Hi lagfish I don,t normally post much to these sites because I now there are people out there with far more knowlege than I have, perhaps its that fear of making yourself look a dummy, probably completely unfounded but there we are.
The reason I ,m replying to yours is that I converted my X3 to 4 axis cnc using the Xylotex board back early last year and some of what I have learned may be useful to you.
My setup is this:- X Y & Z axis have 14mm dia. x 4mm pitch ballscrews, X & Y axis are direct drive to screws, Z axis is geared through toothed belt 2 to 1 and lifts the whole head not the quill. The fourth axis is a 110mm rotary table (90 to 1).
X & Y steppers are 180N.cm, (don,t know what that is in oz. in.)2.5amp, 4.5v. Z axis 220N.cm, 2.5amp 7.5v. This is controlled by an 800Mhz PC currently using EMC2 for control. I intially controlled this using an old Toshiba laptop that took most of the day to boot (it had Windows 95 on it!) using TurboCNC, great program relatively easy to setup for steppers pity its not been upgraded for a long while now.
My experiences are:- X & Y max feed is 1800mm p/min have set EMC2 to default at 1200, I can,t stop the table against the motors at 1200. Z axis max is set at 600mm p/min and this is marginal as it has locked the motor on the odd occasion, but I think that this is more due to the max output voltage of the Xylotex rather than the motor being under powered as this one is a 7.5v motor and would probably be happier at something over 70volts. I do intend to put a different driver on this sometime in the future as it has caught me out. but for now I ,ll just live with it and take care.
I found the X3 ideal for CNC conversion the only scraping I had to do to get the screws to run smoothly was a few thou. on the Y axis screw nut seating, nothing was done to the dovetails apart from taking time on setting the jibs. What I did find when I came to converting it, I had,nt noticed it while using it as a conventional mill, was that the the left hand column dove tail had been undercut for 5 or 6 inches from the top so inspect yours thoroughly if its new.
Am I pleased with the conversion? you bet I am, works for me.
I found EMC2 a bit more difficult to setup than TurboCNC, it took me longer anyway, but is a good program with a selection of GUI,s that should suite most people and has a number of setup configurations already prewriten including a couple for the Xylotex board, these do need tweaking for individual machines though.
For the future I,m looking at making an attachment to fit on the table to give me a 5th axis.
As an aside I have 2 Emco 5 CNC lathes one of which I have coverted to use other control software but retains about 80% of Emco,s hardware including power supply and spindle speed controler, but despenses with its cpu board and its horrible keyboard and makes it a much more useable machine. But I suppose thats for another topic if anyones thinking of going down the same route with their Emco lathe and is interested.
A bit long but hope it is useful.