I have a Shapeoko XXL, HDZ and an 80mm spindle. Months ago with help from members here I got my VFD set up and all has been going well.
Last year I purchased a laser and running Lightburn has been working for me as well. Enter the VCarve Laser Module and some problems have cropped up. Some of those issues have been worked around for now but I am having an issue when doing actual cuts (line burns).
In the image below you can see where “burn dots” occur each time the laser stops and starts and changes directions. When I sent this to JTech they replied that I might want to turn down my acceleration settings to 200 or 100 ($120 and $121). I am not clear on what these settings actually do and was wondering if I need to create a macro to set it back to my current settings (400 and 400) when using the spindle or should I just leave them at 200 if this fixes the issue?
Hey @DanSexton,
Sorry, in troubleshooting the vectric bug I ignored this.
I don’t have a ton of experience with grbl controlled lasers, but do you enable laser mode ($32=1)?
Can you share the entire gcode file?
Edit: I thought this was on the other thread, but I guess I’ll respond anyway.
In the image below you can see where “burn dots” occur each time the laser stops and starts and changes directions
Usually the best way to solve this is dynamic power adjustment. Your CAM tool should produce G-Code that reduces laser power as it slows the motor so that you get the same amount of energy for each segment along the path.
In Lightburn, I think this should be automatic as long as you’re using “GRBL” as the device driver.
For V-Carve, it looks like JTech has a post-processor that should handle it. Are you using that already?
I am not clear on what these settings actually do
They change the acceleration of the stepper motors, that is, they change the speed at which the motor goes from slow to fast (or vice-versa).
JTech is saying you should decrease the acceleration, so make the motor take longer before stopping.
I am not clear on what these settings actually do and was wondering if I need to create a macro to set it back to my current settings (400 and 400) when using the spindle
Which G-Code sender are you using? Carbide Motion will reset the settings by default I believe.
I have a macro that I run prior to using the laser and another prior to using the spindle. One of the settings is turning $32 to on and off. I use it before I run Lightburn which works just fine.
Here is the code for the pic I included. It is using the included GRBL PP since I was sending it to Vectric and didn’t want to confuse things by using your workaround PP
That processor is used when modifying an engraving tool and was created before the release of the Laser Module in Vcarve. That method does work but isn’t as inclusive or flexible as the Laser Module.
Jay from JTech replied that they are working on a new video outlining the new steps recommended for the Laser Module, it was his recommendation to change the acceleration settings
CNCjs
So it sounds like it would add time to the project job in general? Are there any negative affects to quality?
It’ll definitely add time, yes. As for quality, I’m not sure but suspect it would depend on the G-Code. For example if you always accelerate/decelerate outside the stock and maintain a fairly constant speed, the acceleration shouldn’t affect any of your cuts. If you’re doing things like plunging directly into the cut and then accelerating into a slotting cut, it’ll mean more time spent at a feed rate below the intended one, which could result in more time spent at a suboptimal chip load.
But I don’t have a whole lot of a clue what I’m talking about, I’d just add the macro to be safe
