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Re: Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

Posted: Thu Nov 27, 2025 9:29 pm
by Robert
Thanksgiving.
I'm sitting on the sofa still feeling stuffed :) I'm a brit but SWMBO / XYL is a California girl.
My main lathe is an early Myford ML7. I'm only the 4th owner as far as I can tell. I've replaced the old single phase motor with a 6 pole 3 phase motor and variable frequency drive (VFD). The single phase motors are rough and noisey due to torque ripple and don't like frequent starting and stopping. That is why the Super & had a clutch. Adding the VFD makes the lathe much quieter, gives better surface finish and doesn't mind stopping and starting. Next modification is an electronic lead screw (ELS). This is stepper drive for the carriage thet is syncronised to the spindle. It allows you to cut any pitch thread without a gearbox or manually ghanging gear wheels.
Probably of more use for electronics is my small vertical mill. It's lightweight so would not be great for hacking out lumps of steel. However it has a relatively high speed spindle and long X travel on the table. The high speed spindle is good for running small cutters foe light alloy or plastic. It makes tasks you normally hate like cutting a hole in a panel for a meter or display soo easy. 8-)
I don't want to go down the CNC route as A. I don't do enough and B. I don't use CAD.

Robert.

Re: Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

Posted: Thu Nov 27, 2025 10:26 pm
by EC8010
Robert, thank you so much for your post. I was well aware of the difference in torque ripple between single and three phase motors and was wondering whether my heavily tweaked Hobbymat lathe (bought new) would benefit from a three-phase motor, so I bought it a three-phase motor. Annoyingly, my static three-phase converter (used for the Colchester Bantam) won't go as low as 250W. Whoops! Internet searches didn't come up with anything useful regarding VFD drive and ripple. Any other comments you might have regarding VFDs and motors would be very welcome.

I'm happy to swap change wheels (Hobbymat) or pull levers (Bantam) to cut threads, but I can see the attraction of an electronic leadscrew. I have recently learned that it is a stupid idea to think that you can cut internal threads in 306 grade stainless steel; horrible stuff.

I suspect I am fully with you on your A and B points.