Hi everyone! Since I skipped last month’s update, here are the GBX R&D updates from the past two months:
Updated Firmware Pellet 3.0 (Reg, XL, and XLT)
Firmware version Pellet 3.0 for GBX is published and available for download on the re:3D Knowledge Base. Updates in this firmware version include:
- Updated preheat temperatures
- Fixed bug in Change Pellet routine to ensure consistent extrusion rate
- Build chamber dimensions for XL and XLT
- Ditto printing functionality for using a motorized auger in the feed system
Instructions for flashing the firmware on a printer can be found on the re:3D Knowledge Base.
Hopper Gantry Prototyping
As we built more GBXs with larger build volumes such as the XL and XLT, it became clear that the feed system (hopper, feed hose) wasn’t able to supply a consistent flow of pellets while also allowing the extruder to reach all corners of a larger bed. This is because the feed hose had to be long enough for the extruder to move everywhere in its x and y range, but that created slack in the hose when printing in the middle of the bed.
We tried using a more rigid feed tube strengthened with an internal wire, but it wasn’t enough to prevent slack and mitigate the inconsistent pellet flow. Therefore, we completely rethought the feeding system and created a hopper gantry above the machine. In this design, the hopper moves along rails in the x and y directions, following the extruder as it moves around the print bed. This allows the feed tube to be much shorter, preventing slack. This type of solution is also scalable for even larger bed sizes such as the Terabot X. For GBXs with enclosures, the hopper gantry will be outfitted with bellows to passively keep heat within the build chamber.
The second prototype of the hopper gantry is underway and will probably be ready for test prints next week!
Updated Extruder Cover
The GBX extruder cover has received a few updates, including:
- A fan cover
- The fan has moved from the back to the side of the cap
- The walls of all parts have been thickened for strength
- The extruder cap has internal fins that hug the motor to prevent cap movement
- The attachment point for the front barrel cover has been remade for easier assembly
- The motor spacer is updated for better and easier wire management
Feed Tube Updates
As part of the feed system redesign, the feed tube needed upgrading to pull the hopper along the gantry rails without wearing out over time and causing a pellet avalanche. The new feed tube currently getting tested is a 1.25” OD, 1” ID clear vinyl tube reinforced by an internal wire. As a result of the new feed tube, the feed throat and the hopper collar are also getting redesigned to clamp onto the tube.
