I've been chasing a problem for the last two weeks which I thought was a coding issue as I just got this machine and was getting my post processor straight. I've eliminated the code as the problem source but my Y axis was still shifting at the 12 and 6 o'clock positions while cutting a circle.
As I went out to the shop this morning something told me to check the belt to see if it was loose or worn. Take the cover off and belt looks good. I figured while the belt cover was off I might as well see what I can see. Check out the video below.
https://www.youtube.com/watch?v=EtId...er#action=shar
In the video you will see that when I change directions on the Y axis, the motor makes a partial revolution in the reverse direction and then goes correctly. After you let off the feed, the motor continues to walk for a partial revolution. OK, this is good to know, but what is causing it?
There is a sensor on the x and y axis that detects the limit of the table travel. I took the housing off to see if there was any interference. Same thing happens. Unit looked to operate via magnets so I put a small piece of metal in front of each sensor and they appear to work as the metal sets off the sensor and the axis walks slowly off the sensor when held off-center. I was thinking about disconnecting the sensors to see if they are the source of the drift but was unsure of the result of running it with these disconnected. Any ideas if this will cause a problem?
While I was at it I decided to run the program that I've been beating around for the last few days and see what I could see. I ran it at a feedrate of 1 so I could keep an eye on the y position while it was running. Movement got to the position where it changed directions and sure enough the y jumped .01-.015 or so. It appears as though the controller picks up on this position change and corrects it but by then the damage is done. If nothing else, this tells us the machine is reading the travel correctly and correcting but why does it allow the y axis to wonder?
Anyone run into something like this or know where to go from here?
Let me clarify a few items from above to be sure we are on the same page. When the table hits the limit switch, it stops. I have to do a process when I start the machine and one item is to calibrate the axes (all 3). When the table hits the limit switches the movement stops and the table backs off a partial revolution. This happens on all axes. I could not get to the X axis motor cover this morning before I had to be at work but I did check the Z and it does not walk. I checked the X axis and it did not feel like it was walking but I forgot to check the readout to see if it was or not. The X axis did not appear to jump while running the test program. At this point, I believe the trouble lies in the Y axis only. I took the limit switch assembly off to see if it was gummed up or shorting out somehow but visually it is fine. I wasn't sure how it worked so my experiment with the piece of metal was simply to check to see if it was magnetic or not.
As I went out to the shop this morning something told me to check the belt to see if it was loose or worn. Take the cover off and belt looks good. I figured while the belt cover was off I might as well see what I can see. Check out the video below.
https://www.youtube.com/watch?v=EtId...er#action=shar
In the video you will see that when I change directions on the Y axis, the motor makes a partial revolution in the reverse direction and then goes correctly. After you let off the feed, the motor continues to walk for a partial revolution. OK, this is good to know, but what is causing it?
There is a sensor on the x and y axis that detects the limit of the table travel. I took the housing off to see if there was any interference. Same thing happens. Unit looked to operate via magnets so I put a small piece of metal in front of each sensor and they appear to work as the metal sets off the sensor and the axis walks slowly off the sensor when held off-center. I was thinking about disconnecting the sensors to see if they are the source of the drift but was unsure of the result of running it with these disconnected. Any ideas if this will cause a problem?
While I was at it I decided to run the program that I've been beating around for the last few days and see what I could see. I ran it at a feedrate of 1 so I could keep an eye on the y position while it was running. Movement got to the position where it changed directions and sure enough the y jumped .01-.015 or so. It appears as though the controller picks up on this position change and corrects it but by then the damage is done. If nothing else, this tells us the machine is reading the travel correctly and correcting but why does it allow the y axis to wonder?
Anyone run into something like this or know where to go from here?
Let me clarify a few items from above to be sure we are on the same page. When the table hits the limit switch, it stops. I have to do a process when I start the machine and one item is to calibrate the axes (all 3). When the table hits the limit switches the movement stops and the table backs off a partial revolution. This happens on all axes. I could not get to the X axis motor cover this morning before I had to be at work but I did check the Z and it does not walk. I checked the X axis and it did not feel like it was walking but I forgot to check the readout to see if it was or not. The X axis did not appear to jump while running the test program. At this point, I believe the trouble lies in the Y axis only. I took the limit switch assembly off to see if it was gummed up or shorting out somehow but visually it is fine. I wasn't sure how it worked so my experiment with the piece of metal was simply to check to see if it was magnetic or not.