Identify This Microscope

[bostonman]

I can't find the brand name of the microscope in the attached picture.

The other day the head mysteriously stopped holding up and fell. I disassembled it and saw a washer (nylon?) between the U part of the bracket and the block (some of it can be seen in the picture).

From what I can tell, the washer provides friction to hold up the head, however, it doesn't look work indicating maybe other pieces are missing.

Does anyone know the name brand so I can look for a parts breakdown?

[jfiresto]

I have, perhaps, a silly question. Could the black clamp lever have failed so that it no longer engages its internal teeth? If I had to hazard a guess, the microscope looks like a copy of an old Olympus.

[jfiresto]

Here are some instructions for the model I was thinking of.

[bostonman]

I'll disassemble it again and take a look.

From what I could tell, and remained puzzled, it was locked in place by friction, but you bring up a good point, maybe it's completely worn.

[jfiresto]

Except that you did not say the lever was still turning after you tightened.

I wonder how hard the lever bolt must squeezes together the tangs to hold the microscope head. You might substitute a plain bolt and see how tight it needs to be. I would get nervous if it takes a lot of torque. What will you do if the lever strips?

[phil from seattle]

First, are there absolutely no identifying plates or printing anywhere on the microscope? Seems odd given the construction quality that is visible.

From your description, the black plastic lever is not tightening the joint enough and it slips? (I want to be 100% sure I understand the problem).

Is it possible that the plastic lever is partially stripped?  How hard can you tighten it?   It might have been a replacement somewhere down the line. The idea to try a regular nut/bolt is a good.  I would look at replacing it with a cam lever - it's a lot fast to adjust once you get it dialed in. Rockler has some nice ones that aren't very expensive.  Ugly blue, though.

[bostonman]

Attached are pictures of the hardware disassembled.

One picture shows the order of how the parts go with the arm bracket between the two washers. As for a label or model name, I'll look underneath, maybe it's carved on the underside, but I've looked most places and haven't seen anything.

When I tighten the black lever, the head remains in position, but isn't very strong and slips with the slightest touch. Prior to that, I never had an issue, and then suddenly it just slid down.

If you look at the hardware, it looks like it's held in place by nothing more than friction which is why I suspect the washers need replacement, however, they don't look worn.

I can try a bolt and nut, but I'd be reluctant do torque it anymore than I have with the black lever due to the possibility of it cracking.

[jfiresto]

What is the screw thread and length on the black lever? I wonder if the original design was only marginally tight and another with a longer, proportionally stronger lever might be more likely to hold.

[jpanhalt]

Your original picture looks like the Nikon and other brands.  Since there is no brand label or even a place for one, I suspect it is just a knock-off.

As for the problem at hand.  What you probably want are wavy, spring, or belleville washers (lots of names for similar washers, See: https://www.mcmaster.com/wave-washers/).  In that application, a wavy washer versus a belleville might be preferred.

EDIT: The advantage of a wavy washer is a greater range of adjustment and that adjustment doesn't change with temperature or movement nearly as much as a solid washer will.

[phil from seattle]

The joint works on friction. Hard to tell what has changed to make it have less.  Maybe some oil got in? Maybe degrease and reassemble?  Wear would have been very gradual.

Wavy washer is a good idea - will create higher force points rather than distributing the force equally.

[bostonman]

The black handle is about 2.5". Also, I looked all over and didn't see a brand name or model.

I'm thinking the washer has worn, and the cold weather (it's in my basement) has caused it to contract, so the whole thing isn't as tight. New washers, maybe a wavy washer, is probably the solution since I haven't done any modifications to cause this.

I'll also try degreasing it.

[jpanhalt]

I don't think grease is either the problem or the solution.  Clean to the touch should be sufficient.  If you chemically clean it, you may well get galling, and if it is aluminum, maybe even worse. 

You have a clamp, a sliding joint, and a tension adjustment.  For the tension, a wavy washer.  For the sliding joint, something smooth but not overtly greasy.  A thin fiber or other composite washer on both sides might help.  It looks like there may be a plastic one already.  That can be replaced.  Finally for the screw clamp, be sure the screw has a little lubricant on it.

[phil from seattle]

Degrease = alcohol or acetone. Always a good idea when working with friction joints like this. Certainly won't gall aluminum though it looks like the metal is steel. Al would be a terrible design choice for that.

