Where does one define the actual rapid speeds that are used when running? Fusion 360, post processor, GRBL or the GCode sendor (carbide motion)?
It’s a Grbl configuration item, see:
So is it just using the maximum rates?
The maximums are are GRBL settings, but it’s a little more complex than that, as acceleration and length of the rapid change how fast it will actually get (ie. if acceleration is low, but maximum is very high, you’ll never move far enough to actually get to that maximum). Set the acceleration too high on an axis and you’ll skip steps. Set the maximum speed too high, and you’ll skip steps. This needs to be carefully tuned to match the machine. The defaults you get when you set up your SO3 are good, safe numbers. You CAN go faster, but again, you need to know what you’re doing and work slowly.
You can set the rapid speed (G0) in fusion, and often in the sender (which can rewrite it in the gcode as it goes by). If you open your gcode file, you can usually see it set at the first G0xxxxx Fyyyyy. Depending on the post, it may be settable there…depends on the post, some set it multiple times.
@greg5 Can’t I ask WHY you’re asking? What are you trying to accomplish?
The answer may depend on the reason for your asking.
I want to increase my rapid speeds.
I’ll check out the post in F360 to see if anything is set there for it. I do have a license so rapid’s are still enabled.
Ok. Just set them as Will suggested.
It’s your $110, $111, and $112 value for X,Y,& Z, respectively.
Acceleration would be $120, $121, and $122.
Okay so it’s just using the max speeds defined in GRBL for rapid. I will nudge those a bit north. I may actually decrease the acceleration 10% or so as the Husky workbench it sits on is not the sturdiest in the world.
What size machine do you have? On my standard SO3 I have reduced my accelerations by 20% in order to improve finishes. When you reduce your accelerations it reduces the amount of time your machine will actually be moving at the max travel speed.
I’d be curious, if possible, in a post processor to adapt acceleration based on workpiece dimensions. For my own personal needs, a bigger piece will likely be OK with default accelerations. A piece that is 100mm x 100mm not only might improve with 20-30% slower acceleration, but also have almost no impact to the runtime even if there was no benefit from it.
Not with Grbl based machines. Feedrate for rapids is always based on your $$ settings.
Can a post not add these $ settings to the start of the file though?
It could, but that would involve writing to the EEPROM each time the file is run, which is not good practice.
Though I agree, doesn’t Carbide Motion send a G10L2 command every time you start it?
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