retrofit on EMCO PC turn 55

I didn't even try to use ANY of the existing electronics. I just didn't think it was worth the effort and I didn't have sufficient documentation to try it.

I bought Kelinginc KL23256-21-8B steppers. They are physically the same size as the original motors but I'm pretty sure they have significantly more torque. OEM max speed is 30 IPM but I run the new motors at double that and they will even go tripple but I don't think that is a good idea for a number of reasons. Also keep in mind the original motors are 5 wire motors and you may have trouble finding drives to run them. Another piece of important info is the original motors are NOT NEMA motors. The shaft is smaller and the mounting holes are spaced differently. I had to modify the mounting plates and drill out the pulleys to fit on the new motor shaft.

These motors in bipolar parallel are a VERY good match to a Gecko G540. I used the G540 because it is cheap and works very well. It has the VFD interface built in that you will need to control a new VFD to run the existing 3 phase spindle motor. Kelinginc has a excellent price on them as well.

I used the original 24 VDC power supply because I needed 24 VDC for the turret. I was a little concerned that 24 volts might not be enough for high speed stepping but it worked out fine.

The only items I had to buy were:
2 steppers at $30 each
1 G540 at $240
1 GE TECO VFD at $120 (from dealers electric ). I used a 1 HP FM50 with 120V input 240V 3 phase output.

I am using an old PC with 2 parallel ports. the second port is needed for the turret.

chuck1024 wrote:

Also keep in mind the original motors are 5 wire motors and you may have trouble finding drives to run them

As I said, you can run a 5-wire motor on any drive. On a bipolar drive you ignore the centre tap wire and leave it unconnected. On a unipolar drive, it is the 0v return wire.

There are two HAL components for controlling different types of that class of lathe tool holder here:
wiki.linuxcnc.org/cgi-bin/wiki.pl?Contri...oolchanger_component

Are the original motor drives step/dir or do they use an alternative (serial?) interface like the Boxfords originally did?

When I did my conversion, I was misinformed that the 5 wire motors were oddballs and not compatible with gecko drives.

I do not know the EMCO driver interface. I read in another forum that they are step/direction drives but EMCO refused to release any info on products they currently support. Frankly I didn't think it was worth the time to reverse engineer electronics hardware that is almost 20 years old anyway. What are you going to do when one of the old drives fail? Either pay a lot to replace it with more old hardware or do an upgrade. I chose to gut all the old hardware and install a G540. In the process, I remove the entire red cabinet on the back of the lathe and installed the G540 and old transformer in the lathe cabinet. I have less than 500 dollars invested for 2 steppers, a G540 and a VFD.

I wrote a component to control the tool turret. Most of the discussion is in another thread. I can post the code in that thread when jrkeat gets to that point in his conversion.

chuck

So I shouldn't have trouble running the original motors, as long as I don't mind the original slower speed?

As far as the computer is concerened, what are the constraints? For example, could I use on of my laptops and just buy a pair of USB-> DB25 parallel adapters? It has been 10 years since I used any version of Lunux, and at the time it was pretty finicky about hardware compatibility--I'm not sure if this has changed or not. I'm also not sure if come components meet real-time demands, while other don't.

jrkeat wrote:

So I shouldn't have trouble running the original motors, as long as I don't mind the original slower speed?

Yes. Which sounds like it might be easier if you don't have a way to make adapter plates.

As far as the computer is concerened, what are the constraints? For example, could I use on of my laptops and just buy a pair of USB-> DB25 parallel adapters?.

The main constraint is, no USB. It has too high a latency (and the USB-parallel convertors don't give a proper parallal port, they are only useful for printers as the pins are not (typically) individually addressable

I would look at fitting a mini-ITX board inside the existing case. The Intel BOXD425MW is very cheap and known to work well with LinuxCNC. It has one onboard parallel port. You would need to count pins carefully to see if that is enough.

One possible upgrade would be to add a Mesa 5i25 and the 7i76 board (for more IO, much faster step rates and built-in VFD control.)

If it was my lathe, and because I have some nice little NEMA23 brushless servos, I would be looking at a D525MW, 5i23 and 7i39 combination.

How would the D525MW work? Chuck says the job requires a DB25 for the turret, and either the Gecko or the 7i39 requires another. So two DB25 parallel ports, which seems like its one more than the D525MW can be set up for.