Linear guide rail jamming problems

Other Hardware Motors, Mechanics, Power and CNC
21

@DaveX Thanks, this is insightful. Just to clarify, the switches on the driver are set up to 2.8A peak, which I believe is 2A RMS. The current limiting switch is set to Full Current, not Half Current, and the microstep settings are set to 400 pulse/rev.

My bench supply is limited to 30V which is still too low based on your suggestion so I will need to find a bigger supply. When I get home though, I will crank it up to 30V to test- based on what you say I should atleast notice a change/inprovement in the behavior.

22

Not if you don't remove the Serial.XXX :slight_smile:

23

How is your guide rail lubricated?

24

Is the video having a frame rate issue (frame rate making rotating things look stationary)?

25

@DaveX @zwieblum Many thanks, the culprit was indeed the print statements. Here's a new video with the stepper remounted on the linear guide and running without missing steps. I also increased the voltage to 30V, which is as high as my supply goes. The rail itself now seems to be making some noise, but I can probably address that with some grease.

Admittedly, I still don't understand how to choose the right voltage, it seems like I can just crank it up till I get the performance I need. Running this at 30V is definitely higher than I was expecting, but the recommendation in this thread is to go even higher. What is too high? And given the rated current is 2A, why do I never actually see 2A being drawn from my power supply via the display?

Thank you everyone for the help, as someone that does mostly software and light mechanical I definitely learned a lot.
This reddit post was also helpful in understanding a little more: Reddit - Dive into anything

26

Exceeding, or even closely approaching the manufacturer's stated absolute maximum input voltage to the motor driver.

My recommendation is to back off by at least 10%, as inductance in long power leads leads to ringing excited by switching transients.

why do I never actually see 2A being drawn from my power supply via the display?

Because the power supply display is not instantaneous, and shows you some sort of average. The motor driver switches at very high frequency and an oscilloscope is required to see the real action.

27

You don't power the motor, you power the driver. The driver works like a buck converter and converts high voltage/low current into low voltage/high current. So the higher the supply voltage the lower the supply current. You will see a supply current rise when you load the motor at high speed.
Leo..

28

You loose I²R, but the power delivered I*U --> Increase U and you still have the same loss but more power at your hands. That's why you have high voltage lines to distribute energy from powerplant to consumer, too - and you can tell the load the lines carry ba observing the sag of the kables :slight_smile: