Problem with axis over travel
27 Aug 2015 09:03 #61823
by Chris401
Problem with axis over travel was created by Chris401
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.
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.
Please Log in or Create an account to join the conversation.
- kornphlake79
- Offline
- Senior Member
-
Less
More
- Posts: 55
- Thank you received: 10
27 Aug 2015 11:16 #61824
by kornphlake79
Replied by kornphlake79 on topic Problem with axis over 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.
Please Log in or Create an account to join the conversation.
27 Aug 2015 15:40 #61829
by cncbasher
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
Replied by cncbasher on topic 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.
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
Please Log in or Create an account to join the conversation.
27 Aug 2015 17:46 #61833
by Chris401
Replied by Chris401 on topic Problem with axis over travel
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.
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.
Please Log in or Create an account to join the conversation.
Time to create page: 0.093 seconds