Laser Tutorial Question

This topic contains 46 replies, has 4 voices, and was last updated by Profile photo of Jason Jason 3 months, 3 weeks ago.

Viewing 30 posts - 1 through 30 (of 47 total)
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  • #16981
    Profile photo of Jason
    Jason
    Participant

    Maybe I was just dense last night but do I plug the 40mm fan into the fan port on the laser driver? It seems by the tutorial I plug the fan directly into the power supply. Is the little 40mm fan enough to clear the fumes away as it cuts?

    #16986
    Profile photo of vicious1
    vicious1
    Admin

    It is best to plug the fan directly into the power supply, but I have done it both ways.

    I think the fan is technically just to cool the diode in the heatsink, It does okay at keeping the fumes away if it is aimed like my little laser holder. To keep your optics clean you should run more airflow somehow.

    #16987
    Profile photo of Jason
    Jason
    Participant

    Ok.. So if its plugged into the board when does it turn on and off?

    Yes I printed your holder… Nice work on that one. I have 120mm like 250cfm fan which I will use to blow fumes.(Bitcoin miner type fan)

    #16989
    Profile photo of vicious1
    vicious1
    Admin

    The cooling fan always stays on, like an extruder cooling fan. We actually use the fan control pins to control the laser so easy fan control is kinda out.

    #16991
    Profile photo of Jason
    Jason
    Participant

    Ok so if it is always on when plugged into the driver board what would be the point of running a while all the way back to the PSU?

    #16993
    Profile photo of vicious1
    vicious1
    Admin

    Run less power through the little PCB. If you are using a small fan no big deal at least on the driver I have.

    #16995
    Profile photo of Jason
    Jason
    Participant

    It would just be the 40mm fan that is inside the holder. Do I need to keep a separate version of firmware for the laser and cnc?

    #16996
    Profile photo of vicious1
    vicious1
    Admin

    My oppinion it is easiest to just use two versions, flashing only takes 2 minutes.

    #17232
    Profile photo of Jason
    Jason
    Participant

    ok so i modified the firmware to remap pin 9 to 44. I measure the voltage across after setting the fan to 100% it was 4.47v, then turn it off 4.29v… There is always almost full voltage across pin 44 all the time regardless if the fan is set to on or off…

    Whats going on?

    #17237
    Profile photo of Jason
    Jason
    Participant

    I should also add it seemed to work the first time. But when I connected my laser driver the power wires got so hot with in seconds they started to melt then after that pin 44 was always at about 4.5 volts. I had a 10k resistor soldered between the pin 44 and ground as well as per the tutorial.

    #17241
    Profile photo of Leo69
    Leo69
    Participant

    @jason Are the wires you’re using for laser power thick enough to handle the 3 current, or at least 2 amps? Was the laser driver “tuned” before connecting it to the Ramps board and applying power? And finally, double-check the polarity on the driver’s power inputs. I noticed that on some of the newer driver variants out there, the JST connector goes into the power connection with the positive lead connected to the negative output on the board and vise-versa. If this is what happened with yours then you most likely toasted your Ramps and possibly your mega board too. See the link below for details.

    See this post

    #17243
    Profile photo of Jason
    Jason
    Participant

    The wires were pretty thin. The driver was not tuned I had not gotten that far yet, i was just applying power the first time to tune the led light to turn on. How do I check the polarity on the board? The board and arduino still work fine i can move the x y and z axis just the output voltage on pin 44 is not working. it is stuck at 4.47v.

    #17258
    Profile photo of Leo69
    Leo69
    Participant

    The board should be silk screened on the back side and you’ll see the + and – markings by the power terminals. Note which side is closest to the edge of the board per the board markings(+ or -). Now flip the board over and see if the red + lead on the jst connector is actually on the correct side. I’ve seen some boards where the connector leads are backwards and in every case the markings on the board indicated the correct polarity, the problem was always the connector.

    #17259
    Profile photo of Jason
    Jason
    Participant

    You are right… The jst plug was opposite of the silk screened polarity

    #17260
    Profile photo of Leo69
    Leo69
    Participant

    If you want to troubleshoot the 44 pin then you can try flashing a basic sketch to the board that just does an analogwrite to the 44 pin with a value of 127, lots of examples of analogwrite command on arduino site. That should get you a reading of about 2.5 volts on the pin. If that doesn’t work then your 44 pin may be damaged. At that point I’d try switching to 42 pin instead. Same instructions, just use pin42 instead of 44 in the pin assignments and connect ttl to that pin instead.

