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Hi
I have just got a Columbia AT and have a question for you. On the bedplate there are two holes with bolts in them which do absolutely nothing ! They are near two of the bigger bolts which actually attach the bedplate to the works and they are threaded, have smaller bolts in them but do not attach to anything underneath - what are they for ? Also at the back is what appears to be some sort of threaded adjuster which screws against the works underneath - what does it do ?(see photo 1)
Many thanks
Andrew

The bigger thumb screw is the speed control knob.

Larry

Thanks Larry but it's not that one I mean - there is a smaller adjuster at the back as well. I still don't know what the spare bolts are for ?
Andrew

Andrew,

Early Columbia AT's retained the screw attachment points for a Columbia Crescent listening tube rail. These are simply two screws, in the locations your have documented in your pictures. They secure the tangs on the Crescent Reservoir to the machine. The AT was introduced in 1898 and the Crescent Reservoir was still being advertised at that time. As well, the first Columbia AT's were produced with the motor attached to the metal bedplate the same as the earlier introduced A's - directly with screws and rubber gaskets. However, sometime in the first year(s) of production Columbia changed the AT motor mount to what you have - where the motor is attached on hinges and can be adjusted with a screw behind the upper casting (the tall one shown in your first picture). This arrangement allowed for better access to the motor, as well as belt tensioning. All of the earliest AT's I've seen (with the motor attached as in the A model) retain the attachment points for the Columbia Crescent Reservoir. All of the later AT's I've seen (with the hinged motor attachment points) have not had the attachment points. The screws you have documented in your pictures are clearly those attachment points for a Columbia Crescent Reservoir listening tube rail. I would bet your serial number is on the low-side of production and your machine represents a transition between the earlier and later AT motor configuration.

As a reference, I have attached the ad for a Columbia Crescent Reservoir Listening Tube rail from an 1898 Columbia catalog. In the ad, the rail is attached to a Columbia model A.

If you PM me your address I will gladly send you an informative 4 page instruction catalog for the Columbia AT faithfully produced from an original.

Shawn

Shawn wrote:Andrew,

Early Columbia AT's retained the screw attachment points for a Columbia Crescent listening tube rail. These are simply two screws, in the locations your have documented in your pictures. They secure the tangs on the Crescent Reservoir to the machine. The AT was introduced in 1898 and the Crescent Reservoir was still being advertised at that time. As well, the first Columbia AT's were produced with the motor attached to the metal bedplate the same as the earlier introduced A's - directly with screws and rubber gaskets. However, sometime in the first year(s) of production Columbia changed the AT motor mount to what you have - where the motor is attached on hinges and can be adjusted with a screw behind the upper casting (the tall one shown in your first picture). This arrangement allowed for better access to the motor, as well as belt tensioning. All of the earliest AT's I've seen (with the motor attached as in the A model) retain the attachment points for the Columbia Crescent Reservoir. All of the later AT's I've seen (with the hinged motor attachment points) have not had the attachment points. The screws you have documented in your pictures are clearly those attachment points for a Columbia Crescent Reservoir listening tube rail. I would bet your serial number is on the low-side of production and your machine represents a transition between the earlier and later AT motor configuration.

As a reference, I have attached the ad for a Columbia Crescent Reservoir Listening Tube rail from an 1898 Columbia catalog. In the ad, the rail is attached to a Columbia model A.

If you PM me your address I will gladly send you an informative 4 page instruction catalog for the Columbia AT faithfully produced from an original.

Shawn

Catalog 7 H.jpg

That is rather odd, since my AT (SN 214331) has neither the crescent rail attachment points nor the hinged motor attachment…

Bill

Gramtastic wrote:Hi
I have just got a Columbia AT and have a question for you. On the bedplate there are two holes with bolts in them which do absolutely nothing ! They are near two of the bigger bolts which actually attach the bedplate to the works and they are threaded, have smaller bolts in them but do not attach to anything underneath - what are they for ? Also at the back is what appears to be some sort of threaded adjuster which screws against the works underneath - what does it do ?(see photo 1)
Many thanks
Andrew

Andrew: what is the serial number on your AT?

Bill

Hi Bill,

The serial number is 269084 and mine does a hinged motor.
Cheers
Andrew

Guys, great additions.

As with all companies and many different phonographs, there were a good number of production variations. My comments were based on observations of a limited set of data - machines and company documentation and were intended to be a guide rather than the rule.

Shawn