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Thread: Updating an old lathe

  1. #1

    Updating an old lathe

    Been meaning to stop lurking over here and join with something for a long time so decided to put this attempt at converting an old cnc lathe into something modern for anyone interested in doing something like this. Because I dont think there is a perfect example of what to do out there. Just bits and pieces for everything, so please use my failures and findings to help others along this path. First I am pretty terrible with electronics and this is all completely not in my realm of comfort but screw it I am going for it anyway and if I can pull this off then so can anyone else that is halfway functional.

    Unfortunately the memory in my old lathe has started to give out and I decided to go for a mach conversion.

    (stupidly I never took an overall picture this is a real old picture of it after someone gave it a terrible gray paint job)

    What i plan to keep:

    The Zebotronics stepper motors, they draw around 36volts and are 3.5 amp

    The Proximity Home Switches which are a 12v system but I still have very little idea on how this is going to work out
    The circuit breaker for the ac line in

    The fuses on the AC line
    The AC powered fan under the motor/spindle housing and the other AC fan in the computer housing

    What I plan to replace:

    The motor drive board to get something more modern in it
    All the stepper drives
    The breakout board
    The monitor and all the controls
    Eventually modifying the cabinet to use flood coolant
    Eventually modifying the cabinet to be fully enclosed

    What I am using for the conversion:

    A KBMG-212D Regenerative motor drive
    A Gecko G540 board to control everything
    A smooth stepper board so I do not need to use old XP
    A 48 Volt power supply 8.4 amps
    A 12volt wall charger to use to power the home switches
    A 1 signal per revolution tachometer sensor for threading with mach
    an additional outlet from my gecko box for later coolant modifications
    I have a windows 7 32 bit professional tower, that I had for college and havent used in years.
    It has 1 gb of ram, 500gb 7200rpm hard drive, pentium 4 3.something ghrtz, plenty of power for it
    Some usb extensions to easily plug in flash drives.
    I am looking at picking up a usb pendant from VistaCnc
    I have a 10" multitouch monitor to replace the old cvt screen
    I also have a touch screen mouse/keyboard combo which is small enough to fit up top with the screen coming for computer controls
    I hope to just modify the existing face plate up top and cut in the new sleeker displays and keys, there is plenty of room in the box for what I am planning.



    Things I know about the machine now:

    Machine runs on 230 VDC single phase
    The motor is 1/2 hp dc shunt motor drawing around 160 vdc with the stock board, and a field voltage of 180ish vdc, draws around 2 amps under load as far as I measured.
    3 zebotronics steppers, not entirely sure on what sizes they are but they draw 3.5 amps max and run around 36 volt peak at rapids.
    3 proximity h.e.s. style limit switches running at 12 volts
    The tool changer has a 60:1 Ratio that I need to somehow code in down the road but I am completely uneducated on that portion as of now.
    The stock spindle speed was 3000 rpms
    The stock rapids are a bit over 100 ipm (all metric as of right now)
    About what I know

    First attempt is to wire up the motor drive board. Before I did this I was not entirely sure if it was a pm motor or a shunt style. I originally wired it as a pm motor because it is easier.

    I made sure that all the tabs were set correctly for 230 VAC coming in, and had the output set for 180 VDC. I plan on using the Gecko g540 to control the KBMG-212D board eventually off its 10v setting but decided to wire up the 15v potentiometer to try and get the motor driven by something more modern.

    Wiring up the potentiometer I first put a jumper between en and com to get the board to run, then I connected the potentiometer to run the motor in the forward direction. From left to right it was Com, Sig, 15V+ wired into the potentiometer.

    Set the amperage jumper to 2.5 amps and put some power into the board to make sure the potentiometer was changing the voltage coming out at the motor end.

    I then had to figure out which was hot and neutral leading to the two brushes on the motor, both wires were red so I had to run the motor and put a voltage meter on it and see which way read positive and then reversed it to make sure it said negative when I had it backwards to figure out which was hot and neutral.

    Wired them up to the board and tried to drive it... I heard the power going into the motor and it spun slightly, needless to say I was disappointed but then started looking for more wires and found the two that made the field for a shunt motor. I put connectors on these two wires and plugged them into the f slots, didnt know which was which, because they were the same color again, but just went for it. First plug in had the motor spinning the other way, figured I should just switch the field wires again and it did the trick. Started spinning correctly and had good power. I put a reflective strip on the spindle and read the speed with my tachometer and seen that full out it was running at 3400rpms which is great because I am putting 20 more volts into it then the old board could.

    Very successful for day 1, Next up will be wiring in the ac fan and an estop switch on the motor side, as well as mounting the new motor drive board. I decided to keep the bus bar in there and want to use the wires already run through the body to handle all the connections from the gecko g540 board, and the new tachometer that I need to put on the spindle for threading.

