piv:
>>CV ditches the idea of the path going through G code points anyway.
Not really. The idea isnt that the planner has to touch waypoints, it has to touch a either the point or a spot between them. Thats usually the rule, it was reported
to me recently that thats the view of the EMC planner as well. Mach3 doesnt realy have that rule, it can skip over blocks to some extent but the effect is almost the same.
Ive actually tried a planner once as you suggest. Its effect is not what youd expect. Your right that it smooths.. way too much in fact. Consider a square 3" on a side.
Fairly common operation.. If I specify 1ms waypoints that dont have to "much touch line " rule,
what happens is that at low feedrate you get what looks like a square. The corners do tend to be rounded..as you increase the feerate, the square begins to look
like a circle, surprisingly it doesnt take much speed to get there. From the circle, it degenerates to a squiggly line that goes forward and then back..
Its argueable then ,that one could just set a feedrate and the feedrate itself would then determine accuracy. But accuracy would come at the expense of running
slower. Entirely true. What you find though when you try it is that the feedrate must be constrained pretty much to the point Mach3 contrains it in its current
planning methodology before signifigant detail is lost.
Yes, in some situations, like a flowing curve, it works out OK as the data is compliant with the way a servo corrects position anyway, and the output is fine, but in CNC thats a rare situation.I once made MAch3 run the Roadrunner example in such a way for example, normally it runs at something like 500mm/sec .. and I had it so I coudl make it run any speed. At the normal speed it looked like a roadrunner, from the time I got abotu 25% faster it started to look like a rooster and running full out it looked like a triangle. ( but took only 4 seconds to run.)
Its not easy to add such a thing as youve suggested, though it could be done.I havent the time to do it at this point, but Ill consider it in future so you can play with the numbers. Of course you could do that now. Write a program that takes a small block program and rewrites it as the distance along the path at 1ms intervals. Since each line is now longer Mach3 will run it much faster. What youll notice though
is it doesnt take much speed before the cut looks nothing like the input. If you do this, you can see the cut file immediatly upon loading it in mach3, I mean youd see exactly on the screen what such a file would cut like. It typically isnt pretty..
Art