PWM vs Step and Direction - New to CNC


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Thread: PWM vs Step and Direction - New to CNC

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    Default PWM vs Step and Direction - New to CNC

    Hi all,

    I'm helping my cousin with his CNC router but I am new to CNC machines and while he knows how to use it, the spindle has stopped spinning and Mach 3 is not able to control it anymore. We are putting our heads together to try and component isolate.
    I'm trying to learn about Mach3 and the CNC router, which is a 2012 NewCNC machine that was bought second-hand.
    The configuration manual references PWM and step and direction motor types.
    Would anyone be able to point out how to find out which of these two motors are in use on our machine?
    It will help when looking at the settings for one or the other in the Mach3 manual.

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    Registered James Newton's Avatar
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    Default Re: PWM vs Step and Direction - New to CNC

    Spindle motors are most often PWM. Axis drive are typically step and direction. Post some pictures of the motors and drivers and we can do a better job of offering advice.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    Default Re: PWM vs Step and Direction - New to CNC

    Most spindle motors on these smaller machines are PWM, depends on the spindle size but for example: 2.2KW spindle controlled with a VFD, the PWM signal normally goes into a small card to get converted to 0-10V which controls the speed of the spindle. Those little board often have two relays to control the Spindle ON, and the Spindle Direction. If you have a DC type spindle another common one for cheaper smaller machines, in that case the PWM signal goes into a DC spindle control which allows speed control from the PWM signal. Post a picture of your machine and card and it will be much easier to tell you how to address the issue.

    Russ



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    Default Re: PWM vs Step and Direction - New to CNC

    Would anyone be able to point out how to find out which of these two motors are in use on our machine?
    Neither.
    Your spindle is most likely controlled by an analoog voltage, either 0-5V, or 0-10V.

    Whether you use PWM or step/direction, you should have a board that is converting those into the analog signal.

    So you need to find out what type of spindle control board that you have.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: PWM vs Step and Direction - New to CNC

    Hi all,

    A CNC technician visited our shop last week to optimize the machine.
    I wasn't present for what he had done or changed, but when he left, the spindle stopped being controlled by Mach3 and he said we would need to downgrade the Smoothstepper from USB back to ParallelPort to make it work again, which we weren't comfortable doing, seeing as it was working perfectly fine for many years via USB.

    We started to component isolate and have found the following:

    We had a backup of our computer's hard drive from February, when everything was working, so we plugged it in and booted up, which should eliminate software, settings, drivers, plug-ins, config, etc. - Spindle did not start up.

    We replaced the USB-485M adapter that connects to the USB SmoothStepper board and the RJ45 cable that plugs into the VFD motor - Spindle did not start up.

    ***Spindle turns on when manually using the control pad located directly on the CNC machine***

    Right now, the only logical next step would be to look at replacing the Smoothstepper board, or the PMDX-122 breakout board.

    A few things to note - when clicking the "Spindle CW" button in the Mach3 Program Run screen (in the spindle speed area in the bottom right), we can hear a clicking from the machine, but the spindle does not actually engage and turn.

    We ran a diagnostic in Mach3 and when clicking "spindle toggle" the same clicking noise is heard, but no movement and on the right you can see the spindle is off under Port 1 Pins current state.


    Perhaps someone could provide some insight on this, or if someone is/knows a reputable CNC expert in the Greater Toronto Area, we could arrange to have the machine looked at.

    PWM vs Step and Direction - New to CNC-img_0106-jpgPWM vs Step and Direction - New to CNC-img_0112-jpgPWM vs Step and Direction - New to CNC-img_0116-jpgPWM vs Step and Direction - New to CNC-img_0118-jpgPWM vs Step and Direction - New to CNC-img_0119-jpgPWM vs Step and Direction - New to CNC-img_0082-jpg



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    Default Re: PWM vs Step and Direction - New to CNC

    re3f,
    If the relays are clicking that is probably on the PMDX-122 board. You can actually check and see if the relays are closing their contacts, which go directly to the VFD to the FWD and REV pins on the VFD. If the relay contacts are actually closing when they click the next thing to check is to see if the Smoothsteppers is outputting at PWM signal which is send to the PMDX-122. That signal gets converted to an analog voltage which you can actually check, this normally goes from 0 to 10V or something close. If that part is missing the Spindle would not turn on. You mentioned you can turn the spindle on from the remote operator from the VFD. Interesting normally when you setup a VFD for remote use you can't normally turn on the VFD/Spindle with the operator panel, but that might be an option on the Delta VFD. Check the PWM and if that is good this is highly suspect the PMDX-122 is relays are bad or the conversion from PWM to analog voltage is not working.
    Russ



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    Default Re: PWM vs Step and Direction - New to CNC


    A CNC technician visited our shop last week to optimize the machine.
    I wasn't present for what he had done or changed, but when he left, the spindle stopped being controlled by Mach3 and he said we would need to downgrade the Smoothstepper from USB back to ParallelPort to make it work again
    Don't let this guy touch your machine again, because he doesn't know what he's doing.


