Why is my Z axis stalling all the time?

[SWATH]

It has 3 LPH26 male pin headers but no DB25 port for a standard parallel cable.

[mcphill]

Right, you can get the LPH26 to Parallel at Warp9 for $3-5 depending on which you want...

Order

[SWATH]

Alright I switched the Z and Y axis drivers and ran the program again today. This time I heard a bunch of abrupt jolts, sort of like how it sounds when using the MPG set to 10x. I stopped the program prematurely because the Y axis went outside of the travel and hit hard stops. I repositioned to X0Y0Z0 to see which axis was off. The X axis was off 0.0011 and the Z was off 0.0001 but the Y was off almost 2.5 inches. It was the Y axis (using the Z axis driver) that was stalling.

What does this tell me? I think the Z driver is bad or perhaps something upstream from that. What can I test next?

[mcphill]

I would say it is the Z axis driver. Would be a good time to swap it out for a digital driver, I don't think the Mikini would know/care if you didn't use a Mikini driver. All it does is process the steps. You will need to experiment to find out what microstepping Phil is using - he would not tell me what it was or how to change it on the Mikini driver (so he wouldn't be "liable" - ya right). I bought a new digital driver for my 5th axis from Automation Technologies: Stepper Motor Driver Automation Technology Inc

You can use the one step cheaper driver, as we only have 48 volts, for some reason when I was buying I thought we had 66 VDC. So you can save $30 by getting this one: http://www.automationtechnologiesinc...nk-is-included

It is a driver from Keling. I haven't tried it out yet, so can't give feedback, but I liked what I read about it... These are digital drivers (like the new ones on the Tormach) and are supposed to be MUCH smoother than the older ones like on the Mikini. You could spend a good bit less for a cheaper non-digital driver.

[mcphill]

BTW, how did you swap drivers? Did you physically move the driver keeping all Y and Z wiring where it was? If so, it is definitely the driver.

If you "just" swapped the motor output wires between drivers (but kept all the other wiring intact), there could be a chance that the wiring TO the driver could be defective... Could be a bad wire connection in a fitting, or wire running by a noisy part in the machine. If that is what you did, I suggest you physically swap the drivers from one position to the other. If the problem stays on the Y axis, definitely the driver. If when using the Z axis wiring on the Y axis driver you still have issues on the Z, then it is not the driver, but something upstream feeding the driver.

[SWATH]

The drivers are bolted right next to each other in the cabinet, all I did was swap the output wires between the Z and Y drivers on the front panel and the driver outputs to the motors between the Z and Y so all Z output was going to the Y driver controlling the Z motor and all Y output was going to the Z driver controlling the Y motor. I also swapped the X and Z including the cables.

Something like this:

Before the swap

output.....driver......motor
X-----------X---------X PASS

Y-----------Y---------Y PASS

Z-----------Z---------Z FAIL Off about 0.2


After the swap

output.....driver......motor
X-----------X---------X PASS

Y-----------Z---------Y FAIL Off about 2.5

Z-----------Y---------Z PASS


output....driver......motor
X-----------Z---------X FAIL Off about .14

Y-----------Y----------Y PASS

Z-----------X---------Z PASS

So following the logic flow, the data point that is common to the FAIL condition and no PASS conditions is the Z driver.

My stepper power supply is exactly 72v. It seems they resized it. I'll try Pete's driver if it is high enough voltage but if not I'm looking at another driver. Any advantage to Gecko over Keling? Is there anything special that needs to be done with a digital drive?

[mcphill]

Guess I better measure my voltage! The PDF of the schematic you posted states 48V. What'daya know, a mistake (?) on Mikini's documentation... Can't believe it! Glad I got the "oversize" driver now, that's for sure.

Following your technique as posted above, seems it certainly points to the driver. I do seen now a connection in the schematic between the driver and the LCD panel driver... Not sure how that is done or what would happen if you don't use a Mikini part... An unlabeled "pin" on the Mikini driver goes to a pin on the LCD board that corresponds to "N" axis. This may be needed for manual control? Or maybe an enable bit for when in Manual mode? Not sure but you would need to look in to that to ensure a non-Mikini part would work. I may have a chance to mess with my new driver tomorrow - I could try it out on an existing axis on my machine and I could give some initial feedback but I can't guarantee I can get to it...

