Start with DRO to CNC

[pacrat186]

Hello, Very new here and to CNC.

I am planning on converting my knee mill to CNC over the next year, but after I finish building my mini CNC mill.
I need to install DRO on my knee mill to have repeatable accuracy for some of my projects. For the cost of a decent quality import 3 axis setup I could purchase a dedicated computer and 4 high quality linear slides (X,Y,Z-quill,Z-Knee) and a rotary encoder for my rotary table.
My question is this, I believe it is possible by what I have read, but it is currently all a jumble in my mind right now. Can I use the EMC2 software for reading them in just a DRO mode, then as funding allows, use the DRO slide and rotary encoders as positional feedback in a closed loop stepper or (dream) servo motor CNC system.
If this is reasonable and possible then I would have around $600.00 usd available to put toward ball screw upgrades for the table, variable speed motor for the spindle,or stepper motors after building the DRO.

Dave

After writing this I thought, if I use my old laptop I could get the ball screws and rotary encoders (higher resolution I believe) for the X,Y lead screws immediately and already be partially ahead of the game.
Any input would be greatly appreciated.
I know if I purchase a DRO I would have it up and running within a month with shipping where as making it myself would take longer but would have me learning something. I am not afraid to do a little work but need to know if this is a reasonable idea that would benefit me before laying out a lot of money.
Thank you again,
Dave

Already going cross eyed with the information and ideas here.

[stustev]

Yes, you can use EMC as a DRO display as you want. Go to www.linuxcnc.org. Join the users list and ask your questions. They will be happy to show you where to look. Your feedback should be quadrature. You can the hook the A channel to a parallel pin and the B channel to a parallel pin. You will then use a software encoder to accept the A and B pulses. The software encoder will generate the position signal for the display. The connection configuration from the parallel port to the EMC display is done in the HAL section. Do this for each axis and the GUI will show the axis movement. You will have several choices for GUI also. You will not need much hardware. Your laptop will do nicely (protect the keyboard from chips and coolant). You will need a DB25 connector for the parallel port, a signal cable with enough conductors for eight signals, a power supply for the encoders, and a terminal strip to connect the signal wires in the cable to the signal feedback from the position encoders. Make sure the scales and the rotary encoder output quadrature.
Have fun.
Stuart