Jerky Motion on Mazak Rotary 4 Axis Toolpath

[Rotary Ninja]

We just tried running a Rotary 4-axis toolpath on our Mazak and the motion is very jerky. I assume this is a setting somewhere either in the Mazak or the Control def or something but I am not that familiar with the Mazak. Any ideas?

 

Thanks.

[RayD]

what control? what rotary? what are your feedrates? does your post output rotary feed in inverse time?

[Rotary Ninja]

Mazak Nexus 510C-II... I am not sure what model the rotary is since I am at home right now. I think the feed on that tool was set to 125 IPM. I looked in the control def and Inverse Time was unchecked.

 

Is what you are asking about in the post?

use_frinv : no$ #SET_BY_CD Use Inverse Time Feedrates in 4 Axis, (0 = no, 1 = yes)

 

Here is a screeny of the control def settings

[Brando]

switch it to inverse time on 4x feed, if you want to use the ipm mode you have to put the diameter your working at in a parameter, im not sure which one for the matrix control, if your work across multiple diameters unless they're pretty close in size you should use inverse time, google about it and you'll understand why, had a similar prob on a haas with a rotary last week oddly enough haha

[Jack Mitchell]

It's a shot in the dark but it did happen to me once.

Servo Top card error (defective) causing jerking motions - switched with X axis top card and proved the fault.

[Bob W.]

I'll bet it is the 'convert rapid to feed moves' setting. All of my multiaxis parts run MUCH smoother when the rapids are output as feed moves. This is because under normal rapids the XYZ will move much faster than the B axis. When the rapid moves are broken into smaller angular increments you get a machine gun effect when the XYZ rapids are constantly stopping to wait for B to catch up. Of course, this setting makes the rapid override settings useless, which that makes proving new programs pretty exciting even after they have been run through Vericut.

 

I am about 90% confident this is your issue.

[Rotary Ninja]

I wondered about that break motion setting. Will try all of these suggestions today and see what happens. Thanks guys.

[Rotary Ninja]

Hmm. Still problems. Any other things we could try?

[Rotary Ninja]

Got it. Unlock rotary.

[CNC Brett]

M46 is the unlock code

M47 is the lock code

Just in case somebody else (like me) runs into the same problem

[Brute440]

I know this is an OLD thread but.... CNC Brett, THANK YOU! for posting the solution to your problem. I am chasing the same sort of thing on a Mazak VCN with a 4th axis. THANK YOU THANK YOU THANK YOU

[Mjölnir]

yes, the brake on a Mazak rotary axis is on by default. for continuous motion it needs to be released with an M46.

[crazy^millman]

I know this is an OLD thread but.... CNC Brett, THANK YOU! for posting the solution to your problem. I am chasing the same sort of thing on a Mazak VCN with a 4th axis. THANK YOU THANK YOU THANK YOU

 

A good post builder does this for you. Where did you get your post from?