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Hi -

I am trying to repair a Columbia AT. Whenever the horn is on, the feed screw makes a clicking sound and the carriage does not advance. When the horn is off, the carriage advances properly for the most part. I am using the proper small lightweight Columbia horn. I have fixed this sort of problem in Edison machines by adjusting the half nut so that it maintains the proper tightness against the feed screw. But I have never worked on a Columbia cylinder machine, and I do not know how to adjust the machine to fix this sort of problem. I've lubricated the feed screw and carriage rod and the carriage moves smoothly, so I do not think that lubrication is the problem. Suggestions?

Thanks!

The Columbia feedscrew uses a buttress thread, so if the half nut has been removed and installed backwards (easily done if you're not paying close attention), the problem you describe will occur. Try removing the half nut and reversing it.

Good luck!

George P.

Thanks, George.

I can see that the feed screw is down below the bed plate, and I assume that that the half nut feeds into it from the lower end of the carriage. I likewise assume that the carriage rod needs to come off and the carriage removed in order to get to the half nut. I removed the lift assembly no problem, but I can't figure out how to get the carriage rod off. I've tried loosening the one screw on the left that I see that might hold it in, but it won't slide out to the left. If is slides out to the right, then I would assume that the gear on the left would need to come off. I'll probably be able to figure out how it all goes together AFTER I get it apart!

Thanks again - Mike

Mike,

Yes, the carriage tube slide to the left (you don't remove the gear), but remove the screw before attempting this. The feedscrew isn't below the bedplate, but inside the carriage sleeve. You'll be able to move the carriage sleeve only a few inches with the carriage in place. To remove the carriage from the sleeve, follow this procedure, as illustrated on an earlier AT (the process is the same):

viewtopic.php?f=2&t=47942&p=283875&hili ... ut#p283875

Good luck - -

George P.