Geeetech A10 Belt Drive Extruder

thingiverse

Why a Belt Driven Extruder: • If you observe extruder hob gear movements during normal operation, it's clear that many of the movements are very small and likely to be approaching the angular resolution of the stepper motor. • Adding a gear/belt reduction of approximately 3.75 between the stepper and the hob increases the stepper movement by that factor and can only help with this resolution issue. • With very small movements, backlash is completely unacceptable. Gears have backlash, but tight belts have no backlash - that's just basic physics. • Marlin's 'linear pressure' feature appears to have some benefits, but it does place even more emphasis on good extruder control and resolution. This design is the culmination of many iterations, and it should go together and work with no issues. In my experience, at least three iterations are required before a workable product is achieved, and this has had many times that amount. The Guide Arm is the key element, and it's derived from a published Thingiverse item. It's printed at 0.1mm layer height and oriented as in the STL file, with no supports required. Most of the design work was completed using 'Onshape', and the following link gives interested parties access to the design files: https://cad.onshape.com/documents/b359a8b1d095f72d54029ff8/w/28d62f2730310813344fd82a/e/9f02cc14353ee78e1b75055d. Use Alt+right mouse to manipulate the image. Assembly: Body: o Clean up, particularly sliding surfaces o Partially tap M5 and M3 holes - the untapped part will lock threads o Insert two MR105 bearings o Screw in a cut-down M5 bolt as the pivot for the guide arm. It should be 15mm threaded and 26mm non-threaded. o Securely fix the Spring Mount with two M3 screws. Mount-Slider: o Clean up, particularly sliding surfaces Guide Arm: o Clean up o Use a 2mm drill to clean out the through hole o Insert two MR105 bearings o Partially tap M5 hole - the untapped part will lock threads o Insert a pinch MR105 using a cut-down M5 bolt to secure. The bolt should have a non-threaded section. o Thin down a M6 nut and use it to secure the Bowden fitting. o Super glue a small piece of Bowden tube as an input guide. Hob/60T Wheel: o Lock the 60T wheel to one end of a 75mm long 5mm rod. o Place one spacer next to the 60T wheel. o Insert into base. o Place hob spacer and hob on top. Firmly press together and securely fix the hob. Ensure all grub screws are very tight. If necessary, file small flats on the rod. o Check that it rotates freely. Install the Guide Arm: o Place a spacer next to the body/MR105 o Position the guide arm o Place another spacer and then the cap. If necessary, glue the cap in place. Note: The Guide Arm must be free to move up and down to allow it to align with the filament and hob. o Insert the spring and plug, and secure with an M3 bolt On the Geeetech A10: o Manipulate the belt, body assembly, and 16T wheel into place o Fix the Mount-Slider and stepper with slightly longer M3 screws o Use two M3 screws, nuts, and washers to lock the sliding parts o Temporarily use a screwdriver lever to tighten the belt, then lock the slider o Finally, adjust the height of the 16T wheel to ensure that the belt is centered, then securely lock the 16T wheel o Ensure everything is tight and then test the extruder with a piece of filament o The extruder direction will be reversed. Either reverse the stepper connections or better still, reverse the direction in 'configuration.h' before compiling and downloading. o Adjust the extruder steps/mm to approximately 390. Fine-tune by extruding 100mm and re-adjusting. 0.2mm layer - Body, Mount-Slider, Spring Mount 0.1 mm layer - Guide Arm, Hob Spacer, Plug, Push Fit Cap, and Spacer All prints: 3 shells and 10% infill (lines), with no supports required.