G-code editing, Z plunge a retract rate and X&Y AXIS

1

Has anymore done minor g-code editing,
A manufacture of CNC engraver I plan on using recommends the following before running a engrave job with their tool holder to get the best results

Tips:

Touch the job and go .020″ deeper to start… using “rapid” (G00) moves for the “Z” helps to prevent digging in on start/stop positions because of the tool could sit in one spot too long on some slow CNCs. You may also need to give a different “feed” for the G02/G03 moves than you would use for G01 because some slower CNCs cut arcs slower than linear moves. This could result in different depths of cuts. The easy way to change all that in a large program is to simply use the “find and replace” function in a code or simple text editor. First find and delete all Feed functions then “find and replace” all G01 with the desired feed, and then “find and replace” all G02/G03 with the corrected feed for the arcs.

IE:

“find and replace”
G01

with

G01 F???

“find and replace”
G02

with

G02 F???

“find and replace”
G03

with

G03 F???

2

I think it’d be better to get the feeds and speeds right in the CAM tool.

I don’t believe Grbl slows down for arcs — you could test that, write a program which would travel the same distance (say corner to corner) and a circle whose diameter matches that distance and time them. If anything, arcs ought to be faster because there’s less need to slow down for corners.

Note that you’ll need to use regular expressions for this editing — usually the F settings are at the end of the line, so it’ll be something like:

G01 X1 Y2 Z-0.125 F800

If you’ll let us know which editor you’re using we can work up which particular sort of regular expression you’d need — should be something like:

Find: G01 X(\d+) Y(\d+) Z(-\d+) F800

Replace: G01 X$1 Y$2 Z-$3 F500

(and if anyone knows of a text editor for Windows which has a Find-replace dialog box which is resizeable w/ multiple lines for each field, please let me know — I really miss TeXshop.app and its wonderful Ogrekit Find-replace dialog)

3

Thanks will, I think I’ll try right running a few sample tests on scrap pieces with their recommended initial procedure of touch off and 0.020 plunge and vary the feed rates and plunge rate and even run the recommended feeds for the material and see what the results are. Since you stated the Grbl doesn’t really slow down as they state it may not be an issue

I’ll post the feed back and results as the holder will be here in a few days.

It’s a 1/4” shank holder with various sized engraved bits and a variable spring loaded assembled for what particular hardness your material is your engraving.
The tension springs are interchangeable for the type & hardness of the material
Thanks for the help

4

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