fts sensor error

i had been using a self made filament jam sensor based on the sparklab fts sensor . It ran fine and had a number of steps of 2500 .. but since last 2 days i have a weird error. the sensor randomly parks the head and gives a jam message although there is no jam . i printed the same print via the host in debug mode ( with the sensor disabled ) and it printed fine. I tried printing the same print , same filament same gcode and it halts the printer randomly. Is there a way to figure out what is wrong? the sensor in debug mode displays the correct number of steps with a range of 110% - 95%. I ended up changing the sd card as well as the lcd with the sd card reader. Still random halts . Any clue?  thanks


  • Since it is triggered by jam control I would search there. If the wheel looses grip it might not always move as designed any more. I think it moves most of the time but sometimes it might slip enough to trigger it. So clean wheel and/or decrease sensitivity a bit.
  • edited January 2018
    the thing is even i suspected that,, i ran the entire print via the host in debug mode and i saw the output.. there was always number of steps showing 104-95 % ... didnt miss any . i ran the print also via the sd card with the jam sensor disabled . both completed. but when i enable it randomly halts the print. i will check the wheel again.

    is there a way to display jam steps on lcd while printing? or disable jam sensor while printing? 

    thanks again
  • Yes, there is a menu entry calling UI_ACTION_TOGGLE_JAMCONTROL to switch it on/off.

    One solution to find reason is to modify

    void TemperatureController::setJammed(bool on) {

        if(on) {


            Printer::setInterruptEvent(PRINTER_INTERRUPT_EVENT_JAM_DETECTED, true);

        } else flags &= ~(TEMPERATURE_CONTROLLER_FLAG_JAM);


    to not set the flag which triggers the jam, but instead report jamStepsSinceLastSignal so you see on which value it got triggered, but do nothing else so print is not ruined. Then you know what your critical value is.

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