Confused about Laser Mode E override functionality

Kiplo

Greetings! I'm working on a powder bed printer and the laser mode isn't acting the way I think it should.

Before getting into what I'm experiencing:

I'm using Repetier Firmware v1.0.4

Running on RAMPS v1.4

From the configuration tool:

"...If you have a laser - powder system you will like your E override. If moves contain a increasing extruder position it will laser that move..."

Getting this behavior to work is one of the last things I need for my project to be nearly finished with the first prototype. The printer currently does follow the convention of G1 moves are on and G0 moves are off, so control is working. However, my slicer (PrusaSlicer) always outputs G1 whether it's for extrusion or travel. This means that the laser is always on when moving (if I enable the laser with M3 255 beforehand). Running with no laser commands (straight from slicer) results in the laser never turning on.

I would really like to get the behavior described in the snippet I provided working. I don't see any option to enable E override in the configurator or the Driver.h file that's mentioned in the configurator.

If more information about my setup or configuration settings is needed please ask.

Kiplo

Some more information:

The laser control pin is set to Digital pin 44

I digged some more on this forum and tried running the printer with M452 at the beginning of the G-Code with no M3 commands.

This still did not result in the desired behavior.

Kiplo

Ok, so I got it to finally work right. It was a combination of getting the right absolute E positional settings and increasing the difference in E between print lines.

Here's how to get this working with PrusaSlicer:

In the "Printers" option, go to General -> Advanced -> then make sure "Use relative E distances" is unchecked

While still in "Printers", go to Custom G-code -> Start G-code -> add "M452 ; enable laser mode"

Now, go to the "Filaments" option and set your filament diameter to something really low, 0.2 mm worked for me.

This makes the differences between E values high enough for Repetier-Firmware to consider it "increasing"

Then lastly, go to "Print Settings" and set your extrusion widths to your laser spot size. Set your overlap value by tinkering a bit.

This should get the E override laser mode option to work by using G-code from PrusaSlicer.

Note: This was done in PrusaSlicer version 2.8.0