Calibration Problem With A Axis >HELP Please<

Hi Community!

I have a confusing problem with the calibration of my A Axis.
My setup:

1080oz Stepper and 1:5 gear ration realized with a chain (very strong and backlash free)
I found out that the Error has a system, but i can't realize the fault in the Setup.
So I hope that there is someone who can find it out or can give me tips.
I think it could be a software problem but I'm not sure.
I'm sure that i don't lost stepps on the motor.

To show the problem.:

G0 A360 --> turns 359° --> -1° offset
G0 A720--> turns 719° --> -1° offset
G0 A1080--> turns 1079,3° --> -0,7° offset
G0 A1440--> turns 1439,3° --> -0,7° offset
Now I turn back:
G0 A1080--> turns 1080 --> 0° offset
G0 A720 --> turns 720 --> 0° offset
G0 A360--> turns 360 --> 0° offset
G0 A0--> turns 0--> 0° offset

Next symptom:

At the Stepper config wizzard in the test panel for the A Axis:
I let the Axis run for about 1minute for each setting.
If i coose +180° the stepper is very accurate.
If i coose +-180° i got a offset.
It seems that the error is systematic but i can't figure out the cause or root.

So please, if there is someone who can dont hesitate.

THANK YOU!

this is more to do with gear ratio than anything else, and stepper steps , in some cases not adding up to a divideable number
/360
Andy may have an idea

Hi Sarah!

Thank you for your reply.
What do you mean with : stepper steps , in some cases not adding up to a divideable number
/360?
Should i post my setting and hardware to solve the problem?

can you change the ratio ?
you need one that divides equally into 360

if you think that a 1:5 , if used as a straight line will give you 15.7in in one turn ,for example

Hi Sarah!

Yes i can change. I need to buy another gearwheel.
I made all by myself, so i can change.
I think I made a mistake in my description:
The ratio is 5:1. Five turns of my stepper = one turn on the A axis.
360/5=72° per turn.
I can't undestand the problem? Sorry I have not the best english skills.
pi x 5 = 15,7?

Hi again!

i was now on the machine to find out a little more about the Problem.
I made some tests with the "test axis window" and made this:

+20° no error
-20° error
+20° no error...
move to another Position:
+20° error
-20° no error
+20° error...

+-20° error if the rotation came form +
no error if the rotation came from -

It seems that the error happens with the change in the move direction, but not with the direction itself.
I played around with the timing setup but nothing changed my Problem.
I have rechecked the chain system, but i cant find anything wrong.
Any idea?
And please can you explain the point with "ratio should devide by 360"


Thank You!