[allengambrell]

I have just tried my first bench test with the the 878oz Nema 34 kit from Longs Motor. This is for a cncrp style build, and I am new at this and my first cnc.

I got them to turn, but I cannot seem to get them to run smoothly even below 100ipm. I have them wired like the wiring instructions said, which would be the second diagram on the motor spec sheet.

It came with 2 48vdc power supplies, I have the x and a (slaved) wired to one, and the y and z wired to another.

I am trying to figure out what setting on the drivers to set the output current toand the microstep. They came set 7.8a and 51200 microstep. I changed the microstep to 2000 and current to 6.4.

The motors seem to jump and stop spinning. I set them at around 100ipm in mach and the y and z seem to be getting hot (even though I was not joging them for test), but the x and a are not.

I searched around and saw other threads on these, but it seems like noone ever replys with the settings they got to work.

[meo_udon]

I was used same set with you. I'm set 2.0A and 800 microstep. Work great no step loss. If you set more current. Motor is jerk not smooth. You should try from minimum current.

[ger21]

Looks like you have them wired bipolar series, so they should be set to 1.4 amps.
I'd set the microsteps to 1600 steps/rev (1/8 stepping).

You'll get much better performance wiring them parallel, and using 2.8 amps.
But the reality is those motors are a poor match for those drives and power supply, and would need about 130V for best performance. With what you have, you'll only get about 1/3 of what they are capable of.

[allengambrell]

I tried one parallel at 2.8 amp 1600 microstep and it seemed smoother. Looks like parallel is the way to go thanks.

By not a good match what do you mean, I will stay with them for starters, but may replace them later. Would it be better to change the power and controllers for higher voltage ones or the motors themselves. I have not seen many controlers that do 130v like you suggest. PS how did you come by that number?

[ger21]

Gecko has a formula for the voltage that gives maximum motor performance. 32 xsq rt(inductance). Speed is proportional to voltage, so if you are only supplying 1/3 of this maximum voltage, the motor will spin at about 1/3 of what's it's capable of.

For CNC use, you want motors with very low inductance, typically 2-3mH. This will give maximum performance at much lower voltages. The downside, is that these motors typically require much higher current, sometimes in the 5-7 amp range, which will require a power supply capable of supplying much higher current.

In most cases, 800+ oz-in motors are much bigger than you should need. You'll also find that as motors get bigger, their inductance goes up, and their top speed is lower. For this reason, 600oz motors will usually outperform large motors.

As long as your drives can supply enough current, smaller motors should give much better high speed performance than larger ones.

But, if the machine is geared to keep the larger motors spinning slower, they may work OK for your particular application.

[allengambrell]

Running into a couple of issues with the motor testing in mach3

I can run mach 3 and the all 4 of the motors will jog, but if I hold the jog key down they will stop moving at random times. Sometimes they will start back but others they will stall and just sit there. I think the stalling my be more motor tuning, but what is causing them to stop when I am continuing to hold the key down?

I have run drivertest and it says pulsing too fast, but once in a while it pops up excellent then goes back to pulsing too fast. I have tried all the options for the kernel speed in the drivertest and they all say pulsing too fast while the number at the top of the screen is around the set kernal rate. I can barely see the little blips on the graph.

This is a computer with a fresh install of windows 7 and mach 3 is the only program installed. I do not even have a network card hooked to it.

Is the pulsing too fast causing the motors to stop turning or is that something else?

[H500]

Are you using a wireless keyboard? Stepper drives and wiring can generate a lot of interference. It can block the keyboard.

[ger21]

When they stop moving, are they still making noise? If so, then they are stalling. Motors can stall due to resonance very easy if just running them on a table. Especially larger ones like yours.

What are your acceleration and velocity setting in motor tuning?

The pulsing too fast message isn't a good thing? Depending on the particular PC, there are probably several things that can cause that.
Ideally, you should make sure all power saving features are disabled.
In addition, make sure every bit of hardware you're not using is disabled in the BIOS, including ACPI. In some cases, this should be done before installing Windows, and may require a re-install.

[allengambrell]

Ok tonight I changed the power setting in the computer, to make sure it will not go to sleep. After I did this I just ran driver test again and it said excellent! Wanted to check the motors before I tried the bois changes so I loaded mach3 to test.
But now None of the motors are turning when I jog!!!
I have changed nothing on the wiring and the power supply lights and driver lights are on, but no moverment. The DRO for all the axis move in mach, the the motors to not move or make any noise. They do torqe up when I apply power but that is it.

I thought it might be the bob, but the estop button is working!

Any help? I am Lost now.

[ger21]

What are your pulse width settings in motor tuning? Try setting it to 10-15.

[allengambrell]

I changed the pulse to 15 and they are working great now. I can get them up to 600ipm on the test bench with no studder. That was as high as mach 3 would go, I guess if I want to test faster I would have to increase the feanqency.