[Jim Dawson]

Hi guys

Second question - is there any good hobby/light industrial controllers out there that would accept a second encoder input for each axis (for the linear encoders)? Side note - I installed some of the extra 1um encoders on my manual mill as a DRO and I had to limit the decimal places it was displaying to stop me from trying to hit .0000 dead nuts every move.

Thanks in advance for any and all advice/help

I'm not going to try to answer your question on the ballscrews other than to say that 400 W seems a bit light. This is just my gut feel, nothing to really back up that feeling.

The only controllers, in a hobby price range, that I know of that have dual encoder inputs are Galil Motion Control products. There are many units available on Ebay at reasonable prices. There are Galil plugins available for Mach3, and maybe Mach4. I have successfully used 1um linear scales with a Galil/Mach3 system. But be very careful of what you are buying from Ebay, not all of the Galil products listed are compatible.

Having said that, while there are some applications that could benefit from a dual loop system, it is my opinion that using linear scales only is the way to go on a machine tool. I don't care what the motor/ballscrew is doing, the only important position is the table position. On my mill I don't even have encoders on the motors/ballscrews, am only using the linear scales. On the other hand, I am only using the motor encoders on my lathe. Both machines are very accurate and repeatable.