Can't exceed 2000mm/min

[Bad Wolf]

Can someone please point out the obvious to me but I can't seem to get above 2000mm/min when the G-code is set for 3000 and turned up to 300%. It may be in the velocity setting just need someone to confirm before I change it. TIA.

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[OlfCNC]

Can someone please point out the obvious to me but I can't seem to get above 2000mm/min when the G-code is set for 3000 and turned up to 300%. It may be in the velocity setting just need someone to confirm before I change it. TIA.

Your axis velocity setting is 2000 is why it does not go above 2000. The velocity parameter is the speed constraint for the axis.
You should change that higher only if your axis can handle the higher speed, you should verify that.

If your other axis is also set to 2000 velocity just for an example then the fastest feedrate you can get on the path is when the 2 axis move in 45°, then you will get sqrt(2000^2 * 2000^2) speed which is 2828 feedrate on the path and this is when both axis move with 2000 velocity creating the mentioned path feedrate.

[Bad Wolf]

Cheers, thought as much. Machine should be capable of well above 2000.

[Bad Wolf]

lol just dawned on me the min in units/min does stand for minimum it stands for minutes, it's a threshold setting... duh!
Can't seem to get it to save the setting, just going to alter the config file.

[Bad Wolf]

Quick question how do you actually know when the machine is maxed out?

[OlfCNC]

It depends on. If they are servos then you can check at what speed the servo starts to have a following error. Just check the servo error signal.
With steppers you can only test when the steppers will stall and note that speed and then down tune the speed a bit to stay safe.

[OlfCNC]

Can't seem to get it to save the setting, just going to alter the config file.

Make sure the file and folder is not write protected.

[Bad Wolf]

They are Nema 23's with two motors on the X. How do I check stall speed please?

[OlfCNC]

Steppermotors torque drops as the speed highers. You can set a high enough velocity parameter and then try to jog with higher and higher speeds and see at what speed the motor does not start running or stalls while running.

[neilw20]

For a given speed, keep setting the acceleration higher and higher while jogging (or running a program) backwards and forwards until steps are lost on change of direction.
Halve the maximum acceleration setting found, now keep increasing the velocity doing the same until steps are lost on change of direction.
Set the max velocity to about 70% of the maximum velocity found.
Each axis may have different settings due to different inertia of axis. ie. Y axis moves the X table AND the y axis, so it is heavier.
Lost steps are usually obvious by a clunk noise on change of direction, as the step(s) is not achieved.
The 50% and 70% are only my guideline estimates, and may vary with different hardware, drivers, etc.

[OlfCNC]

Yes, that is a good procedure to setup both the acceleration and the velocity.

[Bad Wolf]

For a given speed, keep setting the acceleration higher and higher while jogging (or running a program) backwards and forwards until steps are lost on change of direction.
Halve the maximum acceleration setting found, now keep increasing the velocity doing the same until steps are lost on change of direction.
Set the max velocity to about 70% of the maximum velocity found.
Each axis may have different settings due to different inertia of axis. ie. Y axis moves the X table AND the y axis, so it is heavier.
Lost steps are usually obvious by a clunk noise on change of direction, as the step(s) is not achieved.
The 50% and 70% are only my guideline estimates, and may vary with different hardware, drivers, etc.

Sounds like a plan... I put the units per minutes up to 4,000 on the X (slaved) and Y but although it said 4,000 it really didn't seem to be going much faster than when it was at 2,000. Every time I stepped it down with the +/- it sounded like it changed note, but not speed, almost like a slipping clutch. Does any of that make sense?

[neilw20]

The process is, not setting the maximum velocity that seems to work.
You must find the acceleration limit first, as detailed in my procedure.
Do one axis at a time.
If you have slaved axis, set the master and the slave to the same values.
Best to get it right on a simpler axis first, so that you understand the procedure.
It is the rapid change in direction (when steps are lost) which identifies the critical settings.
The numbers for stepper motors will be quite different to servo driven systems, but the procedure is similar.
Finding the maximum velocity is the LAST step. Acceleration first!
If you are not getting any lost steps at a high acceleration setting, increase the max velocity setting, and test again.\
It is nothing to do with what 'seems right'. You must FIND the limits, and adjust accordingly.
If you can't find the limits, then the settings in the driver may be limiting effectiveness of the test.
READ THE MANUALS on the DRIVERS, and understand what is happening.
Trial and error will fail you miserably.