Be careful when lubricating the screw.  For obvious reasons.

[bostonman]

Tonight I went to the hardware store looking for nylon washers and/or wavy washers.

Unfortunately they didn't have any nylon washers of the same size, but the guy suggested using a round seal from the plumbing department.

He found one that was almost the exact hole size (I had to do some minor filing), however, they were maybe twice the thickness of the existing nylon washers. Unfortunately this thickness wouldn't fit suggesting wavy washers wouldn't fit.

I also tried tightening the lever as tight as I could get it with no improvement - maybe a hex screw and bolt with excess force will be the answer, but I'd fear cracking the metal and/or I lose this adjustment should I need to move the scope head.

There is a hex screw just above this area - you can see the hole in the picture. The hole goes through to the other side and the set screw is sticking out. To access the head, a hex wrench goes in from the front, and, turning the set screw CCW eventually stops; turning it CW allows the set screw to come out. I tried threading it from the front, but it doesn't seem to thread through to the front.

I thought maybe this set screw does something to hold the scope head, however, tightening it didn't help the scope head, nor do I see a purpose for this set screw.

[phil from seattle]

If it really is just a worn washer, I would figure out how thick the current ones are and look for replacements that are slightly thicker. I would take a long browse through mcmaster-carr.  they have a lot of different washers of varying thicknesses. 

Another possibility is to make a couple of shim washers out of thin material.

[bostonman]

I should have dug out my micrometers earlier.

I'm getting a thickness of 0.039", ID 0.516", and OD 0.945.

I planned to look on McMaster Carr, but usually they have large quantities and shipping is usually high, so thought I'd start with the local hardware department and work my way towards the more expensive options.

Edit: also keep in mind I need slightly thicker, so if I buy from McMaster Carr, I could waste money going to thick and it doesn't fit.

[phil from seattle]

No question and I use McMC as basically a last resort for that kind of parts because of it. But when you need that part and you can only find them in Q100, what are you going to do?

[jfiresto]

I should have dug out my micrometers earlier.

I'm getting a thickness of 0.039", ID 0.516", and OD 0.945....

I round that to 1, 13 and 24mm – a thin echo of a common, 2.5mm thick, M12 DIN 125.

[bostonman]

Unfortunately all I've found on McMaster Carr was two items within the thickness that "should" fit; ignoring that ID is a bit bigger.

97985A810 and 90391A113

Not sure if these will work, seems like they should. The biggest question I have is how did the head manage to stay up all these years by depending on the friction of teflon (?) washers?

I keep looking at this microscope trying to figure out how it remained still all these years. Even if I assume the washers have worn, it's still smooth teflon against smooth metal. Also, these washers would have had to lose only a small amount, maybe 0.05mm to 0.1mm in thickness in order to cause a slight spacing forcing the screw not to tighten against the base.

[bostonman]

Earlier today it occurred to me that maybe the mounting post on the microscope is upside down.

I flipped the piece that has the hole the nut barrel feeds through (now it's on the top of the arm). Before doing so, I looked on the inside of the fork and saw a round scratch. This confirmed that the set screw I mentioned, that I couldn't figure out what purpose it served, was normally pushing in that area.

It's kind of a dumb design because you can loosen the black arm to move the head up and down, but in order to lower the head further, you need to move the set screw. The set screw is used for the head bracket to rest on and secures the head from falling because the head can't stay in place by way of friction only (i.e. tightening the black arm). Attached are the pictures showing what I'm talking about.

At first I thought maybe I assembled it wrong years ago, but I wouldn't have disassembled that section. It must have been wrong at my old job; maybe that was the reason it got tossed. Amazingly enough, this remained stationary since I bought it home back in 2011 and one day decided to fall.

[jfiresto]

It's kind of a dumb design because you can loosen the black arm to move the head up and down, but in order to lower the head further, you need to move the set screw. The set screw is used for the head bracket to rest on and secures the head from falling because the head can't stay in place by way of friction only (i.e. tightening the black arm)....

Perhaps it saved a little money. I have a Motic photo tube with a similarly goofy and not very secure arrangement. To save a little machining, its needs some custom optical bench to level the image, more or less for a while. The tube's archetype has a simple trim screw you can exactly set and forget.