This could be normal but whenever i start a print it goes through the usual calibrating part. During this process it moves the extruder to the back of the print bed and vibrates against the motors. I can only describe it as 'Juddering'. it looks quite violent for an extruder that apparently has a highly sensitive accelerometer so wondered if this happens with everyone or if its a fault.
i do have issues printing objects with circular bases. (they aren't accurate circles) which i thought might be related.
any input would be appreciated,
The printer doesnt know where the extruder is in the x and y axises so it runs into the y stop for the full distance of the bed, and then the x stop. That juddering is the toothed belts slipping on the gears that drive them, as the head cannot move any further. It's not the best idea for homing; it will wear the belts prematurely, but it is by design.
Ours does the same ,but when it comes time to print its rather smooth in its motions. This hasn't caused any print failures that were aware of.
yeah i haven't noticed any issues that stem from it (other than my unrelated circle issue).
Happens every time with me. I assume it is normal. Can't speak to whether it is related to your circle problem. Mine seems to print them fine.
Yeah i think Donovan below linked the circle problem to a backlash issue.
still surprised no one mentioned the 'juddering' thing earlier though. it certainly doesn't look normal but i guess it is.
M3D's official firmware only uses the accelerometer for detecting if the gantry clips have been removed from the printer and for calibrating where the Z0 height is. Both of those accelerometer uses have been known to fail and give inaccurate, inconsistent results, so all the fluff about M3D's Micro Motion sensor chip being used for intelligent positioning feedback precision is really over exaggerated. So what your experiencing is normal when the printer homes, and it's what everyone else still using M3D's official firmware experiences.
Fortunately iMe firmware uses the acceleromoter for homing which can help minimize and even reduced the grinding entirely. Due to mechanical wear, all the printers are slightly different, so iMe lets the user configure the jerk sensitivity uses in its homing algorithm which allows it to be fine tuned for each printer.
However your issue with inaccurate circles isn't related to how the printer homes. It results because of the backlash susceptibility of the Micro 3D printer's gantry system design. The individual X and Y backlash values for the printer can be fine tuned to correct this, and there's many methods for determining those values and some of the most commonly used ones are Muele's method and M3D's method.
Thanks Donovan, ill check these out tonight.