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I have sometimes had a hard time getting the carriage to follow the feed screw -- even with no horn attached. I have even tried turning the half nut around but I see that is not allowed -- the holes are drilled so that the nut only sits flat on the screw with one orientation.

Tonight I seem to have got the tracking working well. But the bar that holds the half nut is not quite at right angles to the screw -- it is off by maybe a degree. Is that normal? Does it matter? I guess following the screw is all that matters.

One final question -- could the half nut be worn out?

Thanks!

I believe this is possible, and also the nut can be reversed. The thread is asymmetric, and in the reverse it won't engage properly. Also read here that problems may be about dirt on the threads, misalignment or the carriage night sliding soft on the flat edge run. Also a drop of oil, both on the cleaned thread and on the flat edge. The pressure of the half night is also important and delicate: too much and it will drag, too loose and it will skip.
All this I've learned from our colleagues; I've never seen one cylinder phonograph in the flesh...

You probably already tried this, but make sure that the threads on both the half nut and feed screw are completely clean, and examine both under magnification to make sure that none of the threads are damaged. I've cleaned both with a soft brush with good results. Also make sure that the carriage rod is well-oiled so that the carriage moves very freely. Also apply oil along the entire length of the feed screw once it is clean, and to the half-nut.

There should be a teeny tiny bit of play in the half nut bar to make it perpendicular to the feed screw. But if the half nut is meshing properly with the feed screw and the carriage is moving as it should then I wouldn't be too concerned with the bar being a tiny bit off of being perfectly perpendicular to the feed screw. It seems pretty unlikely that the half nut threads could be worn to the point of not engaging properly with the feed screw. But anything is possible. I would suggest thoroughly cleaning the half nut threads (if you haven't) and examine under some magnification if you're inclined. There are several different ways to adjust the carriage and half nut for optimal function with the feed screw. Presuming that the feed screw and half nut are in good condition and adjusted properly, the belt is not slipping or too tight, the 2/4 minute clutch and planetary gear assembly are engaging with the threaded feed screw properly it seems like it should work.

A video might help us help you if it's still not working for you.

Doug

Thanks all. It is tracking well now though the carriage does not move easily along the bar. I have never seen this before. I am going to rub 0000 steel wool along the bar (again). Seems the bar suffered some abuse. Other suggestions for improving the bar?

mjbarnes wrote: Fri Mar 07, 2025 8:38 pm Seems the bar suffered some abuse. Other suggestions for improving the bar?

On several occasions I've had excellent results by loosening the carriage rod's set screws and rotating it 90 degrees; sometimes 180 degrees.

Good luck.

George P.

When I am adjusting half-nuts, I loosen up the screws on the spring/half-nut and make sure it is lying there, even as could be, and then I tighten it. They are tricky sometimes, but need to be properly aligned to work right. The spring cannot be bent. Also, my eyes might be tired, but your spring does not look quite straight.

phonogfp wrote: Fri Mar 07, 2025 9:08 pm

mjbarnes wrote: Fri Mar 07, 2025 8:38 pm Seems the bar suffered some abuse. Other suggestions for improving the bar?

On several occasions I've had excellent results by loosening the carriage rod's set screws and rotating it 90 degrees; sometimes 180 degrees.

Good luck.

George P.

George offers a very good suggestion. Also remember that the friction can be the carriage, as well. So be sure to clean or polish it.