Messages

71

Mach4 General Discussion / Re: Gcode mishaps

« on: April 01, 2016, 10:48:34 PM »

First, please confirm that you are running Mach4.  And what version of Mach4 are you running (go to Help->About)?  I ask only because I see other posts from you in March that mention Mach3. 

Second - what motion device/plug-in are you using?  Darwin parallel port?  Ethernet SmoothStepper? PMDX SmartBOB? PoKeys?  Something else?

"false estop" - when this happens are there any messages in the status line in the lower left of the Mach4 screen? Can you click on the "History" button and see any messages there?

Bob

72

Mach4 General Discussion / Re: Mach4 carving backwards

« on: March 29, 2016, 10:21:07 PM »

My X axis is made up of two motors slaved in Mach4. Motor 0 and Motor 3. I set both of these motors to reverse and restarted MAch4 and nothing happened they moved in the same direction as before.

Then my guess is that you are not using a PMDX-SmartBOB as your motion device (EDIT: or you are but something is wrong)  [EDIT If you are not using a PMDX device...] Look in your motion device's plugin configuration and see if there are settings for motor direction there.  Go to the Mach4 "Configure" menu and select "Plugins..." and then click on the name of your motion device (or on older versions of Mach4, click on the "Configure" button next to your motion device).

If you tell us which motion device you have (for example, Darwin parallel port, Ethernet SmoothStepper, PoKeys, etc.), someone here might chime in with specific suggestions.  And while you're at it, which version of Mach4 and which plug-in version you are running.

Bob

73

Mach4 General Discussion / Re: Mach4 carving backwards

« on: March 29, 2016, 10:14:19 AM »

Is the "E" letter carved backwards (i.e. open to the left)?  Or it it facing the correct direction but the word has the letters in the opposite order?

Do all of your axes jog the proper direction (i.e. pressing X+ moves the X axis in the positive direction, etc.)?

To reverse a motor, go to the Mach4 "Configure" menu and select "Mach...".  Then click on the "Motors" tab.  Click on the motor name in the upper right to display the tuning parameters below (which motor depends on how you have them mapped to X,Y,Z).  There is a checkbox for "Reversed".  Change that and then click on "Apply".

Bob

74

Mach4 General Discussion / Re: Trying to tune my motors

« on: March 27, 2016, 09:41:37 PM »

Get your steps/inch (or steps/mm) correct before you try to fine-tune your acceleration and max velocity.  The easy do-it-yourself way to determine the actual steps/whatever-units-you-are-using is:

(1) Calculate the hypothetical steps/units based on microstepping mode of your stepper driver and any belt/gear/thread-per-inch ratios of the drive train.  For the sake of this example, say that comes out to 2000 steps/inch.

(2) Manually jog an axis to a convenient starting point (near one end of travel).

(3) Click on the "Zero X" button (or "Zero Y" or whatever axis you are using) to zero the DRO

(4) Using MDI mode, move that axis some nice, known distance.  For example, move the axis 5 inches with "G0 X5".
**WARNING** This presumes that your max velocity and accel settings are realistic enough that the motors won't "cog" or loose steps during this motion.  To be safe,  you can set the accel and max velocity to something kinda slow.

(5) Measure the actual distance moved.  For our example, say that is 5.5 inches.

(5) Now calculate the actual steps/inch. First calculate the actual number of steps that Mach4 (should have) output:

     # of steps = (commanded disatance) * (current "steps/unit" setting)

So for our example, that would be (5 inches) * (2000 steps/inch) = 10,000 steps.

Now calculate actual steps/inch by:

    actual steps/inch = (# of steps) / (measured distance)

So the new, supposed actual steps/inch = 10,000 / 5.5 = 1818.  Enter that as the new "steps/unit" and then re-run this test to verify the setting.

Bob

75

Mach4 General Discussion / Re: Mach4 Spindle setup

« on: March 17, 2016, 11:55:34 AM »

On that scale the error is difficult to see (as Steve pointed out while I was typing this).  Yes, there is a little up-tick at the left side of the graph.

WARNING: the plots I suggest below PRESUME IDEAL RESPONSE OF THE VFD TO INPUT VOLTAGE!!!
That may or may not be the case.  They also presume that your volt meter is correctly averaging the PWM signal to give you the DC voltage reading.  As Steve politely corrected me above, that is not always the case.  Some of the error may be due to the volt meter, specially at the lower RPM settings (and this lower PWM duty cycle).

That said, here are some hints for other ways to look at the data:

(1) calculate voltage error for both the 10V and 5V measurements:
Voltage error = measured - ideal

(2) Then calculate and graph voltage error as a percentage of ideal voltage:
percent voltage error = ((voltage error) / (ideal voltage)) * 100

(3) Calculate what the actual RPM should be for the measured voltages (again PRESUMING IDEAL RESPONSE IN THE VFD):
calculated actual RPM = ((measured voltage) / (10)) * 3600
or divided by "5" for the 5V scale

(4) Calculate and graph the RPM error:
rpm error = (calculated actual RPM) - (commanded RPM)

As a curiosity, how does the VFD reported RPM match up with the calculated RPM in step (3) above?

Bob

76

Mach4 General Discussion / Re: Mach4 Spindle setup

« on: March 16, 2016, 06:02:34 PM »

if I commanded m3 s3600, which is what I have set as max spindle speed, I get 10.01v. If I command m3 s1800 my voltage reading is 5.1v, and if I command m3 s900 my voltage reading is 2.93v. Obviously I have a problem with linearity but am having a B#@%$ of a time tracking down the problem, as I am not that well versed in the electrical engineering process of machine building.

