I see in the backgrounf what looks like a PC 55 Mill. If so, did you convert that machine also? And if so what did you do to that?
I have a PC 55 Mill and am thinking of upgrading it and adding a 4th axis (A). Currently I am in the process of converting a Prazi SD300 to cnc.
Nice work on your lathe.

its a mill50, no it is not converted but a few people have done so, there is little difference between the 50 and 55 hardware wise, drop
binski a line on cnczone, or try mcgyver on cnczone.nl, he did a conversion with 4th axis also.

may aswell pop in a little update while i am here, i made a jog pendant a while back bbbbbbgvxc using a bidirectional LPT2 card, set the bios to 2 way, and a simple parallel interface = 13 I/0's, i can use it semi- manually now or i have some basic auto controls like spindle start/stop feed hold etc,  and spindle speed + /-  and a rotary switch from incremental to constant velocity on the mpeg modes.
some machined ally and formed perspex. yet to detail legend.

Very tidy looking panel
Hood

ta, still feels a bit quirky turning the dials and cutting but i wouldn't be without it now! it gives the machine another dimension, good for the odd small manual op.

I use my MPG for positioning and touching off only and never for cutting as I find it much easier just MDI'ing if I want a quick cut. If I was going to though I would remove the indent from the MPG and maybe fit something to apply a little it of drag, that way it would make things feel and move much better for manual machining. Maybe yours already are like that?
Another thing I would likely do is use a higher count encoder as I think that would help the control of manual operations, but of course pulse count may be an issue if using the parallel port.
Hood

i stored this machine for 3  years, along with the PC, (hello again) and recently just pulled it out of storage.  Funny thing is nothing worked properly, mach was crashing, spindle not keeping speed.
good news is thanks to forums and members posting i seem to have gotten through some of the initial problems.

First problem, spindle index pulse reading upto 1500rpm then counting half ! after that, so i changed the index debounce to 0.  where as before it was 400/100 .  i changed it to 150/0  in the debounce bounces and it reads well now at any speed.  i also have spindle speed averaging checked, the 's true'  fluctuates a few rpm like 4 or so i think its o.k, its a low inertia drive at high speed so its never going to be digit perfect

Second, actual   spindle speed:  i've spent many attempts trying to cal the spindle, but it always left a dip about 1600-1700 rpm.
i realised that dependant on the number you put into the spindle pulley max, that dip either got worse or better on screen
I cant say how important it is to know the actual rpm of the motor from the decal plate, its been a  few years and i just thought it was 2940,  well, of course all the readings were way off, duh, the motor max was actually 2790rpm. face palm time.   so i tried all kinds of settings 2940 right down to 2000, with different velocities.

after finally putting in the correct resulting speed into pulley max (2511rpm@100% mach out)
i got a fairly linear calibration, with a small dip , heres a shot:



after the cal completed i tried commanding speeds throughout the rev range to see what happened, it was about 20rpm+ plus out on each 200 interval, so here's what i did, i went into the spindle motor tuning and dialled back the spindle velocity a little, about 25 units at a time,  and then rechecked the commanded speeds.  i took about 50 units of the total (it was 1500 before).    and now its fairly close and linear through out the rev range within 5 rpms at bottom end, upto about 2000 its still within 5-10,  get to 2500 its 50rpm out.
 its been a week of late nights, it can make dog meat of you easy!



some settings are here if it helps anyone with a similar set up:
for reference, my index pulse disc is 4" diameter and the slot is 0.460" wide, mounted on the back of the spindle. i'm using a c3 pulse board and sensor.










next problem i have is on the main power supply, i  am too close to 50vdc on my stepper drives , and they  trip / protect themselves regularly when other 1-2kw items switch on the same power supply line (heater)

I appreciate some help here, my PS is as follows;
 240ac into ring core transformer which gives 35ac out, rectifies into dc thru bridge rectifier GBPC15005
I have a 63Vdc 22000uF capacitor before the drives. both drives are attatched to cap.

what is the best way to regulate the drives?

i havent found any dc-dc regulator that will cope with 45Vdc +  so i think i'll swap out the ring core to a 30vac out, this should bring the supply into the drives to arund 41- 42vdc, instead of 49.  i am not comfortable with unregulated supply, still hunting for something to regulate 42vdc to perhaps 40.

Here we are a year later, reviving another zombie thread.

Very very nice conversion!

I am intriqued by your use of the 3-phase motor.  I don't see a VFD to run it.
So how did you do the motor conversion?  Is this superior to the OE unit?

For that matter, what stepper drives etc did you use, or are you using the OE drives?

I am converting an Emco 5 CNC using a Xylotex drive board and 170-oz/in steppers. I have not purchased a spindle motor yet, figuring on buying a used OE DC motor. However, I have a 3/4 HP Clausing/Baldor 3-phase looking for a place to be useful.   I'd like to use it on this lathe if possible.