Columbia AT take apart

[ts_13]

The tube that slides on the feed screw is seized up on this columbia AT. Crazy question, but how do you take the tube that holds the reproducer off of the feed screw? I have the feed screw lose and moving but that part will not slide off. It catches on the last part of the feed screw. What am I missing?

[JerryVan]

"...how do you take the mandrel off of the feed screw?"

The mandrel is where the record goes. What is it you want to remove? The carriage, or the tube that fits over the feed screw?

[ts_13]

"...how do you take the mandrel off of the feed screw?"

The mandrel is where the record goes. What is it you want to remove? The carriage, or the tube that fits over the feed screw?

Crap! Im sorry you are right, I was wrestling kids while typing on my phone. Not the mandrel, the tube that fits over the feed screw and holds the reproducer.

[Lucius1958]

"...how do you take the mandrel off of the feed screw?"

The mandrel is where the record goes. What is it you want to remove? The carriage, or the tube that fits over the feed screw?

Crap! Im sorry you are right, I was wrestling kids while typing on my phone. Not the mandrel, the tube that fits over the feed screw and holds the reproducer.

You need to push the half nut down with a screwdriver, or some small wedge, so it doesn't catch on the feed screw.

- Bill

[Curt A]

I can't remember exactly, without looking at mine... but I have disassembled several of these on previous projects. I think there is a set screw in the bedplate casting that the feedscrew and cover run through - probably one on each end of the bedplate that needs to be removed. Also, the carriage has to be disengaged (allowing it to move freely from side to side, with the lever on the front of the carriage) from the feedscrew before it can be removed. As I remember, it was not a hard task to remove the feedscrew and cover once they were released from the casting... I can't look at the machines I have right now, but if you are still having problems, I can look tomorrow if that helps... Let me know.

[Curt A]

"It catches on the last part of the feed screw. What am I missing?"
How about a pic of what seems to be catching?

[ts_13]

It is disengaged from the feed screw. But it will not slide out, it is catching on something that I cannot see. I'm sure it's something stupid I am missing.

[Curt A]

It looks like it is stopping inside the carriage. Try lifting the lever up on the front of the carriage to release it from the feedscrew, or as previously suggested try prying the half nut up and off of the feedscrew to disengage it...

In your video, the carriage is locked in position and is not moving from side to side...

[fran604g]

It is disengaged from the feed screw. But it will not slide out, it is catching on something that I cannot see. I'm sure it's something stupid I am missing.

2 "things":

#1: Take your time. Be very careful with your carriage because it's made of cast "pot metal" so it may be swollen, brittle and/or cracked. Its bore has probably swollen, decreased in diameter and is likely getting hung up on the end of the "tube" (called a trunnion) - which (#2:) could be slightly flared, or has a burr from the stanchion set screw.

The tolerance between the carriage on the trunnion were very close when manufactured. Examine the trunnion at the end for any burrs or flaring and carefully remove any burrs, dents, etc., with a jewelers file and/or fine sandpaper/emery cloth. Check frequently by trying to slide the carriage off the trunnion. You probably won't need to remove much material, and be careful to remove only that material which will be concealed when the trunnion is back in positon in its stanchion. You don't want file marks to be visible once everything is reinstalled, if possible.

DO NOT force the carriage, because it's cast pot metal it can be brittle and/or have hair-line cracks that will cause it to shatter, crumble or break apart.

Best,
Fran

[Curt A]

Fran's advice is good, because if that carriage breaks, there aren't any replacements. Jean Paul Agnard, in Canada, used to make brass replacements but he is no longer doing that.

Someone should take up that project of manufacturing replacement carriage tubes... I think Jean Paul used brass tubing and cut grooves on each end and drilled holes like the originals...