K40 upgrade question

Hello I have been told many different types of upgrades for the k40 whisperer.
Below is what I am leaning towards for my machine since i will be cutting wood.
for the air assist-- :vivison 950 GPH 02 air pump 6 outlets.
for the exhaust—:vivison 4" in line duct booster fan 100 cfm
for the water temp—: still looking for a cheap lcd display with probe for water any ides on this?

I think/hope this will suffice for cutting wood let me know if anyone agrees with this or had any suggestions

Hi John,
The air pump and fan look fine. For water temp monitoring I would suggest something like this.

I’m assuming you are using a pump in a bucket for cooling? If so, the dual thermometer will allow you to monitor the temp in the bucket as well as your tube.

The only other real upgrades I suggest for a new machine are better mirrors and lens. The stock ones are usually pretty crap, especially the mirrors. If your air assist head accommodates a 18mm lens I would suggest that as it gives a bigger sweet spot for alignment.

Does your machine have a digital control panel?

PLEASE ADD INTERLOCKS into the covers of the machine to protect yourself from eye damage and electrocution. These are micro switches installed in the covers and in series with the interlock circuit.

For water you need to do more than just monitor the temperature, you also need:

  • Over-temperature protection in the interlock circuit.
  • Flow protection in the interlock circuit

I would go bigger on the fan for cutting wood: https://amzn.to/3aV8hOt

Info on all things K40 here: https://donsthings.blogspot.com/

You can find parts lists for these upgrades here: https://kit.co/donkjr

Lets us know if you need help with the upgrades.

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Supplementing @donkjr’s site, @keen wrote a K40 getting started document:

(Note that “k40 whisperer” is one open source program that can used to control the k40.)

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Hi Ned,
thanks for the info on the digital thermometer,I like the idea of monitoring the water bucket as well as the laser tube.Is the a wiring diagram on how to hook this up to the k40?Is so please let me know.
Thank you

First, you need to decide what kind of temp measuring device you want with what functions.

The type @NedMan suggested provides temp readings for two probes in one unit but it does not prevent an over-temp. i.e. you have to keep an eye on it.
Its wiring is simple, you have to provide power to it. If you have nothing else connected to your LPS 24VDC you could connect it to the 24V on that stock supply. I am assuming that this meter draws a small amount of current. That said I would add a 12V supply as it can be used for other stuff including a cabinet light. I do not like loading the stock supply as it is already marginal @1amp.

The type I suggested does provide over-temp protection but you will need two meters of this type if you want to measure the bucket temp as well. In this setup, the relay in the meter is added in serial with the water protect circuit which will shut down the laser in the event the water gets over a setpoint you load into the meter.
In my garage setup, I added an aquarium heater which has an integrated temp probe and meter to keep my water from freezing when not in use in the winter. In this way, I have a meter and to-cold temp control in the bucket.
In this setup, I get measurement, tube protection and water heating with two meters. This set up is obviously more expensive and complex to wire and set up. That said since you should already have interlocks wired into the laser power circuit you can just add this meter as well.

This is not intended to suggest one way is better than the other just different costs and functionality. As always upgrades are full of cost/function tradeoffs.

@NedMan jump in if you have different advice!


Nope, all sounds good to me :slight_smile: