I’m looking into using ODrive for my small CNC mill. I’m intending to put 1605 ballscrews on it and I’m thinking about adding ±3µm linear scales and rotary encoders, if it’s sufficiently budget-friendly.
My thinking is:
- To give the linear scales a chance at being useful, I need to be able to hold the ballscrew within ~3µm
- The ballscrew has a pitch of 5mm
- So I need to hold the ballscrew to within 0.003mm/5mm = 0.0006 of a revolution
- So I need an encoder with a resolution of around
(1/0.0006) * 10 = 16666
That means I’m on the very edge of the standard 14-bit CUI encoders. Plus, I’d like a smoother-running motor if I can get it.
So I’m looking into other possibilities.
I found the more prominent encoders from RLS, SICK, Renishaw and the like but these are generally well out of my price range, e.g. >$200 per piece.
This doesn’t make much sense to me because you can buy a whole servo motor with a built-in 23-bit encoder for less than that, so I went looking elsewhere.
I came across this whole thread over at the Granite Devices community (which mainly seems concerned with building racing simulators) that raised some more options:
- Tamagawa - purported to have a 23-bit encoder that costs ~$70. Unfortunately I haven’t been able to determine that the particular encoder (TS5700N5401) actually exists. I’m contacting my local distributor to find out what’s available.
- Yuheng Optics - has a “JKD-4” encoder that supports BISS-C. This one appears to have been used in the simulated racing community on their servo motors. I asked them for a quote for “JKD-4-22PF-G05BL-B-0.3M” (22-bit, 5V, BISS-C) and they gave me a quote for $74.
That brings me to the topic of the main topic of the thread: has anyone been able to find a source of affordable, high-resolution encoders?
Does anyone have experience with the sources I mentioned?