Proximity Homing Switches

Daniel Moran

Dec 26, 2021

1340

Note: This article is a work-in-progress as I've written it all out first... then will perform the actual steps myself taking pictures along the way. I will update this article with the pictures and refine the steps as well as provide additional tips to make things easier.

We've all seen the new features coming on the Shapeoko 3 with a Z-Plus carriage... and wished we could replace those finicky mechanical limit switches that came with our own machine. I'm here to help. Regardless of whether you purchased my limited-run Proximity Switch Kit or your gathering all the parts together yourself... I'd like to go into great detail how to upgrade your machine.

Note: This will likely void any warrantees and you run the risk of damaging your controller if you do this wrong. Please pay attention to these instructions and if you don't feel comfortable with them... feel free to return your proximity kit if you purchased one from me.

Fun tip: You can replace one or more of the limit switches at a time. I had my Z proximity switch installed for several months before finally upgrading the X and Y switches. So you can take this upgrade in 3 stages if you want... or all at once.

Pre-Requirements:

1. You must have a Shapeoko 3... standard, XL, or XXL doesn't matter. I have other brands and over time I will explore adding proximity switches to those brand machines... but since I broke the z-limit switch on my own production Shapeoko 3 XXL... that's what I worked on first.

2. HDZ... really? Well... it has more to do with the 3d printable brackets I've designed. While the X and Y proximity switch brackets will work regardless of the carriage, the only Z bracket I've designed thus far is the one that mounts to my own HDZ. There are other bracketing options on thingiverse. And I've added the other carriages to my to-design list.

Next up... you'll need the following supplies:

While my kit includes all of these things... I'm listing them out here with additional explanation for folks gathering their own supplies.

(3) Proximity limit switches. These can be found in lots of places aside from my kit, Amazon has many on their site... but essentially you need 3 of them; one for the X, Y, and Z.

(3) Extra 3-conductor wire... the proximity limit switches are generic so they only come with a short length of wire, you'll need to add additional length. In my kit i include three 55" lengths. You'll only need two at 50" and one at 40"... but i wanted there to be extra in case you needed to retry a step or two.

(1) 5x wire splitter. I went with the 5x Wago splitter since it was super easy to explain how they work and super easy to make work vs other wire splitting options.

(1) Breadboard wire jumper. I chose this because it comes pre-cut and connectors attached. One will attach to the Shaepoko's controller board.

(4) M3x10mm screws - mounts the X and Y proximity switch to their respective bracket

(2) M3x10mm screws - secures the X bracket to the right side gantry plate.

(1) M4x6mm screw - mounts the Z bracket on the back of the HDZ carriage

Other things you'll need:

My kit gathers the mostly non-consumable parts you'll need but here's a list of tools and consumables you should have on hand as a hobby-electronics person.

Super Glue - The Z proximity switch is attached to the Z bracket via super glue.
Dupont wire crimper and 2-conductor connectors
Electrical tape
Standard Wire Crimper

Nice to have...

Heat Shrink Tubing and a hair dryer or heat gun.
Ferrule Crimper... this thing is super cool and I used it a whole lot while assembling my New-Carve.

Step 1

The very first step is to lengthen the proximity switch wires. You can do this in a variety of ways... add connectors (tons of different types) to each side... but we'll stick to the simplest method for this article. Splicing the wires with electrical tape.

Pro-Tip: Take a look at the brackets... one of them has a hole through them (looking forward to step 2c) you'll need to run the wire through that hole. It is far easier to run the wire through the bracket prior to lengthening it. The splicing section may end up too large to fit through the bracket.

1. Take one of the 55" 3-conductor wires and on one side strip about 1" of the outer insulation material. Careful not to damage the three wires within.

2. Next strip a 1/2" of the inner insulation from each inner wire exposing the copper strands... twist the strands from each wire together.

3. Take one of the proximity switches and clean up the wiring by removing the three pre-cut inner insulations and twist those strands together.

4. Next up we'll be merging wires... and this part is important! We want to merge them in the following pattern:

This wiring pattern will keep give us a consistent experience when we go to wire these switches into the Shapeoko's controller board.

In the end you should end up with something like this:

Very last part of step 1 is to use your electrical tape to bundle it all together.

Pro-Tip: Add heat shrink before merging the wires together as a way to keep things super clean.

When all is said and done... you should end up with 3 proximity switches with really long wires ready for the next step.

Step 2

In this step, we're going to mount each of the switches in three sub-steps for each axis... the X, Y, and Z. You'll need the lengthened proximity switches as well as the 3d printed brackets and screws. Remember to remove each of the original switches as you mount each of these new switches.

Note: that there is no difference between the actual proximity switches... all three are identical at this point. The differences will be introduced when we go to wire it up.

Pro-Tip: When you choose each switch for mounting... label the other end of the wire so our next step goes smoother.

Step 2a - First up is the X axis... mount the bracket and attach the switch.

Mount the switch to the bracket first using two M3x10mm screws.

Next take two additional M3x10mm screws, screw them into the X bracket. Before tightening, place the bracket/switch assembly onto the right side end-plate; then tighten to secure.

