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Question #: 14139

Question: I recently wired my CNC machine with limit switches and tested them before mounting to the machine. They were configured and when tested worked great. After mounting them to the machine, they continued to register as triggered. The frame of the CNC machine is made of MDF so I don't think it is shorting off of the machine. Can you tell me what might be wrong?

Current Solution

We recommend using shield wire for wiring the limit switches.

Respond:

Other Possible Solutions to this Question

  • I have the redleaf system for my black toe machine I have wired my limit switches in series NC after setting up in mach 3 I still get limit switch tripped after apply and ok setup can only run if I disable what am I doing wrong

    If you are using Mach3, the setting for the input pin 10 may be enabled as a default for use with the Emergency Stop. If there is no emergency stop on that pin, the reset will trip every time.

    Click the link to add information to this solution:
    I have the redleaf system for my black toe machine I have wired my limit switches in series NC after setting up in mach 3 I still get limit switch tripped after apply and ok setup can only run if I disable what am I doing wrong

  • I'm using Mach3. I have 2 limit switches on X, 2 on Y and 1on Z for retracted/home. I can go to diagnostics and see the switches/inputs working. But when I move with jog or gcode they have no effect. Also I can go right past the soft limits. I must have something turn off but I don't know what.

    Did you set them up as limit switches or home switches?

    Additional Information:
    Not sure where do I check that?

    Additional Information:
    Go to config, then ports and pins, then input signals.

    Additional Information:
    The limits are labeled x++, x— for example.

    Click the link to add information to this solution:
    I'm using Mach3. I have 2 limit switches on X, 2 on Y and 1on Z for retracted/home. I can go to diagnostics and see the switches/inputs working. But when I move with jog or gcode they have no effect. Also I can go right past the soft limits. I must have something turn off but I don't know what.

  • I purchased limit switches from you mounted them on my machine and wire them to the breakout for using pin 12 and the ground on the breakout board, after a few minutes I got a message about a limit switch trip. Am I supposed to use the extra outport on the board instead of the ground?

    Sure, the USB interface has a place for 4 axes of limit switches.

    Each axis can have two limit switches: one for the ++ (positive) end and one for the -- (negative) end. The positive end would be the limit switch at the end of the machine that, say the machine has a 4'x8' area, reaches a bit after the 8 foot mark. The negative end would be the limit switch behind the 0 foot location behind the origin. If the origin is in the middle, the negative would be at a little more than the -4 foot end and the positive would be at a bit more than the +4 foot end. Note that you can have more than one switch on each pin where the NC is connected in serial fashion and the NO is connected in parallel fashion (this can be seen on the diagram in the multiple limits switch section). The software configurations for the limits switches are under File -> Settings -> Limit.

    A typical limit switch has three connections on it. These connections consist of COM (common), NC (normally closed) and NO (normally open). The COM would generally go to GND and the NC or the NO would go to the pin. If the NC is used, then the the switch is constantly connected until the switch is pushed (engaged) then the connection from the pin to gnd is broken (open). Use the settings in software to set whether in NC or NO configuration.

    Let me know if this information was helpful (or not) by adding information to this question. Thanks.

    User response:
    Thank you very much for this helpful information. I'm still a little fuzzy on how the 6 limit switches physically connect to each other and to the USB breakout board. You've stated one switch (home) goes to positive and another switch (limit) goes to negative. Are all the GND prongs from all 6 switches connected to each other and going to GND on the breakout board, or no? And the NC prongs, how exactly are they connected to each other? And to the board? There has to be a diagram somewhere shows this visually, no? I don't know how to wire the switches in series or in parallel. I have already physically installed all the switches on the machine and ran the wires to where the board is. Now I just need to know where to plug these wires into the board. Also, taking into consideration that I'm using the Planet CNC software, the only settings I have pertaining to limit switches is "Enable/Disable" for each axis, and the actual limit for each axis. Nothing about NC or NO. Is that only in Mach3?
    Thank you.

    buildyourcnc response:
    On the USB interface, the COM on the switch connects to GND and the NC or NO connects to the input pin (i.e. x++, y--, etc.)

