Stepper Squeal/Whine at higher voltage ... So close, but yet so far

[Johnsnd]

Hello all,
I am so close to finishing my cnc build, I can just taste it….

Here is my problem statement:
The stepper motors have a high pitch squeal when not moving, and when directed to move they barely do with a clicking sound.

Back-story:
I have been working on this build for about a year now. The power supply that I had was a switching 24V 12.5A power supply. When I was using this power supply to move the three axis they would move but only at low speeds and with no resistance. (< 60ipm) Even then they would occasionally stall. So I purchased another one of the same supplies and hooked them up in series. As shown here. Now I get the squeal/whine and no movement. If I scale down the voltage the whine goes away but still no movement. Any ideas what could be the problem? Thanks so much for your help. I have the machine completely built and I am just aching to see it work.

System Setup:
X-axis = KL23H2100-30-4BM
Y-axis = KL23H2100-30-4BM
Z-axis = 260 OzIn 4-Wire Stepper Motor
Driver = 55V 3A PicStep
Machine = 5’x3’x3’ Belt driven X & Y. with ball screw for Z
SW = 2.2Ghz, 2GB ram, Mach3

[Johnsnd]

I have been searching the web and cnczone but no luck such far. Some of my ideas include:
Cable to motors is too long. (1-7 meter cables)
Capacitor values could be slightly off. (I used the closest values I had)
Motors are enabled before first step signal is sent.

I am kind of grasping at straws at this point. Any ideas or suggestions would be greatly appreciated

[RomanLini]

So what happens when you go back to using just one supply?

[Johnsnd]

When i go back to one supply it works (well moves with some stalling) and as I scale back the voltage it stops making that awful squeal. I am going to try lowering the voltage of the 2 power supplies as low as they will go and see if it works ...

[Johnsnd]

Well when i adjust the two power supplies as low as they will go i can get it down to 36V. At 36 volts the y-axis and z-axis seem to work fine but the x-axis would continuously stall. I am headed out now to get better capacitors. I'll let you know if that solves it.

[Johnsnd]

Now I get nothing ... after changing out all the capacitor values to the exact one that picstep calls for I get zero movement at any voltage. I hear noise only when Mach3 is directing a movement. Anyone have any suggestions what so ever??
Thanks in advance

[RomanLini]

Sorry Johnsnd, you need to provide more information.

Which cap did you change, and why?

Also you need to keep the total PSU voltage within the right range for the driver you are using.

And there can be another issue if you use 2 PSUs in series and if one or both are SMPS type they can fight each other and cause a high speed oscillation which you might hear as squealing, although your squealing might be from another cause.

[eSilviu]

Originally Posted by Johnsnd Hello all, I am so close to finishing my cnc build, I can just taste it…. Here is my problem statement: The stepper motors have a high pitch squeal when not moving, and when directed to move they barely do with a clicking sound. Back-story: I have been working on this build for about a year now. The power supply that I had was a switching 24V 12.5A power supply. When I was using this power supply to move the three axis they would move but only at low speeds and with no resistance. (< 60ipm) Even then they would occasionally stall. So I purchased another one of the same supplies and hooked them up in series. As shown here. Now I get the squeal/whine and no movement. If I scale down the voltage the whine goes away but still no movement. Any ideas what could be the problem? Thanks so much for your help. I have the machine completely built and I am just aching to see it work. System Setup: X-axis = KL23H2100-30-4BM Y-axis = KL23H2100-30-4BM Z-axis = 260 OzIn 4-Wire Stepper Motor Driver = 55V 3A PicStep Machine = 5’x3’x3’ Belt driven X & Y. with ball screw for Z SW = 2.2Ghz, 2GB ram, Mach3

Driver is build at home?
What's the value of TBA? (R2 and R4 in schematic)

[Johnsnd]

@eSilviu
Yes this is a home build of the Picstep from Alan Garfield. The Current value of the resistors I am using to limit the current is 10K. I had 6.8k but I thought it was safer to use higher resistors, at least until I am sure it is working.

@RomanLini
I changed all of the capacitors out because I wasnt sure of the values of them. My multimeter doesn't have a capacitor setting and I knew that some of the caps were wrong values. I wasnt sure how close they had to be, but now they are exact.
In regards to the total PSU voltage, I agree!! The picsteps are rated at 55V and I am using 48V but I did learn the hard way that the voltage regulator (for the 5V) couldnt hadle that. Also both of the PSU are switching power supplies.

I am hoping that my problem was the blown voltage regulator but I will find out tonight. Deffinatly a learning experience ... Thanks for your help. I'll let you know soon.

[vanjast]

SMPSs usually rely on a voltage feedback for proper voltage control, and max current cutoff feedback. Connecting them in series is most probably messing up this feedback, and causing one or both to oscillate (the noise) into and out of overload condition (switching on and off).

Rather use a single 'larger' SMPS that can handle the power requirements.

[vanjast]

Originally Posted by Johnsnd @eSilviu I am hoping that my problem was the blown voltage regulator

You should be able to smell this... it stinks when cooked