Build Plate Lowering Prior to Starting Print (UM2+)

[WXML]

Here is what is happening:

1.) Build plate / nozzle heat up then move to the upper left corner.
2.) Printer purges nozzle quickly, then slowly.
3.) Printer performs wipe movement to the right upper corner.
(Problem)
4.) Build plate lowers approximately 3-4 mm and starts printing with this huge gap.

What is weird is that this is only happening to recent prints. I have older prints on my SD card that work just fine. Here is what I have done to troubleshoot:

1.) reset all profiles to default in Simplify3D
2.) leveled the bed twice
3.) compared G-Code from an older print to current print[s] experiencing this issue

Everything seems to match with the G-Code, but I am relatively new to printing, so there most likely is something I missed. I am linking the G-Code that has issues as well as the G-Code from a previous model that has no issues. If any clarification or further information is needed, please ask and I will provide.

http://pastebin.com/ZrpwLuk1 - Old Model
http://pastebin.com/RZD13Mm1 - New Model

[CompoundCarl]

Starting script for the first file:

M907 E1400 ; increase extruder current
G28 ; home all axes
G1 X20 Y10 F3000 ; bring extruder to front
G92 E0 ; zero the extruded length
G1 Z10 ; lower
G1 E19 F200 ; purge nozzle quickly
G1 E26 F60 ; purge nozzle slowly
G92 E0 ; zero the extruded length again
G1 E-5.5 F400 ; retract
G1 X190 Z0 F9000 ; pull away filament
G1 X210 F9000 ; wipe
G1 Y20 F9000 ; wipe
G1 E0 ; feed filament back

For the second file:

M907 E1400 ; increase extruder current
G28 ; home all axes
G1 X20 Y10 F3000 ; bring extruder to front
G92 E0 ; zero the extruded length
G1 Z10 ; lower
G1 E19 F200 ; purge nozzle quickly
G1 E26 F60 ; purge nozzle slowly
G92 E0 ; zero the extruded length again
G1 E-5.5 F400 ; retract
G1 X190 Z0 F9000 ; pull away filament
G1 X210 F9000 ; wipe
G1 Y20 F9000 ; wipe
G1 E0 ; feed filament back

Those look identical to me too, so I'd say your problem isn't with the software. It's putting the exact same commands in both files. Perhaps your Z-stepper driver is overheating or it's a power supply issue

[dorsai3d]

I noticed one thing - the one labeled old model is trying to print the first layer at Z=1. Are you sure you labeled them correctly? The one attempting to print a 1mm layer height seems like it would not likely work well (since the UM2 nozzle is what, 0.4mm?). That's from having raft enabled & a 200% first layer height. The raft gets the first layer overrides, but Simplify3D picks its own layer heights for rafts, so doubling one probably would cause trouble.

[WXML]

Starting script for the first file:

M907 E1400 ; increase extruder current
G28 ; home all axes
G1 X20 Y10 F3000 ; bring extruder to front
G92 E0 ; zero the extruded length
G1 Z10 ; lower
G1 E19 F200 ; purge nozzle quickly
G1 E26 F60 ; purge nozzle slowly
G92 E0 ; zero the extruded length again
G1 E-5.5 F400 ; retract
G1 X190 Z0 F9000 ; pull away filament
G1 X210 F9000 ; wipe
G1 Y20 F9000 ; wipe
G1 E0 ; feed filament back

For the second file:

M907 E1400 ; increase extruder current
G28 ; home all axes
G1 X20 Y10 F3000 ; bring extruder to front
G92 E0 ; zero the extruded length
G1 Z10 ; lower
G1 E19 F200 ; purge nozzle quickly
G1 E26 F60 ; purge nozzle slowly
G92 E0 ; zero the extruded length again
G1 E-5.5 F400 ; retract
G1 X190 Z0 F9000 ; pull away filament
G1 X210 F9000 ; wipe
G1 Y20 F9000 ; wipe
G1 E0 ; feed filament back

Those look identical to me too, so I'd say your problem isn't with the software. It's putting the exact same commands in both files. Perhaps your Z-stepper driver is overheating or it's a power supply issue

My assumption was that it wasn't an issue with Simplify3D, but I figured I would start here first to cover my bases. Thanks for the response, I will check out my Z-stepper.

[WXML]

I noticed one thing - the one labeled old model is trying to print the first layer at Z=1. Are you sure you labeled them correctly? The one attempting to print a 1mm layer height seems like it would not likely work well (since the UM2 nozzle is what, 0.4mm?). That's from having raft enabled & a 200% first layer height. The raft gets the first layer overrides, but Simplify3D picks its own layer heights for rafts, so doubling one probably would cause trouble.

Oh man, how embarrassing. Yes, I did mislabel them, thank you for pointing that out. I lower that value and see how it works.