The stock machine is capable of basic laser operations at reasonable speeds but has been ham strung by the use of a proprietary controller board, called a Moshi Board. This board communicates with a computer running Corel Draw. Most of the time, when you purchase a K40, it will come with an illegal copy (Trial Copy maybe) of Corel draw. I personally don't like this as a permanent solution, so I choose right out of the gate to replace the electronics with a more legit, and open hardware/software solution. I knew I would do that before even purchasing the machine. If you are interested in just upgrading the electronics, this guide will cover some of that as well. Even with the reworked electronics, I quickly became tired of the "sub-par" mechanics. My machine would bind and move unreliably. After some tinkering, I decided finally to just rip the old mechanics out. Being committed to gutting the cutter, I decided to see just how big of a cutting area I could get. Please take note that I have included the STP (Generated in Fusion 360) file on Thingiverse, please use this for reference as this guide, being done from memory, may miss a few items.
Get The Files
Most of the parts required for this conversion will be 3D printed. The rest can be ordered through amazon, or Openbuilds.com. Links to many of the items used can be found below in the Bill of Materials.
The 3D printed parts are available over on thingiverse at: https://www.thingiverse.com/thing:3401855. I printed everything out of PETG at a 0.2mm layer height on an Ender 3.
The Tear Down
To start, we will need to empty the case of everything (Proceed at your own risk as we are dealing with high voltage, cutting and Lasers).
Start by FIRST taking a picture of your wiring. That way, you will have a reference of how things were before you/we broke it. Don't stress, there is also a wiring diagram below. However, there is a chance your power supply (PSU) is different, so please make sure it looks the same before using my work as an example.
- Make sure the Mains power is disconnected and let the power supply sit over night (Just to be safe)
I would recommend you unscrew all of the wires and remove all of the switches, gauges, and everything else from the right hand side of the machine first.
- If your machine is like mine, you will have a RED wire going from the PSU (Blue power supply) through the case to the back of the laser. You can follow the instructions online for changing the laser tube to learn how to disconnect this wire, or you can be lazy like I was and just cut the wire half way between the PSU and the Laser Tube. This wire appears thick on the outside but is actually very thin on the inside. It appears to have a LOT of insulation. Keep that in mind when splicing it back together. I wrapped mine with ample electrical tape.
- Next, the two lids (Doors) can be removed. Raise them up and you will find a spring loaded pin on one side of each lid, pull the pin back and the lids should just come right off.
- Disassemble / remove the X-Y mechanism. The whole unit will come out as one piece.
- The center divider as well as the front support "shelf" will need to be cut out. Use a grinder or rotary tool to cut the tac welds. I was able to cut several of the welds and those I couldn't reach I was able to bend the metal back and forth until they snapped.
- I used an orbital sander to knock the metal burs down and get the bottom of the case smooth.
Preparation for new Install
I masked everything off on the case that I didn't want to be painted. Then, I gave the interior of the case a good coat of self-etching primer
- The bottom of the case is not actually super flat, nor rigid. Not to mention the two large holes that the manufacture thought were a create idea to add to the bottom of a laser.
- To solve this problem, I cut a piece of 1/2in MDF (Any 1/2in sheet good will do) to 29.75in x 18.5in.
- I cut a thin piece of aluminum sheet (Purchased at local Home Improvement Store) to the same dimensions.
I then laminated the aluminum sheet to the piece of MDF
- Taking both the primed case and the laminated board outside, I applied several layers of Rustoleum Flat White
Before placing the laminated board into the case, I added the two horizontal pieces of 2020 V slot. Two pieces, both 29.75in long were attached to the board, one along the front edge and the other along the back. I attached these to the board by drilling and countersinking 4 holes along the front and 4 along the back from the bottom of the board. The V Slot was then attached using M5 screws and T nuts:
- Place the Board inside the case, but do not secure it. We will do that later, once everything else is installed. Things will be tight and you want the flexibility for now.
Installing the Y Axis
- Start by assembling the Left Y Axis. Cut two lengths of 2040 V slot to fit (Mine were 17.75in each). All of the screws used were M5. I used full size V bearings with eccentric bushings for the top two bearings and fixed spacers for the bottom two.
- Then Assemble the right Y Axis:
- Place the Left and Right assemblies into the case, lining the brackets up with the front and rear 2020. Install the M5 bolts with T nuts into the brackets, but leave them loose in the V slot for now as you will want to be able to move the assembly in the next step.
- The left and right y carriages are driven by a single motor. They are connected in the back with a piece of 5/16 in threaded rod. Install the Motor to shaft coupler on the left side of the screw. Then Cut the screw to a length that is long enough to get through the bearing mount on the right carriage assembly, but not so long that you can't get it installed with the amount of play you have available. Mine ended up just under 28in. You will want to also install the right pulley as well.
- Now is a good time to attach the belts on the left and right carriage. Reference the photo below for how I did it. I zip tied the belt to one of the M5 bolts on the carriage, then routed it around the pulley and then the idler before I zip tied the other end to the other bolt. (HINT: Loosen the pulley a little before routing the belt, then after the belt is secure, add tension by pulling the pulley back into position and securing.)
- Okay, it is a little out of order, but I felt I needed more light while working. I picked up an RGB LED strip kit from a clearance isle but you can get them from Amazon Pretty Easily. I wrapped it along the top inner lip. It was super easy, super cheap and made a great addition. The one I got was USB powered.
Installing the X Axis
- Cut a piece of 2040 V Slot to length (Mine was 29.3in)
- Assemble the X Carriage using 3 Large V Bearings with an eccentric spacer on the rear bearing. Slide it onto the rail.
- Attach the Motor Mount, with stepper motor and the pulley.
- Attach the mirror mount
- Attach the end stop (M3 screws)
- Attach the Mirror Holder (Stock from K40)
- Route and attach the belt in the same way as the y carriage assembly, loosening the pulley during routing and then tensioning the belt by pulling the pulley back into position.