Automating our MOPA fiber laser

Fiber Laser Introduction

With most Fiber Laser engraving machines you have to use either a switch on the front of the machine or a rotating handle to adjust the height. Then when loading a new piece of work that requires a different height you have to then use the switch or handle again to move the Z-Axis.
Doing it this way can be an inconvenience as you have to keep note of the ruler height you set for each new work piece. This practice becomes finicky using the switch to try and get as close to the ruler setting as you can.

By removing the AC motor and replacing it with a stepper motor, controller and software we can make life a lot easier.

You will be able to store each position in the software, set up homing and automate the whole process.

The first issue we came across when starting this modification is that for some reason they do not seem to use a very accurate ballscrew on the Z-Axis. On our machine our ballscrew had a drift of 7mm over 600mm length.

To get around this we have built a calibration routine in the software and this video will demonstrate that.

Note: With our instructions we mention an adaptor kit, this is a required part of the assembly and for more information on obtaining a kit or requesting more information on this modification please contact

Z-Fiber Utility Tool

The Z-Fiber Utility Tool gives you full control over the focal position of your machine.

This tool boasts a high accuracy of 0.005mm and also a manager for saving, loading and deleting preset configurations.

Built into the software is a simple calibration tool as well. This will measure the length of travel the machine has and adjust to suit any runout. We found our machine had a runout of 7mm over 600mm travel and the software now takes that into account when executing any further movements.

Please note: In order to use the software fully a Pulse Train HAT is required these can be found here Pulse Train Hat Product

System Requirements:

  • Operating System: Windows XP or later
  • .NET Framework: 4.0 or later

Download Z-Fiber Utility Tool

Operation Guide

We have produced a small video with the intended purpose of being a quick start operation guide. For further information please refer to the Help section in the software.

Assembly Prerequisites

Before we proceed with the assembly we recommend that you have some intermediate knowledge of basic electronics to navigate through this guide.

Below we list all the required components for this build.

Our fixing kit is made for a NEMA23 footprint, we also sell the NEMA23 stepper motor with embedded driver that we used on our online shop.

The PTHAT and USB to Serial Board can be found on our website as they are produced by CNC Design Ltd.

Required Tools:

  • M3, M4, M5 Allen Keys
  • Wire Cutter
  • Wire Stripper
  • Soldering Iron

Required Components:

  • Pulse Train HAT Full Package
  • PTHAT USB to Serial/I2C Board
  • NEMA23 – Fiber Laser Adapter Kit – Contact us for more information about this adapter kit
  • NEMA23 Stepper Motor with driver
  • 24v DC 5A DC Power Supply
  • 8mm to 10mm Coupler – These can be found on eBay NOTE: The end of the Ballscrew on our machine is 10mm diameter this may be a different size on your machine.
  • Solder – Self-Fluxing preferably
  • Heat Sleeving
  • Electrical Tape
  • 3 Way Terminal Block
  • Wires/Cables

Optional Components:

These are highly recommended but are optional.

  • Enclosure – The PTHAT has the same footprint as the raspberry pi so most Rpi enclosures should suit.
  • VBH Tape – This bonding tape was used to secure the Enclosure to the frame.

NOTE: Be aware some images are cropped, enlarge a full size version by clicking on the image.

Assembly Instructions

First remove the top and bottom limit switch, they’re held in by 2 x M3 bolts.

Now unbolt the suppressor that’s held in by 1 x M4 bolt.

Then remove the 4 x M5 bolts that support the motor and gearbox.

Loosen the top coupler using an M4 allen key.

Now the couplers loosened off remove the motor and rest it on top of your laser or the floor if it reaches.

Then remove the gearbox.

Unbolt these 3 x M5 bolts and remove the plate.

Unscrew the 4 x M4 bolts from these 4 deep holes.

Loosen the bottom bolt on the coupler and remove it.

Locate the two pairs of red and black wires, these go back to the limit switches. Cut these wires off and remove the limit switches.

Then follow the braided cable all the way back to the conduit.

Snip the 3 wires and screw them into a terminal block and tape it so the live wires are inaccessible.

De solder the existing wiring on the microswitches and replace it with new wires. Be sure to attach the red wire to Normally Open (NO) and the black wire to Common (C).

Afterwards heat sleeve any visible contact points.

You should now be able to pull the remaining wires out of the machine.

Unbolt these 4 x M5 bolts and remove the plate.

Now we’ll attach the microswitches, starting with the bottom one first.

Thread the cables of the micro switch from the bottom opening of the frame to the top. By taping the ends of the wires together with a small magnet we were able to guide the wires up through the frame using a strong magnet on the outside of the frame.

Even though we used magnets to thread these wires through the frame, this can also be achieved using some string or a rod it’s your preference but we found magnets were the easiest solution.

Once the bottom microswitch has been threaded through to the top of the frame. Bolt that microswitch on and bolt the top microswitch as well.

We taped the ends of the Top limit with red tape so we could later distinguish between the two when it came to wiring.

Now we mount the motor. We have the following:

12 x M5*12mm Bolts,4 x M4*16mm 4 x M5*45mm Hexagonal spacers.

1 x Adaptor Kit.

1 x 8mm to 10mm coupler. (The end of our fiber laser ballscrew has been machined to a 10mm diameter yours may be different.

1 x NEMA23 Stepper motor with embedded driver.

Attach the Motor to the Motor adapter plate shown below using 4x M5*12mm bolts.

Bolt the top plate back on with the same 4 x M5 bolts, make sure to thread the limit switch cables through the small hole on the right.

Then roughly align the Support adaptor plate as shown above.

Next take the Spacer adaptor plate and lay it on top of Support adaptor plate and use the 4 x M4*16mm.

Attach the coupler to the Ballscrew then bolt the motor plate onto the 4 spacers aligning the motor shaft into the coupler.

Wire the PTHAT as shown in the wiring diagram below and mount it to the machine somehow.

We enclosed the PTHAT and used 3M VHB tape to secure the enclosure to the machine.


That concludes our assembly guide, your machine has now been modified for use with our Z-Fiber Utility Tool.

For your next steps refer to our Operation guide video.

View our Operation guide video