    Pictures of the outdated spindle control



    (old ohms resistor under motor)

    (picture of the top brush it still looks to be in good condition)



    Pictures of the wiring and new setup

    (just the drive board with jumpers set correctly for my setup)


    (AC line coming in from the other side of the lathe)

    (AC side wired in )

    (potentiometer and jumper wiring)

    (full wiring of the board with the shunt motor field wired in on the bottom left and the motor outputs on the top left)

    A small video of the first bit of success

    (lets see if this linking works)

    Next step is to setup the mach in my computer and try and get the drive board going with the steppers, then stripping out the stepper control cabinet to put in the new components.

    Update My computers mother board died today lol. Ordered a new computer off ebay for $80 its the exact same one funny enough.
    Attached Images Attached Images

  2. #2
    Welcome to my forums. That's a pretty Epic first post!

    I cheated and bought my CNC's as working units, although I have rebuilt parts on the mill a few times. Colin (from Deadlywind) built his lathes IIRC and there are others here that have done similar projects too.

  3. #3
    Insider ElPanda's Avatar
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    this is neat

    love seeing people re-rig their equipment
    ABET accredited level II machinist - CNC Programmer - Mechanical Engineering Technologist
    Rio Grande Inc.

  4. #4
    Insider PBSteve's Avatar
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    Holy crap.
    Ever so many citizens of this republic think they ought to believe that the Universe is a monarchy, and therefore they are always at odds with the republic. -Alan Watts

    I work for the company building the Paragon

  5. #5
    Insider
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    First I am pretty terrible with electronics and this is all completely not in my realm of comfort...
    That is exactly the right attitude! You have our respect with that.



    Those are standard industrial contacts - and they look bruised! Should be a weidmuller or Phoenix Contact or similar. If you need replacing just get a model number, they can be found easy, along with the relay. I deal with them all day long.

  6. #6
    Wayne
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    Very cool project.

  7. #7
    Thanks for the reply guys

    Ok another small update.

    I received the second computer to replace the initial one. I am happy that they are the same computer, I stole the ram out of the dead computer, the floppy drive, the second cd drive, and the hard drive just because I could. The second computer I got had linux mint installed on it so my initial concept was to plug in the hard drive with windows 7 in it and change the load order to load windows first. It started to work then went blue screen of death, tried to recover it and no good blue screen of death again. So I formatted the hard drive with windows and tried to reinstall windows 7 again. It did not like that and I had to do a little research online, where I found that windows doesnt like to make a partition if linux is sitting on a hard drive, so I had to go back in and turn off the linux hard drive before I was able to install windows. After that I was able to turn both hard drives on and change between the operating systems if need be. After that I put mach into the computer and left it at that.

    (old computer stripped out)

    (new computer loaded up with additional features just because why not?)

    (side by side new one is the non dusty one)
    New computer details now
    intel duo core processor 2.66 ghz
    4 gb of ram now
    2 hard drives, one with windows 7 32 bit the other with linux mint 17 I think
    2 cd drives and a floppy drive.


    Next step will be to get the ethernet cable to link to the smooth stepper drive and then get the steppers wired to the gecko g540 board and get them moving in mach, hope to start on this in the morning.

  8. #8
    Linked the smooth stepper board to the computer no real drama there just followed the instructions and copied and pasted the files into the correct area of mach and all was well until I get this error message

    if anyone knows the work around for this I would be very grateful, I need to do some research and head scratching to get rid of this little annoyance. I have an estop setup but its not set to do what that is asking and it lets me through the message its just a small pain Id rather get rid of if anyone knows.

    After the smooth stepper board I enabled the charge pump to get my gecko g540 to go green and be ready to run steppers.




    Here is the old components in the cabinet.

    Up at the top bus bar are all the stepper wires connecting into the old board. I am using the wires from this terminal location.


    (back side of the first pic)


    (some large capacitors and a large power supply I believe)

    So i am not exactly sure which wire goes where but I know that they are 4 wire stepper motors and figured I would just plug the wires in the same way I take them out of the bus bar. I wired up the three steppers and when I jog I get a little movement. I need to adjust the jog amount and the motor tuning section to better work with these, this was a metric machine and I just left the settings that were already there, I need to start stripping the cabinet out and then working on getting the motors running as they should.

  9. #9
    Insider Davros's Avatar
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    Florypb505: Stop lurking, you are a bad ass. Wow.

    If you ever need help with dual booting, please ask me. I could have solved that problem for you with less work. Have done hundreds of successful dual boot installs. BTW, Windows will make a partition if you tell the partition manager to do so. Windows is programmed that if it finds an enemy operating system to destroy its bootloader, but if you make a partition on that drive windows will go onto it. Regardless, point is ask for my help to save time if you need to do this again. (Just the computer, rebuilding that machine is light years out of my reach.)

  10. #10
    Insider Dayspring's Avatar
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    Floppy drive? Can you even get media for that anymore?

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