Simplify3D User Forum

Hello,
S3D adds an initial retraction at the start of every gcode, just after the start script lines. A few lines later, thie initial retraction should be undone by unretracting the same amount of mm (according to a previous topic in this forum, https://forum.simplify3d.com/viewtopic. ... n+at+start .
But in my case, this initial retraction is never undone, resulting in "none-extrusion" for the first millimeters of the first layer. A sample gcode part looks this way (the important lines marked with "***":

G28
G92 E0
G1 E-4.5000 F1200 ; <--- ************* RETRACTION AT START
G1 Z0.200 F1002
; process Process1
; layer 1, Z = 0.200
T2
; tool H0.200 W0.400
; inner perimeter
G1 X90.600 Y90.600 F4800
G1 E0.0000 F360 ; <--- ************* UNRETRACT 0 mm ?????
G92 E0
G1 X109.400 Y90.600 E0.5628 F1350
G1 X109.400 Y109.400 E1.1255
G1 X90.600 Y109.400 E1.6883
G1 X90.600 Y90.600 E2.2510
; outer perimeter
G1 X90.200 Y90.200 F4800

I tried this with different printer profiles, each time with the same result... S3d version is 4.0.1

Can anyone help?

4.0.1 works fine for me. If it disable retractions there aren't any in the file.

Maybe you should post your factory file if you're still having trouble.

Hi,

I'm having this problem too. The first layer is having under extrusion problems due to the retraction before the first layer begin.
Gcode example:

G1 Z0.2 F1000 ; move down to begin wipe
G1 X110 E6.0 F10000 ; wipe print head (extrude material while we do this)
G92 E0.0 ; reset e count <---- END MY GCODE START SCRIPT
G92 E0
G1 E-5.0000 F1500 <------ EXTRA RETRACTION AT THE FIRST LAYER?
G1 Z0.150 F1020
; process Process1
; layer 1, Z = 0.150
T0
; tool H0.150 W0.504
; skirt
G1 X75.029 Y81.763 F7800
G1 E0.0000 F450 <------ NO EXTRUSSION HERE??
G92 E0

The line "G1 E0.0000 Fxxx" already primes the nozzle to make up for the retraction you highlighted. It is using absolute extrusion distances, so moving from E -5 to E 0 will prime 5mm.

If you want more info about this, I recommend reading this nice guide on the S3D site:
https://www.simplify3d.com/support/arti ... -tutorial/

Hi @rrdavis,

I still think it is a bug. I don't know how that G1 command correctly prime the nose if no extrusion if being performed (E 0.0000)?
If I change the parameter "Relative extrusion distances" to True (at the fff profile I posted earlier), the GCODE now shows a correct G1 extrusion command and therefore, a good first layer.

Example:
With relative extrusion distances to true:

; process Process2
; layer 1, Z = 0.450
T0
; tool H0.450 W0.504
; skirt
G1 X42.004 Y72.709 F7800
G1 E4.0000 F510

With relative extrusion distances to false:

; process Process2
; layer 1, Z = 0.450
T0
; tool H0.450 W0.504
; skirt
G1 X42.004 Y72.709 F7800
G1 E0.0000 F510
G92 E0

Is this the expected result?

Yes, that looks absolutely correct to me. Read the link I already posted. It explains plenty about the E-values and how to decipher these commands.