New k40, upgrading

Machine: k40 with digital display

Board: laserboard c3d

Firmware: Smoothie

Problem/ Question:
first I want to add safety switch to cut the laser and the work in case of unscheduled opening of the working area. how to connect it to the laser board, what to change in the smoothie conf file?

second, I want to get rid of the digital display, how to connect a multi-pot and the firing switch?

third, I found on the net that le digital display tune the laser power with a PWM signal. I’m a bit concerned that the mix of 2 different PWM control signal may give strange result (interference course from the physic class )

thank you

1 - safety switches should be added between the H1/H2 terminals on your laser power supply. On many K40s this will be the “laser enable” switch on the front panel. Just add another normally-open switch in series with this. The contacts should close (switch should activate) when the lid is closed and open when the lid is open.

2 - The pot gets connected to the LPSU’s 5V, IN, and GND terminals. 5V to one end of the pot, GND to the other, and the wiper goes to IN. Manual firing switch connects L+ and GND. If you remove the digital panel, make sure you also purchase an analog ammeter to ensure you don’t overdrive your tube. The ammeter gets placed in series with the tube cathode to system ground.

3 - The digital display does indeed pulse the IN pin with PWM. Inside the LPSU there are analog comparators that effectively combine the two PWM signals into a useful control voltage to the HVT without a problem. Surprisingly, the engineers thought of this :smiley:

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thanks a lot

i wonder why the k40 designers thought it is better to add a digital ( and more expensive) display rather than a pot and analog ammeter … more expensive and less accurate …

surprisingly there is a lot of cheap things to do to upgrade the k40 which could be done from the beginning:
air assist ready: a small cone with air intake
safety switch on the lid
better psu position for the cooling

as it is, these machines can’t be sold officially in EU because of safety regulation ( and the electric connection are totally out of regulation - same colour for the neutral and phase main power, blue wire becoming red after in the air connection, hot wire for the laser with only one layer of insulation, no pass-through protection for the wire, pathetic grounding,

anyway, that’s giving us the cheap machine, the occasion to criticize the chinese products, and something to be proud of our amélioration :wink:

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