HeatSinks

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  • January 4, 2018 at 7:08 pm #10721
    appahman
    Member

    can someone point me to a primer on putting heat sinks on the bottom of my board? I’m nervous about putting conductive things onto the bottom of the board and could stand some help, assurances about how to accomplish this…

    January 4, 2018 at 8:47 pm #10722
    Zootalaws
    Member

    The first question I have to ask is; are you experiencing overheating?

    If not, why are you looking to add cooling?; if so, what conditions are you overheating in?

    I live on the equator, my workshop starts off at around 32C in the morning and I don’t experience overheating with my big NEMA23 motors.

    Sometimes what looks like overheating is too little current at the trim pot – have you tuned your trims?

    January 4, 2018 at 10:42 pm #10723
    cmcgrath5035
    Moderator

    The bottom layer of the board is 2oz copper ground plane and well connected, thermally, to the driver devices.
    Fans on bottom work well
    Something like this works well too
    https://drive.google.com/file/d/1152ojWcgC9dErvgmYjxY-RIjGCZL62P1gA/view?usp=sharing

    January 5, 2018 at 12:21 pm #10726
    appahman
    Member

    the trim pots are at about 65% my motors are nema 23, 285oz oz\inch steppers.. but I have had two times where missed steps have happened, cutting pine, 3mm depth of cut, running about 700mm a minute feed rate, 22,000rpm with a 3mm two flute end mill. the missed steps are always on the X axis.. my motors arent hot at all but I’ve had two scrapped parts to what appear to be dropped steps.

    my y axis (double driven) has never had an issue nor has my z axis though it doesn’t receive much resistance nor for long. and it’s always during long cuts in the X direction. usually 300mm or longer.

    I dont have a non-contact thermometer nor do I have an ammeter connected to my axis’ but my suspicion is that a long, deep depth of cut on the single axis is causing it to overheat the chip. I will try maxing out the trim pot on that axis I guess..

    I must also say that I have a 50mm CPU fan blowing down on top of the chips which I thought would be sufficient for how hard I’m working the machine, which I thought was not that hard at all.. if anything it’s hard on the spindle and cutter, which seem to be working just fine.

    having measured the top at 5mm by 10mm I may just get some double stick thermal tape and some raspberry pi alu heat sinks and stick them to the top of the driver chips..

    thoughts?

    January 6, 2018 at 4:42 am #10728
    Zootalaws
    Member

    You can use your finger – if it’s too hot, it is too hot to hold your finger on for ~5 secs. As in ‘bloody hell!’, not ‘ouch’ 🙂

    I tuned mine using the ‘Polulu v-ref’ method, just using a multimeter: http://reprap.org/wiki/Pololu_stepper_driver_board

    Seems to be just dandy.

    January 6, 2018 at 4:45 am #10729
    Zootalaws
    Member

    Another, illustrated method: https://matterhackers.dozuki.com/Guide/Tuning+Motor+Current/37

    January 6, 2018 at 7:07 am #10730
    cmcgrath5035
    Moderator

    The RasPi style sticky tape heatsinks won’t hurt but are not nearly as effective as cooling the board (bottom best, top almost as good). Drivers are in ‘heat slug’ packages and well connected to the board ground plane for dissipation and heat spreading.

    Zootalaws has provided a good and easy to perform test (easy for me to say, it’s your finger). If having performed it, you think you are close to “bloody hell”, then try running you Gcode job above the workpiece (“run in air”) and see if tinyG still seems too hot. With no load (machine load only), things should stay cool to touch.

    From you extended description of situation, I don’t think thermal shutdown is your issue. True thermal shutdown (by the individual driver devices) is most un-elegant, sort of like a self healing thermal fuse. Motors do get a bit cranky when really hot, does X stepper feel >> warmer than Ys or Z?

    tinyG missing steps, particularly on certain arc moves, is an on and off problem for some folks.
    How do you generate Gcode?
    Is this a new issue (a new design) that always fails?
    Inch or mm?
    If inch, try generating in mm and re-run. Most of the Arc issues seem to ultimately due to loss of math precision by the 8 bit cpu, made worse by numerous inch to mm to inch on the fly conversions. tinyG does it’s internals in mm, so inch Gcode sees a lot of conversions.
    If mm still fails, you could try to generate Gcode without arcs, if your system supports that.

    If you are still having issues, a look at your parameter set ($$) and a Gcode listing from the vicinity of the skip, if you can isolate it, might help. Copy these to a Cloud drive and post a URL.

    October 22, 2018 at 9:41 am #11174
    Pia Tinoco
    Member

    Heat sinks is a part of computer hardware its use for the heat of processor to consumes and make its cool with the heat consumed. I really like to say its a good australia writing part of any mechanical device use as a heat remover.

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