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Pi PICO DRO/Quill-Knee combiner

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Hi Fred,
What make of mill?

I am a bit confused on the functionality. I think it is becasue of some slightly loose terminology you are using.

To me, a DRO system consists of two parts: the scale and the display head. I kind of get the impression you are using DRO to mean the latter of these two and that is where the confusion lies.

I am sure you are aware that there are commercially-available 'adder' boxes that combine the knee and quill scales.

The quill scale and knee scale form the inputs to the box. The output of the box goes to your existing head unit display - Sino, Anilam, Sony, whomever.

Hence, please could you confirm that you are aiming to duplicate the functionality of the commercial units in a more affordable package. Thanks.

I'm describing two things with essentially similar hardware:

A) A Digital Read Out  -- i.e. a device that counts/decode and displays numerical position with inputs from a variety of "Scales" or other sources (DRO and Scales are two different things , either can be bought separately) 

B) A Knee and Quill scale combiner that will read two (or more) scales and combines them into a pair (or more)  of quadrature signals for another DRO/CNC/Duberry  . In this case it can Add , Subtract or 'any other function',  if it can be programmed in python.

To be clear, since term-u-know-leggy seems critical  : the scale inputs will initially be TTL (5v) type . Although, I am looking at capacitive caliper type devices , since I have a couple that would do for my small lathe .

While tackling a sine wave resolver with a PICO might just be possible, it might not be quick  (I have a couple of Newall Sphrerical magnetic scales  that i would like to be able to read and heidenhain F series glass scale with sine out  that I'd love to be able to read to sub-micron resolution)  .

I'm building my own because :
1) I can
2) it's cheap
3) It's what we do here ;-)


There was a Brit on Youtube who fitted scales on both the knee and quill of his Bridgeport clone and did something similar, so that he didn't need to reset his  home every time he changed the knee height. John somebody(?). May be worth seeing how he did it, although it may have been in the CNC controller itself. It wasn't somebody on here, was it?

John Rudd:
I too remember seeing a’device’ for combining the readings from a knee and quill, but was done with Arduino….might have the code still somewhere…never got round to implementing it on mine…


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