    Limit switch configuration is rather difficult to understand, especially with series and parallel. You can think of series as a single wire going from GND to the axis letter input terminal (i.e. X++ or X--). If the wire is broken, then the circuit is open (or the switch is engaged in a normally closed scenario). Normally closed is like an actual wire, and when engaged, the switch "opens" (breaks the wire). This is why we recommend in some systems that you can put many switches in series on a single pin. When one of the switches is engaged (breaking the connection) then the entire circuit of switches is broken and the machine stops.

    In a parallel scenario, the state of the circuit is always broken until the one of the switches is engaged and the circuit is then closed or connected. The topology looks like a ladder. All the switches connect to both sides of the ladder and the switches are like the runs of the ladder (the horizontal bars that the feet are placed while climbing). Imagine all of the switches broken in this scenario (normally open). It would be like the ladder could be split in two, but if one of the ladder runs (switches) is closed by engaging it, then that run would connect both sides of the ladder and the two sides of the ladder would have a connection.

    There is a diagram on the USB page of the various limit switch configurations. If you need more information (visual and/or otherwise), please let us know and we will immediately add that information to benefit everyone.

    Click the link to add information to this solution:
    I purchased limit switches from you mounted them on my machine and wire them to the breakout for using pin 12 and the ground on the breakout board, after a few minutes I got a message about a limit switch trip. Am I supposed to use the extra outport on the board instead of the ground?

  • I have nearly completed the CNC machine from the book, but I am using it with a USB breakout board, and have no idea how to wire the 6 limit switches to the board. I'm having difficulty following the diagram on the USB breakout board screen. Can someone please help me?

    Sure, the USB interface has a place for 4 axes of limit switches.

    Each axis can have two limit switches: one for the ++ (positive) end and one for the -- (negative) end. The positive end would be the limit switch at the end of the machine that, say the machine has a 4'x8' area, reaches a bit after the 8 foot mark. The negative end would be the limit switch behind the 0 foot location behind the origin. If the origin is in the middle, the negative would be at a little more than the -4 foot end and the positive would be at a bit more than the +4 foot end. Note that you can have more than one switch on each pin where the NC is connected in serial fashion and the NO is connected in parallel fashion (this can be seen on the diagram in the multiple limits switch section). The software configurations for the limits switches are under File -> Settings -> Limit.

    A typical limit switch has three connections on it. These connections consist of COM (common), NC (normally closed) and NO (normally open). The COM would generally go to GND and the NC or the NO would go to the pin. If the NC is used, then the the switch is constantly connected until the switch is pushed (engaged) then the connection from the pin to gnd is broken (open). Use the settings in software to set whether in NC or NO configuration.

    Let me know if this information was helpful (or not) by adding information to this question. Thanks.

    User response:
    Thank you very much for this helpful information. I'm still a little fuzzy on how the 6 limit switches physically connect to each other and to the USB breakout board. You've stated one switch (home) goes to positive and another switch (limit) goes to negative. Are all the GND prongs from all 6 switches connected to each other and going to GND on the breakout board, or no? And the NC prongs, how exactly are they connected to each other? And to the board? There has to be a diagram somewhere shows this visually, no? I don't know how to wire the switches in series or in parallel. I have already physically installed all the switches on the machine and ran the wires to where the board is. Now I just need to know where to plug these wires into the board. Also, taking into consideration that I'm using the Planet CNC software, the only settings I have pertaining to limit switches is "Enable/Disable" for each axis, and the actual limit for each axis. Nothing about NC or NO. Is that only in Mach3?
    Thank you.

    buildyourcnc response:
    On the USB interface, the COM on the switch connects to GND and the NC or NO connects to the input pin (i.e. x++, y--, etc.)

