I'm not sure where to put this so decided to start a new thread. I mentioned I was converting a Sherline Lathe to CNC here. (http://www.modelenginemaker.com/index.php/topic,6206.15.html) I've taken another step and it seems to be working.
The basic machine is a Sherline Lathe with the Sherline CNC conversion, NEMA 23 stepper motors and a Gecko G540 drive. I'm only using two of the four axis in the G540 but it was an easy way to go and I may need them for another project some day. I'm using LinuxCNC through a parallel port. I put the 50V power supply, a 5V supply for the encoder and the G540 in a nice driver box.
(http://www.currin.us/LinuxCNC/Lathe-1.jpg)
I designed and built an encoder system. It uses a 60 ppr encoder with index on a 1:1 timing belt to the spindle. (If anyone wants the drawings for the encoder mount let me know.)
(http://www.currin.us/LinuxCNC/Encoder-Graphic.jpg)
(http://www.currin.us/LinuxCNC/Encoder-4.jpg)
(http://www.currin.us/LinuxCNC/Encoder-3.jpg)
In setting up LinuxCNC for the Sherline I was amazed to find encoder settings in the Stepper Wizard. This made set-up very simple. Some of the LinuxCNC diagnostics showed the encoder was being read by LinuxCNC. Woo Hoo!
Long story short, I turned a short piece of AL to .25". Then with great faith and a prayer I typed in a threading G-code (G76) and pressed the go button. I was amazed and mesmerized that it cut a thread.
https://www.youtube.com/watch?v=F4BSlNbms2E
In fact I was so mesmerized that I got around to adding more lubricant just after the last pass. Anyway, there is progress. Now I have another neat tool, I just have to learn how to use it. Oh yeah, also add spindle control and home switches. But it works. There is a write up on the LInuxCNC forum (https://forum.linuxcnc.org/26-turning/30181-sherline-lathe-conversion?limitstart=0) with more blow by blow descriptions if anyone has an interest. Glad to answer questions here though.
Hope this is of some interest to you. Thanks for looking it.
Hugh