Learning while building a cheap and precise robotic arm

Goal is to create a robotic arm with a precision of 0,5mm - 1mm, with a limited budget, basic parts costs somewhere around 100-200€. Another main goal is to learn about mechanics, and try out various mechanical designs (e.g. bevel gear drive, pulley & belt drive, gears, counterweight, ball & thrust bearings etc.).

This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/learning-while-building-a-cheap-and-precise-robotic-arm

This looks like a really interesting project. I’m looking forward to watching your progress.

The bevel gears look very familiar - QTC Gear? If so, you’d really need to find used since a pair would easily be $50+.

Getting 0.5mm accuracy from a system which has backlash or imprecision would be problematic.

  • Stepper motors indeed can provide high angular “accuracy”, so that’s likely a good choice. Weight & heat are not great though.
  • Bevel gears will likely have backlash issues.
  • Belt & pulley would need no slack at all (tensioner)
  • Lead screw: extra potential for small motions (essentially same approach as positioning on a 3D printer for example)
  • Bearings: rarely cause issues

If you have a 3D printer, explore cycloid gearing.

Hope this helps.

Great tips. I have no idea of the manufacturer of the bevel gears. Found an “unbranded” pair from ebay (China), and bought it to try it out. Very little backlash for angular moments, but possibly there is some axial backlash, and most certainly, motor vibration causes issues. Next step is probably to test out a tapered roller bearing on top, but I have to design and manufacture the support for it. I don’t have a 3d printer, but local FabLab has pretty much everything imaginable.

Great project! Very detailed and informative. Thank you for sharing it with us.
I would love to see a video of the robotic arm in action :slight_smile:

Nice to see this in action now. What control software you planning to use?

I’ll probably write a custom control software for desktop computer that will communicate with the Arduino via serial. There are still mechanical obstacles I have to resolve first though.

I am really interested in how you made this robotic arm, could you share the files?