If it ain't broke, don't fix it!
I made my first newbie mistake with my Zeiss Standard stand, and I'd appreciate advice on how to best repair it.
Specifically, one of the condenser centering adjustment screws was a bit sticky. I decided to remove both of them, clean them, and re-grease them. Big mistake. One of the screws went back in quickly. The other was impossible for me to get back in -- It turns out that I damaged the screw threads either when removing the screw from the holder, or when I was trying to screw it back in.
How should I best go about repairing this microscope?
If I acquire a new condenser centering adjustment screw, there's no guarantee that whatever defect or obstruction that is present in the hole that caused the damage to the first screw won't damage a new screw.
Enlarging the hole for a larger diameter adjustment screw might work, but I don't have the capabilities to do that repair.
Acquiring a second stripped-down Zeiss Standard stand and either moving the condenser ring assembly to my scope, or moving all of the good parts from my scope to the replacement stand, seems like the best repair option.
Thoughts?
Fixing a Zeiss Standard Condenser Holder
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Fixing a Zeiss Standard Condenser Holder
Last edited by hoarybat on Tue Sep 16, 2014 1:56 pm, edited 1 time in total.
I know one or two members use a Zeiss Standard, though I wonder if they really are all the same ..
I also wonder what could have damaged your screw.
Can you photograph the screw? At least you won't need a condenser for that
. It would be interesting, to speculate what caused the problem, and also let us compare. Do you know the thread dimensions?
I would think of putting the right thread-cutting tap into the hole to clean it out, though that may not be possible. If not a tap, then a length of brass or steel studding, possibly with filed "teeth". My local toy-aeroplane shop sells studding to very small diameters.
Once the hole is cleaned maybe you could sort out the screw; either with a die, or a steel nut, possibly with a slot cut through one side to make a C shape, etc.
I also wonder what could have damaged your screw.
Can you photograph the screw? At least you won't need a condenser for that
. It would be interesting, to speculate what caused the problem, and also let us compare. Do you know the thread dimensions?I would think of putting the right thread-cutting tap into the hole to clean it out, though that may not be possible. If not a tap, then a length of brass or steel studding, possibly with filed "teeth". My local toy-aeroplane shop sells studding to very small diameters.
Once the hole is cleaned maybe you could sort out the screw; either with a die, or a steel nut, possibly with a slot cut through one side to make a C shape, etc.
Re: Fixing a Zeiss Standard Condenser Holder
With the exception of the Standard WL (with removable condenser carrier common with the large Universal/Photomi) changing the condenser holder is doable but doesn't seem easy at all, at least dismounting the stage holder and remountig it is quite difficult for no experts, I did it with one of my stands to relube it and remounting it was quite painful, likelly your second option (a replacement body) will be easier and with a bit of patience not expensive.hoarybat wrote:If I acquire a new condenser centering adjustment screw, there's no guarantee that whatever defect or obstruction that is present in the hole that caused the damage to the first screw won't damage a new screw
A replacement screw seems difficult to find if it doesn't come from another Zeiss Standard, they are not normal metric screws but have very fine pitch.
Because the screws are steel made and the holder is brass, very likely the holder thread will be also damaged (but you can test it carefully screwing your other bolt).
Pau
Although it is more common for manufacturers to protect the end of those screws with a bushing , or cut them down and harden them, it sounds like the shaft is mushroomed from working against the collar and has chewed the threaded tunnel a bit on the way out.
If the end is mushroomed , file it down. It would be good to get a qualified machinist to measure the thread for you. You might be able to find a tap and die ( likely on ebay) to clean up the threads. and get it working. You will need heavy damping grease to help take up the slack in the thread.
Damping grease is the real stuff for microscopes and is expensive.Nye lubricants makes it , as well as others. It is almost identical to valve and stopcock and o-ring grease. That stuff is cheap . Dow Corning silicone 1 11 O-ring grease is good( ebay again). Don't use regular grease on a microscope. You will lose the smoothness of the controls. Damping grease only.
Maybe the tech. who sold you the scope can cough up a part for you?
worst case scenario----drill and tap for a new larger screw!
If the end is mushroomed , file it down. It would be good to get a qualified machinist to measure the thread for you. You might be able to find a tap and die ( likely on ebay) to clean up the threads. and get it working. You will need heavy damping grease to help take up the slack in the thread.
Damping grease is the real stuff for microscopes and is expensive.Nye lubricants makes it , as well as others. It is almost identical to valve and stopcock and o-ring grease. That stuff is cheap . Dow Corning silicone 1 11 O-ring grease is good( ebay again). Don't use regular grease on a microscope. You will lose the smoothness of the controls. Damping grease only.
Maybe the tech. who sold you the scope can cough up a part for you?
worst case scenario----drill and tap for a new larger screw!
If it ain't broke, don't fix it!
I was able to transfer the working components from my scope to another Zeiss Standard stand, and am up and running again. That was a $50 lesson in not unnecessarily tinkering with old equipment.
