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?

You can add a limit switch to either the USB or the parallel board. Please refer to the product pages for these items to view wiring diagrams.

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I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

You can add a limit switch to either the USB or the parallel board. Please refer to the product pages for these items to view wiring diagrams.

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I want to add limit switches but I have no connections on the breakout board. Can I use a usb interface board for the limit switches as well as the parallel port for the running?

Yes, the best way to attach a relay to the output of the Mach3 USB board is to use an SSR (Solid State Relay) at the 24 Volt rating. This is the standard supply for this side of the Mach3 USB board.

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I am converting from a Parallel Port to the Mach3 USB. My limit switches can accomodate up to 5VDC and I want to Drive a Relay from one of the outputs. Will my switches work and do I need a 24VDC Relay?

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 computer does not have a parallel port, all you will need is a low cost PCI parallel adapter card (these can be found on amazon for $15-$20). If you plan on using a laptop (not recommended) you can try to find a PCMCIA parallel adapter, but many people have frequent issues with this setup. A more expensive solution would be to purchase a USB smooth stepper board. Unfortunately, we do not supply any of these adapters and cannot attest to their reliability.

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ur gay

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MY COMPUTER DOES NOT HAVE A PARALLEL PORT. HOW DO I INTERFACE WITH THE MACHINE?

Sure. If you had your own computer to start with and now need a replacement for it, consider our redSprout and redLeaf systems. You can find information about them here: https://buildyourcnc.com/AssembledElectronics.aspx If you started with one of our assembled systems, and only need to replace certain components, contact our sales department at sales@buildyourcnc.com for a quote.

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Can I get a replacement computer only ? I have a blacktoe with parallel port and it seems to have stopped working.

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.

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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

Here is how to connect your router to the parallel breakout board through the on-board relay. You will need a spare extension cord. You will need to remove a portion of the outer jacket of the extension cord to expose the white, black and green wires (white = neutral, black = live and green = ground), understanding that the neutral and live create the completed circuit.

See this image of a similar connection. The terminal has the same connections.
https://www.buildyourcnc.com/images/vacuum-pressure-controller-relay-terminals-700.JPG

Image of the relay terminal:
https://www.buildyourcnc.com/images/breakoutboardrelayNONC.PNG

The live/black wire would be cut and one end of the cut would be secured into the P terminal and the other cut end would be secured into the S terminal. The live and ground wire would be uncut and travel from the plug to the router.


Additional Information:
You can also connect other high powered devices to the breakout board using any of the output terminals. You will need to supply extra relays like the one shown here:
https://www.buildyourcnc.com/item/electronicsAndMotors-breakout-Relays-relay-board-250V-12A-5V

Or you can find SSRs (Solid State Relays) that will accept 5v to drive the relay coil. Make sure the SSR will protect the 5V line from Back EMF as there is a coil in the relay. The one we sell contains a fly-back diode to protect the 5v terminal.

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I have your breakout board with relay parallel port , how can I wire up a regular router to that board so I can control the router

Make sure to wire the limit as normally open.

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[575] I had limit switches working and on input 2. Now looking at Mach 3 diagnostics, Input 2 is continuously on and triggers limit stop. I removed all input 2 so the machine can run. Rebooted all. Anyway to reset Input on card?

The largest CNC machine we make at this time (12/04/2015) is the GreenBull 6'x12' model. This model has 2 options for Z-axis travel.

The short-z option has a total Z travel of 5.75 inches. From that you would subtract the length of the end mill used and the thickness of the spoil board to determine the maximum material thickness. (Example: If the end mill extends 1.25" from the collet and the spoil board is .75", then the material could be up to 5.75 - 1.25 - 0.75 = 3.75 inches in thickness). This is good for most sheet-type materials.

The long-z option, used mainly for large 3D carvings, requires a custom frame and allows for up to 36" of travel.

The tolerance of our machines, like any machine, depends on several variables. The major variables include the manufacturing tolerance, the type of machine control used, the precision of assembly, the thoroughness of maintenance, and the initial and ongoing calibration of the machine. Because we sell kits only most of these variables are outside our control. Therefore, we are hesitant to guarantee a certain level of tolerance for an end user. However, in our experience, tolerances of .001" are readily achievable with our machines.

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What tolerance can I expect from your largest cnc machine and the laser cutter? Also, what depth can I get on the z axis?

Modifying the Z-axis to accommodate a larger motor will be a worth while task and is possible, however we have not calibrated the z-axis therefore using the 1600 Steps-per inch in the motor tuning on our machine in our shop. We have not noticed any significant depth increments from not calibrating the z-axis but only from zeroing the z axis too close to the material. Also in your design did you specify the actual depth and the length of tool (end mill/ bit) that you are using?

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I bought a Blacktoe 2 x 8 three years ago and have always had a problem with the Zid axis. No matter how tightly I've calibrated the axis it always cuts to deep. Can I put a larger Stepper motor on Z-axis using the same motion electronics that came with the original machine.

The diagram for wiring the USB interface board is located here: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout#prettyPhoto/2/

Under the board illustration, there are three smaller diagrams of limit switch wiring. On each, there are two connections, the GND and the pin which are labeled at the ends of the circuit on the diagrams. The pin side would go to the axis label ++ or -- terminal (i.e. X++, or X--). The other end, labeled GND would connect to any ground terminal on the board.

