pm

I may be able to help with your stage movement problem. If you wish you may contact me at gw2brown@earthlink.net

Gary