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Z axis faster than xy axis

Posted by IgorBiemann 
Z axis faster than xy axis
October 21, 2017 04:22PM
Hello everyone, i'm strugling in feedrates and aceleration, cause I cant insert more than 5mm/s in xy feedrate and 5mm/s2 in aceleration(more than this value and i get skiping steps), but in z axis i can uise more and get no trouble, but they are same step motors.Im using drv8825 , 2,2 kgf stepmotors with no microsteps, and ramps 1.4.
Re: Z axis faster than xy axis
October 21, 2017 11:40PM
Why do you drive the steppers in full step mode?
Did you adjust the driver current?
Can you move the XY-mechanics easily without binding?
Re: Z axis faster than xy axis
October 22, 2017 09:59AM
I'm using marlin as firmware, i'm not an expert, but if i use microsteps, they lose their strenght, right?I've told that z axis can handle more feed rate and aceleration, but I did a test with my father today, and even if I put 50 mm/s in feed rate, looks like its going still in5 mm/s, even if I adjust xy axis with 50mm/s, to make then work in same speeds, xy axis skip steps, but z axis looks the same speed.but in terms of aceleration, with 5mm/s2, z axis works with no variation, looks like it has a unchange aceleration, but if a insert something like 50mm/s in feedrate, I can hear the diference in start (getting acelerated)middle travel, and final travel (loosing speed)Maybe has a problem with the drv8825?motors have s 1A , so I've set driver with Vref 0,5, is it correct?I'm not sure if you have undestood all of this.tomorrow I can send pics in here to a better explanation.By the way, It's a 3d printer that I build with my father from zero, but we've managed to build a CNC from zero too, but grbl ir much more easy to .Thanks for replying.
Re: Z axis faster than xy axis
October 22, 2017 05:09PM
I was Reading in this forum, that maybe exist a problem with pulse widht in drv8825, maybe is there a connection?
Re: Z axis faster than xy axis
October 23, 2017 01:45AM
Quote
IgorBiemann
I was Reading in this forum, that maybe exist a problem with pulse widht in drv8825, maybe is there a connection?

This is only an issue with faster 32bit controllers.
Microstepping will not reduce torque, that's just an "urban legend".
Re: Z axis faster than xy axis
October 23, 2017 02:33AM
But even if I use microsteps, I'll not "gain" strenght as well in motors, so I Suposed that they should work in same condicions with no microsteping, right?when I use microsteping, the feed rate is the same, or like, if I use a 16 microstep in drv8825, to insert feedrate, as maximum I can get with no microsteps is 5mm/s, i could do something like 5*16=80mm/s or this owrks automatically?I think there's something wrong about z axis, cause I can change to any high value in feedrate as aceleration, it still works like 5mm/s, even if I adjust all others axis feedrates and aceleration.

Edited 1 time(s). Last edit at 10/23/2017 02:37AM by IgorBiemann.
Re: Z axis faster than xy axis
October 23, 2017 03:28AM
Need more information:

1. What is the construction of your X and Y axis motion systems, and what are their steps/mm at x16 microstepping?

2. Please supply the data for the X and Y stepper motors you are using.

Edited 3 time(s). Last edit at 10/23/2017 03:32AM by dc42.

Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: Z axis faster than xy axis
October 23, 2017 05:22AM
Quote
dc42
Need more information:

1. What is the construction of your X and Y axis motion systems, and what are their steps/mm at x16 microstepping?

2. Please supply the data for the X and Y stepper motors you are using.

1- I'm using threaded bars in xyz, Not using microsteps, I'm at full step using 141.7322(X),141.7322(Y),141.7322(Z),6.6790352505(E0)

2-#define DEFAULT_MAX_FEEDRATE { 5, 5, 5, 5 }

/**
* Default Max Acceleration (change/s) change = mm/s
* (Maximum start speed for accelerated moves)
* Override with M201
* X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
*/
#define DEFAULT_MAX_ACCELERATION { 5, 5, 5, 5 }

