Hey guys, I’ve been playing around with some modified GRBL settings for awhile now with the hopes of one day convincing Rob to open up the throttle a bit more on default machines. Please consider these “beta” settings, but if you’d like to test them on your Shapeoko I’d welcome any feedback.
Here are the parameters I’ve modified:
$25 = 1700 // Homing seek speed (for initial touch-off) that I run. If you haven’t flashed settings for your machine since 2018, you may be be at 1000mm/min which would be painfully slow on an XL or XXL. In documentation we’ve suggested 1500mm/min, and in recent builds it may even have been bumped to 2000mm/min. This setting isn’t a big deal, but wanted to give a heads up to anyone rocking the OG grbl settings from launch.
$27 = 1 // Homing Pull-Off reduced, this makes homing super quick. You can use 1.5 or 2mm if you don’t trust your switches or deceleration, but I haven’t seen any issues from this on my machines.
$110/111 = 10000 // X and Y max rate doubled. 5k mm/min was less than 200 IPM. That’s super slow if the machine is repositioning for a new cut on a big project, or even small but numerous repositioning moves in adaptive toolpaths. I would not program any hard cuts at these feedrates, but for rapid (non-cutting) movements these should be safe.
$112 = 1400 // Z max rate for HDZ only. The default is like 1000 or 1200 which is kinda slow, especially if you use Fusion which can plunge fast before slowing down for entry. Above 1500mm/min you’ll want to double check your rail alignment, to ensure sliding resistance is sufficiently low. Would not recommend going above 2k.
$120/121 = 500 // X and Y acceleration increased 25%. I know @Vince.Fab has pushed way more aggressive settings, but baby steps for now… The 400mm/min^2 values have been unchanged since launch, so I have a better shot convincing Rob to make a modest change first…
$122 = 200 // Z-axis acceleration for HDZ. Not sure if this is default or not, but its what I use. Acceleration and feedrate are coupled, so adjusting one may affect the other.
Let me know if you run into any problems with these settings, and/or if you’ve successfully and reliably pushed more aggressive motion parameters. Also please indicate if results for Z are with stock or HDZ where relevant.