    Limit switch configuration is rather difficult to understand, especially with series and parallel. You can think of series as a single wire going from GND to the axis letter input terminal (i.e. X++ or X--). If the wire is broken, then the circuit is open (or the switch is engaged in a normally closed scenario). Normally closed is like an actual wire, and when engaged, the switch "opens" (breaks the wire). This is why we recommend in some systems that you can put many switches in series on a single pin. When one of the switches is engaged (breaking the connection) then the entire circuit of switches is broken and the machine stops.

    In a parallel scenario, the state of the circuit is always broken until the one of the switches is engaged and the circuit is then closed or connected. The topology looks like a ladder. All the switches connect to both sides of the ladder and the switches are like the runs of the ladder (the horizontal bars that the feet are placed while climbing). Imagine all of the switches broken in this scenario (normally open). It would be like the ladder could be split in two, but if one of the ladder runs (switches) is closed by engaging it, then that run would connect both sides of the ladder and the two sides of the ladder would have a connection.

    There is a diagram on the USB page of the various limit switch configurations. If you need more information (visual and/or otherwise), please let us know and we will immediately add that information to benefit everyone.

    Click the link to add information to this solution:
    I have nearly completed the CNC machine from the book, but I am using it with a USB breakout board, and have no idea how to wire the 6 limit switches to the board. I'm having difficulty following the diagram on the USB breakout board screen. Can someone please help me?

  • hi, I atacched a laser system to my modified book machine. it worked fine for a few trials but for some reason has lost power and is not cutting through any more, it does engrave thou. what can I check for? I´ve tried everything I can think of.
  • I'm trying to test cnc with Mach 3 as it says in the book. When I send the g codes, nothing happens. I occasionally hear a bump from the machine, but there's no real rhyme or reason as to when it will bump. What could be wrong?

    If the machine is not moving when you use a control program to control the electronics, there could be a many reasons this could happen.

    First, make sure that you followed the electronics videos: https://www.buildyourcnc.com/CNCElectronicsandWiring.aspx

    The computer sends pulses from the conmputer while the control program interprets the g-code. These puses from the computer should be received in the correct form from the breakout board, or interface. Make sure that the step low active is enabled if the pin is connected to the CP- (PUL-, or STEP-) and the 5v is connected to the CP+ (PUL+ or STEP?+) at the driver.

    Click the link to add information to this solution:
    I'm trying to test cnc with Mach 3 as it says in the book. When I send the g codes, nothing happens. I occasionally hear a bump from the machine, but there's no real rhyme or reason as to when it will bump. What could be wrong?

  • I've read your book and I'm looking to purchase the hardware kit with DVD as well as an electronics kit. I would like my machine to have a working area of at least 24" wide by 48" long. Can I just make the bed (and gantry) wider to accommodate larger priceslike 30"x60"? If so what electronics kit would you recommend?

    Considering enlarging the machine, might have its down sides do to the structural integrity of the scratch build machine. Primarily by making the width longer it will start to sag in the center, which will lead to having to redesign the gantry to be more structurally rigid to support the added length. Which then will increase the weight and height of your gantry to support the add size, which will always end up to creating a larger CNC.

    We usually do not recommend modifying the scratch build CNC, due to the very limited capabilities, and the structural design of the scratch build. We also do not recommend using longer than 48" ACME screw/leadscrew due to the increasing chance of warping and bending in the ACME screws/leadscrew in the given length.
    We do recommend modifying the CNC machines we sell to accommodate the added requests that some of our customers desire, but you will be limited to the width of the gantry with our machines.

    Click the link to add information to this solution:
    I've read your book and I'm looking to purchase the hardware kit with DVD as well as an electronics kit. I would like my machine to have a working area of at least 24" wide by 48" long. Can I just make the bed (and gantry) wider to accommodate larger priceslike 30"x60"? If so what electronics kit would you recommend?

  • I recently had a mishap with one of my stepper drivers which resulted in a resistor being burned out. Would you be able to tell me what the resistance is for the R25 resistor inside the 6.0 amp driver?

