Problem- Intermittent x axis failure

[ronateah]

Good day all - I have recently converted my mill drill using a gecko540 and a dell optiplex. I am using Vetric Cut2D for my GCode generation. Every thing was looking pretty good untill I started doing some milling outside of my initial testing. First I will say i dont think i am losing counts at least in a direct sense. Drilling holes for instance seems to be bang on. The problem I am experiancing is that the x axis will simply stop runing while the other axis will continue to run including the X axis internally to EMC but not physically.

If i stop running the g gode and jog the x axis all is fine (other than X axis needing to be homed). At this point I am not sure if it happens at the same point in the code. I can say that it will occur in more than one file. The problem seems to conincide with a change in the Z axis.

Any thoughts on this one would be greatly appreciated.

I should add these are open loop steppers

[BMG]

Certainly sounds like lost steps.

You should review the wiki (http://wiki.linuxcnc.org/cgi-bin/emc...StepGeneration) for setting up steppers and make sure you did not skip any of the steps.

Take the time to carefully verify your computer's latency and remove any binding issues in your machine.

I as of late have had difficulty with my X axis (48" long) developing a tight spot aroun X=0-4". I lose steps in the area very easily. I still have not completely figured out the problem, but its probably a combination of leadscrew whipping and binding on my pipe side rails.

BMG

[acondit]

Originally Posted by ronateah Good day all - I have recently converted my mill drill using a gecko540 and a dell optiplex. I am using Vetric Cut2D for my GCode generation. Every thing was looking pretty good untill I started doing some milling outside of my initial testing. First I will say i dont think i am losing counts at least in a direct sense. Drilling holes for instance seems to be bang on. The problem I am experiencing is that the x axis will simply stop running while the other axis will continue to run including the X axis internally to EMC but not physically. If i stop running the g gode and jog the x axis all is fine (other than X axis needing to be homed). At this point I am not sure if it happens at the same point in the code. I can say that it will occur in more than one file. The problem seems to coincide with a change in the Z axis. Any thoughts on this one would be greatly appreciated. I should add these are open loop steppers

It sounds like you are trying to push the X-axis faster than the stepper, drive and/or power supply are capable of handling. If you used stepconf to set up the machine, and the testing of the axis seemed ok there, it is possible that the problem is a lack of sufficent current when multiple axis are moving. Remember it takes more power to cut than to just do a rapid move. When you are testing, you are just testing the ability to do a rapid move.

How fast is your configuration set for on the x-axis? How fast are you commanding it to move when it stops moving? What is the rating of your power supply (volts? and amps?)? What kind of mill did you start with?

In short we need more info to accurately diagnose your problem?

Alan

[ronateah]

BMG

The reason I am not convinced it is lost steps is that one part i am milling is square top and bottom (milled perfectly along the x axis - y movement only) but the both sides are indexed inward 0.100 in two locations. It is along this axis one side only that the new Z is applied not in a step but a ramp. It apears at this point that the path is shifted maybe 25 to 50 thou in the same direction and on both sides. In other words the overall width is on target but the it is offset with each new z. (for ref Z is perpendicular to x and y)

The other issue, and i am sure it is related is in a step change for z while x is moving. It is like x stops z moves x resumes on the screen but some one forgot to tell the drive.

I did deal with computer latency in the beginning of this exercise but I am going to revist it all again to double check

Thanks for your thoughts

Originally Posted by BMG Certainly sounds like lost steps. You should review the wiki (http://wiki.linuxcnc.org/cgi-bin/emc...StepGeneration) for setting up steppers and make sure you did not skip any of the steps. Take the time to carefully verify your computer's latency and remove any binding issues in your machine. I as of late have had difficulty with my X axis (48" long) developing a tight spot aroun X=0-4". I lose steps in the area very easily. I still have not completely figured out the problem, but its probably a combination of leadscrew whipping and binding on my pipe side rails. BMG

[acondit]

