8
« on: October 27, 2020, 18:52:46 pm »
after getting odd results i finally figured out what is going on with the geometry. having been a carpenter and built many flights of stairs greatly helped. in this example i used real life 3/4" plywood, which actually measures .71" thick. I was wanting in this example to cut a slot an inch wide with a 45° tapered side profile. the 45° line shown is the desired shape. using rough steps illustrates better what happens with the "stair steps" that are actually milled. the geometry is such that the "stairs" will always be built on top of the sloped line, never cut any material below it, which is desired. so the "stairs" start at the bottom with a "riser" the height you specify. the next "tread" will be whatever the distance horizontally over to the sloped line. this repeats up thru to the top height of the material. so even if the "risers" incrementally match the material thickness, say it was .75" and we stepped .25", the top of the material will always have a "tread", or a portion of a tread on the top, which of course makes the slot thickness measure smaller than what was desired. the geometry for the side profile is measured thru where the "risers" touch the inside of the tread, like where your toe would hit when standing on a tread. this all makes sense now, but i found no detailed explanation anywhere. even the VALUE parameter doesn't specifically say that unit is in degrees from vertical [it is]. if you compute what that top "tread" measurement is, you can add a negative ROUGHING CLEARANCE value and force the "stairs" to be cut below the sloped line.