Emco Unimat lathe CNC retrofit


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    Default Emco Unimat lathe CNC retrofit

    I recently purchased a used Emco Unimat lathe. Model no. is not mentioned on the name plate. I gather it would be a DB200 or SL1000 or even an older machine than that.

    Emco Unimat lathe CNC retrofit-emco-unimat-lathe-jpg

    I am planning to retrofit this to a CNC.
    Currently I have planned for 4 motors

    1. Replace Universal spindle motor (this seems to be around 100W) to a 100-150W BLDC motor with speed control.
    2. Stepper Motor (7kg-cm, NEMA17) for tool X movement.
    3. Stepper Motor (7kg-cm, NEMA17) for tool Y movement.
    4. Stepper Motor (10kg-cm, NEMA17) for tailstock linear movement) for drilling and threading operations.

    Will Mach3 or any other software will be capable of controlling these 4 motors. I mean does any CNC software support speed control of spindle motor and also tail stock motor control for drilling tapping. In this case what kind of controller will I need for the spindle?
    I am aware that x and y axis need a driver that will receive step / direction signals from Mach3 but am not so sure about Mach 3's capabililty at handling 4 motors.

    If Mach3 cannot do this is there any other software that can achieve these functions?

    Thanks in Advance.

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    Default Re: Emco Unimat lathe CNC retrofit

    Mach 3 will certainly manage a 2-axis lathe and control the speed of the spindle, and with a suitable spindle sensor will do threading. Lathes don't normally do cnc drilling from the tailstock, the drill would be mounted in a suitable holder on the carriage possibly with automatic tool changing. In mill config Mach 3 can control 3 axes plus spindle, but not in the standard lathe config.



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by JohnHaine View Post
    Mach 3 will certainly manage a 2-axis lathe and control the speed of the spindle, and with a suitable spindle sensor will do threading. Lathes don't normally do cnc drilling from the tailstock, the drill would be mounted in a suitable holder on the carriage possibly with automatic tool changing. In mill config Mach 3 can control 3 axes plus spindle, but not in the standard lathe config.
    Thanks for your valuable inputs.
    From your post I believe I can at least achieve spindle speed control, and x, y control of tool carriage with Mach 3 right? And I also would need an encoder for the spindle?.
    I just need to check on suitable spindle motors.
    With regard to the tail stock in threading mode, the tapping tool is mounted into the tailstock right? so wouldn't that need to be controlled in a reciprocating motion for proper thread profile?

    Also is it necessary to add some anit-backlash for the cross-slide ?

    Last edited by ZeroBacklash; 05-24-2018 at 02:52 PM. Reason: Backlash question


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    Default Re: Emco Unimat lathe CNC retrofit

    "From your post I believe I can at least achieve spindle speed control, and x, y control of tool carriage with Mach 3 right?"

    Correct.

    "And I also would need an encoder for the spindle?"

    Yes if you want to do threading and have Mach 3 control spindle speed. Mach 3 can only cope with a single index pulse per rev which it uses to synchronise threading. However, though threading works OK for me with a Myford Super 7 with plenty of power and inertia in the chuck, threading sync may not work so well on the Unimat unless you take the lightest of cuts. The encoder can be a slotted disc on the spindle with an opto-interrupter.

    "With regard to the tail stock in threading mode, the tapping tool is mounted into the tailstock right? so wouldn't that need to be controlled in a reciprocating motion for proper thread profile?"

    No! You can thread from the tailstock using a tap but it's essentially a one-pass operation - you know what a thread tap is I assume?

    In the lathe, external and internal threads are cut with a single-point tool on the carriage, which is moved in sync with the spindle to form the thread. On a normal lathe this uses gears; in CNC the sync is done by the controller. For internal threads the tool looks like a boring tool but has a pointed tip to match the thread form. For external threads again you have a pointed tool. Typically you might be cutting a 1mm deep thread in 10 x 0.1 mm passes, or even more passes with less infeed.

