View Full Version : Z axis trouble

22-02-2013, 09:03 AM
I have just up graded my electronics to a system 4 from Roy at diy cnc.
I now seem to have developed a problem with my Z axis.
The motor doesn’t seem to have the power to move the axis.
I have re tuned all the motors which were working fine, now the Z won’t move up and only moves down.
Can anyone me with this.


22-02-2013, 10:21 AM
Does the motor stall when you try to move the Z-axis up, or does it just move the Z-axis down regardless of whether you command it to go up or down? If it's the latter then there's most likely a problem with the direction signal on the Z stepper driver, so check that. You could also try plugging the Z motor into a different axis to determine if the problem lies with the Z-driver, or the motor.

22-02-2013, 07:52 PM
Thanks I will give this a try in the morning.

24-02-2013, 09:39 AM
Thanks for the advice, I have tried swapping the drivers over when I swapped them back everything seemed to work fine.
Now the Z axis is plunging through the work piece or just cutting air. I have tried to run code I have used in the past which worked fine.
But now I get the same results, either plunging through the work piece or it just cuts air.
Any suggestions?

24-02-2013, 11:39 AM
Test the voltage on the Direction pin while Jogging up/down. It should read 0v or close to it in one direction and around 5v in other direction.

If you get around 3V in one direction then it's probably your parallel port is low power 3.3v type.?
Even thou your old system probably worked ok the BOB could have had pull up circuitry to bring the pins upto 5V.?
If there's not a clear enough difference in voltage between high & Low the drives gets mixed signals and doesn't know which way to jump.? But it has to jump because there's another signal coming down the track so it just takes it's best guess and thats why you get erratic behaviour.!

If your still using the same BOB and your sure the wire connections are all sound and swapping to another drive cures the problem for a prolonged period then I'd say you have a intermittent faulty drive.?

One other thing to check is the PSU. If it's rated close to the minimum the Sys4 needs then it could be dipping below and some of the circuitry like Opto's etc are not getting what they need.? . . . . Maybe Clutching straws here and I'm no Electronics Geek but I've seen similar things before.!

24-02-2013, 08:30 PM
Thanks for the advice Jaz.
I have got the z axis to jog up and down perfect now,although I don’t know what was wrong with it.
Some of the connections weren’t looking the best so Idecided to re-wire the motors.
At this point I have managed to blow a driver by mixing thewires up (what a donkey).
I don’t have a multi meter so haven’t checked the voltage onthe step pin yet, but will do this tomorrow.
When I tested the system before I blew it up, it wouldengrave fine, when I tried to pocket or profile it just slammed straightthrough the work piece.
When I click on go to home the x and y are where they shouldbe but the z wants to be lower. Any thoughts on why this is happening?
Also does anybody know how to get the magic smoke back intothe chip on the driver board?

27-02-2013, 03:38 PM
Thanks guys all fixed now (I think) and thanks to Roy at DIY cnc for the speedy dispatch of a new driver.
Looks like it was the psu that was faulty.