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Go to Clearance Height Z first before going to XY (no limit switch CNC, no G28; GRBL post)

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Message 1 of 6
sergey.drob
183 Views, 5 Replies

Go to Clearance Height Z first before going to XY (no limit switch CNC, no G28; GRBL post)

Dear All, 

I am not an every-day miller, and time after time I forget about annoying pecularity of my CNC + Fusion,  and ruin my stock every couple of months.

 

I've got a "regular" Chinese CNC3018 with no Limit Swiches, using Fusion 360 GRBL post-processor. (with Safe Rectracts set to Clearance Height). In most of the cases it works fine, except one case: If Home Point is below the top material surface - machine plunges through all the stock while going to first XY coordinate without raising Z to the Safe Rectract. 

 

Indeed the g-code contains the right Z value, but it comes AFTER this first XY movement, and it is too late 🙂

 

When I remember about this - I just change the order of the first XY and Z movements. But sometimes I forget and ruin the stock.

 

What will be the right way to permanently fix my problem? 

 

 

Example of  post-processor generated code:

G0 X47.351 Y45.475
Z23.2

 

How I change it so it actually works:

G0 Z23.2
X47.351 Y45.475

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5 REPLIES 5
Message 2 of 6
a.laasW8M6T
in reply to: sergey.drob

When you select the Clearance height mode it basically disables the retracts, so it cannot retract the Z before moving in XY.

 

The posted code does have a warning to make sure to raise the Z height before starting the program

alaasW8M6T_0-1700866251069.png

 

 

This is definitely not ideal as you can forget to do this(Although it is good practice that I always do anyway)

 

There could possibly be a better implementation of the clearance Height mode in the post but that's beyond my post editing skills

Message 3 of 6

This is my EDITED post that works and does what you want. It sets clearance relative to your g54, not your machine home. G28 should never be a default on these grbl machines which more often then not do no have switches on Z.

Each clearance can be modified per job in the Post window as well! 

Please click "Accept Solution" if what I wrote solved your issue!
Message 4 of 6

Looks promising, but unfortunately it does not work for me 😞 

Tried to open 3 different CNC designs, and it does not want to process them...

 

The error says:

Information: Configuration: Grbl
Information: Vendor: grbl
Information: Posting intermediate data to 'G:\Ьњюѕщ№ фґшёБЃъє\3d\+CNC\Gainta\1001.nc'
Error: Failed to post process. See below for details.
...
Code page changed to '1251  (ANSI - ъєшёАЂшёы»ы»шёЖ†р°)'
Start time: Tuesday, November 28, 2023 2:14:30 PM
Code page changed to '20127 (бЎиЁРђ-ASCII)'
Post processor engine: 4.6034.0
Configuration path: C:/Users/dROb/AppData/Roaming/Autodesk/Fusion 360 CAM/Posts/grbl-v8 (1).cps
Security level: 1000
Include paths: C:/Users/dROb/AppData/Roaming/Autodesk/Fusion 360 CAM/Posts
Configuration modification date: Tuesday, November 28, 2023 2:11:39 PM
Output path: G:\Ьњюѕщ№ фґшёБЃъє\3d\+CNC\Gainta\1001.nc
Checksum of intermediate NC data: a8b63f38309d93359e5bbb4d9661a18d
Checksum of configuration: 8dee38799fe8c2f6370db0a6bfb8187b
Vendor url: https://github.com/grbl/grbl/wiki
Legal: Copyright (C) 2012-2016 by Autodesk, Inc.
Generated by: Fusion 360 CAM 2.0.17721
...

###############################################################################
Error: Spindle speed out of range.
Error at line: 339
Error in operation: '2D Adaptive1 - pocket'
Failed while processing onSection() for record 435.
###############################################################################

Error: Failed to invoke function 'onSection'.
Error: Failed to invoke 'onSection' in the post configuration.
Error: Failed to execute configuration.
Stop time: Tuesday, November 28, 2023 2:14:30 PM
Post processing failed.
Message 5 of 6

Open the post and edit to match your machine. Mine is set for 8-24k

"Grbl post processor configuration modified"
line 339 and 342 to set your spindle speeds."

Please click "Accept Solution" if what I wrote solved your issue!
Message 6 of 6

Thanks mate! Your post is working very good!! I like the approach!

 

Best regards

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