1. Home
  2. Docs
  3. LongMill Benchtop CNC
  4. Hardware
  5. Touch plates

Touch plates

A touch plate can make it quicker and easier to find your origin point on your material. There are a lot of different types of touch plates, but the vast majority use some sort of metal block that detects when your end mill makes contact with its surface by completing a circuit.

Amongst touch plates, you can find ones that measure just the Z axis or some that can also find the offset between the X and Y axis as well. The Sienci Labs Touch Plate is an excellent example of a touch plate that lets you find the corner of your material in all three axes automatically.

Setting up and using your Sienci Labs Touch Plate

This guide will help you set up and use your Sienci Labs Touch Plate with UGSPlatform. If you have a different touch plate, these steps may help you set up yours as well.

Inside the package:

  1. One touch plate
  2. Red and black wire with banana plug and magnet (1.8m)

Step 1: Wiring and plugging in your unit

Your LongMill control board (the LongBoard) comes with a detachable two pin screw terminal on the Probe/GND pins. With a small flathead screwdriver, start by screwing the two bare wires into this terminal. Ensure that the red and black wires are in the correct spot as in the photo.

When properly wired, the red wire will be on the Probe pin and the black wire will be on the GND pin.

Next, plug the banana plug into one of the two holes on the touch plate. Ensure that it is well seated. You can pick the hole you want to use that helps keep your wires out of the way.

Ensure you have an end mill firmly secured in your collet. If you are planning on doing a probe on the X and or Y axis, make sure that you have at least 15 to 20mm of your bit coming out of the collet. For other notes on end mill compatibility, please go to the end of this guide.

Attach the magnet to your end mill. You can also attach it to the collet nut or another part of your router or spindle as long as you have a conductive path through your end mill.

At this step, you are ready to start setting up your touch plate in UGSPlatform!

Step 2: Setting up Probe Module in UGSPlatform

UGSPlatform comes with a simple plugin that allows for your machine to send the commands to your machine to utilize the touch plate for finding the X, Y, and Z-axis.

Start by going to the top of your screen and clicking Window -> Plugin -> Probe Module. You will see a new tab appear on your screen.

Next, we will change a few settings. Click on the “Settings” button on the plugin.

  • Units: Choose between millimeters and inches. For this guide, we will be using millimeters.
  • End Mill Diameter: This is the diameter of the end mill you will be using. You can find this diameter based on your manufacturer’s specs, or you can measure it yourself.
  • Fast Find Rate: This setting adjusts the speed at which the machine will move to touch off the touch plate on the first pass. Set this to 150.
  • Slow Find Rate: This setting adjusts the speed at which the machine will move to touch off the touch plate on the second pass. Set this to 25.
  • Retract Amount: This setting adjusts how far your end mill moves away from the touch plate on its first touch off. Keep this setting at 1.

Within the left side of the plugin, you’ll also see a few more tabs

  • XYZ: Finds the origin/datum point on the corner of your material in all axes.
  • XY: Finds the origin/datum point in the X and Y direction only.
  • Z: Finds the Z height only.

In these sections, makes sure that these settings are changed. If your section does not have that setting available to change, you can skip it.

  • Probe X Distance: 25
  • Probe Y Distance: 25
  • Probe X Offset: 10
  • Probe Y Offset: 10
  • Probe Distance/Direction: -15
  • Touch Plate Thickness: 15

Step 3: Operation of your machine

We’re pretty much ready to go!

If you want to measure XYZ,

  • Place your block on the bottom left corner of your part. Make sure that both of the insides of the plate is contacting the edges of your part.
  • Move your machine to position the end mill above the circular logo on the touch plate. Place it approximately 10 – 25mm above this circle. Make sure to double-check that your touch plate and magnet are properly connected.
  • Press “Measure outside corner” on UGSPlatform. The LongMill will go through a cycle to home and take its measurements. You will see the digital readout (DRO) on UGSPlatform change to reflect the measurements.
  • You can check that your position is correct by pressing “Return to Zero”. Your end mill should be positioned right above the corner.

If you want to measure XY only, follow the same steps, but your end mill will have an indeterminate Z height.

To find only the top of your material in the Z direction (Z),

  • Flip your touch plate upside down.
  • Place your touch plate on top of the material that you want to find the top of. Position the machine so that the end mill is above the touch plate.
  • Press “Initiate Probe”.

Remove your magnet and set your touch plate aside, and you’re done!


You may have some issues with using this touch probe in the X and Y direction if your end mill is

  • Irregularly shaped (v bits, dado bits) and the side of the widest point of the bit does not touch off on the side of the touch plate.
  • Non-conductive

If you get false detections when using your touch plate, double-check that the polarity of your wiring and the connector are correct.