    Currently we do not know the values of the electronic components inside our drivers, since these drivers are supplied by our manufacture and replaced by them if a manufacture defect is present.
    Please email us at customerservice@buildyourcnc.com for more information on possible replacements.

    Click the link to add information to this solution:
    I recently had a mishap with one of my stepper drivers which resulted in a resistor being burned out. Would you be able to tell me what the resistance is for the R25 resistor inside the 6.0 amp driver?

  • Hello, I have a blacktooth laser cutter, the machine has 10hrs of work, suddenly in the middle of a job the laser beam lost all power, I can still se the purple plasma beam but with no power or intensity, the tube is fine, water is running through and there is no arcing to the chasis or some other part. I think it might be a faulty PS how can I test it, Do I have a warranty on it?

    To verify, you are still getting the laser tube to fire, but the laser beam is weak and cannot cut or engrave any materials correct?

    Have you checked your tube's tungsten post terminals to make sure they are getting good contact?
    The Laser tube and laser power supply both have manufacture warranty, please email customerservice@buildyourcnc.com for further assistance.

    Click the link to add information to this solution:
    Hello, I have a blacktooth laser cutter, the machine has 10hrs of work, suddenly in the middle of a job the laser beam lost all power, I can still se the purple plasma beam but with no power or intensity, the tube is fine, water is running through and there is no arcing to the chasis or some other part. I think it might be a faulty PS how can I test it, Do I have a warranty on it?

  • Hello I recently read your site and have a question. I have a driver model DM2722A but I can't connect it to my usb controller due to the fact that the driver is not marked enable, but instead it is marked: mf-, mf +, alm-, alm +. I will be very grateful if you explain to me the meaning of the latter and tell me what should be related to "enable" Thanks in advance!

    Not a problem. The ALM is rather self-explanatory as this is a closed-loop stepper motor and driver that you are using. The ALM (alarm) is a signal that is used to tell the driver/controller that the motor is not in the same condition that the driver expects. In a closed-loop system, the motor has an encoder that tells the driver exactly how many steps that it turned, and if this value does not coincide with the driver's outputted number of steps, and within a specified amount of time, the alarm will trigger so the system can stop and the workpiece can be salvaged.

    The MF is simply a signal that tells the driver that there is impending direction and step pulses coming. If the MF signal is high, then that is similar to an enable signal.

    Click the link to add information to this solution:
    Hello I recently read your site and have a question. I have a driver model DM2722A but I can't connect it to my usb controller due to the fact that the driver is not marked enable, but instead it is marked: mf-, mf +, alm-, alm +. I will be very grateful if you explain to me the meaning of the latter and tell me what should be related to "enable" Thanks in advance!

  • Limit switches for axis. The print shows that you can wire the limits either n.o. or n.c. so if this is correct I would need to tell the board in the software how to look at these limits, I'm either going to get an input or loose an input depend on how i wire it.

    BYCNC Response:
    This is correct. You will need to use a method appropriate for the software you are using. Also remember that NC switches are typically wired in series, while NO switches are normally wired in parallel.

    User Response:
    I am using the cnc planet software for your USB board. Are the limit configurations in this software?

    BYCNC Response:
    Yes, Planet CNC software is compatible with the use of limit switches. Configuration information will depend on your specific application. You can view Planet CNC's information here: http://www.planet-cnc.com/files/CNCUSBController.pdf

    Click the link to add information to this solution:
    Limit switches for axis. The print shows that you can wire the limits either n.o. or n.c. so if this is correct I would need to tell the board in the software how to look at these limits, I'm either going to get an input or loose an input depend on how i wire it.

  • The X-axis stepper motor on my BlackToe suddenly started acting up. It is wired bipolar series, and was working great but then in the midst of a cutting operation the stepper started sounding rough- as though one of the phases was shorting out. However, all the connections and wires are in tact. Any ideas what would most likely cause this?