    For a lathe, it is useful if the cross slide has minimal backlash - I have fitted a ballscrew to the S7 x-slide. It isn't so important in the Z direction because you are almost always cutting towards the chuck, so I use the standard leadscrew. I doubt you could fit a ballscrew on the Unimat so you could experiment with a Delrin nut or a split nut.

    From your questions, I suggest that you download the Mach 3 turn manual and read it carefully, especially the part about threading; and also a book on ordinary non-CNC lathe work.



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    Default Re: Emco Unimat lathe CNC retrofit

    Many thanks again these are amazing insights and it has certainly been a highly enlightening experience reading your posts!



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    Default Re: Emco Unimat lathe CNC retrofit

    For control software there is also LinuxCNC - LinuxCNC
    Index of /testing-stretch-rtpreempt this is the best place to get it currently - includes the operating system. Totally free if that matters...
    Can run through the parallel port (Mach3 compatible type BOBs) or other control cards (Mesa plug in pcie cards or ethernet cards, and others .
    Although there is initially a bit more learning involved, the LinuxCNC software is very adaptable and great to learn on as its scaleable to larger and more complicated machines, plus doesn't have the quirks that Mach 3 is known for (and isn't dependent on a 16 year old operating system).

    For threading LinuxCNC can take in both the index pulse and an encoder pulse for better control while threading ( with the caveat of more inputs and need for more configuration).

    I've got it in use on a lathe and a mill - and I've used it with standard parallel ports and the mentioned Mesa Ethernet cards and I think its great.
    Cheers,

    Mike



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by ZeroBacklash View Post
    I recently purchased a used Emco Unimat lathe. Model no. is not mentioned on the name plate. I gather it would be a DB200 or SL1000 or even an older machine than that.

    Emco Unimat lathe CNC retrofit-emco-unimat-lathe-jpg

    I am planning to retrofit this to a CNC.
    Currently I have planned for 4 motors

    1. Replace Universal spindle motor (this seems to be around 100W) to a 100-150W BLDC motor with speed control.
    2. Stepper Motor (7kg-cm, NEMA17) for tool X movement.
    3. Stepper Motor (7kg-cm, NEMA17) for tool Y movement.
    4. Stepper Motor (10kg-cm, NEMA17) for tailstock linear movement) for drilling and threading operations.

    Will Mach3 or any other software will be capable of controlling these 4 motors. I mean does any CNC software support speed control of spindle motor and also tail stock motor control for drilling tapping. In this case what kind of controller will I need for the spindle?
    I am aware that x and y axis need a driver that will receive step / direction signals from Mach3 but am not so sure about Mach 3's capabililty at handling 4 motors.

    If Mach3 cannot do this is there any other software that can achieve these functions?

    Thanks in Advance.
    What kind of BLDC motor are you planning on using? If you're thinking an RC motor and speed control you may have some issues. Generally 3-phase induction motors are used with VFD's, but finding fractional HP setups at prices you would be happy with might be an issue.

    I'd skip the tailstock stepper and leave that manual. Drilling and tapping one-offs don't usually need CNC that badly, and if you have something you do want to automate, put the drill in a toolholder. What are you planning for a tool post? At the very least you'll need a decent quick change toolpost.
    Are you planning on using the existing screws?



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    Default Re: Emco Unimat lathe CNC retrofit

    I do threading using a stepper (Nema23 2Nm) mounted on the spindle and control it as C-axis. This works fine and you can do any pitch threading. No need to have a box full of taps. For most jobs, 2 Nm is strong enough, can't even run it at max speed otherwise deflection of the part will be to much. And for the larger threads, just reduce speed and cutting depth. Takes i bit longer but who cares, it runs automatically. I recently changed to Nema24 4Nm because i had trouble threading ER32 (M40) on Cr42Mo4 steel. Works even better though i found out today the problems where caused by the power supply (now outputs only 14 Volts). If you have a stepper mounted on the spindle, you can do other cool things like broaching, knurling and grinding drills and end mills. It turns your lathe in a very versatile tool.

