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GBX Update Mar 17 2020

Hi everyone! I hope everyone is staying safe given the pandemic. In the meantime, below are the GBX R&D updates from the past month:

Material Testing

  • rToner Colorant Pellets: Black chairs were printed from coloring Innofil rPET pellets with recycled toner pellets from (2D) printers.
  • Fiberon HDPE: Kara has been testing the Fiberon HDPE and had some initial success printing on milk jugs and packaging tape (made from PP). Will be ordering HDPE film from McMaster Carr to print on. 
  • Basalt: A customer came in wanting to print with a lunar simulant (basalt) mixed into PLA. The material came in jagged pellets that looked like gravel. To help the material flow better, it was discovered that a vibration motor mounted to the feed throat was enough to shake the pellets into the screw and prevent material clogging.

 

Standard enclosure
Previous temperature testing of a standard GBX enclosure showed the build chamber only reached up to 40C, which is much less than the 60C reached by standard enclosures on re:3D’s FFF printers. Bellows designed for the high temperature enclosure were added to the standard enclosure to decrease the volume of the build chamber. Temperature testing shows that the build chamber now reaches up to 55C when the bed is heated to 115C.

A bottom panel for GBX was designed and must be manufactured and installed on an in-house GBX. The addition of the bottom panel will probably help the build chamber heat up an extra 5C to reach 60C.

New Feed Throat
The stopper location on the feed throat is moved to the side to improve material changing. Also, lofted surfaces are extended to have smoother flow through the part. Lastly, the top ring is thickened to prevent breaks.

Testing Higher Material Output
Many parts have been updated to improve max extruder torque: motor coupler insert, radial bearing around the extruder screw, updated motor driver, new gear box, and stronger extruder motor. Maximum mass flow used to be 0.31 kg/hr (Innofil rPET with a 1.75mm nozzle at 30mm/s). Any higher, and the motor could not turn the extruder screw. With the new changes, GBX can extrude 0.41 kg/hr (Innofil rPET with a 1.75mm nozzle at 40mm/s). Further testing will be conducted to find the new maximum flow rate.

GBX Cover
To cover the extruder and tidy up the wiring, a 3D printed cover was designed to slide over the fully assembled extruder of Gigabot X. The cover is made of polycarbonate to withstand the higher operating temperatures of the machine. The cover still allows for air flow from the fan on the heat sink. Pellets can still be easily loaded or removed from the feed throat without needing to remove the cover because of the new stopper location on the feed throat. 

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