You may be having this issue that @KyleJacobs identified and solved.
It may be worth looking at if your Z axis works fine at the bottom of the rod and then binds near the top.
Is there a measurement we can check on the Delrin nut?
What is the current pot and how do you adjust it?
Current pot stands for current potentiometer.
They are on the gshield and look like plastic screws next to the stepper driver chip.
Do not over-torque these pots - they are tiny and gentle and will break. The pots have 270 degrees of rotation.
See here for more detail:
I had a 3D printer that would loose steps if the Z did short rapid up moves. The steppers have to move the spindle and fight gravity. If your current setting is not correct then this compounds the problem.
I donāt know if you can set the acceleration rate on standard X-carve machines with the electronics that are provided.
The other thing that is talked about on other CNC forums is electronic noise having an adverse effect on machines. If your wiring is not shielded and wiring is running close to one another you can have problems with lost steps.
Dave
Just an update in case anyone has the same problem as I did - adjusting the z stepper pot most of the way up has fixed my problems so far! Iām pretty sure I did something in the z-axis to make it ever so slightly out of key that somehow got worse when the spindle heated up the whole assembly.
1 Like
I too had the same problem. When doing Z axis intensive work it would slowly dig itself down. In a 12 inch piece doing a 3D raster type cut it would cut 3 -4 random steps into the work. I checked the forum and saw someone else point out that the guy had his fan on backwards. After checking the install video to verify I found my fan was on backwards as well. I changed it so the fan blows on the chips and not suck the air and then adjusted the pod to where the roughness just went away. I ran two tests using the same gcode and success!!!
1 Like
For people having this issue I believe I have discovered a possible answer. I am using the normal threaded rod, but I suspect the ACME rod would have the same issue.
I noticed that the Z carriage was offset towards the back of the machine in a way that caused the delrin nut to not sit comfortably behind it when it was at the top of itās range of motion. To fix this in my own build I took a total of 8 extra washers and place 2 on each of the Z carriageās V wheel assemblies. This spaces the carriage away from the delrin nut so that it mates perfectly with the carriage even at the top of the range of motion. Doing so provided me a better solution than just increasing the current since previously even when doing that, my machine could not raise the Z all the way to the top of the machine to activate the homing switch. I just thought I would mention this in case anyone else was having similar difficulties and didnāt realize why.
1 Like
Maybe this is what is wrong with mine. They sent me a new threaded rod and nut, but since the issue was only a problem at the top, I have not swapped it out yet.
Allen,
did you solve this problem?
What was the cause?
I have the same problem. Z axis not retracting sometimes.
The first symptoms were losing height of Z axis !?
Lately Iāve noticed that when I do ācoldā start of the machine and pressed the button to move the z axis upwards, Z axis do not do the movement or do partial movement - it collapses, after that first ācollapsā Z axis executes commands properly.
I have DC servo drive, massive machine - stone procesing. I use V carve and mach3. I engraving letters in stone.
I worked for a year without problemsā¦The problems began when the driver went to the āFault errorā condition after overloading. Shoul I check a PID settings? Mechanically everything seems okā¦
thanksā¦
As with most difficult to solve issues my problem turned out to be a combination of multiple things. FIrst, my Z axis was not perfectly aligned, this was causing the screw to bind in the delrin nut. This was the primary cause of the problems, but I did not figure this out till last.
That binding would put a lot of stress on the Z stepper (I was using a NEMA 17) which caused it to miss steps.
Since it was missing step I figured the problem was low voltage to the motor so I increased the voltage to the Z motor (with the gshield pot). Increasing the voltage only caused more stress and heat on the Z motor which eventually caused it to fail.
I purchased a NEMA 23 motor for the Z axis and in the course of removing the old motor and putting the new motor on I finally discovered the binding issue. I fixed that and have not had any problems with the Z since.
If I had fixed the alignment issue first, I could have saved myself a lot of trouble.
The best way to check for binding is to remove the Z drive belt and then turn the threaded rod by hand through itās full range. It should turn easily and smoothly over the entire range, if it does not then you need to adjust till it does.
thanks for time you spent to answer, I will certainly check the things you suggested