Dual Extruders and Retraction

[jsc]

From this old thread, viewtopic.php?f=13&t=1431

Simplify3D does some really strange things with the tool change code, like changing from T0 to T0, then from T0 to T1, then T0 to T1 again. It seems broken. I had to go in and fix up the gcode in an editor. The comment at the top of the tool change script makes that easier, as you can just search for "->". You need to remove any instances of weird tool changes manually. Thankfully, they appear to all happen only near startup. Make sure you keep looking until it seems that all the tool changes are swapping back and forth between T0 and T1 regularly.

Also, remember that it's usually running in absolute coordinates, so G1 E-0.5000 isn't retracting the extruder to -0.5, it should be setting the position to -0.5 from wherever it happens to be, and if that is -12 from a previous retraction it should advance by 11.5 (unless the position has been reset in the interrim.

[Tim]

remember that it's usually running in absolute coordinates, so G1 E-0.5000 isn't retracting the extruder to -0.5, it should be setting the position to -0.5 from wherever it happens to be, and if that is -12 from a previous retraction it should advance by 11.5 (unless the position has been reset in the interim.

Ah, right, absolute coordinates. That caught me off guard. I would not expect the extruder to run in absolute coordinates. I guess the firmware doesn't selectively choose absolute or relative coordinates? Then if you want to run the X/Y/Z positions in absolute coordinates, you'd have to keep resetting the extruder coordinates, which is what it does. . .

So the only error in the default Simplify3D code is that they don't do a retraction of the inactive extruder during the first layer. But the solution I have with the gcode script for the tool change actually works without having to do the complicated mess of saving the gcode, editing, and reloading.