[morebits]

FYI homeing is not mandatory but maybe advised. I have not used/homed my robot for years, the current/last XY position is stored/known if the table microcontroller always has power. If I ever lose power, I simply rotate the arm to center the ball because I have easy access to the SCARA arm. The position of Axis0 arm is irrelevant, but can be positioned to have a proper rotation to the viewer. When u start a pattern (.thr or seq) file, and the ball is centered this will become X0,Y0 and the software will then know where it is going forward.

Also below is a detailed breakdown of the home seq commands for reference.

example string: “FR7;A+10000n;B-10000;#;A+1000N;B-1000;#;B+10000n;#;B+1000N;#;A=h;B=h;$”

Feedrate Commands

– F – Set feedrate for homing movements
– R – Units in RPM (e.g., FR7 = 7 RPM)
– S – Units in steps/second (e.g., FS100 = 100 steps/sec)

Axis Commands

– A, B – Axis identifiers (A=axis 0, B=axis 1)
– +/- – Movement direction ClockWise or CounterClockWise depending on the stepper pin wiring
– Number – Step count (e.g., 10000 = 10,000 steps)

Endstop Test Modifiers

– n (lowercase) – Stop when endstop 0 is NOT hit (moves until clear of endstop)
– N (uppercase) – Stop when endstop 0 IS hit (moves until hitting endstop)
– x (lowercase) – Stop when endstop 1 is NOT hit
– X (uppercase) – Stop when endstop 1 IS hit

Control Commands

– # – Execute accumulated movement command
– $ – Mark homing sequence complete
– ; – Command separator
– A=h, B=h – Set current position as home for specified axis

[morebits]

if you are using stepper motor controllers like a TMC, the vref (voltage reference) could be too low as the arm is missing steps causing your drift. Make sure they are adjusted low enough to minimize power/heat waste but high enough to maintain accurate steps. I’d added 0.5v per test on both axis, and test until you find the right power for your device. I’m using the Silent-Step-Stick TMC2100 variant, and my vref is 0.55v, keeps my steppers much cooler

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