    Last edited by hfjbuis; 05-31-2018 at 11:18 AM. Reason: Spelling


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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by ninefinger View Post
    For control software there is also LinuxCNC - LinuxCNC
    Index of /testing-stretch-rtpreempt this is the best place to get it currently - includes the operating system. Totally free if that matters...
    Can run through the parallel port (Mach3 compatible type BOBs) or other control cards (Mesa plug in pcie cards or ethernet cards, and others .
    Although there is initially a bit more learning involved, the LinuxCNC software is very adaptable and great to learn on as its scaleable to larger and more complicated machines, plus doesn't have the quirks that Mach 3 is known for (and isn't dependent on a 16 year old operating system).

    For threading LinuxCNC can take in both the index pulse and an encoder pulse for better control while threading ( with the caveat of more inputs and need for more configuration).

    I've got it in use on a lathe and a mill - and I've used it with standard parallel ports and the mentioned Mesa Ethernet cards and I think its great.
    Cheers,

    Mike
    Thanks for sharing your wonderful experience.
    I wish I had reach you post earlier currently for the emco unimat I have purchased

    Nema 17 stepper motors 4kg-cm bipolar for the carriage
    Leadshine DM422 stepper drives
    For spindle I am thinking of Leadshine DC brushed servo 80W, 3400RPM, DCM50205
    And for the servo drive Leadshine DCS303
    For the motion controller UC400ETH from CNC drive
    For breakout board HDBB2 from CNC drive.
    Software I am planning UCCNC from CNC drive

    I wasn't aware that you go do without the motion controller(I was planning to run this system on Windows), because I had read a lot of posts saying that a PC might not handle so many realtime motion of 2 x, y and also spindle motor, I had even planned to motorize the tail stock.



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by skrubol View Post
    What kind of BLDC motor are you planning on using? If you're thinking an RC motor and speed control you may have some issues. Generally 3-phase induction motors are used with VFD's, but finding fractional HP setups at prices you would be happy with might be an issue.

    I'd skip the tailstock stepper and leave that manual. Drilling and tapping one-offs don't usually need CNC that badly, and if you have something you do want to automate, put the drill in a toolholder. What are you planning for a tool post? At the very least you'll need a decent quick change toolpost.
    Are you planning on using the existing screws?
    I was intially planning on a BLDC BLM57090 from Leadshine but currently I am settling on a DC brushed servo model no. DCM50205 its a 80W, 3400RPM, peak torque seems to be 3Nm.
    Here is the link
    Leadshine Brushed DC Servos

    Now when I see the drive specs DCS303 it shows only step and dir inputs and not 0 to 10V so I was thinking is this the right motor for this application.



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by hfjbuis View Post
    I do threading using a stepper (Nema23 2Nm) mounted on the spindle and control it as C-axis. This works fine and you can do any pitch threading. No need to have a box full of taps. For most jobs, 2 Nm is strong enough, can't even run it at max speed otherwise deflection of the part will be to much. And for the larger threads, just reduce speed and cutting depth. Takes i bit longer but who cares, it runs automaticaly. I recently changed to Nema24 4Nm because i had trouble threading ER32 (M40) on Cr42Mo4 steel. Works even better though i found out today the problems where caused by the power supply (now outputs only 14 Volts). If you have a stepper mountedon the spindle, you can do other cool things like broaching, knurling and grinding drills and end mills. It turns your lathe in a very versatile tool.
    That's amazing to hear I intended to do that (mounting a stepper on the spindle) but I was a bit sketical of the rpms its would achieve like 3000 rpm or so for regular facing operatiosn etc..So I decided to focus on a brushed or bldc servo with a built in tach. But you have opened up a good a new avenue, would the stepper acheive rpms of 3000?



