Your g-code probably has the feed rate too high. You set the velocity and acceleration in your motor tuning, but g-code may be able to override these values.

Try lowering the feed rate in either your CAM program or in the g-code manually. The feedrate code has an “F” then a number after representing the velocity.

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I'm using Mach3 and I tuning the motors. As is they all seem to jog nicely, smooth and quiet. However when I make moves using gcode they bind and don't move or jerk violently when they do move. What step did I miss?

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.

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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?

This is most likely a wiring issue. I would disconnect all of the power to the drivers and reconnect one at a time to isolate the problem.

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that was not helpful. I already did that way before submitting this question. there are not that many wires here and I have already rewired this a few times. I actually think its a software or interface board issue because it does work sometimes but then trips (possibly a amperage / voltage issue) I am using the interface board that has a parallel port and usb for 5V. are there different settings that I need to setup?

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I'm using the big 651oz in stepper motor for X and Y and the smaller 325 for the z and X and Y keep tripping when I try to tune the motors on Mach3 but Z seems to work. I have to turn power on and off to reset....is this a wiring issue?

You will want to connect the homing switches (which may also serve as your near limit switches) to different input terminals. It's ok to add more limit switches with the home switches, but each home should be on independent inputs. For example, connect home X and any other limit switch to IN1, connect home Y and any other limit switch to IN2, and so on. This will allow you to properly use the "ref all home" button in Mach3.

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In the instructions (diagram 1) you show all the home switches connected in parallel? But here you say they need to each have their own inputs. "You will want to connect the homing switches (which may also serve as your near limit switches) to different input terminals." I dont see how the second and third axis can go home if the first axis has already closed the parallel circuit unless they back off a bit until the switch opens up again before the next axis goes to home? My machine has no limit switches so I assume they are home switches.

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[575] I have finally got my limit switches wired and working - thank you. Can they also used as homing switches and if so it it just a question of looping the two inputs on the board i.e. the limit and home terminals IN2 to IN3

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

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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 are using Mach3 do you have your hotkeys set up correctly?

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The office was closed on the weekends and during Dr. Martin Luther King Jr. Holiday.

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I got my Blackfoot 4.3 built. Hooked it to the Redleaf and when testing the axis controls Im able to move the X axis using the Right arrow key, but unable to move it with the left key. I have no control on my Y axis. Tried calling for tech support and recieve voicemail 2 days in a row after a few calls each day.

We recommend using shield wire for wiring the limit switches.

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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?

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.

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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?

You will also need to check if the mach3 configuration and the wiring. Since you tested the connection from the motors to the drivers, the connection from the computer to the interface may still be the issue. It could also be the connection from the interface to the drivers, but we test all of these units going out, so I don't believe that would be the problem.

If you have a redfly that uses a parallel cable, you may need to check to make sure the parallel cable is functioning properly, and also, make sure that the interface is also powered using a usb cable.

If you have a usb interface (the terminals will be labeled XD, XP and so on), then there may be a wire not seated correctly in a terminal.

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I plug in my redFly for the first time and after configuring Mach3 and rechecked my settings axes Y and Z are working well, but X is not working, just for testing I plugged in each motor to the Y and Z and they work fine, but no motor works when plug into the X axes of the redFly, also one of the NEMA 24 425 Oz motors dose not turn just jitters.

The fact that you cannot move the motors with the keyboard serves as a clue to a couple possibilities.

- The software may not be communicating with parallel port. (One possibility may be that your step pins are not low active, or vice versa depending on your drivers).
- You may not be in the correct tab of Mach3. Make sure you are in the Program Run tab.
- The jog on/off button on the program run screen may not be lit (invoked).

This address below shows the complete troubleshooting for this type of situation. It will show how to test each pin at the parallel port at the back of the computer and everything else associated with correctly wiring the electronics.

https://buildyourcnc.com/CNCElectronicsandWiring.aspx




Additional Information:
6 axis robot with Mach3 Card 6 Axis Motion Controller

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I have a home built CNC running Mach 3. I have power to all the motors and the breakout board but no movement when running g-code. I cannot even manually move the motors with the arrow keys or page up and down. It also has an integrated 120v receptacle showing an open ground. I don't know if all this is related.