Originally Posted by ronateah BMG The reason I am not convinced it is lost steps is that one part i am milling is square top and bottom (milled perfectly along the x axis - y movement only) but the both sides are indexed inward 0.100 in two locations. It is along this axis one side only that the new Z is applied not in a step but a ramp. It apears at this point that the path is shifted maybe 25 to 50 thou in the same direction and on both sides. In other words the overall width is on target but the it is offset with each new z. (for ref Z is perpendicular to x and y) The other issue, and i am sure it is related is in a step change for z while x is moving. It is like x stops z moves x resumes on the screen but some one forgot to tell the drive. I did deal with computer latency in the beginning of this exercise but I am going to revist it all again to double check Thanks for your thoughts

If x is moving on the screen and not actually moving, that is the classic definition of lost steps. Emc is sending step commands but the drive or stepper is not responding ( i.e., steps are being lost).

[ronateah]

Alan - I have been running this very slow 10 % of my feed rate and it is a 0.125 end mill at 0.05 cutting depth. My power supply is 50 volt supply at 12.5 amp ( i have to double check current -might be 20amps) I have to go to the shop to get the actual feed rates. This mill is a "First" at least 30 years old.

Also please read my response to BMG

Thanks

Originally Posted by acondit It sounds like you are trying to push the X-axis faster than the stepper, drive and/or power supply are capable of handling. If you used stepconf to set up the machine, and the testing of the axis seemed ok there, it is possible that the problem is a lack of sufficent current when multiple axis are moving. Remember it takes more power to cut than to just do a rapid move. When you are testing, you are just testing the ability to do a rapid move. How fast is your configuration set for on the x-axis? How fast are you commanding it to move when it stops moving? What is the rating of your power supply (volts? and amps?)? What kind of mill did you start with? In short we need more info to accurately diagnose your problem? Alan

[ronateah]

Alan

Agree - steps are lost. My perspective is that in a classic sense timing/latency issues are going to cause an intermittent and varing percentage of counts to be lost in all axis and any direction. These problems are some what repeatable and result in counts lost in one axis only.

Originally Posted by acondit If x is moving on the screen and not actually moving, that is the classic definition of lost steps. Emc is sending step commands but the drive or stepper is not responding ( i.e., steps are being lost).

[acondit]

Originally Posted by ronateah Alan - I have been running this very slow 10 % of my feed rate and it is a 0.125 end mill at 0.05 cutting depth. My power supply is 50 volt supply at 12.5 amp ( i have to double check current -might be 20amps) I have to go to the shop to get the actual feed rates. This mill is a "First" at least 30 years old. Also please read my response to BMG Thanks

I did read your response to BMG. My point is that it is definitely lost steps, the only question is what is causing them to be lost.

10% of 10 ipm is fairly slow but 10% of 1000 ipm is relatively fast. So what is your specified feed rate? And what are you trying to cut? That depth of cut would be fine for somethings but questionable for others.

I am not familiar with a "First" mill. The G540 is a wonderful drive but it is not the answer to every cnc conversion. So I am first trying to figure out whether it has enough power to do what needs to be done.

If the answer to that question is yes, then next one looks to other questions. So, how heavy is the 'Z' that you are trying to move? How big is the table on the mill? What size steppers are you running and what are their power requirements? How fast is your spindle turning?

Alan

[ronateah]

Alan

I will get back to you with that tomorrow

[Big John T]

Take a look here:

http://www.linuxcnc.org/docview/html...tics.html#r1_3

John

[ronateah]

Well it's late and little to report. In other words no improvemnt. Attached are my ini and hal files. I will add more tomorrow

[Big John T]

Originally Posted by ronateah Good day all - Every thing was looking pretty good until I started doing some milling outside of my initial testing. First I will say i don't think i am losing counts at least in a direct sense. Drilling holes for instance seems to be bang on. The problem I am experiencing is that the x axis will simply stop running while the other axis will continue to run including the X axis internally to EMC but not physically.

The load on the X and Y axis will be zilch when your drilling. If your X or Y axis stalls when your milling then you are simply overloading the steppers... nothing more nothing less. The fact that EMC still runs indicates that the problem is outside of EMC.

What have you tried?

John