[SOLVED] Missing first layer

[WatsonGravy]

First time OP, long time lurker

I have a specific stl file that S3D cuts the first layers (including skirt) off of when generating the gcode. I have tried to print this gcode and the nozle raises to high off the bed and it begins the print at layer 2 or 3.

I tried about 20 other stl files leaving the process the same and the gcode generates correct, and starting from the first layer.

This is the gcode in question, you can see the Z raises without printing the first 2 layers or skirt:
G90
M82
M106 S0
M140 S70
M190 S70
M104 S200 T0
M109 S200 T0
G28 ; home all axes
G29
G92 E0
G1 E-1.0000 F1800
G1 Z0.475 F1002
; layer 1, Z = 0.225
; layer 2, Z = 0.475
T0
; tool H0.250 W0.420
; inner perimeter
G1 X143.982 Y87.825 F7800
G1 E0.0000 F540
G92 E0
G1 X144.436 Y87.189 E0.0348 F3060
G1 X145.034 Y86.555 E0.0736

Example of a different stl file with the same process:
G90
M82
M106 S0
M140 S70
M190 S70
M104 S200 T0
M109 S200 T0
G28 ; home all axes
G29
G92 E0
G1 E-1.0000 F1800
G1 Z0.225 F1002
; layer 1, Z = 0.225
T0
; tool H0.250 W0.462
; skirt
G1 X114.790 Y123.330 F7800
G1 E0.0000 F540
G92 E0
G1 X114.801 Y123.320 E0.0007 F1260
G1 X114.860 Y123.268 E0.0045

Any help is appreciated.
Thanks
WG

[brian442]

It would probably help more if you posted the factory file (File > Save Factory File)

[WatsonGravy]

Attached the factory file to OP.

[dkightley]

The bottom of the mesh is not fully flat. The two strengthening webs three quarters way down the side have something too small to actually extrude slightly lower than the rest of the face.

Change your models Z position to -12.75mm, reslice and you'll see what I mean.

Change it to -12.70 mm and you get a full first slice.