New Steppers for an old CNC Lathe
by John
My Boxford TCL125 CNC lathe was missing steps in the cross slide, with resulting inaccurate work. Obvious causes, like cutters not sharp, or gibs too tight were excluded. Changes in the stepper motor settings maybe helped a bit, but not enough.
Stuart T suggested replacing the stepper motor, since the machine is a 1985 model, and the steppers look original, and therefore the 32 year old stepper permanent magnets are probably not as strong as they were originally.
We had changed the electronic controls in the lathe 3 or 4 years ago, so it would work with a Windows PC, and Mach3. Mostly I use “Easylathe” for generating the G codes.
Stuart had a spare stepper motor in his junk box, and it was the correct size (Nema 23), but more powerful than original. So I swapped it, and missing steps disappeared. Hooray! A minor problem was that Stuart’s stepper had shafts at both ends, and I was not comfortable about cutting off the unwanted shaft end, and I had decided to change the Z axis stepper also , so I ordered some new stepper motors.
A carton of 3 motors arrived a few days after placing the order. They are made in China, and are nicely finished. Each new motor had 4 wires, whereas the originals had 8 wires each, but reference to the wiring diagrams quickly determined the connections. Total cost for the 3 motors was $AUD90, including postage, and now I have a spare.
A big advantage of the NEMA mounting system is that the motor mounting dimensions are fixed, so swapping motors is simple. More powerful stepper motors are longer, but the dimensions are all available online, and can be checked before ordering.
A simple CNC turning test worked well, so I am hopeful that this problem is fixed.
John,
What specification where the Nematode 23 you used please. Had some luck with the second of the machines I have, was told it didn’t work at all. Plugged in hit reset emergency stop and she all works. This one has the Gemini controller for the spindle.
Cheers
Paul
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Hi Paul, they are Nema 23, 75mm long (slightly longer than the originals) and the code is 23HS30-2804S
I used the same motors for both X and Z axes.
Have also replaced the spindle motor with an AC Servo, and replaced the Gemini controller with the controller which came with the Servo. Not cheap, about $AUD600 inc postage, but it has totally transformed the lathe!
John
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This is awwesome
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Thankyou Kayla!
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