gear torture test

thingiverse

I'd like to know if a 3D printed gear can withstand more torque than a Nema 23 stepper and which gear design and material is suitable for this purpose. To gain some understanding, I designed a destructive test. Here are the results: https://youtu.be/Ik0hf_iBz6g For me, it was enough to know that PLA and PETG gears can handle 9 to 12Nm of torque, which is 4 to 6 times the holding torque of the strongest Nema 23 stepper I could find (2Nm). If torque exceeds this limit, I will lose steps but not damage my gear (at least for static loads). I decided to use PETG because it can handle the torque and I expect better performance than PLA if friction increases the temperature. To my surprise, the ABS version failed relatively early. I assume this is due to poor quality ABS. If you want to test it yourself, you will need: * A hanging scale with a capacity of over 20kg * Some strings * Three M5x50 carriage bolts (recommended DIN 603) * Three M5 nuts * A camera To calculate the torque, use this formula: t = 0.1m * weight on the scale * 9.81N/kg * cos(angle of the lever relative to the ground) The "angle of the lever relative to the ground" is a small correction. I measured it based on the camera images. While not very accurate, its influence is only around 10%, and I just needed an order of magnitude. You can use each sample for two tests and don't forget to post your results as a make or comment. Here are the parameters of the gear: * Double helical gear * Module: 1mm * Teeth: 18 * Pitch diameter: 20.785mm * Thickness: 15mm (2x7.5mm) * Designed in Fusion 360 using the helical gear tool The materials used are: * PLA white from Hobbyking * PETG bronze from Das Filament * ABS blue from Hobbyking