[aninventor]

I have a set of Baldor DC servo motors and a set of Siemens DC servomotors - both from about 1980 - both in comparable condition.
I need to choose between the two for a CNC knee mill project. Both sets came off of comparable sized mills to my project.
Any opinions as to quality and reliability and usability of these two sets of servomotors would be appreciated.

[RCaffin]

Both brands are good. Both are 'industrial' rather than model aeroplane toys.
I am running Baldor DC servo motors. A lot of grunt.

Cheers
Roger

[Al_The_Man]

One thing to watch for is the usability of encoders where fitted.
Occasionally Siemens used Heidenhain sinewave encoders instead of the more usable square wave RS485 incremental type.
If no encoders fitted then you need to look for suitable mounting features.
Al.

[James Newton]

Just FYI, and probably not worth mentioning here, but... a neat trick you can do with sine wave encoders is to use a flash A2D converter to read the phases instead of digital. The result is /massive/ resolution. E.g. if you have an encoder with 256 slots and you do an 8 bit A2D, you get 65535 positions per revolution. Of course, those aren't perfect, and you have noise, and speed issues, but it CAN be very nice. Haddington Dynamics does this on their robot arm and manages all the readings, filtering, etc... via FPGA for stunningly fast readout via a low resolution 3D printed encoder.
Haddington Dynamics