    If the motor starts acting rough or is excessively trying to move without physically moving the input shaft. Re-check that your pins are in the correct settings and always set the amps required to the closest needed but not exceeded (ex. required 3.00A, but only having 3.14A revert from using 3.14 and go lower to 2.57A).
    Also a software issue that can affect the motor is Config/MotorTunning/(x,y,z)-axis, if you are trying to push your motor to move at a faster rate by modifying the acceleration and velocity could cause your motor to fail if the settings are to high. Lastly out of those two tests, would re-check wiring for continuity lastly.

    Additional Information:
    Also, even if the wiring was checked thoroughly, re-check the wiring for any chafing from wire ties or any other means of causing a short with two or more of the motor wires.

    You can also try swapping the motors from another axis to determine if the cause is derived from the driver or the motor.

    Additional Information:
    I disconnected the stepper motor entirely except left the yellow and blue wires tied together and the motor still made the sound when manually rotating the shaft. When I disconnected the yellow and blue wire the motor rotated smoothly again, so there must be a short inside the motor. Is there a warranty on the motors you sell?

    Click the link to add information to this solution:
    The X-axis stepper motor on my BlackToe suddenly started acting up. It is wired bipolar series, and was working great but then in the midst of a cutting operation the stepper started sounding rough- as though one of the phases was shorting out. However, all the connections and wires are in tact. Any ideas what would most likely cause this?

  • I have a breakout board and it appears that the pin 12 connection has failed: when i move my limit switches to pin 11 they work; they don't work on pin 12. Do i need a new breakout board?

    For safety's sake I would recommend a new board because they are inexpensive compared to the electronics that they support. Alternatively, it's possible that the one dead pin is a simple fix, such as a bad connection or solder joint; if you feel comfortable making those repairs then it could be worthwhile to check. Finally, if you are not using all the input pins, you could continue to operate the limit switch on pin 11 and hope for the best.

    Click the link to add information to this solution:
    I have a breakout board and it appears that the pin 12 connection has failed: when i move my limit switches to pin 11 they work; they don't work on pin 12. Do i need a new breakout board?

  • I wired my vfd (2.2kw version) and tried test running the spindle. I configured to your specs on this website, only issue is we got an error code. Err 02, do you know what this is? OR have a list of error codes? Thank you

    Can you provide the model number of your VFD?

    Yes, I have the "YL600 - 2S - 2K20"

    It just came with a small booklet that is all in Chinese...

    Click the link to add information to this solution:
    I wired my vfd (2.2kw version) and tried test running the spindle. I configured to your specs on this website, only issue is we got an error code. Err 02, do you know what this is? OR have a list of error codes? Thank you

  • I recently received missing stop button and limit switches in my 5x kit. Thank you. Is there suppose to be any bulk wiring in kit for limit switches and 2.2 spindle? If not could you please describe correct gauge wire for both? Cheers.

    The hookup wires you will need is 22 to 24 AWG stranded and shielded for the wiring of the limit switches and E_Stop. Our kit customers select various places for these switches, so we don't supply the wiring. If you don't use shielded cable, you will need to change the debounce setting in Mach3 (if that is the control program you are using).

    We typically use 14 AWG stranded wire for the VFD to Spindle (U, V, W) connections.

    Click the link to add information to this solution:
    I recently received missing stop button and limit switches in my 5x kit. Thank you. Is there suppose to be any bulk wiring in kit for limit switches and 2.2 spindle? If not could you please describe correct gauge wire for both? Cheers.

  • Hey Guys, I have a brand new redleaf and 5x. In the final stages of wiring and wondering a few things. Can I connect the Mach3 USB board V+ V- to my frequency inverter (type YL600-2s-2k20)? If so where? Will your upcoming (part 2)video deal with this as well as final connections for limit switches and stop button? Merry Christmas!

    Yes, the Mach3 USB board has two terminals that require 24V connection. Most VFDs have a 24V output that can be used to power this part of the Mach3 USB board.

    The V+ and V- on the Mach3 USB is not absolutely necessary to operate the CNC machine/router. The V+ and V- of the Mach3 USB board powers the outputs, inputs, and spindle's speed and control.

