CNC Skipping G Code Instructions

More
04 Aug 2020 02:22 #177159 by M Sills
For some reason, my linuxcnc set up will skip a rapid. It happens infrequently enough to be an annoyance to trouble shoot but too often to ignore.
When this happens, the DRO and position on the screen update, but the command gets lost somewhere else.

I'm pretty sure it isn't skipping steps. I have a closed loop stepper controller. It doesn't feed back to my board though.
I am not getting the the real-time latency or really any errors. I am running at the default speeds in pncconf.
The board I am using is a 7i76E. I am also using a Rpi4 with a realtime kernel.
My motors are running at 2000 steps per revolution. I have 1/2 - 20 lead screws. My maximum speed is 70 in/min.

If I need to provide more information, please let me know.
Any help is appreciated.

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 05:13 #177173 by cmorley
What makes you think it's skipping rapids?
Unless your rapids are all really short, skipping rapids and missing steps shouldn't be in the same ballpark.

Unless your closd loop stepper closes the loop to linuxcnc it can miss steps without detecting it.
If there is interference between the mesa card and the step driver you can miss steps.

Please post your config files and mention what version of linuxcnc you are using.
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 05:41 #177174 by M Sills
I am using linuxcnc 2.8.
I am also running a lathe.

In one case, I made 2 parts successfully with the same G code. While making the third, it skipped a roughly 1 inch rapid, move to the next line and plowed the bit into my part. When I checked linuxcnc to see what happened, it showed that the tool had move to the front of my part. My tool being embedded in my part begged to differ.

I mentioned skipping steps since I come from a 3d printing background. When issues like this occur, its usually blamed on missed steps or belts slipping. Neither of which are the case on my end.

I also had this same issue running 2.9 on the same setup.

Attached should be my entire config file. One file didn't copy to my usb due to symbol links or something.

If I am missing something, please let me know.
Attachments:

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 05:52 #177175 by cmorley
could you post the gcode file too?

Did the graphics display show the missing rapid?
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 05:58 #177176 by M Sills
I dont have the exact gcode file anymore.
I've been tweaking my setting to set the lathe up better so it has different setting. My problem has still been occurring though.

The specific file I was talking about earlier worked 2 time and failed on a third attempt without any change to the g code or setting.

On both linuxcnc and in fusion 360 the Rapids were shown. I double checked after it had happened.

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 06:15 #177178 by cmorley
To be clear: When I was inquring about the graphics - I meant the after run lines that show you where the tool actually ran (vrs the programmed lines shown when first loaded)

How about G64 could that have got changed between runs?
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 06:28 - 04 Aug 2020 06:29 #177182 by M Sills
If it's the yellow line that gets put down over where it moved (live plot?) then yes, it was there. The tool had only moved on the display.

As for G64, I don't believe I could have changed them.
I'm not really sure how to change it in the first place aside from editing the post proccesssor or G code.
Last edit: 04 Aug 2020 06:29 by M Sills. Reason: clarification

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 06:36 #177184 by cmorley
Do you set G64 to anything in your program or startup code?

yellow lines are jogging.
rapids are shown by a light blue thin line
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 11:43 #177217 by Mike_Eitel
Given your puls length / space would be a bit too short. Not very probable but worth a check?
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

More
04 Aug 2020 12:56 #177237 by tommylight
As Mike said, set the signal length higher, so
DIRSETUP = 6000
DIRHOLD = 6000
STEPLEN = 3000
STEPSPACE = 3000
to
DIRSETUP = 20000
DIRHOLD = 20000
STEPLEN = 5000
STEPSPACE = 5000
The following user(s) said Thank You: M Sills

Please Log in or Create an account to join the conversation.

Time to create page: 0.077 seconds
Powered by Kunena Forum