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    Default Re: Emco Unimat lathe CNC retrofit

    I use the stepper only as C-axis and it is engaged by a lever. For all other turning tasks, I use the original motor. I mounted the motor on top of the lathe, but the next build i will place it in the gearbox and use the tumbler lever (lever for changing spindle direction)... for engaging.
    For drawings, information and photo's, look at:Welkom op www.mwt.messageboard.nl

    I don't think you can run this large steppers that fast and still having some useful torque left. You could mount a closed loop stepper. I have never tried them but the specs look pretty good. Just for information, the first i found on google
    https://www.banggood.com/High-Speed-...r_warehouse=CN



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    Default Re: Emco Unimat lathe CNC retrofit

    That's a tiny motor. I don't think .25 Nm continuous will be enough to do any real threading. According to the specs you linked, the 80W motor only has 1.6Nm peak torque. Peak torque/power, if they don't give a spec is usually only for 1 second or less. If you were planning to buy at the prices listed through those links ($150 for the motor,) it's a really poor value as well.
    A large stepper could probably do what you want, you'd probably need to do about a 2:1 ratio to get the 1500 RPM output of the stepper up to 3000 though.
    Something popular these days are integrated servos. They're brushless and a pretty good value.
    For $300, you could get a 350 watt: https://www.teknic.com/model-info/CP..._voltage=75VDC
    If that's too big, they've got a 205W NEMA 23 for a few bucks less: https://www.teknic.com/model-info/CP...del_voltage=75
    People seem to like the clearpath's quite a bit and they're a good value. I think there are other similar integrated servos, but I haven't heard as much feedback on them.
    Also, before you go with something that only takes step-dir inputs, make sure the controller you're going to use supports that for a spindle. Not all do, some only can do PWM (which can easily be converted to analog.)



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    Default Re: Emco Unimat lathe CNC retrofit

    That's a tiny motor. I don't think .25 Nm continuous will be enough to do any real threading.
    If you refer to my post, i did not specify the stepper i used.
    I used a Nema 23, 2Nm stepper 57BYGH627 it has a holding torque of 2 Nm. The largest thread i did was M40 x 1.5 in Cr42Mo4 steel at 15 mm/min, depth of cut start/final 0.180/0.014 mm, 40 passes, full step, geared down 45/20.
    I recently replaced it with a Nema 24, 4 Nm stepper, did the same thread at 15 mm/min, depth of cut start/final 0.220/0.021 mm, 27 passes, full step, geared down 45/20.
    Consider the steppers where feed with just 13.7 Volt. So I can do threading!
    Any controller can do step/dir. It is not the controller but the GCodes that make the threading. I use GRBL as controller. To do threading this way you need a 3 axis step/dir controller.
    BUT you need CAM software that can do threading this way or write macro's for mach or any other controller you have.
    I don't like cam for simple parts that are only made once. So i wrote my own software that communicates with the GRBL controller. It doesn't need cam and it does all the tasks you can do on a conventional lathe in an automated way.



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by hfjbuis View Post
    If you refer to my post, i did not specify the stepper i used.
    I wasn't replying to your post, ZeroBacklash had posted a link to his 80 watt servo with .25 Nm torque.



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    Default Re: Emco Unimat lathe CNC retrofit

    I was i bit agitated and in a hurry, not a good state of mind to reply.
    0.25 Nm torque is not enough for threading and probably not enough for turning.



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by skrubol View Post
    That's a tiny motor. I don't think .25 Nm continuous will be enough to do any real threading.
    For this tiny machine do you think 2Nm for spindle is sufficient to do the usual lathe operations and threading. I am also getting a bit confused in spindle motor selection for a lathe what would I need speed control or position control. I was going for a dc brushed servo with a tach, so will this be suitable for the usual lathing operations like facing etc which required speed and the other operations like threading which require accurate sync and positioning.