    Here is the Mach3 USB link for more information:
    https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

    The new YL600 VFD we have in stock may not have this 24V output. There is a 12V terminal, but I have not tested that terminal if it outputs 12V, or if it is a 12V input. If you are only conecting limit switches to the Mach3 USB and need to power that portion, 12V will be sufficient.

    I will delve into these aspects in far more detail on video.

    Thanks and Merry Christmas to you as well!

    Click the link to add information to this solution:
    Hey Guys, I have a brand new redleaf and 5x. In the final stages of wiring and wondering a few things. Can I connect the Mach3 USB board V+ V- to my frequency inverter (type YL600-2s-2k20)? If so where? Will your upcoming (part 2)video deal with this as well as final connections for limit switches and stop button? Merry Christmas!

  • How can I decrease the rapid acceleration of the cutter from a completed cutting operation to a new location so that the stepper motor will not lose its steps and mess up the machine zero settings? I am using CamBam and Mach3 on my machine with a chain drive. what is the best way to reduce accleration

    Decreasing the speed of acceleration in the cutter? Meaning of your router/spindle?, To modify the speed of a router will be going to the router itself and modifying the speed, but if a spindle is being used modifying it will be done either manually in the VFD (VFD Setup:
    Change PD001 to '0' (source of run commands)
    Change PD003 to 300 (main frequency - Hz)
    Change PD004 to 300 (base frequency - Hz)
    Change PD005 to 400 (max operating frequency - Hz)
    Change PD006 to 2.5 (intermediate frequency - Hz)
    Change PD008 to 220 (max voltage - V)
    Change PD009 to 15 (intermediate voltage - V)
    Change PD010 to 8 (minimum voltage - V)
    Change PD011 to 100 (frequency lower limit - Hz)
    Change PD142 to 7 (rated motor current - Amps)
    Change PD143 to 2 (motor pole number)
    Change PD144 to 3000 (rated motor revolution))<- make sure these are your settings in the VFD. If the spindle is wired to the breakout board and is working through Mach 3 then the modification will be done in your CamBam/Feed rate settings.

    Click the link to add information to this solution:
    How can I decrease the rapid acceleration of the cutter from a completed cutting operation to a new location so that the stepper motor will not lose its steps and mess up the machine zero settings? I am using CamBam and Mach3 on my machine with a chain drive. what is the best way to reduce accleration

  • When the machine hits the limits it stops but the switch is still tripped so clicking the Mach3 RESET button doesn't do anything. How am I supposed to get the machine to move off of the limit switch so I can continue working?

    If you select the Settings Page and select or tick Auto Limit Override - this will allow you to back off the switch.

    Additional Information:
    limit and home switch

    Click the link to add information to this solution:
    When the machine hits the limits it stops but the switch is still tripped so clicking the Mach3 RESET button doesn't do anything. How am I supposed to get the machine to move off of the limit switch so I can continue working?

  • Many moons ago (when we were all a lot younger) you offered an export plan that consisted of various combinations of hardware/electronics and SketchUp of the CNC machine. Do you still offer SketchUp of your projects? I bought the new BlueChick and would like to build a roll-around cart for it. I might also wish to make modifications so a SketchUp would be most helpful.

    We did give out the plans for our machines many moons ago, but a few winters back we had to cease this practice as the night was young and full of terrors. Unfortunately we no longer offer the .dxf files or g-code files for any of our CNC machines.

    To build a roll cart for your blueChick, check out the similar cart we created for our blackTooth laser. (https://buildyourcnc.com/tutorials/Tutorial-sketchup-fabrication-fabricate-cad-cam-dxf).

    Click the link to add information to this solution:
    Many moons ago (when we were all a lot younger) you offered an export plan that consisted of various combinations of hardware/electronics and SketchUp of the CNC machine. Do you still offer SketchUp of your projects? I bought the new BlueChick and would like to build a roll-around cart for it. I might also wish to make modifications so a SketchUp would be most helpful.

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