    We replaced the USB-485M adapter that connects to the USB SmoothStepper board and the RJ45 cable that plugs into the VFD motor
    I think you're mistaken here. The Smoothstepper only has one USB port, that goes to the PC.
    It sounds like you're controlling your spindle with the RS485 connection, using Modbus, or Brains. That's where your problem lies, I believe.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Registered James Newton's Avatar
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    Default Re: PWM vs Step and Direction - New to CNC

    For what it's worth, you don't need a CNC expert, you need an electronics repair tech. Someone who actually knows how to troubleshoot and has a meter and scope... and a brain... your prior help was... brain dead.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    Default Re: PWM vs Step and Direction - New to CNC

    Hi, I have a problem something like that. The point is to buy a 6040z Chinese router with a 4-axis VFD control box. Since I bought it, I have not been able to turn or control the speed of the spindle from the Mach3. I have read a lot to try to solve the problem. That is why the BoB card (JP-845) that the router brings is missing something that makes it impossible to control the spindle so you have to buy it separately. I decided to buy a new BoB card for 5 axes and replace the other one and still I still do not light the spindle. Run the wiring as it should have been, put the wiring of the original BoB card to the new one in the same way and add 3 additional cables from the Nowforever to the BoB card that are supposed to turn the spindle on and off and control the speed , Make the configuration in the Mach3 and also in the Nowforever programming. The question I have is if I have to connect some cable to the "Spindle On / Off" ports and if so, where should I connect them? Attached some photos of what you modify. When I send an M3 Sxxxx I listen to the relay making clac and the VFD screen when it changes from 0 to xxxMhz. When I send an M5 it goes off and reduces the display to 0 but the spindle does not rotate. I am a precision mechanic and I program in G code and I use software Cam but I am not an electronic technician so I do not know what it is that I need to connect. I still do not know what PWM or Step & Dir is, or is it the original BoB card (JP-845) if it can do the turn on / turn off the spindle and control the speed? If anyone here can help me thank you enormously.

    Original BoB




    This is the wiring from the VFD to the board.
    White is X1 terminal, goes to pin 17 on the BoB
    Red is the AN1 terminal, goes to 0 - 10V spindle speed pin on BoB
    Black is COM terminal, goes to GND pin for spindle control on BoB



    New BoB



    VFD programmed as per this video

    <font size="5"><strong><span style="color: rgb(0, 0, 0); font-family: Tahoma, Calibri, Verdana, Geneva, sans-serif; font-style: italic; background-color: rgb(242, 246, 248);">

    Attached Thumbnails Attached Thumbnails PWM vs Step and Direction - New to CNC-20170810_082559-jpg   PWM vs Step and Direction - New to CNC-20170829_125617-jpg   PWM vs Step and Direction - New to CNC-20170829_125836-jpg   PWM vs Step and Direction - New to CNC-new-bob-jpg  

    PWM vs Step and Direction - New to CNC-bob-new-jpg  


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    Default Re: PWM vs Step and Direction - New to CNC

    Need Help,
    Still working on the trying to get Mach3 to control my spindle
    Tried RS485 it worked a little but quick got Smooth stepper errors

    I am now think about replacing the BoB and get and away from the Smooth Stepper

    Any advise is appreciated



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    Default Re: PWM vs Step and Direction - New to CNC

    You might want to consider getting the Centroid Acorn board. It was just released and it quickly getting a strong following. You do not need MACH3, this comes with the Centroid software. It costs $265, and should do all the things you need. You can look on youtube and you can find several videos of users using this new card. The software has been proven over many users on commercial centroid upgrades on many machines. Watch the videos and think you will be impressed. One issue is you need to have a PC with Windows 10, it also likes you to use a touch screen, but will work without one.

    Russ


    Acorn CNC controller, Step and Direction 4 axis CNC Control board with ethernet communication



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    Default Re: PWM vs Step and Direction - New to CNC

    R.
    Something else to check. I noticed earlier that you mentioned that you could control the vfd from the front panel. Some vfd mfg will not allow both front panel and remote control. My Hitachi 200 VFD requires an internal run signal from PCS to terminal T1 for forward (or T2 for reverse) "and" the 0-10 v input on the "O" terminal from my BOB. Check your vfd settings prior to spending $$$ on parts not needed. Make sure your vfd is set for remote control and all the voltages are present in the VFD when trying to run.
    Hope this helps and good luck.
    Bill

    billyjack
    Helicopter def. = Bunch of spare parts flying in close formation! USAF 1974 ;>)


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