/**
* Default Acceleration (change/s) change = mm/s
* Override with M204
*
* M204 P Acceleration
* M204 R Retract Acceleration
* M204 T Travel Acceleration
*/
#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION 3000 // X, Y, Z acceleration for travel (non printing) moves

/**
* Default Jerk (mm/s)
* Override with M205 X Y Z E
*
* "Jerk" specifies the minimum speed change that requires acceleration.
* When changing speed and direction, if the difference is less than the
* value set here, it may happen instantaneously.
*/
#define DEFAULT_XJERK 20.0
#define DEFAULT_YJERK 20.0
#define DEFAULT_ZJERK 0.4
#define DEFAULT_EJERK 5.0

I've printed somethings with this config, but if I try to hise feed rate, or acelation, step motos start to skip steps
Re: Z axis faster than xy axis
October 23, 2017 10:43AM
actually, I've discovered something.in marlin 1.1.6, you can adjust max feedrate, max acceleration, etc, and feedrate in lcd. but there's something strange.I can insert max os 600 mm/m(I guess it's in mm/m) in lcd feedrate and motors will not skip steps, but if i insert more than 5mm/s in max default feed rate, when i'm printing something, I get skipping steps.why am I capable of moving axis with at least 10mm/s but for printing maximum of 5mm/s?

Edited 1 time(s). Last edit at 10/23/2017 10:54AM by IgorBiemann.
Re: Z axis faster than xy axis
October 23, 2017 11:26AM
okay, so I've noticed one thing.I've insert 600mm/m in homing feedrate.if I only send an individual axis to be homed, it goes normal, but if i insert to xy homing together, y goes normal at his endstop but x skips steps until y reach his endstop, then x goes normal to his endstop.Maybe it's something about energy?
Re: Z axis faster than xy axis
October 23, 2017 02:22PM
The motor data I was after was the rated current, inductance and holding torque of the X and Y stepper motors, not the firmware settings. Anyway, if your steps/mm with full stepping is as high as 141, then almost certainly the problem is that you need very high motor RPM to achieve reasonable speeds, and you do not have enough motor drive voltage to overcome the back emf of the motors at those speeds.

If you have the motor specifications, this can be calculated. See [duet3d.com].


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: Z axis faster than xy axis
October 23, 2017 02:45PM
Quote
dc42
The motor data I was after was the rated current, inductance and holding torque of the X and Y stepper motors, not the firmware settings. Anyway, if your steps/mm with full stepping is as high as 141, then almost certainly the problem is that you need very high motor RPM to achieve reasonable speeds, and you do not have enough motor drive voltage to overcome the back emf of the motors at those speeds.

If you have the motor specifications, this can be calculated. See [duet3d.com].
But 2,2 kgf motors should't be capable of get higher feed rates or accel?
Re: Z axis faster than xy axis
October 24, 2017 12:38AM
Quote
IgorBiemann
Quote
dc42
The motor data I was after was the rated current, inductance and holding torque of the X and Y stepper motors, not the firmware settings. Anyway, if your steps/mm with full stepping is as high as 141, then almost certainly the problem is that you need very high motor RPM to achieve reasonable speeds, and you do not have enough motor drive voltage to overcome the back emf of the motors at those speeds.

If you have the motor specifications, this can be calculated. See [duet3d.com].
But 2,2 kgf motors should't be capable of get higher feed rates or accel?

Only if you supply them with enough voltage.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: Z axis faster than xy axis
October 25, 2017 06:47AM
I'll buy new stronger motors and see what happens, but thanks a lot for your help!
Re: Z axis faster than xy axis
October 25, 2017 04:45PM
Stronger motors won't help if problem is that your printer design uses a very high steps per mm and therefore the motors have to rotate very fast. If you can't reduce the steps/mm then you need low inductance motors and a higher voltage supply to the motor drivers.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
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