5. Installing & Mounting Proximity Homing Switches

This article covers how to properly install and mount the proximity homing switches included with PwnCNC Conversion Kits.

Correct homing is foundational. When done properly, it gives you:

Reliable startup behavior
Repeatable zero positions
Accurate squareness between axes

When done poorly, it leads to:

“Won’t home” errors
Random homing failures
Machines that slowly drift out of square

The good news is that proximity switches are very forgiving once you understand a few basics.

What Type of Switches We Use

All PwnCNC Conversion Kits ship with normally open (NO), inductive proximity switches.

That means:

The switch is inactive by default
It becomes active only when metal
No physical contact is required

This is intentional. Normally open sensors are:

More tolerant of noise
Easier to diagnose
Safer in the event of wiring issues

You do not need to configure normally closed logic for these switches.

How Proximity Switches Detect Position

Inductive proximity switches detect metal, not motion.

They do not care about:

Speed
Direction
How hard something hits them

They do care about:

Distance to the metal target
Size and type of metal
Alignment and repeatability

What Can Be Used as a Target

The following all work well as homing targets:

Steel plates
Steel angle
Steel machine frames
Steel screw heads or bolts
Aluminum

📸 Photo placeholder: examples of acceptable targets

If your machine does not already have metal targets, adding a simple steel bolt or plate is often the easiest solution. Alternatively you can also use conductive copper tape: https://amzn.to/3ZYusik

Mounting Distance and Alignment

This is the most important part.

Typical detection range is:

1–2mm from the target surface

Best practices:

Mount the switch so it approaches the target squarely
Avoid angled or glancing approaches
Ensure the switch sees the same surface every time

📸 Photo placeholder: correct vs incorrect alignment

You do not need micron-level precision here. Consistency matters more than perfection.

Normally Open vs Normally Closed (In Practice)

With normally open switches:

Open circuit = not homed
Closed circuit = homed

This makes troubleshooting straightforward:

If the machine says a switch is triggered when nothing is near it, something is wrong
If the machine never sees the switch, you’re likely too far from the target

This simplicity is why we standardize on NO sensors.

Axis Squareness: How Square Is “Good Enough”?

Short answer: Very good, not perfect.

Homing switches define repeatability, not absolute squareness.

Key points:

The machine frame defines mechanical square
Homing switches just return you to the same reference point every time
Minor misalignment is corrected by machine calibration, not switch placement

As long as:

Both sides of a gantry trigger consistently
Switches are mounted securely
Targets do not move

You are well within acceptable limits.

📸 Photo placeholder: dual-Y homing example

Common Mistakes to Avoid

Avoid these and you’ll prevent most homing issues:

Mounting switches too far from the target
Using aluminum or stainless targets with low magnetic response
Letting the switch or target flex during motion
Mounting the switch where chips or dust can pack between it and the target
Over-tightening the switch body and damaging the internal sensor

Quick Test Before Final Mounting

Before committing to final mounts:

Temporarily zip-tie or clamp the switch in place
Manually jog the axis toward the target
Watch the Masso input status
Confirm repeatable triggering

Once confirmed, finalize the mount.

When to Pause and Ask for Help

Stop and reach out if:

A switch triggers randomly
An axis refuses to home consistently
The input shows active with no metal present
You’re unsure whether your target material will work

📩 [email protected]

Photos go a long way here.

Next Steps

Once switches are mounted:

Proceed to Homing Verification & Direction Checks
Then First Motion Test (No Spindle)

Correct homing is the foundation of a stable CNC. Taking the time here pays off immediately.