[ny_prototyp]

I have read here now and then since many years, but this is my first post.

Background:
During the years I have bought stuff for a CNC machine build, or actually several, when I have found them cheap.
What I will build now is a router-looking, moving gantry, mill for aluminum. It will be built out of a granite surface plate and some additional granite and aluminum.
I have both ball screws with 5 mm lead, 20 mm lead, and a couple with 2 mm lead. I think the ones I will use for this project will be 5mm lead.

A couple of years ago I bought these closed loop steppers:

34SSM1460-EC1000
Mine are Long Motors, but ACT Motor seems to have the same motor.
- Model No: 34SSM1460-EC1000
- Motor Type: 34 Closed-Loop Stepper motor
- Step Angel: 1.8°
- Rate Voltage: 2.4(V)
- Rate Current: 6.0(A)
- Phase Resistance: 0.4±10%(ohms)
- Phase Inductance: 4.2±20%(mH)
- Holding Torque: 9(N.m.Min)
- Detent Torque: 12.5(N.cm Max)
- Rotor Inertia: 2300(g.cm2)
- Motor Weight: 4(kg)

With these controllers:
HBS86H
When I look at different sources, different input voltages ranges are mentioned:
36-100VDC/18-80VAC
30-100VDC/20-70VAC
And, printed on the controller, there is actually no mentioning of DC:
24-80VAC

I know now that these may have not been the best buy, but now I own them, so would like to use them if they are not totaly wrong

So, my question so far is, what is the maximum voltage power-supply I should use? I have read statements before as "getting as close as possible to the upper Voltage limit of the contrloller is desired, for better motor performance.".
So, I kind of did. I bought two plain toroidal AC transformers with the following specs:
625VA
2*68VAC

I will use the windings in paralell and also connect the two transformers in paralell to get:
625VA*2 = 1250VA

4 motors*6A*0,7: 4*6*0,7=16,8A

1250/68=18,38A, so everything looks good to me so far. Any comments on my post are appreciated, even though my main question arrised when I now have read this in the forum and on Gecko:
"To figure out what the maximum power supply voltage should be, use the following formula with the motor’s inductance in millihenries (mH) used for the L value" ... "This will ensure that your motors will not overheat due to the voltage being too high."

32 *sqroot(L) = VMAX
32*sqroot(4,2)
32*2,049=65,568V

And I now instead will be feading the motors with 68*1,44=97,92V.
So, what is right? Highest voltage the controller can handle, or 32*sqroot(L) of the stepper?

By the way, I also have these older NEMA23 motors:
VEXTA PK266-02A
2-Phase
Holding Torque: Bipolar (Series) 166 oz-in, Unipolar 127 oz-in (0,9Nm)
Connection Type: Bipolar (Series) Unipolar
Current per Phase (A/phase): 1.4 [Bipolar (Series)] 2 [Unipolar]
Voltage (VDC): 5 [Bipolar (Series)], 3.6 [Unipolar]
Resistance (?/phase): 3.6 [Bipolar (Series)], 1.8 [Unipolar]
Inductance (mH/phase): 10 [Bipolar (Series)], 2.5 [Unipolar]
Step Angle 1.8 °
Rotor Inertia (oz-in2) 1.64 oz-in2 (g-cm2: 300)

But think that they are way too weak?

Best Regards

[peteeng]

Hi NY - Electronics is not my strong point but I have researched the Gecko eqn and can't find how it is derived. Many systems use much higher voltages then that eqn recommends. The N34 motors have high inductance and inertia so use the highest driving voltages possible from the drivers to overcome the back emf generated as the motor speeds up. Peter

[joeavaerage]

Hi,

32 *sqroot(L) = VMAX
32*sqroot(4,2)
32*2,049=65,568V

This is a rule of thumb that Gecko came up with, no idea what they based it on. There is no 'maximum' for a stepper, or at least until it starts to arc out inside. The rule is use the highest voltage drivers
and power supply you can get. The higher, the faster they will go without losing steps.

I had 5 phase Vexta steppers on my first mini-mill. They had direct off-line drivers that delivered a little over 150VDC to the steppers.......they flew. I had them tuned for 2400rpm but could in fact get them to
3000rpm. They had a 10:1 low lash (<2 arc min) planetary gearbox, so they had plenty of torque. The real takeaway is the the high input voltage allows high speed operation.

Craig

- - - Updated - - -

Hi,

32 *sqroot(L) = VMAX
32*sqroot(4,2)
32*2,049=65,568V

This is a rule of thumb that Gecko came up with, no idea what they based it on. There is no 'maximum' for a stepper, or at least until it starts to arc out inside. The rule is use the highest voltage drivers
and power supply you can get. The higher, the faster they will go without losing steps.

I had 5 phase Vexta steppers on my first mini-mill. They had direct off-line drivers that delivered a little over 150VDC to the steppers.......they flew. I had them tuned for 2400rpm but could in fact get them to
3000rpm. They had a 10:1 low lash (<2 arc min) planetary gearbox, so they had plenty of torque. The real takeaway is the the high input voltage allows high speed operation.

Craig

[ny_prototyp]

Thank you both peteeng and Craig! Answers from you means a lot, especially since I know that you are very active here, and if people would have problems from too high voltage, you would know!
I will use the transformers I have.

Any other comments on my calculations or other? I will of course also appreciate answers from others that are not that experienced as well