[fogassa]

Hi All,
I´m doing a axis cnc router retrofit with closed loop steppers Hbs86HD made by PFDE and ddcsv 4.1 controller, the machine runs fine but Im getting jerk movments on gcodes when doing a 2d planar offset. it happens on the same code line every time then it runs fine for another 200 lines or so of code and does it again and it goes on like this till the jerk is so bad that that the drive goes in fault alarm , some times on y some times on x . I´ve checked all connections, cables etc... have switched the controller by another one and it still does it, have switched the stepper drive and it still does it. the code is correct. can not find the stepper drive company on line only on sale at aliexpress. drive and motor made by pufe ide motors co.
I think there is something wrong with the motor or the encoder but both are brand new.
it works fine when doing any countour cut
I did retrofit another cnc router with the same controller but with open loop steppers and it does run fine on the same gcode. any ideas on what is going on?

[joeavaerage]

Hi,
it sounds to me like the motion buffer is running out of data.

Most controllers have a motion buffer in which are stored PVT (Position, Velocity over Time) data, typically in 1millisecond time slices.The data frames describe the position of the machine
at each 1 ms interval, and the motion control issues the pulse to the motor drivers so that the machine can arrive at the designated location at the required time. The motion buffer can be several hundred milliseconds long.
It requires and presumes that the CPU can give service to the trajectory planner so the planner can work out the required waypoints and fill the buffer up. The CPU is then free to go and do other things, like
updating the screen and a thousand other little tasks that a PC does. Hopefully the CPU gets back to the trajectory planner before the buffer runs out. If it does run out the machine will stall as you have described.

Craig

[fogassa]

yup, it´s something related to the drive but without a descent manual it is hard to figure it out. the drive´s manual is vague on explaning the settings. since it happens at the same code line it can not be noise being picked up. I´ll try run it at lower feed rate to see if gets any better.

[fogassa]

Update on this, it turn out to be faulty stepper drives. 5 defective drives brand new.

[samlevy0515]

So all the 5 drivers are defective? what the brand name?