A: It is recommended to first watch EP.1 ~ EP.3 of the project compilation on my YouTube channel. You will need to purchase materials such as Raspberry Pico, HX711 load cell amplifier, NJ5 load sensor (YZC-133), TB6600 stepper motor controller, and 57x56 stepper motor. These materials are easy to prepare and not expensive. If the example program runs smoothly, you can prepare the remaining materials. The subsequent production process leans towards mechanical machining. Additionally, you will need tools such as a bench drill, angle grinder, soldering iron, and some basic mechanical machining skills. Follow the tutorial videos step by step to complete the project.
A: No, you cannot. Initially, this project was also made with a sampling frequency of 10Hz, which can be used normally. However, after testing, it was found that a sampling frequency of 80Hz provides more precise, delicate, and faster response control of tension. Therefore, in version 1.96, I added a check for the 80Hz action.
A: You can refer to the test program in EP.3. After testing, the normal drift value of HX711 at 80Hz is about 0.5 ~ 1 gram. Therefore, in version 1.96, I added a drift value sampling during startup for 1 second. If it exceeds 1 gram, it cannot be used. If the check passes, generally speaking, the real-time tension displayed in the lower right corner of the LCD within -10 ~ 10 grams during standby is normal linear drift.
A: Of course, you can use HX711 load cell amplifiers from other brands, but the premise is that they can pass the test program in EP.3. In my experience, other brands' normal HX711s will be as stable as SparkFun's. Unfortunately, other brands may have many defective products that drift. If the drift exceeds 50 grams, it is an error value of 0.1 lb, which will cause repeated fine-tuning of the Constant-pull system.
A: Recently, some people reported passing the EP.3 HX711 test, but still encountering this error during startup. This check is performed on a value obtained by the Wheatstone bridge on the load sensor (YZC-133) after being amplified by the HX711, serving as the initial reference for zero-point calibration. In the EP3 test program, this output is displayed using V0. During development, I found that the value of the HX711 I purchased that tends to drift was negative, and after repairing these drifting boards, the value became positive again. Therefore, I added this check condition. Perhaps my test sample size was not large enough, and positive or negative values do not affect usage. If subsequent confirmation shows that negative values are not a problem, I will remove this check. If you encounter this issue now, please comment out this check (lines 447 and 448 in version v2.12), and then report back to me if it works properly.
A: This has also been something I've always wanted to do. The Wise 2086 bead clip easy head is the most expensive hardware in the entire project, but it's also because it can be easily installed on the NJ5 load sensor (YZC-133) and has excellent clamping functionality. So far, I haven't figured out how to replace it. If you have a good bead clip head design, you can install it yourself. Just make sure to pay attention to the precautions mentioned in EP.9.
A: If all high-quality components are used, the durability should theoretically be quite high. Even if repairs are needed in the future, all the parts are relatively inexpensive and easy to replace.
A: I plan to add English subtitles in the future, but because my usual work is quite busy, I only have some time to work on projects each day. If possible, please give the video a thumbs up and subscribe, as this is a great encouragement for me.
A: Please turn to the back and try adjusting the blue variable resistor to change the LCD contrast. Also, check if the jumper for the LCD backlight is inserted. If everything is functioning normally, you can try connecting only the 5V power, GND, and the 4 pins of the LCD to the Raspberry Pi Pico, if there are no issues, the boot screen should appear when powered on. If it still doesn't work, please check if the four necessary files—main.py, src/hx711.py, src/lcd_api.py, and src/pico_i2c_lcd.py—are present on the Raspberry Pi Pico.
A: Please check if you mistakenly purchased the Active Low Trigger version. The correct version should be the Active High Trigger.
Q: The newly assembled machine cannot perform HX tension calibration and directly causes string breakage.
A: Please check if the 20KG NJ5 sensor (YZC-133) is installed. If a 50KG version is installed, the tension during calibration will fall around 48LB, making proper calibration impossible.
A: If slippage occurs when reaching a certain tension, try replacing the power supply with one that has a higher amperage, such as a 19V 4A or higher. The TB6600 supports a wide voltage range, from DC 9V to 35V, so theoretically, any power supply with 19V and 4A or higher should be sufficient. Additionally, ensure that the 5V converter can handle the input voltage and provide a stable 5V output. If the issue persists, please describe the situation in detail in the discussion area, and I can help analyze the cause.