If you can (I don't know the C32 board), see if you can measure the voltage on the PWM signal as it comes into the C32 board from the ESS.  You can (carefully) probe the pins on the bottom of the board on whatever connector the C32 has for the ESS (DB25 or 26-pin ribbon header).  That will tell you if the issue is the ESS or the C32 board.  The voltage should be linear 0 to 5V if the PWM signal is correct.

77

Mach4 General Discussion / Re: Mach4 Spindle setup

« on: March 16, 2016, 02:40:39 PM »

caveat: I do not know how the ESS calculates the PWM value, and I don't know how the C32 board converts that PWM into an analog voltage.  But in general:

For PWM generation, the plug-in *should* only use the min and max spindle RPM fields, along with the currently requested RPM.  The "Max Motor Speed" can be ignored for PWM and is (probably) only used for step pulse rate spindle control where the plug-in needs to know the actual spindle *MOTOR* RPM as well as the spindle RPM itself.

Feedback ratio is only used when you have a sensor or encoder on the spindle to measure actual spindle (or spindle motor) RPM.  This gives the ratio between # of pulses (or encoder counts) and one spindle revolution.

Generally, for PWM the formula could be one of two equations, depending on how the plug-in treats the "min RPM" setting:

If "min RPM" is the RPM that results from 0V (or 0% PWM duty cycle), then:

PWM duty cycle in percent = ((RequesedRPM - minRPM) / (MaxRPM - minRPM)) * 100
     or, to calculate voltage (0 to 10V):
Voltage = ((RequesedRPM - minRPM) / (MaxRPM - minRPM)) * 10

If "min RPM" is interpreted as the minimum that this particular pulley configuration can support, but 0V (or 0% PWM) still means 0 RPM( usually the case):

PWM duty cycle in percent = (RequesedRPM / MaxRPM) * 100
     or, to calculate voltage (0 to 10V):
Voltage = (RequestedRPM / MaxRPM) * 10
and the "min PWM" setting is only used to restrict allowable values in the "S" command.

And for "min RPM" == 0, these two equations become the same.

Now depending on how your hardware converts the PWM into the 0-10V output, there could be, and likely WILL be, some non-linearity in the analog transfer function.  You can test the linearity if you have a digital volt meter.  For various commanded RPM, measure the voltage on the PWM output pin from the ESS (or at the input to your C32 board).  It should be 0 to 5V (or pretty close) and *should* be linear with PWM duty cycle.  Then measure the 0-10V analog output.  If the analog conversion is linear, then the analog output should be exactly twice the voltage measured on the ESS PWM output.  Now this presumes that your PWM frequency is high enough that the digital meter is able to average a good number of cycles per meter reading.  If you put the meter on the ESS PWM output and you see the voltage changing more than a few millivolts (or whatever "noise" you usually see on DC voltage measurements), then the PWM frequency is low enough that the meter is not able to average enough cycles for a stable reading.

Bob

78

Mach4 General Discussion / Re: Omron MX2 problem

« on: March 10, 2016, 09:16:21 AM »

See my edit in the previous post.  The PMDX-105 won't work here.

Bob

79

Mach4 General Discussion / Re: Omron MX2 problem

« on: March 10, 2016, 09:10:36 AM »

If the MX2 takes a variable frequency pulse train... then it looks like a stepper motor to Mach4.  Presuming the ESS supports out-of-band motors (I don't know), then configure the spindle for step pulse control and assign it to OB1 (or OB2, etc.).  Set the max sep rate to 32 KHz (I presume... you would need to read the MX2 manual to figure out how to map step rate to spindle speed).  Then you will need a way to convert the ESS outputs to 0-24V.  You don't mention if you are using a breakout board along with the ESS.  The PMDX-105 (http://pmdx.com/PMDX-105) can do this for you.  See Figure 5 on page 7, and wire J5 pin 1 to your +24V supply.  The MX2 would connect where the diagram shows the PLC, though you would only connect 1 signal.

[EDIT] Oops - I just double-checked the specs on our PMDX-105.  The opto-couplers won't pass a high enough frequency to work here.  The max is around 500 Hz, nowhere near 32 KHz.  See the option below.[END EDIT]


Though I'm wondering why you don't use the 0-10V analog input.  Then you can use any number of spindle control boards including our PMDX-407-S (http://pmdx.com/PMDX-407, which can operate stand-alone with any motion controller/breakout board).  Confirure Mach4 and the ESS to generate a PWM signal.  Then the MC2, terminal "H" provides the 10V reference into the 407's "Aref" input, and terminal "O" takes the "Aout" from the 407, and the "L" terminal goes to the "Agnd" on the 407.  If you go this way, make sure to order the "-S" version.

Bob

80

Mach4 General Discussion / Re: DMM servos and Mach4

« on: March 03, 2016, 12:37:31 AM »

One other thing is that Z axis(Lathe profile) jogging is backwards when I push the jog buttons on the display with the mouse. x axis is proper direction. I don't know if these things are related and really am frustrated at this point.

I can't help with the homing issue, though there have been several other posts on this forum about SmoothSteppers and homing that sound like you problem.

As for the Z axis jogging backwards - if the GCode motion is in the correct direction and only jogging is backwards, check the soft limits settings.  Go to the "Configure" menu and select "Mach...".  Then click on the "Homing/SoftLimits" tab.  Having the "Soft Max" value less than the "Soft Min" value will cause this behavior.  And since the "Soft Max" column is listed first (which is not what most people expect), it is a common mistake to presume that this is the "min" column.

Bob