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I am using 5 limit switches on my 3 axis machine. I am using the usb controller for planet cnc. I would like to know where all the wires related to the limit switches get connected? A diagram would be helpful.

The USB Interface page: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout

On this page, there is a datasheet that explains the connection schemes for the limit switches on step 1 of the instructions. The datasheet explains single and multiple switch configurations and parallel/serial connections schemes for the NO/NC (Normally Open/Normally Closed states).

If there is further information you need, please reply on this FAQ.

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Please provide detailed instructions on how to connect limit switches to CNC USB BOARD. I can not find instructions anywhere. I am new to cnc world and really need help. Thanks

You will need to build the table unit for your machine. There are instructions on how to do this at the bottom of the product page here, https://www.buildyourcnc.com/Item/cnc-machine-blackFoot-v4
There is no estimate on how much this will cost though, since there are too many variables involved to do this.

- PC with parallel port and USB port
- 20awg stranded wires for the motors - http://www.buildyourcnc.com/electronicscombo.aspx
- 18awg stranded wires for power supply to drivers
- 24awg stranded wires for breakout board to drivers
(location and spacing of components varies from one person to another, so we do not provide cables/wires)
- General purpose extension cord (cut the female end off) to provide power to power supply
- USB cable to power breakout board
- Parallel cable to communicate to breakout board
- Router
- (optional - instead of router) Spindle with power inverter http://www.buildyourcnc.com/SpindlesAndAccessories.aspx
- (if purchasing spindle with inverter) General purpose extension cord (240v) (cut the female end off) to provide power to power inverter
- End Mill(s) http://www.buildyourcnc.com/ProductsEndMills.aspx
- CAD, and/or CAD-CAM software (to produce geometry, machine operations, and g-code) http://www.buildyourcnc.com/CNCsoftware.aspx
- CNC control software (to read g-code and control machine) http://www.buildyourcnc.com/CNCsoftware.aspx

This answer is applicable to most of our machines with the exception of the greenLean and the blueChick since those machines are equipped with a table structure.

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Can I purchase a computer off Amazon (I have a machine I want to use) and still use the USB interface to drive it with LinuxCNC?

When trying to use two motors on a single axis, there is a multitude of methods to get them to work together.
First: There should always be a slave option in the CNC control software(mach 3/ planet-cnc/emc2/etc.), this will be the easiest way to make the dual motor configuration work. However some adjusting might be necessary due to the orientation of the motor when mounting it on the opposite side of the CNC machine.(Mach3/config/slaveaxis, planet-cnc/file/settings/axes).

Secondly: Dealing with our interface boards(maybe third-party as well), you can have two drivers going to the same axis on the interface board. Which then will have one motor per driver, this will use the same motion and control from the (ex.) x-axis to driver two motors. However some adjusting might be necessary due to the orientation of the motor when mounting it on the opposite side of the CNC machine.

Adjusting of the driver or motor wires, can be done separate from the control software with the use of a hex inverter, that can be used and to switch the signal (ex. takes a low signal and brings it high, and takes a high signal and brings it low) of one of the motors, to run the same as the other motor.
There is also another method of inverting the orientation of the motors movement without the use of a hex inverter. This method you will have to wire the coil's of the motors oppositely of what is recommended for one of the motors. Example, you will wire our Nema 24 as follows(recommended): A+ - red/blue, A- - yellow/black, B+ - white/brown, B- - green/orange. However to run another motor with with it you will have to switch the A/B connections to: A+ - white/brown, A- - green/orange, B+ - red/blue, B- - yellow/black.

These method's are usually needed/used when trying to control two motors and setting it up without the help of the CNC control software, and also due to the mounting orientation of the second motor, the inverting the direction of motion will be necessary so they work together instead of working against each other.

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From the BOB how can I reverse one of my steppers - i'm running 2 on my Y Axis

We have sent machines everywhere across the globe and we can work with freight companies to get you a good rate on a shipment. Please email sales@buildyourcnc.com to request a quote.

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Im from chile have you ever send any machine to south america? can i buy only the mechanic and electronic things ( wood parts are much weight)

If your axis shutters and will not move unless moved by another force, that sounds like your acceleration is set too high. Lower the acceleration until it works well, then lower it a bit more to have a margin of safety.

IF that didn't work, try swapping the X and Y drivers. That way you will pinpoint if the issue is the driver. If the proplem persists, then there may be an issue with the motor itself.

The X and Y drivers can be easily swapped by swapping only the motor wires.

- Remove the x-axis motor wires from the X driver.
- Remove the Y motor wires from the Y driver.
- Insert the X motor wires into the Y driver.
- Insert the Y motor wires into the X driver.

Now the Y-axis will move the gantry. Test the Gantry movement by moving the Y axis using the up and down arrow keys (mach3).

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X AXIS STEPPER MOTOR STALLS AND SHUTTERS WHEN COMING FROM A STAND STILL WON'T MOVE WITHOUT PUSH BY HAND. I TOOK THE CHAINS OFF SPUN FINE WITH OUT LOAD. HAVE CHAIN HOOKED UP CAN MACHINE BACK FORTH HAND, NO HANG UPS OR ANYTHING, BUT TRY TO IT DOESN'T JUST SPINS OUT. ANY SUGGESTIONS?

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.