Problem with axis over travel

Thanks to some help in the forums I was finally testing my machine with Gecko 203V drivers through a BO board.

In my first test though I noticed that travel on the X and Z axis were as commanded as far as I could measure but
the Y axis is traveling more than commanded to the order of 12 3/4 + for a 12 inch requested. Axis display of course showed it was moving 12 inches.
The return to zero was correct.

It was repeatable proportionally at 6 inches and repeatable at full and half movement rate. All axis use same steppers and same 10 tpi lead screws.
I even went as far as to count the pitch over 10 inches of lead screw ( yes the screw really is 10 tpi ). All the axis have the same variables in the .ini file.

This seems to be awfully far off. Before I start messing with scale factors does anyone have an idea what could cause too much travel.

I have a similar issue, my machine has 8 tpi lead screws, but for some reason when I command a 1" movement it is off about .010". I ended up getting the right distance by changing the scale, it works fine. It does bother me a little bit that using the "right" numbers doesn't work, but at the end of the day as long as I can get the desired results consistently it doesn't really matter how I got them.

Chris401 wrote:

Thanks to some help in the forums I was finally testing my machine with Gecko 203V drivers through a BO board.

In my first test though I noticed that travel on the X and Z axis were as commanded as far as I could measure but
the Y axis is traveling more than commanded to the order of 12 3/4 + for a 12 inch requested. Axis display of course showed it was moving 12 inches.
The return to zero was correct.

It was repeatable proportionally at 6 inches and repeatable at full and half movement rate. All axis use same steppers and same 10 tpi lead screws.
I even went as far as to count the pitch over 10 inches of lead screw ( yes the screw really is 10 tpi ). All the axis have the same variables in the .ini file.

This seems to be awfully far off. Before I start messing with scale factors does anyone have an idea what could cause too much travel.

This can be a number of things , if the y axis is belt driven the gearing ratio may be different on that axis , dont presume they are all the same
microstepping drives switch settings incorrect geko's by default are 10
axis velocity too high
incorrect calculation
thinking the ballscrews are imperial when there metric

post your calculation or spec's and they can be confirmed
is it directly driven or a belt etc ?

the fact you say it returns to the same point repeatedly , should discount missing steps
but see if the distance multiplies x2 over say 2" and then 4" do not return to zero make both moves in the same direction
if you dont have the distance try say 1" & 2" , but the longer the distance the easier it is to find the problem

Not an issue with the mechanics. All pulleys were shop made and teeth cut into 2 inch nylon stock the pulleys sliced off.
X,Y and Z really are the same. The drivers are base 203V without the variable microstep add on so nothing for me to change there.
The lead screws match. I will go ahead and try scaling Just seems like %6+ is a big miss to start with. Maybe I've an issue with one of the drivers.
I guess I could switch the X and Y drivers and see if the issue follows the driver.