Just received my new Sienci spindle. Installed the spindle mount and the spindle and the Z-axis gantry immediately starts running down under gravity. I haven’t installed the power cable, dust-shoe or vacuum hose yet.
I do have the spring-loaded anti-backlash nuts installed. Have never “adjusted”. They are as right out of the box.
I have read of locking the Z-axis stepper motor. Is that the only option?
I wonder if an M12 lead screw would be better, But that would take some re-engineering.
@JohnJ Welcome to the group, John.
For a start, what machine are you running?
The spring loaded anti-backlash nuts are not adjustable as far as I know. They self adjust.
There should be no need to consider changing to an M12 lead screw.
Sorry, I should have noted that it is a Longmill MkII 30x30 with an SLB.
Don’t know if they are, but if the M8 and the M12 have the same pitch (threads/mm), then the thread angle on the M12 would be less and the weight of the spindle might not overcome the increased inertia needed to get it moving.
Thank you for any advice/experience
I am not familiar with the mechanics of a Long Mill but maybe there is a way of helping things with a spring to counteract the weight of the spindle? I assume the spindle dropping is only an issue when the mill is not working because the motor holding current should have no problem holding the spindle stationary when the mill is doing a job. Is the mill controller supplying holding current to the motors when it is not actively working?
Anyway, I am just floating some ideas that may or may not help …
I did go ahead and lock the stepper motors - Firmware setting #1. As I read elsewhere I changed from the original setting of 254 to 255. And that locks up the motor, as long as the control board is powered. Seems to work fine.
I had read that leaving the motors locked could reduce their lifespan. As I looked around in firmware, I found settings for axis hold current. Each axis (settings 210-213) has a separate setting.
They were currently set for 35%. I may try reducing that in the future - maybe to 10%. Anyone have any thoughts?
@JohnJ I suggest that you read the SLB tech manual. You will see in it that setting $1=255 is not recommended with the SLB.