The switch is aligned such that when the carriage is all the way to the right, the switch roughly aligns with either my aluminum track brackets or with the carriage aluminum.

Remember metal is required to trigger the switch so if you have my acrylic track brackets... you may need to add a small piece of foil tape to the right edge of the track bracket to trigger the switch properly.

We're going to run the wire through the end plate's opening... but pause here as we'll be running the Y wire along the same path in our next sub-step.

Step 2b - involves installing our Y switch. In this case we'll be reusing two screws and risers.

Before mounting the switch to the bracket you'll want to mount it to the end plate first. Insert one of the original long socket head screws into my bracket, add the riser and loosely screw into the right end plate. Repeat with the other screw and riser... and secure.

Now it's time to mount the Y switch using two M3x10mm screws. For folks who've purchased the kit... you'll have socket head screws and they are different from what i've mounted to my own switches in the picture here.

Once the switch is mounted, run the wire through the little hook in the 3d printed bracket and up to the same end-plate hole in step 2a.

Step 2c - Next we'll be installing the Z proximity switch.

First step is to run the really long wire through the Z bracket... assuming you've followed our pro-tip above, then this part is done.

Add some super glue to the black side of the switch.. press that glob of glue ;-) into the bracket and secure with a little painters tape to allow it to dry fully.

Next we'll be snapping the wire cover piece into the main body of the Z bracket. This will help align the wire to keep it secure and clean.

Finally we can use the M4 screw to secure the bracket onto the HDZ carriage.

The switch is position so it is perfectly inline with the Z track. This also sets the sensor in the right position so when the Z plate is raised, it will come within range and properly trigger the proximity switch.

Lastly run the Z switch wire through the X cable chain.

The X, Y, and Z wires should come together along the left side X gantry plate. Run them though the Y cable chain so they come out near the controller box.

At this point you should have 3 new wires with each one labeled: X-Limit, Y-Limit, and Z-Limit.

Step 3

If you've made it this far it is very impressive... especially if you're pre-reading this and haven't touched your machine yet ;-). Only a few more steps to go.

In step 3 we'll be cutting the wires down to length and attaching some 2-conductor Dupont connectors... new tool fun!

Step 3a Remove your controller's cover. Feed the wires through the covers hole (if it's the old style full circle holes) and lead them over to the limit switch connectors side of the controller board. Add about 3-4 additional inches and, after relocating your labels), snip them down to length.

Step 3b On each of the limit switch wires... remove about 3" of the black insulation from the wire exposing the 3 inner wires. Be careful not to damage the inner wires in this step.

Step 3c Again on each of the limit switch wires... remove about 1/2" of insulation from each of the 3 inner wires and twist the copper strands together.

New tool time!!!

If you decided to get the Ferrule crimper... now's a great time to take the RED wire and add appropriately sized Ferrule connectors to each one. The RED wires will all lead into the 5x Wago splitter... but for now we're just preparing wires.

Another new tool time!!!!

Now... we'll need to use the Dupont crimper... and this one may be tough.

Pro-Tip: If you've never used this tool before, use the extra bits of wire you snipped off in step 3a to practice on.

Your Dupont crimper kit came with all the supplies you'll need to make this happen. First up are the female inner metal parts.. they look like this:

Snip them off the long strand and trim them like this:

Pro-Tip: Take needle-nose pliers to gently pinch the tongs on the female piece to make it easier to crimp.

Take the crimper and gently set one of these into the crimper and tighten the crimper a few clicks.

Take one of your limit switch wires, carefully bend back the RED and BLACK wires... leaving the YELLOW wire pointing out and slide it into the female piece sitting within the crimper. Then crimp it.. crimp it good... but not too good. These are very delicate... as you gently grip the crimper, pay attention to when the crimper releases the lock... the instant the lock releases, release your grip and you're done.

Now... repeat step 3c for each of the YELLOW and BLACK wires. Each one will need a female metal piece attached before you can proceed.

Pro-Tip: The controller board doesn't really have dupont connectors for the limit switches but they are extremely close. We'll need to make one small modification to the white plastic dupont pieces so they slide into the Carbide's controller board nicely. Take a box-cutter and trim the guides off the side of the white plastic pieces like this:

Step 3d Now it's time to assemble these connectors. each limit switch's YELLOW and BLACK wires will be plugged into the same white connector piece with a particular orientation like so:

When finished you should have a completed connector like this:

Repeat this for the other two limit switch YELLOW/BLACK wire pairs.

Hard part is over... time to plug it all in!

Plugin the yellow/black connectors just like you did with the original limit switches:

Next we'll need to run the 3 red wires over to the 5x wago connector like this:

The three red wires get inserted into the wago connector with the breadboard jumper wire as pictured.

The other end of the breadboard connector gets plugged into here: IMPORTANT! This specific pin supplies the power needed by the proximity switches to work properly.

Conclusion

That's the bulk of it... clean up your wires and cable chains, recover your controller and you're good.

Ready to turn on your machine and test thing out by homing. If that works then you're good... and truly done with this upgrade, congratulations!

I would love to hear how it went... Come share your story with all of us in the PwnCNC Users Group on facebook.