if speed is an issue, consider the solution of being a doctor: have patience.
--- On Thu, 4/19/12, Stephen Dubovsky <smdubov...@gmail.com> wrote: > From: Stephen Dubovsky <smdubov...@gmail.com> > Subject: Re: [Emc-users] Trajectory planning and other topics from a > EMC(LinuxCNC) newbie (TheNewbie) > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Date: Thursday, April 19, 2012, 6:04 AM > I don't think that would work > well. Think about the situation where you > have several (mostly straight) short line segments, the last > being the > shortest, and then a 90deg turn. I think many would > find it unacceptable > to overshoot the last segment 10thou if you were doing > something like > inside corners. > > I only have two machines running linuxcnc so far (both > commercial gantry > routers, both steppers) as a hobby so have limited > experience but I don't > think the look ahead is that big of an issue *IF* the > machine has decent > acceleration capability & is properly tuned to use > it. I can process > complex 3d profiling in wood on the big one right about the > limit of my > spindle hp (~100ipm w/ a 1/2" ballmill). Yes, it > probably does limit me > slightly when doing a final finishing pass w/ a smaller > bit. When Im doing > aluminum sheet at ~30ipm its a total non-issue though. > I have a factory > CNC 3hp Wells Index knee mill w/ DC servos that Im > retrofitting (slowly.) > If LinuxCNC can keep up on the gantrys it will be no problem > FOR ME on the > knee mill. > > But I see how it might be a limiting factor for a modern > Hass class speed > machine w/ massive spindle hp and feed rates possible when > profiling. But > those would typ have very high acceleration levels to > match. Machines w/ > very low acceleration levels will suffer the most as they > won't be allowed > to get up to speed if you can't slow them down very > fast. Its like what > they say about driving at night: "Dont outdrive your > headlights" :) > > More segments of look ahead would no doubt be an > improvement. But how > much? (seriously, I think we'd all like to > know.) Can people give > examples of machines and jobs where cutting speed is a > problem due to > limited look ahead? I don't have enough experience to > even be able to > guess the magnitude of the issue. > > Best, > Stephen > > I think that if this is actually the case it would make more > sense to > > set a lower limit on this distance (INI file setting?) > so that the > > motion system would guarantee stopping in the next > program line or > > (for example) 0.01" > > > > > ------------------------------------------------------------------------------ > For Developers, A Lot Can Happen In A Second. > Boundary is the first to Know...and Tell You. > Monitor Your Applications in Ultra-Fine Resolution. Try it > FREE! > http://p.sf.net/sfu/Boundary-d2dvs2 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
