Centre Finding Microscope - is this a defect or feature?

Hello everyone,

I've got an old centre finding microscope, propably for an old german manual mill.

The microscope seems to have a defect, or is it a feature? Inside the optics there is a black, hollow cylinder and it is not fixed in place but moves around. This seems odd to me, but on the other hand I can't make out how this part was mounted fixed in there... I hope some pictures make it clearer. The black, off-center part moves around inside the optics.

Yes, you have to adjust the reticle to the center of your spindle, an easy way to do this is, Have a clean shiny piece of metal held down, then make the smallest mark you can do with a drill on the metal piece.
Install the optical sight, and center the cross hairs on your mark.
Perkins Elmar optical center finder, Moore jigbore

It could be your finder has come loose inside.

There may have been four screws at 90 degree points around the loose part. Look for tapped holes, or maybe the screws are still there, but backed out. The screws could adjust and lock in position a reticle with a crosshair or a series of concentric circles that is visible when looking through the scope.

Larry

Cycles said:

Hello everyone,

I've got an old centre finding microscope, propably for an old german manual mill.

The microscope seems to have a defect, or is it a feature? Inside the optics there is a black, hollow cylinder and it is not fixed in place but moves around. This seems odd to me, but on the other hand I can't make out how this part was mounted fixed in there... I hope some pictures make it clearer. The black, off-center part moves around inside the optics.

View attachment 290490View attachment 290491View attachment 290489

Click to expand...

Maybe some more pictures or a sketch,

Generally for any optical assembly loose tubes rattling around are not normal.

Unfortunately with a lot of optical assemblies , cells , cartridges etc. adhesives and optical cement(s) tend to get used a lot [instead of mechanical clamping and location], especially thread lock type compounds (cyanoacrylate based) and other. Old school incrilak (sp) is carbon black and cellulose nitrate based lacquer...

So it could be the way "they" stuck that cylinder in place (to absorb stray light and block out external light from the sides / light baffle.) was using an adhesive type hack. It could be the instrument took a few spins in the spindle and that black cylinder became dislodged or it got knocked or dropped on the floor. cyanoacrylates can de-polymerize after time especially in humid environments (essentially fall apart to its respective monomers) ~ a glue that becomes unglued to itself.

Maybe it just needs to be glued back into position.

I'm not familiar with this gear, but I agree with cameraman. Some optical adhesive has probably let loose.

Can it be a level of some sort?