MicrobeHunter.com Microscopy Forum

Got the Reichert Microstar IV I ordered the other day. In great shape, was packed really well! Assembled, cleaned, adjusted the light path and checked all functions. Looked at a couple of things (I've ordered slides, regular, well slides, a ruled slide, covers, immersion oil and a microtome) and took a couple of afocal shots with an old P&S digicam. The results gave me confidence that I will be able to shoot with this method and get decent results. I will be looking in to better ways to shoot in the future. Only one thing slightly concerning. The coarse focusing just seems kind of rough, and by rough I mean the feel and a slight scraping sound. It moves in its full range and other than that it seems fine. Fine focusing is smooth and quiet. Any idea what this could be and/or how to smooth it out? Should I be concerned? I downloaded a manual for this scope as well as the parts list with exploded view. I'm not really clear in looking at the diagram how this focuser functions. I am generally not one to "fix what's not broken" and am loathe to tear in to it if not necessary.... Ideas?

There are somewhat better drawings of the focus mechanism in a patent. Some parts are omitted and a few details don't match the actual implementation but they may still be useful:
viewtopic.php?f=5&t=10113

I would start by trying to isolate whether the roughness is coming from the coarse focus shaft/cam/follower vs. the bearings supporting the focus arm. In those patent drawings 42 is the cam, 40 is the follower bearing, and 44 is a pin that limits upward travel of the arm away from the cam. Try lifting the focus arm slightly away from the cam and moving it up/down while simultaneously turning the coarse focus knob back and forth such that neither 40 nor 44 is contacting the cam. You may be able to feel which side of the mechanism the roughness is coming from.

Thanks Hans! I will look in to that and thanks for for the link to the superior patent drawings.

Jim

Is it the right or the left or both... I had a similar issue on one of mine and my approach was to inspect the rear of the scope first, there is a vertical shaft where the nosepiece mechanism attaches to that might need a bit of lubricat since old grease can cake over time, while you're at it, check the focus cam to make sure that it's smooth and that no grease or particulate built up has managed to accumulate on the surface. Lastly I would take the fine and coarse mechanism apart, this of course only if is necessary, there's a lot of washers and gears that go in certain order and can get tricky, there is a thread that has pics of the mechanism and how to put it back together. To be honest the neoplan set that comes with the Microstar is quite parfocal and you'll rarely will have to use the coarse focus. Ps while you're back there also check the "stage" lock the spring can sometimes get stuck.

Seems to be both. I've exercised it a bit more and seems to be better. I'll also look in to the nosepiece suggestion. As stated before, overall, it does scare me a bit to take it apart to any great degree. I'm generally not averse to digging in to some things but this design sure looks packed with parts as you allude. I've thought the same about not really needing to use the coarse focus much. To be continued .................................Oh, and thanks for your input. This forum is already turning out to be an enlightening resource!

You don't have to dig too deep to do an inspection. Four Philips screws remove the back cover and four more like it, drop down the circuit board. All is then revealed, at least in the bowels, where the likely problem is. The cam follower mentioned above is a ball bearing.
They are as vulnerable to compression as the cam is, so having the focus train banging on them can pop a few balls out, since the outer race is quite thin. From there it is downhill. What happens then is that the outer race runs eccentric, balls fall out, the race crumbles and the bearing finally ceases to rotate at all. The focus train drops down slightly, allowing the shoulder of the bearing mount to become the cam follower. The focus still works but is a little rough and there will be a scraping sound but not always, since sometimes the bearing supports the focus train and will rotate a little and sometimes the shoulder. There will be a double track on the cam separated by a white grease trail.
I had to fix one of these and just happened to have a bronze bushing that worked perfectly, so I can't give you the bearing #.
If this turns out to be the culprit, continue to use it until you get a new bearing. It won't really hurt the cam because the part scraping isn't normally a surface that is use. I still have the dashed bearing here. I will measure it and give you the specs. A bearing shop or even on-line , ebay or other should cough one up.
To replace it. It is best to remove the bracket that is affixed to the vertical focus shaft. You will need a stubby slot screwdriver or a 1/4" drive ratchet with a slot screwdriver bit. Two screws. Ratchet is easier.
Be carefull removing the bearing. Possibly some fittings have already fallen off but the grease should keep them handy.
There are two shim washers and a tiny circlip on the outside of the bearing. The tiny circlip is important. It might be difficult to find one if lost.

