The Talking Machine Forum — For All Antique Phonographs & Recordings

Very nice to see the final product. They are stunning!

Do you mind sharing how the bearings are sealed air tight? I’ve been curious how this was done on these machines. In modern times one can buy bearings with rubber seals, but you run into the problem that most times these are not able to move freely enough to serve as a good tone arm bearing.

In both photos you will see (part of) the shoulder at the bottom of the bore in the tonearm bearing casing. The spigot screwed onto the end of the tonearm (bottom left, second photo) is a close but free-running fit into the bore of the tonearm bearing casing which is carefully, but lightly, greased. The internal diameter of the shoulder is identical to the internal diameter of the screw-on spigot to allow seamless audio transfer. When everything is assembled there is a small clearance (less than ten thousandths of an inch) between the end of the spigot and the start of the shoulder. This very small gap is easily filled with grease so that no air can enter or escape.

The bearing (ball-race) itself fits onto the register just above the threaded section of the spigot, thus there is also a good distance of further grease filled structure before the final gap is encountered. The bearing itself is not sealed and is best operated with either very light grease or oil to keep friction to an absolute minimum.

Incidentally, you may have seen (in the second photo) that some of the toneam sand castings contained small elements of pitting which necessitated thick copper plating to eliminate, followed by careful polishing before the final nickel coating.

Very nice! Thanks for the photos. I had it in my head somehow that these used a more modern type of ball bearing, rather than loose balls. Beautiful work!

Many thanks and there are not loose balls but---ball-race.

I was thinking originally more something like this, but with no seals. Does the ball race type of bearing come with the hardened steel races in addition to the balls mounted in the bronze/brass/copper cage that keep the bearings balls separated?

I don’t think I’ve ever laid my hands on one like you have, and am curious now how they secure the balls in the cage/separator, or if they’re able to be easily removed from it, when the bearing is apart. There’s a lot of interesting technology that gets lost when we come up with new designs for parts.

anchorman wrote: Tue Jan 24, 2023 2:21 pm Does the ball race type of bearing come with the hardened steel races in addition to the balls mounted in the bronze/brass/copper cage that keep the bearings balls separated?

Yes. Exactly the same---standard unsealed ball-race without grease retainer.

Ok, I am seeing it now! It’s hard to see the inner race there with the bottom part of the arm attached.

Yes, sorry, the LED lights made the contrast a little difficult to see. I am afraid I do not now have a loose bearing to photograph.

Graham,hi!
What is the internal diameter of the tube at the inlet and outlet of the tonearm.