[robertspark]

I have created a few axis testing files, remember g0,G1,G2 and G3 are modal...
Ie once activated you do not need to keep typing g0,G1,G2 and G3

I created the files in excel and copy+pasted them to notepad and saved as a text file, given in excel (or OpenOffice equivalent), and basically dragged the same cells down for 100 lines of code.

Then prefix the first line as G0 x100
Next lines x0; x100; x0...

Following the previous posts for tuning and retesting.

Then I run combined axis motion with X&y and then xyz or even a etc.
________________________________

Out of curiosity...
What voltage is your power supply?
What stepper motors are you using (inductance and ampage rating)
What axis motion are you using (ballscrews, threaded rod, belts chain, string whatever)
What microstepping setting are you running?
What pitch per stepper motor rev are your axis running?

What is your application (plasma, wood router, mill, laser etc...)

[ger21]

You must find the acceleration limit first,

No, you need to set the Velocity first. Say your velocity is set to 1000 while you adjust your accel, and then you find that velocity can be set much higher, say 2000-3000. A velocity setting that works at 1000 velocity may not work with a higher velocity, because the motor has less torque at the higher velocity.

You should set the acceleration to a low value, and find a safe max velocity before adjusting the acceleration.

[Bad Wolf]

I have created a few axis testing files, remember g0,G1,G2 and G3 are modal...
Ie once activated you do not need to keep typing g0,G1,G2 and G3

I created the files in excel and copy+pasted them to notepad and saved as a text file, given in excel (or OpenOffice equivalent), and basically dragged the same cells down for 100 lines of code.

Then prefix the first line as G0 x100
Next lines x0; x100; x0...

Following the previous posts for tuning and retesting.

Then I run combined axis motion with X&y and then xyz or even a etc.
________________________________

Out of curiosity...
What voltage is your power supply?
What stepper motors are you using (inductance and ampage rating)
What axis motion are you using (ballscrews, threaded rod, belts chain, string whatever)
What microstepping setting are you running?
What pitch per stepper motor rev are your axis running?

What is your application (plasma, wood router, mill, laser etc...)

Think these should answer those questions.
48v on the 2 X axis motors
36v on Y and Z axis motors
36v not used built for A and B should I ever go 5 axis

Ballscrews on X axis roughly 1600mm long 3210
Ballscrew on Y axis roughly 1000mm long 2510
Ballscrew on Z axis roughly 500mm long 2005

DIP switches 1,6,7 on everything else off
on, off, off (1,2,3) 3.76A peak 2.69A RMS
off (4) Half current
off, on, off, off (5,6,7,8) 10,000 pulse/rev

EDIT: 6 and 7 are both on so that should have been.
off, on, on, off (5,6,7,8) 2,000 pulse/rev

[ger21]

Your motors are too small to get good performance with 32mm ballscrews. You'd have been better off with 2510's everywhere.
Set your microstepping to 2000 (1/10), and increase the current to 4.2 amps

[Bad Wolf]

Don't think it will make any difference but I will be swapping from a UC100 to a UC300ETH-LPT5 once I have time to fit it. Also currently making new end plates for the CNC so probably won't try do any adjustment to the setting until I have the new end plates fitted as they will be lighter.

[Bad Wolf]

Your motors are too small to get good performance with 32mm ballscrews. You'd have been better off with 2510's everywhere.
Set your microstepping to 2000 (1/10), and increase the current to 4.2 amps

Would I be better off with NEMA 34s on the X? I have the plates water jetted for both bolt patterns. I can easily make a plate for the Y axis as well if deemed necessary.

The reason I turned down the amps was because previously I only had one X axis motor hooked up and the motor ran very hot, now that I have the second motor hooked up they only get to warm (as in I can hold my hand on them).

[ger21]

Depends on the specific motor. To really take advantage of bigger motors, you'd probably want better drives, and more voltage.