Just finished opening the top and back. The piece of plastic (isn't listed as a discreet part number but part of the bearing flange assembly) that the bearing rides on was very dirty(cleaned it). Already a bit quieter and smoother in motion The bearing does look a little tilted as it rides on the flange but I don't think it is broken. Does the bearing/flange surface get lubricated?

Upon closer inspection it appears that it's possible the bearing is frozen. A thorough cleaning has made the function smoother and less noisy but it still not normal.

There will be a light grease coating on the cam and the bearing should be well packed. If the bearing was stuck and dragging on the cam, that might have been the source of the scraping. Bearing size is 1/8" bore, 5/16" o.d. and 9/64" width, if you ever need one.
If the bearing is cockeyed it may have lost some balls or be badly worn. It is a tiny deep groove ball bearing with a race. It should be tight and rotate perfectly smoothly, just like any precision ball bearing. A sealed version should be available for about 3.00.

Thanks apo. I will lightly grease the cam as it is completely dry. I will also order a new bearing. Used to deal with bearings and had quite an assortment when I was an IMAX projectionist.

James Lahti has his vineyard near to me. He still does Imax stuff. I just bought a pack of 10 sealed 693ZZ bearings from China for 3.17 + free shipping. Ridiculous, really.
They are metric, so 3mm x 8mm x 4mm. The original is 3.17mm x 7.938mm x 3.572mm . There is enough room to accomodate the extra 1/2mm width: probably better, the o.d. is fine and the little bit on the shaft can be emeried away in less than 5 min. I'm sure they will last for quite a few years.
https://www.ebay.com/itm/10x-693ZZ-Mini ... ect=mobile

Great! I have been looking around this a.m. but will check these out. Looks like an easy enough replacement except for the tight quarters and the often p.i.a C clips. I was terminated after 35 years in the giant screen biz. The museum that my theater was located closed in March, I went to our summer place in April for the spring/summer/fall season and was unceremoniously severed by phone in May. Theater re-opened in Aug. and was again closed before Christmas (one of the busiest seasons) I was an uber dedicated employee and helped our institution make millions of dollars. C'est la vie! Did capture a lot of glorious images and plan to do the same this year!! Thanks again for all your help! https://photos.app.goo.gl/EpWLg5SJS3KbFAkW7

Out of curiosity, I spotted this ad
"10pc R155zz (5/32" x 5/16" x 1/8") Metric Shielded Ball Bearing Bearings R155"
https://www.ebay.com/itm/10pc-R155zz-5- ... Sw9N1Vt6iX

the data sheet indicates Imperial sizes. The emboldness is mine...

Hobbyst46 wrote: ↑

Thu Jan 14, 2021 2:28 pm

Out of curiosity, I spotted this ad
"10pc R155zz (5/32" x 5/16" x 1/8") Metric Shielded Ball Bearing Bearings R155"
https://www.ebay.com/itm/10pc-R155zz-5- ... Sw9N1Vt6iX

the data sheet indicates Imperial sizes. The emboldness is mine...

Maybe just the shields are metric

apochronaut wrote: ↑

Thu Jan 14, 2021 12:20 pm

I just bought a pack of 10 sealed 693ZZ bearings from China for 3.17 + free shipping. Ridiculous, really.

Hi Phil,
I would suggest that you check the size and put a file to it to check whether they are actually hardened. I had two occasions where dimensions of chinese ball bearings were completely off and the steel was soft. They were off in a way that made clear that the company who made them had no idea that certain dimensions and properties were neccessary. Just "smaller medium but not tiny size". If I remember right it was 26,1 instead of 25mm and 10,6 instead of 10mm. There also were no corresponding imperial sizes that would have fitted.
I informed the sellers and they asked their "technical department": Everything within tolerance!

