Mitutoyo toolmaker's microscope

[mtt.tr]

The lenses didn't all clean up perfectly, this one, part of the objective, has some kind of residue IPA doesn't want to remove (a light scrub with a cotton bud didn't help either). You can just barely see it and only in the right light so I thought I'd try my luck and reassemble it.
View attachment 286018
Here's the view now, wonder if anyone can guess what it is? It's 30x magnification.
View attachment 286019

I don't think the focus is as sharp as it could be, maybe I'll have another go at it. The reticle is still dirty, it looked spotless when I assembled it.

Has it partially removed a coating? Or fungus attacked?

 

[Maker]

I’d drop the lenses into a specialist with a clean room

I suppose it can't hurt to get a quote, I'll be very surprised if it's anything like my budget though.

Has it partially removed a coating? Or fungus attacked?

I'd assumed they'd be uncoated lenses but don't really have anything to back that up. It's 99.9% IPA I'm using, I wonder if the residue is that last 0.1%.

 

[Pete.]

You're not taking photos through it if you can see the part that's all you need. FWIW I cleaned my lenses with acetone and cotton swabs. I was advised to use ether but I didn't have any.

 

[Stupoty]

Don't have a lens pin wrench (I'll order one on Prime in a moment) but I was able to bodge one to get the objective out.
View attachment 285876

That came apart to be cleaned and dried.
View attachment 285878


View attachment 285877
Hopefully I get it back together as easily as it came apart.

Notice in the DaveCAD drawing the front lens is a doublet...
View attachment 285882

It doesn't come across well on camera but there's some gunk between them, don't know what do do about it. I'll reassemble it and hope it doesn't show up but if it does, I'm thinking soak in acetone then superglue (Special optical superglue?). Hopefully no expensive Edmund Optics orders will be needed.

I found a company that sells the spray coatings for lenses the other year, they do laps and everything.

Surfacing

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Stu

 

[Maker]

You're not taking photos through it if you can see the part that's all you need. FWIW I cleaned my lenses with acetone and cotton swabs. I was advised to use ether but I didn't have any.

That's true, it's certainly clean enough for my uses. Having said that, I do need to order some more acetone, it can't hurt to get a bottle of petroleum ether (I assume you didn't mean diethyl ether? ) and combine shipping.

 

[Maker]

Couldn't find M2 thumbscrews in stock in the UK but a little JIS machine screw (It's a Japanese tool after all ) will do, just to stop me losing the vernier. I've still got the knurled part of the original screw, when I go home I'll bore it out and loctite in an M2 grub screw, that way the knurling will match the rest of the screws.

 

[chrisg3103]

For what its worth regarding cleaning your optics, I built high end laser systems for about 8 years and all we used was methanol and folded lint free lens tissue held in forceps. Also used lint free swabs for some optics.
Methanol has to be 'fresh' as its hygroscopic, got changed every week.
I would go for swabs, the forceps and tissue technique took a bit of practice. Also use a bright torch at an angle to check the surface, shows up any specks of muck.
A laminar flow hood would also help, but don't think you can get one of those on amazon

Regarding acetone, it was almost treated like a controlled substance! Only allowed in the packing area for stickers. Was great for shifting stubborn marks on optics, but also shifted some of the coatings... be careful with it if you use it

 

[Maker]

A laminar flow hood would also help, but don't think you can get one of those on amazon

You've got me thinking about building a tiny little one now, ply enclosure, HEPA filter, airline regulated down to 1.2 bar...

It's lucky I'm at uni at the moment or I'd be out in the garage wasting time attempting it.

Good to know acetone can be dangerous to lens coatings, I've ruined many paint jobs and plastic windows with it in the past. Is there a good reason to go for methanol over IPA? More volatile perhaps?

 

[chrisg3103]

Not sure, ipa is pretty harmless to optics I think but was always methanol. Possibly something to do with the speed it flashes off, less chance of streaks

Also, I was wrong

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YJINGRUI Air Flow Clean Workstation Laminar Flow Hood Bench Dust Free Room Clean Bench Workstation for Phone LCD Repair Work 220V : Amazon.co.uk: DIY & Tools

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[Maker]

I keep the micrometers from this in a drawer with all my other metrology toys, to keep them from getting damaged. Imagine my shock when I got them out to use it and found this;


No idea how that's happened, something to do with the cold maybe? Luckily the other (nicer) one is fine, and it still works as a non-digital mic. It's gotten worse now I've prodded and poked it a bit.


There's a data port on the back, I wonder if it uses any sensible format (Like rs232) and could be decoded with a microcontroller with a separate LCD, like a miniature DRO.

 

[Maker]

Just a little update on this, it's an absolutely fantastic tool, every machine shop should have one IMO. Here's a few things I've used it for recently:

Snapped plastic bolt, the remaining thread wasn't long enough to get a reliable reading on a thread gauge, microscope made it dead easy to measure the pitch.



I needed to measure the chamfer on this bolt head, I wasn't sure if it was a 45 degree chamfer either just looking with the naked eye, put it under the microscope and it's clear as day (To measure that is, the images are far from clear, but good enough to make measurements).




Last one, which I do all the time, is check the angle on HSS lathe tools, particularly threading tools.




The only thing it doesn't do so easily is measure radii, which would be really handy for lathe tools. Optical comparators have screens with radius markings but I'd have to make a custom reticle if I wanted to recreate that, and etching miniature features on glass is a bit out of my tool and skill level (for now). They make (Or made) a rotary table which could be used to measure radii, but I haven't managed to find one yet. The overhead lights are pretty rubbish too, I mainly use the backlight but eventually I'll upgrade the overhead ones to much brighter LEDs. I still need to make a proper cover for it too, I throw and old shirt over it to keep the shish off it, but a fitted cover would be much nicer. I haven't repaired the damaged thumbscrew on the angle Vernier either, I should really get on that.

 

[daedalusminos]

Blimey those nails need a good clean

 

[julianf]

I've got a newinghall microscope that I never really use as it's in poor condition, instead going for the chinease thing instead.

I've always thought of it in the same context as a watch spring - that I'd take the screws out and a load of small parts would launch themselves, never to be found again.

Your thread(s) have almost given me some confidence!

 

[Maker]

Blimey the lenses need a good clean unless the camera is playing up

The camera's fine, the lenses are filthy, I'd like to have another go at cleaning it at some point. I did try to separate that foggy doublet element in the objective a little while ago but acetone didn't touch it, I was gonna try boiling water next, assuming it's fir balsam, failing that I'll deep fry it (Okay mineral oil on a lab hotplate), no glue likes sustained heating so that should get it apart. It's usable as it is, just pictures look really poor great and inspecting a surface can be annoying, but luckily I've got a crystal clear Zeiss for that.

Blimey those nails need a good clean

Those are pretty clean as my nails go.