Filament holder with weight sensor

thingiverse

This is a filament holder with an integrated load cell to weigh the filament spool in real-time, allowing for precise tracking of remaining filament without needing a separate scale. I designed this to ensure I always have enough filament for a print without having to resort to using a scale. Pros: It works as intended. After testing it on several prints, I've found that the load cell is accurate to within +/- 0.05 lbs. However, calibration and accuracy will depend on how well you calibrate the load cell. Cons: 1) I need help with this issue: when I power cycle the load sensor PCB from Spark Fun, the calibration and tare weight settings are not saved. I'm not familiar enough with software to modify the code that was pre-loaded in the PCB to save these settings. 2) Because of this problem, I never turn it off, which is inconvenient. 3) A load cell with a range closer to the full weight of the filament (typically 2 kg) would be more accurate. Most sensors offer some percentage-based sense errors based on full scale. In this case, I'm using a 10 kg load cell, which means the error is slightly higher than if I were using a load cell that's at 4 kg. However, I still get +/- 0.05 lbs accuracy, which is good enough for me. Assembly BOM: 1 x Spark Fun Open Scale (SEN - 13261) 1 x Spark Fun Load Cell 10 kg, Straight Bar (SEN - 13329 ROHS) 3 x McMaster Carr 6389K228 4 x McMaster Carr 2515T180 (Optional if you want the leveling feet) 2 x M5 x 25mm L Socket Cap Head screw 3 x M4 x 16mm L Flat Head Socket Cap Head screw 4 x M3 x 10 mm Pan Head Philips screw 1 x USB to mini-B USB cable Tools: M4 Tap M3 Tap 5/16 - 18 Tap Wire stripper for 0.8 mm wire (Be gentle when stripping back insulation) Software: Serial Port Communicator - Options below 1) Arduino IDE serial port communicator 2) Tera Term (This is my preference) Go to this link for a tutorial from Spark Fun: https://learn.sparkfun.com/tutorials/terminal-basics/tera-term-windows Assembly Tips: 1) When mounting the load cell, ensure the M4 side of the load cell faces the filament side. You'll see an arrow sticker on the end of the load cell; make sure it points up to avoid a negative weight reading. 2) Practice cutting insulation back on the load cell wires before cutting to length. Take your time, as you can easily cut through both the conductor and the insulation. 3) Sorry for making you tap threads. Using Spark fun load cell: Go to this site for tutorial on the open scale PCB: https://learn.sparkfun.com/tutorials/openscale-applications-and-hookup-guide For setting tare weight (Setting weight to be Zero with an empty filament spool), use your most often used empty spool. I'm guessing most filament spools will be close in weight, so using your most often used spool ensures you have the best weight info most of the time. Feedback for improvements is welcome. Print Settings Printer Brand: MakerGear Printer: MakerGear M2 Rafts: Doesn't Matter Supports: Yes Resolution: 0.2mm per layer Infill: 50%