4-axis postprocessor problem... 1

[Bailar]

I have problem with 4-axis post. When I mill cylinder (for example) with variable contour method I have the following :

N0088 B0.0
N0089 Y9.563
N0090 B112.5
N0091 Y9.562 B120.
N0092 Y9.563 B135.
N0093 Y9.562 B150.
N0094 Y9.563 B165.
N0095 Y9.562 B180.
N0096 B210.
N0097 Y9.563 B270.

As you can see I have a jitter on Y coordinate
Must be:

N0088 B0.0
N0089 Y9.563
N0090 B180
N0091 B270


How can I avoid of this jitter?

 

[wmalan]

First, does it show up in your cls output?

--
Bill

 

[Bailar]

Yes Wmalan, I can see the same trembling in CLS output. It's look like problem with NX not postprocessor? I use 6.0.1.5.

 

[joycejo]

How are you defineing the tool axis and projection vectors?
What is the Intol / Outtol set to?

For 4 axis work I will usually set the tools axis as towatd line and use the centerof rotation. Then set the projection vector to tool-axis.

In Post builder you can remove the redundent 4th-axis moves by including the custom command pb_cmd_combine_rotary.tcl



John Joyce
Tata Technologies
1675 Larimer St.
Denver, CO

http://www.myigetit.com

NX3,4,5,6 Solid Works, Pro/e, Solid Edge

 

[Bailar]

Joycejo,

I defined tool axis and projection as you had explained before (toward line -> center of rotation ), also I used pb_cmd_combine_rotary.tcl to reduce number of rotary coordinates.

Intol / Outtol set to default = 0.03

I uploaded part example(NX6), post and post output. Please take a look.

 

[Jaydenn]

First off,
You must remove the "PB_CMD_combine_rotary_check" from the linear move event.
I have verified this. you will NOT get combined blocks if the event is there. Read the instructions carefully.

As far as your file goes, Try replacing the drive "solid" with something else...

I modeled a hole thru the part and used that as a drive surface. It sometimes makes a difference.

Also, I got better results using a ballnose endmill.

Good luck

J

 

[Bailar]

According to instructions I placed "PB_CMD_combine_rotary_init" to "Program Start Sequence", "PB_CMD_combine_rotary_output" to "Linear Move", but I'm a little confused where to place "PB_CMD_combine_rotary_check"?

"
# This function will only work with NX3 or later.
# Add the follow line (without the #) to the custom command
# PB_CMD_before_motion.
# PB_CMD_combine_rotary_check
"

Where must I place these two lines? It's not quite clear from
instructions.

 

[Jaydenn]

That is a little confusing...
It's actually only one line you are placing.

Read it like this...

This function will only work with NX3 or later. Add the follow line (without the #) to the custom command PB_CMD_before_motion.

# PB_CMD_combine_rotary_check

You just add the one line.

J