The only bugaboo in the replacement Zeiss Standard stand is that the objective turret doesn't turn as sweetly as the older turret -- there's a gumminess to it I don't like. I'm going to leave it alone, however!
I was able to transfer the working components from my scope to another Zeiss Standard stand, and am up and running again. That was a $50 lesson in not unnecessarily tinkering with old equipment.
The only bugaboo in the replacement Zeiss Standard stand is that the objective turret doesn't turn as sweetly as the older turret -- there's a gumminess to it I don't like. I'm going to leave it alone, however!
poor lubricant. leaving it alone, will allow it to continue to get worse and worse over time as the volatiles continue to slowly evaporate.
you don't have to take it apart.
I don't know which model you ended up with but , it likely has a ball race around the perimeter of the nosepiece. Some one on the forum might know for sure. You can usually tell however, by grasping the grooved ring in the semicircle created between your index finger and thumb and rotating the nosepiece. If there is a ballrace, you can almost always feel a slight sense of vibration or rotation of the bearings close to the perimeter, as you turn it.
The gummy grease could be in the ballrace or on the central spindle or both.
Since it for sure has a sleeve bearing at the central spindle , lubricate that first and see if that improves things.
A tiny amount of very light oil will replace the lost volatiles and blend with the existing hardened grease, thinning it a little.
Get a container of 3 in 1 oil or some other light oil such as sewing machine oil, which has a dropper nozzle. Alternately use an eyedropper and any very light oil such as mineral. Even 5 w 20 or 10w 30 motor oil will do.
Remove the eyepieces, invert the microscope in your lap, or nestled into something soft on a bench, so that it is firmly supported and the nosepiece is almost perfectly horizontal. A little tip off horizontal is good. Rotate the nosepiece a little and locate the seam where the nosepiece body moves against the fixing screw, or washer. Drop one drop of oil into this seam on the high side, as you rotate the nosepiece. Continue to rotate the nosepiece. The oil should work it's way into the seam quickly and if the problem is there, you should fairly quickly feel a a slight improvement in the freedom during rotation. After a few minutes of rotation, you should feel a slight change. If there is but it is subtle, try one more drop. If it cures the problem, good.If there is absolutely no change, then the problem is likely elsewhere-----usually in the ballrace. Any oil that hasn't worked into the seam, by the time you consider the job done or not working, should be wiped off with a tissue. Once you determine that there is a ballrace, then you can use the same technique at the seam between the rotating ring and the nosepiece body, if it seems necessary but this time with the microscope standing upright.
99% of the time this cures the problem. Don't go over 2 drops at any one point or even 1 , if you do not sense any reduction in friction because the problem could be elsewhere-----broken spring washer or abnormal physical contact.
Normally, I would recommend removing the objectives at this point and inspecting the back lenses for debris and murk, cleaning them and replacing them in their respective ports but I don't know how comfortable you are with that.
you don't have to take it apart.
I don't know which model you ended up with but , it likely has a ball race around the perimeter of the nosepiece. Some one on the forum might know for sure. You can usually tell however, by grasping the grooved ring in the semicircle created between your index finger and thumb and rotating the nosepiece. If there is a ballrace, you can almost always feel a slight sense of vibration or rotation of the bearings close to the perimeter, as you turn it.
The gummy grease could be in the ballrace or on the central spindle or both.
Since it for sure has a sleeve bearing at the central spindle , lubricate that first and see if that improves things.
A tiny amount of very light oil will replace the lost volatiles and blend with the existing hardened grease, thinning it a little.
Get a container of 3 in 1 oil or some other light oil such as sewing machine oil, which has a dropper nozzle. Alternately use an eyedropper and any very light oil such as mineral. Even 5 w 20 or 10w 30 motor oil will do.
Remove the eyepieces, invert the microscope in your lap, or nestled into something soft on a bench, so that it is firmly supported and the nosepiece is almost perfectly horizontal. A little tip off horizontal is good. Rotate the nosepiece a little and locate the seam where the nosepiece body moves against the fixing screw, or washer. Drop one drop of oil into this seam on the high side, as you rotate the nosepiece. Continue to rotate the nosepiece. The oil should work it's way into the seam quickly and if the problem is there, you should fairly quickly feel a a slight improvement in the freedom during rotation. After a few minutes of rotation, you should feel a slight change. If there is but it is subtle, try one more drop. If it cures the problem, good.If there is absolutely no change, then the problem is likely elsewhere-----usually in the ballrace. Any oil that hasn't worked into the seam, by the time you consider the job done or not working, should be wiped off with a tissue. Once you determine that there is a ballrace, then you can use the same technique at the seam between the rotating ring and the nosepiece body, if it seems necessary but this time with the microscope standing upright.
99% of the time this cures the problem. Don't go over 2 drops at any one point or even 1 , if you do not sense any reduction in friction because the problem could be elsewhere-----broken spring washer or abnormal physical contact.
Normally, I would recommend removing the objectives at this point and inspecting the back lenses for debris and murk, cleaning them and replacing them in their respective ports but I don't know how comfortable you are with that.