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    Default Re: Emco Unimat lathe CNC retrofit

    I would keep the original motor for all lathe operations and would add speed control later. I do not use speed control on my lathe.
    I normally run my Nema17 and 23 steppers at 1/8 step to reduce noise. Even then, i can't run them at full speed because i normal have small work pieces. So nema17 for Z and X and Nema23 for the spindle is sufficient.
    I don't regret the change to Nema24 for the spindle, but it was after all not necessarily. On the other hand, the price difference is small.
    I am not trying to achieve the highest speed. I am glad if it is working. So i can not benefit from the expensive leadshine and others. I use TB6600 steppers bought from ebay and also use the chip in my own designs. I suits my needs very well.
    Having separate stepper drivers makes it easy to changing the controller. And even if you later decide for a leadshine driver, the money wasted is small. The same could be said for the controller. If you go for linux you can do it with a cheap BOB. For Windows GRBL is cheap and used a lot. The CNC conversion of my lathe is done for $100,-- and it works very well. I have learned a lot and never regretted it to do it "the cheap way". I make my own gears (and gear cutters) but used the original late gears for the gearboxes. Just to show how (easy) it can be to do a CNC conversion of the lathe.
    Your first car wasn't a ferrary, so why should your first CNC build be one. I know you get a lot of response from every body and they "all" are right from their perspective. You just have to ask your self what you would like to achieve and consider what is doable with your budget. In the end, it is a hobby and you do it for the fun.



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    Default Re: Emco Unimat lathe CNC retrofit

    a cnc retro fit in USD100 is amazing. Basically before buying this I had read that PC's cannot handle multiaxes without missing steps so I went in for the motion controller. Also I had gone in for an ethernet one because of USB being more susceptible to noise. Maybe I got a bit carreid away by that. But my intention was to learn from other's experiences. Unfortunately I didn't get this kind of advice earlier.

    Also another reason I going for a stronger motor for the spindle is currently I cannot get larger that 0.2 mm cut on the emco unimat on Mild Steel without the spindle motor slowing down. So I wanted to get a stronger one to get more out of this lathe.

    So do you use linuxcnc as the software? Also do you think 4kg.cm steppers are sufficient for the cross slide / carriage?



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    Default Re: Emco Unimat lathe CNC retrofit

    Quote Originally Posted by ZeroBacklash View Post
    Also another reason I going for a stronger motor for the spindle is currently I cannot get larger that 0.2 mm cut on the emco unimat on Mild Steel without the spindle motor slowing down.
    Cutting 0.2 mm means 0.4 mm in diameter. In steel i do 0.2 mm max. My spindle will drop a bit in speed but who cares. As long a the finish is ok. And to get a good finish, i do a final 0.01 mm pass at a low feedrate. I rareley use inserts, basiccaly I use HSS, it is (re) grinded in seconds on a dremel with a cutting disk and the finish is very good. I can cut tough steel like Cr42Mo4 using inserts (CCMT060204) 0.05 mm thicker than using HSS. But in the end, time is not an issue.
    Quote Originally Posted by ZeroBacklash View Post
    So do you use linuxcnc as the software
    I tried mach3 and Linux CNC but i found it to complicated for simple jobs. Combined with CAM (Fusion360) it took more time to prepare than to turn. I looked at making an extension for Mach but the documentation was to confusing. Commercial controllers like USBCNC (Eding CNC) where to expensive to start with. So i start building my own CNC controller based on a CNC controller i made for the electronic clutch for my motorcycle. Then i stumbled over GRBL, it had all i needed and i must say I can't do it better. So i decided to use GRBL for controller. Combined with my own software i can do 'Conventional" turning the CNC way without CAD or CAM. For free style parts, witch i haven't made yet, you can still use CAM and one of the available GCode senders.
    You can take a look at the software CNCL in the Microsoft store, download, try it.
    Quote Originally Posted by ZeroBacklash View Post
    Also do you think 4kg.cm steppers are sufficient for the cross slide / carriage?
    I use Nema17 0.5 Nm for the cross slide (direct connected 110 mm/min) and carriage (20/50 gearbox 300 mm/min), that is enough for me. Also when you make an mistake, due to the "low" force, the damage is low. I have spare Nema 23 and 24 stepper but i am not going to use them for the lathe X or Z axis.



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