Erik Christiansen wrote: > On 15.06.13 15:00, Charles Steinkuehler wrote: > >> I've seen some setups where the filament loop closed a switch when it >> began getting 'tight' and triggered the spool to unwind a bit. >> > > But if that isn't what the "filament loop" always does, then do current > printer implementations just drag the spool with the filament feed > capstan, leading to loss of any filament loop soon after starting? > > Yes, most I've seen work this way. A VERY unsophisticated scheme could be a light-touch microswitch that activates a gear motor to turn the spool (or feed the filament off a spool) to keep a small loop. > I don't recall whether the old Pertec tape drives used switches or a > potentiometer (allowing PID control of the unspooling motor), but they > maintained a tape loop at speed. Yes, and that was a LOT more dynamic than a makerbot. There were drives with vacuum sensors in the columns, photocells across the columns, spring-arm loops with switches or pots, and one I have here even has little rollers with AC tachometers to sense speed of the tape paying on/off the reels. The speed of these tachs is supposed to match the capstan speed. When tuned up right, the tape hardly ever touches the pressure sensing holes in the vacuum columns.
Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