Polabs prepared step by step user guide for PoKeys57CNC and Mach4 to try answering such questions. It is available in our downloads section: https://www.poscope.com/wp-content/uploads/downloads/Pokeys/LibrariesAndPlugins/Mach4 and PoKeys57CNC - step by step guide.pdf

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I need your assistance... I have two items left to setup on my Pokey57CNC and Mach4, Home switches and Spindle Speed. I have watched the videos, but they are for Mach3 and the screens are different in Mach4. Can someone please explain the setup of these two items in Mach4?

If some axes are not moving in two directions, the direction signal is not making good contact at either the controller or the driver.

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I have USB Interface board. All axes are working if using MDI , using program some of the axes are only moving one direction. Example using Gcode X50 Y50 Z50 and then X45 Y45 Z45 then online one of the axes is turning correctly. But also shows on Mach3 screen that all axes are moving correctly.

When you press the x-axis limit switch, does the LED emit light?

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I currently have my whiteant build complete. But when I go to print the 20mm x 20mm box I seem to be having issues. The Z axis does not seem to move. Also the X axis hits the limit and does not move of of it. What is the best way to trouble shoot this issue?

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

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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.

If your motors are hot to the touch, this is normal. Current is being drawn by the motor coils as the motor moves and as the motor stays at a position. If the motor is not using the current in the coils to move (holding it's position), the energy will be translated as heat (rather than motion, sound or light). Even while moving, some of the energy will be lost as heat. Remember that energy cannot be created nor destroyed.

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I have followed all the "CNC Electronics 1 - 9" videos and I'm using almost the exact same components (motors run and sound good) but the motors are runing very hot in just 15min with no load - have I done something wrong or do steppers run very hot?

Not sure what you mean by the statement "I don't know when you answer". Please explain. I answer all of the incoming emails until my inbox is completely empty and all phone calls to the company go straight to my cell phone and I answer all of the calls, and if I don't answer, I call back immediately.


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I just searched my email and found no emails with your email address associated with the email listed with this question. I cannot answer questions if no correspondence was provided by you.

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Please send an email, I am giving up on buying a machine from you because I don't know when you answer. I was asking about getting just the working parts and rails sent to Fiji. You sent an answer and some questions, but I have no way of knowing if you responded again.

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

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LIMIT SWITCHES FOR AXIS. THE PRINT SHOWS THAT YOU CAN WIRE LIMITS EITHER N.O. OR N.C. SO IF THIS IS CORRECT I WOULD NEED TO TELL BOARD IN SOFTWARE HOW LOOK AT THESE LIMITS, I'M GOING GET AN INPUT LOOSE DEPEND ON IT.

Are you trying to use the MPG (tab), or the keyboard for jogging the motors? You mention 0,0,0, are you trying to home the machine with the "ref all home"?

If you cannot move the motors with the keyboard, check if the jog is enabled.

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[596] I have my motors and limit switches working correctly but I am unable to get any movement from the 'jog step' so that I can set 0,0,0. What should I check

If your motors are hot to the touch, this is normal. Current is being drawn by the motor coils as the motor moves and as the motor stays at a position. If the motor is not using the current in the coils to move (holding it's position), the energy will be translated as heat (rather than motion, sound or light). Even while moving, some of the energy will be lost as heat. Remember that energy cannot be created nor destroyed.

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I HAVE FOLLOWED ALL THE "CNC ELECTRONICS 1 - 9" VIDEOS AND I'M USING ALMOST EXACT SAME COMPONENTS (MOTORS RUN SOUND GOOD) BUT MOTORS ARE RUNING VERY HOT IN JUST 15MIN WITH NO LOAD DONE SOMETHING WRONG OR DO STEPPERS HOT?