This really is a pity as for many applications a second or third class bearing would be perfectly good enough. But it should be a bearing in the first place.

Bob

apochronaut wrote: ↑

Thu Jan 14, 2021 12:20 pm

I just bought a pack of 10 sealed 693ZZ bearings from China for 3.17 + free shipping.

Wow, that's $0.31 per bearing. What are the quality of these things? The old saying "you get what you pay for" comes to mind here.

Stomias wrote: ↑

Thu Jan 14, 2021 10:51 am

The piece of plastic (isn't listed as a discreet part number but part of the bearing flange assembly) that the bearing rides on was very dirty(cleaned it).

On one of mine the "dirt" was I think plastic particles wearing off from the cam surface which had also clogged up the bearing. The bearing was fine, just needed to be flushed out with solvent and lubricated. I also had to lightly sand and polish the cam surface to remove the rough, deteriorated layer for completely smooth focus action.

Stomias wrote: ↑

Thu Jan 14, 2021 10:51 am

Does the bearing/flange surface get lubricated?

I don't see any reason it should be since the bearing is supposed to roll on the cam surface. None of the ones I bought had lubricant on the cam when I got them.

That might very well be the case as I've cleaned said particles up on mine..

Well got back inside to figure this thing out and the outer race of the ball bearing actually had a chunk missing. There was only one ball in there. Had to mangle it up to get the whole thing out. Tight working conditions in there for sure. Ordered the $11.00 direct replacement which should get here tomorrow and I can button this thing up. Thanks everyone for all your generous help!

Jim

Paid $11 for the bearing and another $15 to get it today and the bore was too small. Then whilst trying to get it on and it fell in to the bottom and disappeared. Oh well. It actually focuses smoother and quieter with no bearing at all..Go figure. This is how I will use it.

Stomias wrote: ↑

Fri Jan 15, 2021 9:30 pm

...the bore was too small.

Which size did you buy, the original fractional inch size or the metric approximation apochronaut suggested that would require narrowing the shaft a little:

apochronaut wrote: ↑

Thu Jan 14, 2021 12:20 pm

...the little bit on the shaft can be emeried away in less than 5 min.

Stomias wrote: ↑

Fri Jan 15, 2021 9:30 pm

Oh well. It actually focuses smoother and quieter with no bearing at all..Go figure. This is how I will use it.

You may want to at least put a bit of soft, sacrificial material (polyethylene plastic from a food container maybe?) over the metal shaft to minimize wear/damage to the cam surface. However I think the friction with the cam (which affects fine focus as well) will probably lead to some noticeable backlash and not be nice to use at 40X or 100X where smooth, precise focusing is necessary.

As a point of reference for the future, The A/O. Reichert, Leica fixed stage , focusing nosepiece microscopes are shipped with the Nosepiece in the upper most position and the nosepeice secured in that positions, usually with a block of demse foam under the objecitves are are mounted on the nosepiece. Also a small rectangular piece of foam is placed between the back of the stage and vertical column of the stand. Always covered by a plastic bag and then secured in place with tape. This prevents the stage from moving fore and aft and protects the gearing. This essentially applies to the Series 10/20, Series 100/110/120, Series 150/160. ATC2000, Microstart IV and Diastar. Hope this helps for future shipments. The DMLS DMLB, DM 1000, 2000, 4000, 5000 , 6000 have a foam block that is placed below the stage under the condenser rack as well as another foam block behind the stage surface with the stage secured in the furthest rearward position.

JGardner wrote: ↑

Thu Jan 14, 2021 6:24 pm

apochronaut wrote: ↑

Thu Jan 14, 2021 12:20 pm

I just bought a pack of 10 sealed 693ZZ bearings from China for 3.17 + free shipping.

Wow, that's $0.31 per bearing. What are the quality of these things? The old saying "you get what you pay for" comes to mind here.

