K40 enhancements and modifications

There are a number of things that people have done to make their K40 lasers more usable, more convenient, and/or reliable.

Added Power Supply

The K40’s stock power supply is adequate, just barely, for K40 operations. If you add stuff on (like LED strips for viewing the lasing through the window while engraving, or for better visibility to set up stock to work on) it may cause issues because the power supply is just barely able to put out the power.

There is a cheap alternative that will let you add on many more electrical mods. I bought a Mean Well RT-85D power supply for US$25.79 from Jameco Electronics. This supply provides 24Vdc at 2A, 12Vdc at 1A, and 5Vdc at 6A. This is plenty to provide all of the +24V the K40 needs for its X-Y motors, vastly more +5V than it needs for the logic and controls, and also gives you 1A of 12V for anything else, like maybe those LED strips. It takes the 24V and 5V loading off the stock power supply entirely, and so the stock power supply is not running so near the edge of the power cliff. There are probably other 2- and 3-output power supplies that would do much the same. A 24V and 12V supply would do most of this, and maybe be cheaper.

Moveable bed / table

Several people have built DIY powered Z beds / tables. Some are only hooked up to buttons on the front panel, others are software-controlled. The M2nano board cannot support a software-controlled Z table. Some other controllers have an extra stepper driver or can use an external stepper driver to control height from software.

Rotary axis


Enhancement suggestions

@donkjr maintains a spreadsheet to help compare levels of machine, also suggesting classes of useful modifications and their relative value.

He has listed the following modifications and described their value:

  • Verify system and subsystems grounding
  • Interlocks for cabinet covers disables laser with user access
  • Laser coolant flow monitoring interlocks laser firing with water flow
  • Laser Cooling Pumping
  • Laser Cooling Pump
  • Vent cabinet for contaminated air removal and better cutting
  • Air assist blows air on cut line for better cutting
  • Moveable floor to change focus for various size objects
  • Rotary accessory to allow the marking of cylinders
  • Beam finder: LED added to the laser head
  • Cabinet lights adds better lighting to marking cutting area
  • High Capacity 24VDC supply for add on electronics
  • High Capacity 12VDC supply for add on electronics
  • Alternate Controller for Open source compatibility
  • Power fuses for better electronics protection
  • Upgraded pot and postion display
  • Upgraded optics
  • Remote control of air and cooling subsystems
  • Monitor laser tube temperature
  • An indicator that tells the user if interlocks are open

@funinthefalls is selling an upgraded “BeamBuddy” High Resolution Laser Head for Chinese laser engravers aimed at engraving (not cutting).

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Russ Sadler has just started a video series on the K40 called the K40 Laser Extreeem Laser Cutter Upgrade Series. Image of the K40 Xtreeem.

In the first video, Russ rips out the original flaky X-Y axis frame and completely revamps it by adding some simple inexpensive components. Russ then goes onto the important job of designing and fitting a reliable tube mount and 1st mirror solution.

Please Note: I benefit from sales and advertisements run on the LaserUser Site


I’ve seen all 6 and like what he’s done. I have a 400mm and a 300mm linear bearings ordered. But instead of a long strap of aluminum to mount the 400mm(X axis) bearing onto, I was thinking of first making 3D printable attachment adapters for each end of the 400mm X Axis bearing bar.

His lightweight #3 mirror mount and lens tube holder is a great idea and pretty much eliminates the need for an adjustable bed.

It does look like I’ll be needing a larger 0.9 deg stepper motor on the X axis if I want to try to get 400mm/s rastering going. He didn’t mention using 0.9 deg motor and had some calibration issues so I wonder if he’d used a standard 1.8 deg motor.

His motion platform mounting system and bottom plate of the case look WAY better than on my K40. My motion platform rests on some bent sheet metal tabs and my bottom has no structural ribbing so it wobbles like someones doing the Foley for the original Lost In Space show. Will probably end up cutting the bottom out all together.

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Yes the larger X stepper was a 1.8 degree motor from Cloudray

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When I rebuilt the X stepper motor I was surprised it was an 0.9 deg motor and not a 1.8 deg. Probably makes little difference scanning but doing cuts and lines it has twice the resolution with better torque at low micro-stepping for the same size. Larger 1.8 deg with a higher micro-step amount could get same results though.

I’d take a trinamic driving a 1.8° motor over say an 8824 driving a 0.9° honestly. And if you need more torque for some reason, some of them can take 36V or even 48V… :relaxed:

Russ Sadler put a Ruida controller into his K40 Extreeem so I don’t know what drivers those have.
But, having put some TMS2208 and 09s in a board on my Ender 3 I will agree wholeheartedly that the Trinamic drivers are da-bomb over 8824 and A4988 drivers.

In Russ’s 5th video he tries to drive the engraving upto 400 mm/s and can only get 200mm/s out of the stock 0.9 deg motor before steps are lost. So he replaced with a larger(more torque) 1.8 deg motor and continued testing and went above 400mm/s but tube/LPS limitations brought him back to 400mm/s for engraving. I guess the torque isn’t as big a deal when doing cutting since cutting is done at far less speed than engraving so missing steps is less likely and so a higher micro-step setting can probably be used so the accuracy at least matches the 0.9 deg motor.

I bring up cutting vs engraving because when doing cutting we are driving both X and Y motors all over the design whereas for engraving, the X axis is swiping back/forth only stopping at the far sides of the design and the Y axis is just incrementing slowly line-by-line.

It’s a dance adjusting in more micro-stepping which reduces holding torque compared to a 2x higher resolution motor having fewer micro-step but being a weaker motor to begin with.


A friend of mine has done the K40 Xtreeem upgrade minus the Ruida controller(still has the M2Nano) and still has the stock stepper motors. He was able to get the machine engraving at 500mm/s and said anything above that would result in skipping steps and other erratic movements.

Since it still had the M2Nano it was tested with the Aztec calendar Russ uses and it was using K40 Whisperer.

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