How to Repair a Microscope Thread

Microscope repair by Carl Lodstrom.  Carl who is no longer with us was a retired engineer from Sweden who wanted to keep busy.  Carl had brought many of his working tools from his homeland.  I wanted to share this with you as he took this microscope part home to his shop and took photos for me of the repair!

First I had to set up the tube so it was centered. Using an indicator, I got it to better than 1/1000 inch.

The threads were really mushy and it would not even have been possible to force them in. The mating threads were in good condition. It must be a harder material in that part.

Glue would not be strong enough, and the depth and possibly the angle of the tube would be wrong.

You can see that on the right edge is thicker than the tips of the threads further in, where they are quite OK.

As I follow the present threads with the cutting steel I see that the pitch is not 0.75 mm, as I thought, it is 0.5 mm.

Changing gears for to get a 0.50 mm feed.

Here the threads are cut free from the “blob”. Not beautiful, but at least threads all the way out.

The tube now fit the housing with at least five turns, and it felt solid, so this should be a pretty good and strong repair.

Ende Gut, alles Gut!

All the best,

Carl.