Laser Cutter Usage Timer wanted

Laser
#21

I can be there in the afternoon onward.

#22

Cool - let’s pencil in the afternoon sometime on 23 April.

Bill, are you trained on the LaserSaur, and are you familiar enough with it’s construction to help dig into the guts? Or will we need other helpers?

#23

I am trained to use the LaserSaur. We will need to find someone to help with its innards.

#24

I’ve had my hands inside the saur

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#25

Cool - should we leave a note on the machine indicating scheduled maintenance? Would 1:30 work for everybody?

#26

1:30 is OK for me, though later is better.

#27

Cool - how about 3pm?

#28

OK, see you then.

Did you line up Pearce or someone else to do the poking of the internals?

#29

@PearceDunlap - you in for about 3pm on the LaserSaur?

#30

Today? I’ll be there in a bit to work on the Nova

#31

@PearceDunlap no sorry for confusion - on Saturday 23 April, 3pm - LaserSaur…

#32

Status update:

  • usage timer is back online, connected to the LaserSaur

  • thanks A TON to @Bill for hanging in there for hours, soldering away on the interface circuit and running test cuts and generally helping to keep this fit check integration moving along

  • As a reminder, the usage timer works as such:
    — backlight is purple when first apply power => showing adruino code version # and # of writes to EEPROM
    — backlight is red when laser tube is on
    — backlight is yellow when laser tube is off and user time is > zero (think ‘trip odometer’ ie. please pay for your usage time :slight_smile: )
    — when you’re done accumulating user time, hit the Blue button to clear the user time (ie. trip odometer)
    — backlight is blue when user time is zero
    — timer saves latest tube time (Cumulative Lasersaur odometer) and user time to EEPROM when you hit the blue button (or if you don’t, every ~ 5 minutes if the values have changed since the last save)
    — tube time can be used for things like laser tube life estimation and preventative actions maintenance e.g. scheduling optics cleaning before dirty optics cause degraded cuts

  • to get the usage timer working on the LaserSaur, we
    — replaced the display contrast potentiometer with fixed resistors, since the pot was going intermittent
    — adjusted the interface circuit comparator threshold to about 2v vs 2.8 volts, since the LaserSaur seemed to run at lower logic levels
    — connected the usage timer to the laser power supply “L” terminal (low when laser firing just like the Full Spectrum), even though the LaserSaur control circuit is connected to the power supply “H” terminal (high when laser firing)
    — verified it was working with a few cuts

The plan now is to run it for a while and see how it works in practice, then decide what if any changes to make, for example better mounting… It should work as it is, but no guarantees, please let me know if you see issues…

I’ll update the GitHub repo in the next few days with the minor circuit changes we made.

I’ll also replace the kludgy blue tape with marginally less kludgly gaffers tape, perhaps Tuesday evening, unless somebody beats me to it…

IMG_0945.JPG3264×2448 1.89 MB

3 Likes
#33

…and thanks to @cottjr for being the motivating force for getting this done and updating the documentation after the fact…along with putting up with my faded ability to reliably read resistor color codes. Together, we confirmed that divide and conquer truly does work.

1 Like
#34

I liked it when we used the laser last night, however when I was running it at low power (less than 15%) it wouldn’t pick up many of the seconds, like for every 10 seconds that it was on, only 2 or 3 seconds were recorded on the timer.

Is there anyway for this to be updated?

Great work @cottjr

#35

It is probably tracking the PWM duty cycle. But I actually believe on the Saur, running reduced power may actually wear the tube a bit more than full power. So it would be ideal if the PWM frequency were identified and off times shorter than one cycle counted as on time.

#36

Thanks for bringing this up. Glad to hear it was helping at least in some scenarios :slight_smile:

I did notice a difference in the signal behavior compared to the old FSL when we installed it the other night. But there was no chance to dig into it as we ran out of time, and it seemed to work reasonably well for higher power level => duty cycles.

I believe the correction will involve revisiting the interface circuit betewen the power supply and the arduino nano / display. It should be possible to adjust that circuits R/C filter & voltage trigger thresholds to get closer to the minimum counter loop tick, which (if memory serves correctly) can measure to something like the nearest 0.01 sec or 0.001 sec…

Let’s see when I can get back out there - perhaps as early as this weekend…

2 Likes
#37

FWIW - I made some updates to the timer circuit this afternoon. It now seems to register pretty well down to about 40% power levels, but it seems to start missing between 30% and 40% power levels, and it largely loses ability to count time below about 30%.

The issue is that the LaserSaur modulates laser power much differently & more quickly than the original timer was designed to accomodate. As a result, the laser beam turns on and off before the timer is able to notice that it’s on - a classic undersampled waveform issue. This afternoon I increased capacitance on an existing RC network to hold the “on” signal for a little longer. It’s a little kludgy, and I suspect it will tend to under-report a little, so I’ll revisit it again later with more careful measurements, and make more robust changes.

Meanwhile, please let me know if it seems to behave better after this afternoon…

#38

Our only solution may be to adjust that time constant to recognize narrower pulses.

#39

Congrats guys! the machine is beautiful. What a great boon.

Thank you!