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KeyboardWarrior
Posts: 478
Joined: Thu Jun 19, 2014 5:02 pm

Tip of the Day 26- G-Code tab, a technical analysis

Thu Mar 26, 2015 3:19 pm

Screen Shot 2015-03-26 at 3.00.07 PM.png
5D firmware (include E-Dimensions): 5D firmware means that your printer supports X,Y,Z,Speed and Extrusion amounts. Almost every printer currently on the market does, so this should remain checked for 99% of printers.

Relative Extrusion Distances: The options for G-Code creation are absolute or relative extrusion distances. For relative extrusion distances, each line would have an E-value that only applies for that line, whereas for absolute extrusion distances the E-values stack up.

Relative Extrusion:
G1 X## Y## E2.5
G1 X## Y## E2.5
G1 X## Y## E2.5
G1 X## Y## E2.5

Absolute Extrusion:
G1 X## Y## E2.5
G1 X## Y## E5
G1 X## Y## E7.5
G1 X## Y## E10

Allow zeroing of extrusion distances (i.e. G92 E0): When using Absolute extrusion mode, the printer keeps a running virtual position of the extruder. Using the command G92 E0 can reset this virtual position to zero, this command is in most the starting scripts for RepRap machines prior to and after priming. Certain printers have firmware compatibility issues with this command and certain printers (relative extrusion machines) don't need G92 E0 commands, so this command will vary from printer to printer.

Use independent extruder axes: Certain firmwares (MakerBot/Sailfish) will track the extrusion rates of printers individually, whereas RepRap printers will use a single running tally (not independent) for extrusion rates.

Include M101/M102/M103 Commands: The tool-tip states that these are legacy commands and not used by modern printers. In looking up these commands this was what I found they used to do (incase your interested):

M101 Extruder on, fwd
M102 Extruder on, reverse
M103 Extruder off

Firmware supports "sticky" parameters: Sticky commands is a great way of preventing much larger G-code files. The way to think of "sticky" commands is something won't change unless it's told to change.

If sticky commands were not supported, changing the X value and extruding
G1 X10 Y10 E1 F100;
G1 X20 Y10 E2 F100;
G1 X30 Y10 E3 F100;
G1 X40 Y10 E4 F100;

With Sticky Commands:

G1 X10 Y10 E1 F100;
G1 X20 E2;
G1 X30 E3;
G1 X40 E4;


G-Code Offsets: If your prints are off-centered or too high off your build-plate the G-Code offsets are a great way to fix that. For instance, if your prints are 2 mm too high off your build plate, apply -2 mm in the Z-axis. If your prints are 10 mm to the right, place -10 mm in the X-axis. You will see these shifts in the G-Code previewer, but since these offsets are what works for your machine then that shouldn't be an issue!

Update Machine Definition using settings below: There are two ways to set the Machine Definition in Simplify3D. Under Tools-->Options (Windows) or Simplify3D--->Preferences (Mac) and under the FFF Settings window. If you set the Machine Definition under the Options window and then find that it's being overwritten everytime you click on your process, that would mean that this option is enabled and overwriting your build volume with different values.


Build Volume: This is pretty straight forward, the only time that it gets a bit tricky is with Delta style printers. For a delta printer, take your diameter and multiply it by .707 (Since Simpliy3D measures the largest square that will fit in your build-plate), you will still get to use your entire build volume when printing, it just uses a different number when setting the build volume.

Origin Offset: If your origin is at the bottom left of your printer (RepRap), it would be 0,0,0. If your origin is in the center of your machine (MakerBot/Sailfish and Delta printers) you take your build volume # and divide by two to place the origin in the center of your build plate.

Homing Dir: This setting doesn't change the print instructions, but just changes the G-Code previewer. You can set where your homing endstops are relative to your axis that way when Simplify3D has a G28 command (home all axis) it will know where the extruder gantry is.

Flip Build Axis: This is for the build area in Simplify3D, generally can leave this as default. If you need to flip one of the axis relative to your origin for your printers configurations you can do so from here.

pinthenet
Posts: 29
Joined: Wed Jan 28, 2015 11:07 am

Re: Tip of the Day 26- G-Code tab, a technical analysis

Wed Jan 11, 2017 4:17 am

I'm puzzled how negative G-Code Offsets can be applied. I have a Vertex K8400 printer, which has end stops on each axis. When I home any axis it moves the print head (X,Y) and/or print base (Z) until it hits the end stops. If that is so, how is it possible to apply a negative offset, eg for Z - the end stop prevents moving the build plate any closer to the nozzle.

Positive offsets are clear. Maybe I misunderstand the concept or the mechanics or FW, or is it just for certain printer types?

?

John

brian442
Posts: 1243
Joined: Mon Nov 28, 2016 5:35 am

Re: Tip of the Day 26- G-Code tab, a technical analysis

Wed Jan 11, 2017 4:37 am

Your first layer is likely printed at Z=0.2mm or something like that, so it's pretty easy to apply a -0.05mm Z-offset. That just shifts the Z position to 0.15mm for the first layer.

If you try to apply larger offsets to where the Z-axis would actually go negative, the printer's endstops will prevent you from moving there, so you're already protected ;)

pinthenet
Posts: 29
Joined: Wed Jan 28, 2015 11:07 am

Re: Tip of the Day 26- G-Code tab, a technical analysis

Wed Jan 11, 2017 8:04 am

OK I think I understand, but I still think it won't work on the K8400.
To calibrate Z I home the Z 'platform' then I raise/lower the the print plate relative to the platform so that it's 0.2mm from the tip on all corners, but the Z platform is still at the end stop so I don't see how I can move it any closer using. Or am I barking up the wrong extruder?

:?

brian442
Posts: 1243
Joined: Mon Nov 28, 2016 5:35 am

Re: Tip of the Day 26- G-Code tab, a technical analysis

Thu Jan 12, 2017 4:51 am

You should really start a new thread if it's something about a specific printer

alderallan
Posts: 1
Joined: Thu Jul 13, 2017 1:34 am
Contact: Website

Re: Tip of the Day 26- G-Code tab, a technical analysis

Thu Jul 13, 2017 2:59 am

Really thanks for sharing the technical analysis. Every time you share a new, informative and helpful thread with us. Keep sharing.

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