You are making unfounded assumptions The same bearings are available from U.S. sellers for 10 times the price plus a whacks worth of shipping. They bought them for the same price I did and are remarketing them. Same photo. You have to understand how it works in China. They surplus items very fast, if there is no market or if a market dies. That's why you can only get certain sizes of many items. It's all industrial surplus. Many of the Chinese sellers on ebay are surplus dealers who get subsidized shipping, to help move out the stuff. Obviously those bearings are being dumped. Why would they put a seal on a useless bearing?

Microbob. Sure they may not have the hardest steel but look at the application they are going in. They are not exactly being used at high speed or have to sustain any heat or torque. There is a small amount radial thrust.
I'll let you know when they do the job fine.

Stomias. I wouldn't use it without the bearing for ever. It does work but the focusing is a bit rough. The mounting flange for the bearing shaft becomes the cam follower and it will wear the cam down dragging on it. Why did your bearing not fit? The shaft is exactly 1/8". The inner race is fairly tight on the shaft. I had to pry the one off I repaired. It wouldn't come off with the outer race.

I bought the 1/8" bore, 5/16" o.d. and 9/64" width. I will try the plastic trick. I also noticed there is a pin from the shaft assembly to the flange/cam. So there is added stability through that. Didn't realize it was there until I really took a look around.

Well i did a temp fix that seems to be working. Wrapped the shaft with a healthy amount of teflon plumbers tape. I feel like a surgeon working in there. Headlamp, 2 forceps and my sausage like fingers all stuffed in the case (which should have been designed with easier access to this mechanism ) to apply this tape. The focus is smooth and quiet. I am sure I will need to re-apply at some point but now that I've done it once and have a system it shouldn't be a problem and the plastic focus flange/cam is protected.

A pin? The only pin is the 1/8" bearing shaft with a small circlip relief near the end. That bearing shaft fits through a hole in the mounting bracket up to it's shoulder and is secured with a nut. The bearing fits on the shaft and is secured with a circlip. By removing the bearing, the vertical focus shaft should drop down by 3/32" ( 1/2 the total bearing diameter minus 1/2 the shaft diameter) bringing the length of the bearing shaft onto the focus cam. However, the shoulder of the bearing shaft is in the way and that contacts the focus cam first. It is a very small surface to be riding on the cam and will for sure wear away at it.
From your description, it seems you did not remove the two screws that fasten the whole assembly to the vertical focus shaft, as advised? You tried to fix it in an impossible location and lost the bearing in the bottom of the microscope?


Why don't you remove the bottom cover from the microscope , find the bearing , remove the two screws that hold the entire assembly, remove the assembly and install the bearing? The shaft may be a bit beat up a bit from the mechanism being used without a functional bearing. A light polishing with emery paper or waterpaper will clean up the shaft but you need to have the assembly off the microscope, on a cloth on a bench or table to do a good job.

You could use a plastic or nylon roller as a sleeve bearing. I used a bronze bushing in the same capacity. It it is well lubricated it will work but the plastic will eventually develop a flat spot and increasingly develop rolling resistance, and start to drag on the cam. The efficiency of the system relies on the cam follower rotating as it moves along the cam, not dragging on it.


I just saw your last post. I repeat. It takes the removal of two screws to put the assembly in front of you, so you can work on it comfortably.

Thanks apo

I just looked at one of my stands that is already partially disassembled and there was some thread-lock adhesive both where the follower shaft threads into the little block at the base of the main linear bearing rod, and also between the follower bearing and shaft. Not sure if that is normal and I don't remember it on the other stands I have taken apart, but some remnants of thread-lock adhesive could explain why the new bearing didn't fit easily.

apochronaut wrote: ↑

Mon Jan 18, 2021 1:49 pm

A pin? ...

Maybe talking about the small pin below the follower bearing that catches the underside of the cam and limits upward travel when the nosepiece and focus arm are lifted?

Yeah, some of that on other set screws but not on the pin/shaft that the bearing rides on. I cleaned the s#*t out of that but I'll have to say it that that bearing would have taken a hammer and Thor's arm to get it on that pin. There is just no way that bearing is the right dimensions for that shaft.

Yeah sounds like something wrong. With the adhesive scraped off the shaft measures a couple tenths over 0.124" and the bearing is a smooth slip fit.