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Author Topic: Y axis is jumping  (Read 287 times)

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Y axis is jumping
« on: March 27, 2021, 04:02:09 PM »
Hello All,
I run a program and it goes through the program just fine. I put in another part, Y axis jumped about .125, I keep running the program and it does fine except for the .125 initial jump. I put another part in and Y jumps another .125.
I run the  program from a cad drawing or enter the g code myself, and it does the same thing. When I use jog it is consistent through all parts. Could this be a glitch in the mach4 program?

Offline smurph

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Re: Y axis is jumping
« Reply #1 on: March 29, 2021, 02:03:47 PM »
The short answer is NO.  It is either a setup issue or a mechanical issue (steppers losing steps).  And is it about .125 or exactly .125?

Steve
Re: Y axis is jumping
« Reply #2 on: March 29, 2021, 05:20:31 PM »
Hi Steve, I love short answers. It's around .125. it worked just fine for a long time.  I did mess with the config control, motor. I changed the X axis, then put it back where it was. I just went and checked and all 3 axis are inconsistent. I'm a a manual machinist and built my cnc machine from drawings. I got lucky I guess because it worked right off.
Randy

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Re: Y axis is jumping
« Reply #3 on: March 30, 2021, 04:01:04 PM »
Hmm...  I would say if the error is inconsistent that there is a mechanical issue.  Look for screws binding or couplers slipping.  I had a screw started binding as the nut wore on my little Joyo desk machine that we always used as a demo at the shows.  All of that air cutting wore the nut.  :)  It was especially noticeable when it did a rapid move.  If my "air" part was all done at feeds speeds and then it did a rapid to get ready for the next part, I would see the error right of starting on the new part.

Slow the max speed down and drop your accel in the motor tuning and see if it starts hitting the numbers.  This might tell you if you are losing steps.  I say might because some of these mechanical issues can be VERY hard to diagnose.  Because it might not be readily apparent if you are losing steps because of an overload situation or losing position because of a lose coupler, etc... 

Steve
Re: Y axis is jumping
« Reply #4 on: March 30, 2021, 05:08:39 PM »
Hi Steve, Thank you for the suggestions, I will let you know>
Randy