FabLab - 3D printing updates

Two things!

Gigabot Calibration! X Y Steps/mm
One while investigating calibration I found a recently updated Slic3r Config from RE3D! They included new calibration settings in their custom Gcode. I don’t know how to update the Gbots firmware (it reverts upon reboot) but here are the new steps/mm:

118.52 steps/mm (X and Y)

Otherwise you can copy paste the custom Gcode to the end of your config ( find the slic3r ini in the fastor/gigabot )

Test result: 1.008in on x & y, from a 1 inch part!

Polar: Loose DC jack
I’ve noticed a developing loose connection on the DC power jack of the polar. It’s severe enough now that moving the Polar can interrupt the connection. Thus, please don’t move the Polar while printing. This occurred when I moved the Polar, and it did not recover, but froze.

My guess is that it was the USB connection that froze it… dropping the power and reapplying it would simply cause the print to skip… we need to secure both of them to the printer to make sure it remains stable.

As for the Gigabot, I downloaded their config files the other day… and unless they’ve been changed, those are the correct values. The command to update the firmware M206 X{value} Y{value} and M500 to save it should be avoided in your code to prevent it from reverting. However, the size I printed the rack for my printer came out 100% dead on using the current values in the printer.

The size of the final part is dependent on the material you are using as well. ABS shrinks drastically when cooled and PLA doesn’t as much. You can fine tune adjust your sizing in slic3r to accommodate that difference… but setting it for one value and expecting to to work for the other simply will not work. The mechanical motion is the value we adjusted the printer default to, not the final parts.



Is that a typo? I can update the firmware with those commands? But avoid doing that?

I just fired up the Gbot, the steps/mm is 121.64 in firmware. So unless someone uses the custom Gcode from RE3D, they will continue to get slight over-sized parts.
Should I go ahead and use this command to try to save it?

M206 X118.52 Y118.52


In my experience, and Ryans, and the Battleships… Parts were always coming out about 2% larger, previous iterations of the same part with 121.64 came out 1.03-1.04"

On this topic, I’m discovering my parts off the Polar are over-size also, but not in a linear fashion.

Part 1:

Interior Diameter 7.88mm ( 6.92mm spec)

ID 83.82 ( 82.68 )

Part 2:

ID 35.08 ( 33.84 )

OD 55.06 ( 53.50 )

Any idea what would cause this? I’m almost wondering if it’s partially a Slic3r issue, but this profile was imported from P3D (high quality)

I should have said M92 is the command to update the steps per mm… but yes, avoid doing it! Setting it to a particular material is not the correct way to achieve accuracy for the printer. Setting it to a mechanical distance is… then adjusting the slicing per material to compensate for the materials differences.


The values of 118.52 are what I set up initially for the Gigabot. They should not be changed… if you’re saying they are now 121.64, then someone else is mucking around with them.

As for the Polar 3D printer, based on your numbers, your print did not start in the center. Most likely it was bumped during the move and knocked out of alignment. I will re-calibrate it tonight.


Well, I haven’t changed them, and anytime I’ve changed settings through the LCD I’ve noticed everything reverts after a power cycle.

  • So yes, let’s change them back to the 118.52 values you set! Does the LCD need flashed to do this?

I’m printing some little test pieces to see where the error is. I will admit I’ve given up on auto-home and resort to sliding the build plate to the end of it’s travel (with the motors off), I just ran two test pieces and this yields a very slight (.4mm?) aberration at the center versus about 1.3mm with normal, 2x homing.

In theory… since I am OCD enough to need this as centered and consistent as possible… I may develop a shim to find home more precisely. It would be nifty if these had some sort of mechanical stop that enables the calibration of “home” or an exact, manual home.


  • Bill discovered that the firmware settings for properly sized parts can only be updated via USB, so until we get that set up use the following GCode in the start of you file:

M92 X118.52 Y118.52

  • Check out RE3D’s default Gigabot config @ FASTOR/GIGABOT/Gigabot_slic3r_config.ini


  • My part suffered some sort of mysterious failure last night… Not sure if it got moved/bumped or skipped a step… Bill I’ll leave it out if you want to take a look. Somehow how the interior is not concentric and the part warped slightly.
  • I’ve erected a crude shield to discourage interaction but also minimize any airflow/warping.
  • I restarted the print, and confirmed the initial dimension is correct! (hoping for the best!)