    #17261
    Profile photo of Jason
    Jason
    Participant

    I will try pin 42. If that does not work I will try the voltage divider on D9. To confirm there is a 7k resistor between the + and – and a 10k on the + side as well?

    #17262
    Profile photo of Leo69
    Leo69
    Participant

    In that case, there was likely damage to the ttl pin when you powered up the driver. Try switching over to pin 42 and cross your fingers:) Worst case is you’ll be out 10 bucks for a new mega board. The driver i used for the tutorial can’t be found anymore. It was much easier to work with and the power input was not polarity sensitive and could be connected either way. The board you’re using should be tuned with a diode test load as explained In the guide.

    #17263
    Profile photo of Jason
    Jason
    Participant

    It would have fried the mega and not the ramps? I built the test load with 1 resistor and 3 diodes as per the instructions.

    #17266
    Profile photo of Leo69
    Leo69
    Participant

    I’m pretty sure the auxilliary pin blocks on the ramps board are just breakout pins going directly to mega but I’m not positive. I’m curious about this now. I’ve tried a resistor voltage divider on D9 but didn’t have much luck with it.

    #17268
    Profile photo of Jason
    Jason
    Participant

    Shoot ok. I thought the voltage divider was a safe option.

    So to clarify the procedure I should follow is
    1. Flash to pin 42
    2. Test for variable voltage ~5v at 100% fan at pin 42.
    3. Connect 12v to driver (possibly where i made a mistake.. I connected ttl at the same time)
    4. Turn on Current LED then adjust voltage to 5.5v turn off current led.
    5. Attach load to laser + -, connect 12v and ttl.
    6. adjust voltage to 1.7

    #17357
    Profile photo of Jason
    Jason
    Participant

    Ok so some progress… Flash it to pin 42. Now I have on and off at least. I do not however have variable voltage. It turns on at 51% – 100% it is off at 0% – 50%. Always sitting at approximately 4.5v it does not go above that voltage.

    I completed all the steps I outlined. The laser burns but it seems to be stuck at max power I guess if 42 is 4.5 volts. Is the mega board toast? Surprisingly enough after hitting it with the 12v polarity reversed the driver still seems to function normally.

    #17360
    Profile photo of Leo69
    Leo69
    Participant

    Can you zip up and post your marlin folder? I’ll take a look after work. If the laser responds then your connections are good.strange that you’re not getting pwm output, just digital on and off.

    #17361
    Profile photo of Leo69
    Leo69
    Participant

    I still think you should troubleshoot by flashing a simple sketch that does analogwrite to pin 42 with a value of 127 and then check to see if you read about 2.5 volts on the pin. If you do then your firmware configuration is the issue, otherwise you have a damaged mega board.

    #17362
    Profile photo of Leo69
    Leo69
    Participant

    My bad:( I think I gave you some bad info.I just reviewed the mega pin mapping and ramps schematic and it looks like pin 42 isn’t PWM capable which explains why you’re only getting digital highs and lows out of it. The A5 pin on that aux2 block should be able to generate the pwm output that you need.

    #17366
    Profile photo of Jason
    Jason
    Participant

    ok so change 42 to A5 in the pins_ramps_13 file?

    #17367
    Profile photo of Leo69
    Leo69
    Participant

    Yup. That should work but you’re the guinea pig here. Definitely won’t hurt to try it.

    #17368
    Profile photo of Jason
    Jason
    Participant

    No problem. I trust you. 🙂

    Info I can find suggest that, that pin is PWM capable so hopefully this works as planned… Exciting lol

    #17383
    Profile photo of Michael Hensen
    Michael Hensen
    Participant

    I understand that this is full a full diy laser component..
    But if I would buy a 2W laser with ttl support and driver from a cheap Chinese store, I assume I can still follow the steps for the Arduino control?

    I just have my MPCNC built and doing my first testruns with a pen, so I am sourcing my toolset now.

    #17384
    Profile photo of Leo69
    Leo69
    Participant

    @Michael Hensen
    Yeah, a cheap Chinese laser should work as long as it supports the 0-5V TTL control signal. In that case you can just follow the instructions for re-mapping the pin. Some drivers, like the Jtech Photonics , support 12V control signals and can be connected to the D9 fan output on the Ramps board directly without re-mapping to a different pin.

    #17385
    Profile photo of Jason
    Jason
    Participant

    Changed Fan_pin to A5 and now I get the error

    temperature.cpp: In function ‘void tp_init()’:
    temperature.cpp:894: error: ‘DIOA5_DDR’ was not declared in this scope
    temperature.cpp:894: error: ‘DIOA5_PIN’ was not declared in this scope

    any ideas?

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