Problems drawing a 10cm line

[charlie5653]

Hi,
When I drive the machine to draw a 10cm line I get a 12cm vertical and 6cm horizontal.
To fix this I’ve tried:
-Triple checking the machine measurements. The width is measured from the centre of the shafts. Height is from the shafts to the bottom of the board.
-adjusting the machine width in the software +/- 5mm.
-Raising/lowering the home position

If I hit the ‘boarder’ button the pen goes straight up, way above the limits of the board.
If i jog the motors, “in” moves pen towards the motor, “out” moves it away.

I’m using software 7.23 & firmware 9.2 with a Mega+ramps (no endstops).

In robot_polargraph.h I changed machine hardware to Makelangelo 3 & changed the motor steps to 200
In configure.h I change the board to ramps & degrees per step to 1.8.
Microstepping is set to 16 on the ramps.

Machine is 515mm wide x 600mm high.

What else am I missing?
Thanks!

[Dan]

1. Which direction was your original line supposed to go? ie what was the gcode?
2. Did it move horizontally left or horizontally right?
3. Did it move vertical first, then horizontal sideways?
4. Does it do the same error every time? (is it testable)
5. Did you start at the home position? (is the initial condition always the same)
6. If you swap the motors does it do the same thing in reverse? (eg is it the motors or the brain)

Um…

1. If you jog in 10x and jog out 10x, does it always return to the same point? (test on each motor)
2. As this is a makelangelo 3 (huge), are you certain your starting point is in the middle? Calibrating a 3 is the hardest part.

[charlie5653]

Hi Dan, thanks for you input & time

1 & 2. Using the manual driving section in the Makelangelo GUI, gcode output is:
G0 X100.000 Y0.000 = moves right 6cm.
G0 X-100.000 Y0.000 = moves left 6cm.
G0 X0.000 Y-100.000 = moves down 12cm.
G0 X0.000 Y100.000 = moves up 12cm
after jogging each motor in & out they always return to the same point.

1. It moves in correct direction according to the gcode and manual drive buttons.
2. Same error every time.
3. Yes, always starting at home.
4. physically swapped motors, left & right movement still correct, up & down reversed. jogging motors is reversed.

measured & drew centre line on board to ensure home is centred.

Is it possible that my machine is just too small? I know there is a “golden triangle” area for optimal drawing and this machine is only 515mm wide.

[Author]

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