-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 6/15/2013 2:31 PM, Ed Nisley wrote: > On 06/15/2013 12:04 PM, Charles Buckley wrote: >> you could treat the spool feed as an additional axis whose feed >> rate is the same as the 4th axis. > > I think that would come heartbreakingly close to working, because > the feed rate depends so much on the effective diameter of the > gear/pulley/wheel. A teeny difference in hobbing will eventually > (i.e., over the course of a dozen hours) cause the filament loop to > either vanish or spill off the table: gotta wrap some feedback > around the filament coming off the spool. > > But it might be close enough. Do a coarse positioning at the start > of the print to put "enough" filament in the loop, then run the two > motors in parallel for a few hours without feedback. That would > eliminate the need to keep track of the filament while it flops > around, which sound like a Good Thing.
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. I also want to try putting one of those fancy "laser tracks on anything even glass" optical image sensors they use in mice at the hot-end and use that to monitor how much filament is going by. That should make the bowden setup used on many delta-style printers work a *LOT* better. Another thing that should be easy to do in LinuxCNC but likely very difficult to do with the existing AVR software. The current firmware is having a hard time generating step pulses with decent timing, so running the stepper in velocity mode and closing a servo feedback loop is probably asking a bit much. :) - -- Charles Steinkuehler char...@steinkuehler.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlG8x9cACgkQLywbqEHdNFw7JQCfVSSK2AwJGi0VdApzsafbvTl3 JYkAoJMILnCJaSNPKdpv8cuRaHv21QiT =J0nn -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ 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
