Re: Building A Cheap DRO

--- In CAD_CAM_EDM_DRO@y..., "cutsgems" <chuknospam@a...> wrote:

> I'd like to add a 3 axis DRO to my mini-mill. I've investigated the
> Calareo/Wholesale tool import digital machine scales & readout box,
> nearly $500 to cover all three axis. So what I had in mind was some
> encoders from US Digital, something like 2000 PPR?? to get 0.0005"
> resolution, use a simple wire under tension wrapped around the axle of
> the encoder to convert the linear motion to rotary. Use an old laptop
> & printer port & available software for the readout.
>
> My questions are the mechanics for the encoder.
> Would a 1000 PPR encoder give me the resolution required if I used
> 0.6369" diameter hub on the encoder as opposed to a .3183 diameter hub
> which would only yeild a .001" resolution. Or am I better off using a
> 2000 PPR encoder with the .3183 hub? (The .3183 is a rough calculation
> required to convert 1" of travel into 1 rev on the encoder).
>
> Secondly, when calculating the hub diameter, how do I account for the
> wire diameter in the calculation? Is it 1/2 the wire diameter +/- the
> hub diameter???? Thanks.

Hi, I came across this site in my travels, and it seems to be just
what you are talking about. http://ns1.dicomm.net/~axtein/dro1/

I am considering experimenting with a system similar to this to drive
servo encoders.

Dean