Viesturs Lācis wrote: > I think that this issue is fighting the consequence instead of fixing > the real cause. > People want to change the "look ahead" behavior, but I am completely > sure that fixing the cause - getting normal g-code is much easier. At > least for those things that my machines are doing. > There are two issues. One is certainly G-code that asks for what the machine cannot deliver. High speeds into 90 degree turn.
The other, however, is more subtle. Assume a surface profiling task where the machine flies along in an almost straight line but moving, say, the Z axis up and down a bit. There are many short segments, but the G-code is well-behaved, never asking for great acceleration anywhere, but the vectors (or arcs) are very short. And, it gradually slows down at the end of the line, so no excessive deceleration is asked for. Well, LinuxCNC forces this program to run slowly, because it demands that the velocity never exceeds what the machine can decelerate to a stop in the next block. > My personal opinion is that instead of trying to tweak LinuxCNC for > this, users with the "g-code consists of very small linear moves" > problem should join their effort in finding a suitable CAM > application. > In the case above, there may NOT be a CAM solution for this problem, if you are forced to specify all moves in basic G-code, and only check velocities and accelerations for this block and the next one block. NURBS might solve the problem, at least by vastly reducing the number of "blocks" to be scanned. One quick and dirty fix (I tend to do things this way and regret it later) is to have an option that turns off the velocity limiting. If the G-code is well-behaved and gives decreasing velocities as it approaches a corner, this should allow the program to run faster. But, if the G-code ever fails to handle this well, it will cause a following error stop in the middle of a program! Not a good thing. Jon ------------------------------------------------------------------------------ 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
