That is unusual. I just tested locally, and a substantial weight has to be added to the axis before it begins moving without power. You may have a slightly different tolerance between the leadscrew and the leadscrew block. We’re working on a firmware patch to keep the z-axis motor powered to keep the axis in place.
Ok thank you for your reply. This is definitely not good to my robot. I also got another in the forum to have the same problem as me.
Please look at the video
So the theory says that tolerance between screw and nut is too loose. I have the following ideas but requires some adicional work.
Ordering another nut from you to test if problem is solved. Can I order it in relatively fast?
Manufacture another nut myself but the has 3 threads and it is acme. So in a CNC lathe I will also need special tooling to do it.
Another idea maybe not so direct is to cut the nut at the middle. Then adding some little spacers inside the cut. This will add pretension to the nut. Similar to the spacer used in the ball screws. That are used to remove backlash
This will be an elegant way to solve it as long as enable can be on and off from the ramps.
I am not an expert but i think that in stepper motors If are enabled they are locked and consuming most of they power even if they don’t move. Just when you disable them current don’t flow through their coils and they became idle again.
I haven’t considered the power consumption yet, might be worth to measure. Does anybody know how much current they draw in enabled mode ? If there is a software solution in place, I totally agree that there is no need for enabled being default, however some people do not use rotary encoders. In such a case, one could simply home z-axis via a endstop each time before the bot start moving. This would not take much time and would also be a quite stable solution.