[slowtwitch]

When i was thinking of changing the mikini drives with digital ones, i to was kinda of confused with mikini's pinout. I did some searching and asked a couple questions. Lucas in Belgium helped out

This is the driver in question....


Here is Lucas's response.....

"
Found this crappy translation but it helps.

57/86 stepper motor driver high subdivision 4.3A voltage: 60VDC-$48.33


Drive has 3 opto signal inputs, it can be either step/dir or CW/CCW control, Free is the enable signal.
There are also 2 outputs for drive faults.

Pulled and edited the relevant text:

CW- CW+ Pulse signal input: Drive response to the rising edge of the pulse signal (internal optocoupler current to flow through) signal is high, the range of 4-5V, low 0-0.5V. For reliable response to the pulse signal, the pulse width should be greater than 2.5ms.

DR/CC- DR / CC+ Direction of the signal / reverse pulse input: Single pulse signal for the direction, in order to ensure motor reliable commutation, the direction of the signal should be the pulse signal is at least 5ms establish.

FREE- FREE+ (6 feet) Off-line signal input: When this signal is active, the drive to force cut off the motor current, the motor is in a free active when this signal is in an invalid state, the normal current of the driver output, the motor is locked.

TIM Pole E-pole Motor relative to the origin of the signal output: This signal output and TIM light synchronization, in some specific occasions for.

O. H Pole E-pole Protection action signal output: This output signal is synchronized with the O.H indicator. Use this signal when the drive protected action can notify the host computer drive is faulty. "

I haven't tried switching over ...since I'm going with all new electronics. But, it seems that the only pins needed are the 2 dr/cc(Dir) and 2 CW(Pulse)pins. I would assume either the top two pins are positive and the bottom two pins being negative.. or their reversed.

[mcphill]

Thanks! You link didn't work for me but I found this:

PD2064M-??????? (Google can pseudo-translate to English for you)

[slowtwitch]

The link has been repaired

[SWATH]

Something else I might mention is that my stepper motors are always blazing hot, I mean you could fry an egg on them. Is that normal?

[SWATH]

Has anyone thought about hybrid closed loop steppers like this one:
High-Torque Stepper Motor, Stepper Motor, Driver, Stepper Motor kit, DC Servo Motor, DC Servo Motor kit, Stepper Motor Power Supply, CNC Router, Spindle, and other Components. Automation Technology Inc

And one from Leadshine:
Hybrid Servo Drives - Leadshine Technology Co., Ltd. (they call them hybrid servos)

[mcphill]

It is normal for steppers to be very hot. The use the most power when stationary, so I power down when I know it will not be in use for a long while. The driver I bought has a setting to drop current by 1/2 when stationary. I think that is to help drop the temps a bit.

[mcphill]

That could be an interesting option for a rotary table...

[SWATH]

So out of curiosity I swapped X and Z drivers and motors but this time I switched the input wire to the drivers instead of the side coming out of the front panel. I ran the 45min program twice and the X did not jump or lose position, nor did the Z. The Y did however even though I didn't even touch it. I didn't really hear it but the Y was off about .005 both runs. Though not catastrophic, still unacceptable. I should get the ESS tomorrow so hopefully I can hook it up without it being a comedy of errors (as is the Mikini theme).

On that note, I picked the silicone out of the ethernet jack on the Mikini computer and it came out fine, but there is a problem. When I plug an ethernet cable into the jack the LED doesn't light up. So I went into the BIOS and the onboard LAN is disabled and it is greyed out so I can't change it to enabled. What do I do now? Flash the BIOS with something else?

[SWATH]

When poking around in the BIOS I found a message that says "Intel Integrated Toolkit has modified this BIOS". So It seems that Mikini in addition to filling the RJ45 connector with silicone they have also used the ITK to disable the LAN and lock it so it cannot be changed. I went ahead and flashed the BIOS with the latest version (1/15/13) but the LAN is still locked and it still says "Intel Integrated Toolkit has modified this BIOS." What a Mikini clusterfluck. The BIOS from Intel has the LAN unlocked and enabled so I don't know why the BIOS flash is not working. Any suggestions?

