Emco Compact 5 CNC lathe with tool changer - LINUX CNC, opto isolated parallel port?

Hey guys! I picked up this wonderful little CNC lathe! I want to protect the original electronics as much as possible, so before I do any conversion, since this can easily be controlled by LinuxCNC already, ( see: https://www.forum.linuxcnc.org/30-cn...nless?start=20 ) I want to be extra careful not to damage the original boards since they can be used and my lathe works perfectly : )

Are there any good opto isolated pci parallel port cards or some kind of opto isolated adapters I should look for? A quick search did not reveal too much.

https://www.cnczone.com/forums/attac...d=471640&stc=1

Please forgive the picture being in the wrong orientation, for some reason the forum rotated it that way despite it being correct on my PC.

https://www.cnczone.com/forums/attac...d=471642&stc=1

A lot of the work has already been done on the setup by others except I don't see anything about the automatic tool changer. I'll cross that bridge when I get there.

I'm currently looking for a small 500 watt 3 phase motor if anyone has any suggestions!

I don't know how easy it will be to convert that lathe to linuxcnc . Sam's configurations is for a compact 5 pc which doesn't have that big control panel and connects to a separate pc . I may be wrong but I'm guessing it will need a fair bit of tweaking to get everything functional

I have a tool changer on my compact pc , except it is only connected to use a manual push button through an arduino board , rather than fully automatic . If I spent the time at it I'm sure I can get linuxcnc communicating with it but I'm good with it as it is

Why not a DMM Technologies servo https://www.dmm-tech.com/

or

A SureServo2 (Delta) from Automation Direct. https://www.automationdirect.com/adc...%20asc&start=0

I think what you are looking for with isolation are often called break out boards. Think they used to be more popular a few years ago before other interfaces became available and parallel ports were more common. Here's a link I quickly found.

https://www.cnccookbook.com/cnc-breakout-boards/

Thanks for the tips guys!

Metal Mayhem: you're right about that. I did lots of digging and not every function on my lathe was controllable via the DNC board, atleast from the documentation I had available.

Jim Dawson: Thanks for the links! I probably would have bought those a little bit ago, and I possibly still will in the future. I was able to find though, through days and days of looking, a suitable 3 phase motor. I wound up buying an MR SERIES THREE-PHASE MOTOR - 63 FRAME, 0.45 KW, 3600 RPM, 265/460/60 MR63C2 from RANKIN usa.

The motor is rated at 450 watts (stock motor is 440 watts but the control board can only output around 2 amps continuously making it about 200 watts, it could output 400 watts for a short while, it was some soft of thermal slow blow fuse)

That being said my VFD is only rated to output 240V so I will have a small reduction in watt output to about 390 watts. I bought a 1hp VFD so I should be able to take advantage of some torque boost. Another version of this machine evidently came from the factory with an 800 watt motor (referenced in manual COMPACT 5 PC 90-7 EN2 031) so it's possible the machine may have the rigidity to handle a slightly stronger spindle motor but I was not aware of this at the time.

Jim27, thanks for the resource link! I had previously been looking for an opto isolated parallel port card because I was going to have a db25 cable to straight from the PC to the machine if I could get the PC to control the machine that way. However, with that not being possible I will either use an opto isolated breakout board or a MESA card. I haven't made my mind up, quite yet, on which route to take.

guys I am curious if anybody has any resources on stepper motors SM-072-0060

The lathe uses those and they are 8 wire units, however, they are wired in such a way from the factory that it is a 6 wire output to the stepper motor driver - weird.

I have searched the internet and found some wiring diagrams for 8 wire stepper motors, however, when I go to identify the coils using a multimeter every wire has some amount of connection to every other wire - weird.

I would expect that each respective coil is only connected to wires on the same coil if it is a proper stepper motor.

One very odd thing is that this stepper motor does not exhibit any cogging. And the resistance changes (or seems to) as I rotate the shaft. It almmost seems like a brushed motor, but that can't be possible. The change in resistance measured is probably due to it generating minute amounts of current when I spin it. I did open it up and it appears just like a stepper motor, except with a minimal amount of teeth on the rotor.

8 wire steppers are usually two windings for each phase that can be put in parallel or series depending on the driving voltage. They usually aren't connected in the motor. What are the resistances you measure? The resistances shouldn't change with position but while turning it the coils will generate voltage that can throw off the readings. If they have smaller number of teeth it may be some sort of switched reluctance motor. Those type have no cogging since they don't have magnets.

I haven't had my lathe apart to verify but it sounds like the motors are connected to unipolar drivers

I couldn't find my fluke meter, my cheap multimeter kept giving changing ohm readings! I cannot disassemble the motor enough to take a good look. The halves are pressed together and they're not coming apart!

I did find suitable motors here: https://www.stepper-store.com/produc...x52mm-4-wires/

Getting those would mean I am able to reuse the original stepper motor heat sinks and all of the wiring! I'll just have to notch hor dremel a small part for the wires since they exit differently on these motors.

The only stepper motors I was able to find with a shaft long enough to use the original pulley was x-carve stepper motors. Others with a longer shaft were larger in diameter than the original 6.35mm

Since my motor has a different length shaft, I had to go with a pulley for a 10mm belt vs. the original one for a 12.7mm (1/2") belt. Small tradeoff I think. Should be just fine I hope!

looking at the pics it looks like it is a running machine at least controller-wise . Can you not run it as is ?

Quote:

---

Originally Posted by metalmayhem

looking at the pics it looks like it is a running machine at least controller-wise . Can you not run it as is ?

---

I can, and I have, however the machine only has volatile memory. The only long term storage solution on the machine is a tape drive. When the tape drive breaks it can damage the main board. So then you have to remove the tape deck for the safety of the machine.

The machine only has a gcode capacity of a few hundred lines, and without the proper setup, every line has to be typed in manually on the machines keypad.

There was a DOS program to generate the g code but then you either needed a tape deck to transfer it, or I think you could also do rs-232. But I haven't found the dos software or have patience for that.

I'd rather convert it to some modern controls with the pitfalls of the technology.

Excellent way to learn g code though, young it in by hand really allows you to get a feel for things

bummer , with that considered it's worth an upgrade . As far as learning g code on , they are great little machines for the size and they are fairly precise , I think you'll have fun .
I was fortunate and Sam's configs made things easy for me . The lathe has it's obvious limitations but it has done a great job on the parts I do , and the repeatability is almost dead on once the spindle has been warmed up . At times I get a .0002-.0003" taper over a few inches , which is a bit excessive unsupported stick out on 5/8 -1/2 bars . That can be compensated for by editing the taper into the program

On a side note ,I bought a turret afterwards and finding info on running it wasn't too easy , but they are dead simple . 12v rotates the turret one way and 5v rotates it the other to lock it into place .