columbia 202 tone arm removal from base.

[anchorman]

I've got a 202 with a slightly floppy tone arm that I would like to get adjusted properly. unfortunately when I snug up the little bolt on the front of the arm to the point where it doesn't flop, there is some sort of problem inside the bearing where it doesn't want to turn smoothly anymore. probably old grease or some dirt or something. Any tips on how to pop the arm loose from the pot metal base without breaking anything?

[Phono48]

There is nothing you can do to cure this problem. The socket is made of pot-metal and has distorted over time. It will never go back to being perfectly circular, and therefore the arm will never run smoothly without a certain amount of "floppiness". I would estimate that 90% of 202s in existence today suffer from the same problem. Incidentally, you were very lucky, because any attempt to tighten that nut results in the pot metal shattering!

Barry

[anchorman]

I had the pot metal bracket on a Columbia 100 shatter yesterday as I tried to remove the arm. I’ve started drawing up a replacement part that I can make out of better metal. Maybe I’ll figure out similar for the 202.

So there is no way to remove the arm from the mount? How did they get it and the balls in there in the first place?

[Phono48]

So there is no way to remove the arm from the mount? How did they get it and the balls in there in the first place?

At the time the balls were put in, the gap in the mount was much wider, and the pot metal more pliable than it is now. The arm was inserted into the mount, the ball bearings dropped in, then the bolt was tightened, closing the gap. If you tried to open the gap now to remove the arm, I guarantee the mount will break. The arm will then be easily removed, but the mount broken beyond repair. Better to put up with a bit of sloppiness? Good luck with the 100, I've scrapped four of them because of the broken arm mounts. Because the internal groove that holds the bearings must be perfectly formed, to make anything acceptable is almost impossible. Someone once suggested getting a new base made by 3D printing, but unless you have a perfect one as a pattern, all you'll end up with is a copy of an out of shape original!

Barry

[anchorman]

The better way to make the arm mounts would be to have an angled steel race built into the mount, with a threaded piece that has an angled (preferably hardened steel) race. both angled inward, maybe 30° from horizontal to push the balls towards the groove in the arm. The only issue then is how to make a proper lock nut to keep the upper race from turning in its threads. perhaps a drop or two of loctite would be enough? or make the ring split with a set screw at the split that forces it the ring outwards against female threads of the bracket.

I hope you didn't toss the 100's! they're great little machines, and some day we'll have an easy solution to the arm bearing problem.

[anchorman]

I cleaned and packed the 202 arm with moly-grease, and will resist the urge to open it. I'm also trying to figure out a way to use an off the shelf ball bearing with the columbia 100, perhaps use loctite to secure the inner race to the tone arm, then have some sort of cap over the top of the outer race which gets bolted to the motor board. The only concern is how to seal things properly so that there is not a leak there. "sealed" ball bearings with the rubber lip are not particularly great at swinging from side to side compared to open or "shielded" bearings, but perhaps with the relatively low compliance of the soundbox compared to a modern system, we can also get away with a fair bit more bearing friction. The cap could be made in two pieces, and easily 3-D printed. I need some stuff from my favorite industrial supply, so perhaps I'll get a bearing and try with the 3D printed cap.

[anchorman]

I cleaned the bearings again with solvent, blew everything out with compressed air, added fresh moly grease (with the idea that maybe it will help fill in any imperfections in the bearing race or on the bearings). I then tightened it to the point where there was no more floppiness, but that was too tight for easy movement. In a last ditch effort, I simply spun the arm around over and over in the bearing with the bearing snugged up too tight for ordinary movement. sometimes using a tiny bit of pressure this way and that. I then loosened to the point of floppiness, re-tightened just to where the floppiness went away, and voila! no more chunking and stiffness. All's well that ends well. Now looking for where I put the extra black felt to pad the outside of the horn against the case, need to clean the motor, but otherwise all is good.

I also figure out a hopefully easy and not too expensive way to make a new bearing and housing for the columbia 100. I'll start a thread for that when I get the parts and put it together.

[anchorman]

So there is no way to remove the arm from the mount? How did they get it and the balls in there in the first place?

At the time the balls were put in, the gap in the mount was much wider, and the pot metal more pliable than it is now. The arm was inserted into the mount, the ball bearings dropped in, then the bolt was tightened, closing the gap. If you tried to open the gap now to remove the arm, I guarantee the mount will break. The arm will then be easily removed, but the mount broken beyond repair. Better to put up with a bit of sloppiness? Good luck with the 100, I've scrapped four of them because of the broken arm mounts. Because the internal groove that holds the bearings must be perfectly formed, to make anything acceptable is almost impossible. Someone once suggested getting a new base made by 3D printing, but unless you have a perfect one as a pattern, all you'll end up with is a copy of an out of shape original!

Barry

Thanks for convincing me not to try to take it apart further. I put the motor back together tonight and listened to a few records, and it's really nice. Still no issues with the arm. It is no longer floppy, and still able to move with relative ease, and no "chunking" as it turns (as though it were too tight). I got some appropriately sized ball bearings ordered to make the columbia 100 replacement bracket. I bought the cheapest I could get on eBay, so not holding out a ton of hope for them, but hopefully they turn smoothly enough at slow speed that they will work for the tone arm. The bracket design is relatively simple, and will be easy enough to 3D print, and would be easy enough to machine from aluminum too. It will be a drop in replacement if all goes well, needing at most to use longer screws.

[Phono48]

I obviously don't know what your new base will look like, but having tried to make something similar, a word of warning. Don't make the new base any higher than the existing one, or the arm will be too high for you to shut the lid!

Barry

[anchorman]

I obviously don't know what your new base will look like, but having tried to make something similar, a word of warning. Don't make the new base any higher than the existing one, or the arm will be too high for you to shut the lid!

Barry

thanks! I'm planning to keep the overall heigh the same as it was originally, or very close to it.