[SWATH]

When poking around in the BIOS I found a message that says "Intel Integrated Toolkit has modified this BIOS". So It seems that Mikini in addition to filling the RJ45 connector with silicone they have also used the ITK to disable the LAN and lock it so it cannot be changed. I went ahead and flashed the BIOS with the latest version (1/15/13) but the LAN is still locked and it still says "Intel Integrated Toolkit has modified this BIOS." What a Mikini clusterfluck. The BIOS from Intel has the LAN unlocked and enabled so I don't know why the BIOS flash is not working. Any suggestions?

[SWATH]

Well that was another lesson in WTF were they thinking. I spent all last night and most of today trying to unpimp ze auto so to speak to enable the onbord LAN so I could use the ethernet smoothstepper. I pulled out all sorts of mental gymnastics to figure it out but I did. I've unhacked the Mikini modified BIOS and the LAN is now enabled. I installed the smoothstepper and it works on the axis drives great but the spindle is still a little quirky and needs to be sorted out. It took me awhile playing with the PWM settings to get it to turn and now it does but it's backwards and its speed is not quite right so I might rewire the phases going to the motor or if there is a Mach feature that reverses M3 and M4.

I ran the test program twice and all axes were within .0004 at the end. Which is great (I wonder if it could be improved though). I wonder if the ESS will improve the overall precision of the machine. The homing works fine, but I don't think those home switches are accurate beyond about .001 or so. Does anyone have that little macro that pings them twice (the second time very slowly) and is supposed to get within something like 0.0002 repeatability? Thought I saw it on the Tormach forum somewhere.

The only other issue was during a test program when I started rotating the toolpath display and it hard stopped all the motors and gave a "ran out of data" error or something and said the PC was not able to keep up with the ESS demand. What should I set the Mach Kernel too with the ESS? It's on 45khz right now. Anyone have any idea of settings to optimize the ESS with the Mikini? Especially as it pertains to the spindle.

Also Pete, the drivers you have are the same as mine which begs the question...If yours are rated for 60VDC and mine are rated for 60VDC why do I have a 72VDC power supply?

[slowtwitch]

Swath, the drivers will work with your supply...but I think the amps may be capped out at about 4.5 or 4.6 amps. The Mach issue your having may be the kernel speed, but instead of increasing it, lower it to 3500Hz.

My ESS settings with the Mikini spindle were... all my axis were set at 256Khz,.. my spindle ... 32Khz. PWM base Hz is set at 1000. Under ports and pins, my spindle was set at 1000 steps per...Velocity..60...Accleration..5000....G's..12. 95...Step pulse..2..Dir pulse..2

Also double check your Spindle pulleys setup... The Mikini was set at 210 (low speed) 5259 (high speed). To reverse the rotation of the spindle you can switch any two wires of the three going into the motor....I think you can also do it in Mach..under ports and pins...motor outputs..spindle ...check the Dir low active.

[SWATH]

Thanks Pete,
I got the spindle direction sorted out by unchecking the Dir Low active like you said. There are 2 problems now. One is that the commanded speed does not match the actual speed. I can put S1000, Mach says S1000, but the Mikini front panel says 824 or something and then that's the speed it goes to. Sometimes the front panel speed flashes between 2 numbers, like if I command S1000, then the front panel will flash between 824 and 786 like it doesn't quite know what the speed should be. In fact it is not accurate at any speed, it is always much lower than commanded. However when in manual mode the actual speed always matches the commanded speed. I don't know if this is a problem in Mach, the smoothstepper, or more Mikini voodoo. The other problem is that the minimum spindle speed is 500RPM. Not that the motor is even usable at that speed but anything below that either doesn't turn the spindle or gives a PWM signal too low error. The spindle still can only achieve a max speed of around 3300RPM. These are tentative issues as I will completely replace the spindle at some point but I need it to work as best as it can until then.