In this installment I will show you how to install homing switches on your CNC Construction Set build.

The material I used for the mounting brackets is 1/4” PVC.

You can purchase a sheer here:

12” x 12” PVC Sheet

The Y axis mounting bracket is cut from a piece of 4” x 4” x 1/4” stock.

You will need two of these. One will be used on the Y axis and the other on the A axis.

The X axis mounting bracket is cut from a piece of 1.5” x 3.5” x 1/4” stock.

The Z axis mounting bracket is cut from a piece of 3” x 1.5” x 1/4” stock.

All the parts have been cut and hardware collected.

If you are going to paint the mounting brackets now is the time.

These will be installed on my orange build.

You will need four roller ball switches and hardware. They can be purchased here:

CNCCS Homing Switches

Attach one of the switches to the Y axis mounting bracket as shown here.

Use two #2-56 x 3/4” machine screws.

Secure with two #2 washers and hex nuts.

Finger tighten only.

Repeat on the A axis bracket. Note that the A axis is a mirror image of the Y axis.

Attach one of the switches to the X axis mounting bracket as shown here.

Use two #2-56 x 3/4” machine screws.

Secure with two #2 washers and hex nuts.

Finger tighten only.

Attach one of the switches to the X axis mounting bracket as shown here.

Use two #2-56 x 1/2” machine screws.

Secure with two #2 washers and hex nuts.

Finger tighten only.

All the switches installed.

You need to solder a pair of 12’ wires to each of the switches.

Connect to the common (C) terminal and the normally open (NO) terminal as shown here.

Important!!!

If you plan on adding heat shrink to the connections, be sure to add it before you solder the wires.

All the wires attached.

The wires I used all came from a 12’ length of CAT6 wire.

Purchase here:

Cat6 Cable 12’

Add a lock washer and two plain washers to a 1/4-20 x 1” hex bolt. You will need two of these.

Insert them into the mounting holes on the Y switch assembly as shown here.

Add a 1/4-20 T-nut to each bolt, as shown here.

If you have a cover attached to your Y carriage extrusion, you will have to remove it.

Slide the Y switch assembly into the slot shown here.

Finger tighten only.

Install a 1/4-20 x 1” carriage bolt into the slot shown here. This will be used for cable management later.

Install the same 1” hex bolts, washers and T-nuts on the X switch assembly, as shown here.

Slide the X switch assembly into the slot on the Y carriage extrusion, as shown here.

You want the X switch roller to come in contact with the X carriage plate, as shown here.

Once in position tighten the two hex bolts.

The Z switch assembly is held in place against the front of the Z bearing mount, as shown here.

Use a 1/8” drill bit to mark and drill two pilot holes about 1” deep into the bearing mount.

Secure the Z switch assembly with two #6-32 x 1” machine screws and washers.

Note that if your Z bearing mount is made from PVC or MDF, you can simply insert the screws. They will self thread the holes.

If your Z bearing mount is Corian or Aluminum, you will need to tap the holes with a #6-32 tap first.

The following is how I ran the wires on this build. Depending on what you have or have not added to your machine, you may have a better way.

I like to add split loom cable when using smaller wires. While it is optional, it needs to be added before you start fishing the wires through the system.

You can pick up some split loom tubing here:

1/4” Split Loom Tubing

The Z axis switch wire runs up and over the Z stepper motor.

The X and Y wires run around the back and enter E-chain about two thirds of the way into the chain.

The Z axis wires are routed down and into the X E-chain.

All the wires, including the A axis switch wire then enter the Y E-Chain.

The wires exiting the Y E-chain.

I make sure I have plenty of slack in my cables so that I can raise and lower my electronics board as needed.

I cut the wires so that They can reach the two terminal blocks shown here.

When cutting the wires, I always cut a few inches longer than I think I need. This gives me a little more play, and I can always trim the if needed.

Twist each of the leads from the X, Y, and Z switches together, as shown here.

IE we are connecting the switches in parallel.

Note that you can connect any leads you wish, polarity is not an issue here.

Connect each set of leads to the terminals shown here.

The X, Y, and Z switches share the same port on the G540. If you already have a probe connected, just combine it with the switch wires.

Then connect them to the terminal block shown here.

If you don’t have a probe connected, connect a wire between the terminal block here and the G540 terminal 1 shown below.

Connect the A axis switch to the two terminal blocks shown here.

Connect a wire from the terminal block shown on the right, To the G540 terminal 2 shown below.

Note that the A axis homing switch and the Plasma ArcOK signal share the same port on G540. IF you have the ArcOK signal wired to you machine, just combine the two wires and secure.

Open the Ports & Pins dialog and select the Input Signals panel and set the following parameters for the X, Y, and Z switches.

Note that You don’t want to enable the A axis switch yet, we will do that later once we have our X, Y, and Z switches working properly.

Open the Home/Softlimits dialog and set the following settings.

Click OK when you are done.

Note that you can tune the Soft Max settings later.

Go to the Mach3 diagnostic panel by selecting the Diagnostics tab at the top of the screen.

Press any of the X, Y, or Z switch rollers and the M1, M2, and M3 indicators should turn on, as shown here.

Press any of the A switch roller and the M4 indicator should turn on, as shown here.

Move your Y axis to the front of the machine. You want to adjust the switch so that the roller is just starting to rise.

Snug up the switch mounting screws and the bracket mounting bolts.

To test the Y axis switch, back the Y axis off just a little and hit the Ref Y button shown here.

The Y axis should move forward until it activates the switch then backs off.

If it does not, go back and adjust the switch position.

Snug up the X axis screws and bolts. Move the X axis until it engages the roller on the switch.

To test the X axis switch, Move the X axis to the right just a little and hit the Ref X button shown here.

The X axis should move to the left until it activates the switch then backs off.

If it does not, go back and adjust the switch position.

Snug up the Z axis switch screws. Move the Z axis until it engages the roller on the switch.

To test the Z axis switch, Move the Z axis down just a little and hit the Ref Z button shown here.

The Z axis should move up until it activates the switch then backs off.

If it does not, go back and adjust the switch position.

With the X, Y and Z switches configured and adjusted, you can now reference your X, Y, and Z axis by hitting the “REF ALL HOME” button shown here.

Open the Ports & Pins Inputs dialog and make the changes to the A Home setting shown here.

Note that if you are using a UC100 the port number will be 1.

Click OK to save the settings.

Adjust the A axis switch until the roller is just starting to rise, as shown here.

Snug the Screws on the switch and the bolts on the brackets.

To test the A axis switch, back the Y axis off just a little and hit the Ref Y button shown here.

The Y axis should move forward until it activates the Y or A switch. It will then back off then moves the other switch until it makes contact, then backs off.

You can now home and square your machine by hitting the “REF ALL HOME” button shown here.

Note that now that you can reference your machine, when you close Mach3, it will ask you if you want to save your current position. If you select yes, your machine will start up with the DRO settings where they were when you closed the program.

Another benefit of homing your machine, is that you can enable soft limits by hitting the “Soft Limits” button shown here.

When soft limits are enabled, your machine will start to slow down when it gets near zero and the max settings you entered earlier.

Note that this does not apply to the Z axis.

Later we can add a Safe Height adjustment so the the machine can be quickly moved to the Z switch trigger point.