Hi Alex! Sounds like an interesting thing to do :) Do you need full control over the needle (i.e. coordinated moves), or do you want to let the needle be driven by a single motor in continuous motion and synchronize the X/Y movements to it? In the latter case, you would only need position feedback from the needle, which could be as simple as a single switch telling you when the needle is up and the X/Y can move. With LinuxCNC, you could then hook that switch signal to the adaptive feed input, so that the position is freezed whenever a stitch is being made. If you then connect the velocity command for the needle motor to the spindle control, you could really write a program just like for a mill (except no Z of course). So you'd use G0 to rapid to the starting point of the sew, then set the desired spindle speed using S, start the "spindle" and program your path using G1/2/3. The combination of spindle/needle speed and feed rate would give you the stitch length.
Oh, and I'd go for motors with position feedback if possible. Open-loop driven steppers may seem easier to handle as usually no loop tuning is required, but then you need to test veeery carefully how fast you can go without losing steps. Especially if you want to move really fast and have a variable load. Just a few thoughts. Regards, Philipp On 27.08.2014 18:55, alex chiosso wrote: > Bari , thank you for your reply. > How is working a sewing machine for me it is clear (I really did the > application I described). > I read into a Brother industrial sewing machine user/maintenance manual and > their electronic control manage encoders > for the motors. > > > On Wed, Aug 27, 2014 at 6:42 PM, Bari <bari00...@gmail.com> wrote: > >> Alex, >> >> We started using Linuxcnc to control all sorts automation in the lab. >> >> Breaking down the steps to stitch: >> >> Move X,Y to start of the stitch (with Z at max height) >> >> Move Z down to min. (needle to lowest point) >> >> Raise needle >> >> Start Loop (spin looper motor) >> >> Finish Loop >> >> Needle to max height >> >> Move X and/or Y >> >> >> https://www.youtube.com/watch?v=BAvQBLHMrw4 >> >> On 08/27/2014 10:58 AM, alex chiosso wrote: >>> Hi Bari. >>> Nice to know you. >>> Have you experience with this particular application ? >>> So for you closed loop positioning it's not needed ? >>> >>> >>> On Wed, Aug 27, 2014 at 5:52 PM, Bari <bari00...@gmail.com> wrote: >>> >>>> Alex, >>>> >>>> I'd use Linuxcnc to build it. >>>> >>>> You can use steppers to control the needle motor and looper in open >>>> loop. Your G-code could be written to just stop X and Y when the needle >>>> is below the surface of the fabric. >>>> >>>> On 08/27/2014 10:21 AM, alex chiosso wrote: >>>>> The application can appear "trivial" but it is not especially because >> of >>>>> needle speed and sycronization between the needle position and the X-Y >>>>> movement. >>>>> During the sewing the X-Y can move only when the needle it's outside >> the >>>>> label otherwise the needle can be broken and the clothe/label can be >>>>> damaged . >>>>> That's why the position feedback is needed. >>>>> Additionally the command for some actuators sycronized to the sewing >>>> cycle >>>>> + sensors, pushbuttons, button lamps management. >>>>> I would like to discuss with you what do you think about the conversion >>>> to >>>>> LCNC. >>>>> >>>> >>>> >>>> >> ------------------------------------------------------------------------------ >>>> Slashdot TV. >>>> Video for Nerds. Stuff that matters. >>>> http://tv.slashdot.org/ >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>> >> ------------------------------------------------------------------------------ >>> Slashdot TV. >>> Video for Nerds. Stuff that matters. >>> http://tv.slashdot.org/ >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> >> ------------------------------------------------------------------------------ >> Slashdot TV. >> Video for Nerds. Stuff that matters. >> http://tv.slashdot.org/ >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > ------------------------------------------------------------------------------ > Slashdot TV. > Video for Nerds. Stuff that matters. > http://tv.slashdot.org/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users >
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