Centroid Community CNC Support Forum

• why did you go the servo route for the spindle - do you think this approach is simpler than a VFD? I saw that you've basically set it up with a magnetic clutch - does that mean that you generally use your existing motor at a standard/pre-set speed for regular operations, or have you eventually just gone full servo for the spindle? my lathe has a DC motor already, is it safe to assume i can tap into it for CNC control (rather than needing a VFD) or are there certain criteria it (or the control board) needs to meet?
• do you even need the spindle encoder any more, now that you have the servo control?
• are there any headaches/challenges that you face today, or are there any things you wish you knew before you started?
• what did you do for limit switches - and did you do any gear ratios with the servos or is it all 1:1?

suntravel wrote: ↑Sun Feb 05, 2023 2:39 am Thank you-

I use a servo because it is smaller and better rpm control

C-Axis with clutch because of the lash in the gearbox

Encoder is needed because the gear ratio is not 1:1

Limit switches are NPN on one end, other end soft limit

Gear ratio for axis drive 2:1 with HTD belt

The conversion works like expected.

Uwe

guitarchitect wrote: ↑Sun Aug 20, 2023 9:59 am

So in other words, would you have skipped the clutch and encoder if the lathe didn't have a gearbox and was fully belt-driven?
I'm in the final planning stages of my build and trying to figure out what I should do for the motor. the lathe has a fixed-speed AC motor and handles speed changes via belts, so a servo makes a lot of sense. If I can do both speed and position with one motor it would sure help!

vanadium.f wrote: ↑Thu Sep 28, 2023 11:40 am HI Uwe
what ingenious solutions...

you are a precious source of ideas

What model of electromagnetic clutch did you use?

Fabrizio

johannes wrote: ↑Sat Nov 25, 2023 6:26 pm Hi Uwe,
I am converting a Colchester Triumph 2500 lathe using the AcornSix, and happened to have a 3.8 KW AC Servo that I would love to try out for a spindle motor, driving the spindle direct with a 40mm wide belt.

I understand I should use an input on the AC Servo to switch between speed control and position control, but how did you wire this to AcornSix?

Is it correct to assume that you would run the AC Servo in Speed control mode using -10-0-10V analog outputs from AcornSix, and then use an input on the Servo to switch to Position control/C Axis. And use the Step/Direction outputs from the AcornSix for this.
Or do you use the Step/Direction outputs from the AcornSix only, to drive both Speed and Position mode of the servo?

Kind regards
Johannes