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Z axis on my clone I3

Posted by Nigel Kelly 
Z axis on my clone I3
March 30, 2023 04:03AM
Hi all, my wild imagination is going again, having got my printer working with the diamond mixer hot end and my head turned to the slow speed of the Z axis which was causing head crashes when I tried to speed up printing and so looking at the Arduino /Ramps layout and noting that X and Y use their own A4988 driver the Z axis driver shares with 2 steppers, so my logic says that each Z axis motor must receive less power ? hence the slower settings in Marlin. I started thinking about the add on driver board used for the 3rd extruder and thought "what if I extended the step direction and enable pins of the Z axis A4988 to another remote driver board with its own 12volt and 5volt power supplies I could drive each Z axis motor with its own driver and thereby speed up the axis without altering any firmware settings". So I tried out my thoughts and drove one motor from its original driver pins on the Ramps and the second from the remote board and sure enough it worked both motors worked and I changed the speed settings from 5 to 100 which worked but both motors are not turning the same amount i.e. when I lift the Z axis say 100 mm the left motor controlled from Ramps travels 100mm but the right motor lifts 110mm or so, I have balanced the trim pots on both drivers thinking that may be the cause as the steps must be the same as they are from the same pin but the more I move the axis up and down the greater the error becomes. Can anyone suggest why please
Re: Z axis on my clone I3
April 04, 2023 09:09AM
I have no idea TBH,

Z has the most mass to carry, if one side is driving most mass then it will stall easier.

I found that setting low acceleration and movement speeds on a Prusa style gave most consistent prints, and tuning Z led to a tiny decrease in print times compared to x and y improvements
Re: Z axis on my clone I3
April 04, 2023 01:13PM
Hi Thanks for your reply , I think you may have not fully understood my first message so I have enclosed showing the separate driver board with second axis driver and the stepper driver for the Z axis on the Ramps board that I have extended the Enable Step and Direction pins with 3 wires to share the instructions from Ramps not only with the onboard axis but with both the onboard and remote axis, and it does work. The next image shows The two drivers attached to the Z axis on a the Ramps board. My problem is each axis motor having its own A4988 driver with trim pots balanced does not move equal distance even though the remote driver must have the same number of steps etc as the ramps axis. The two separate drivers do make it possible to greatly increase the Z axis speed but until I find a way to equalise / balance the movement of both motors printing is not possible. I appreciate your reply and look forward to future help on the subject.

Edited 1 time(s). Last edit at 04/04/2023 01:15PM by Nigel Kelly.
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