- Apr 14, 2018
Can you please explain your method with a numerical example.
oookay, let's say the part is 3.25" diameter. If you want to do in your head (22)(3.25) / 7 = 10.2142857142857 or 10.2 in short.
Or if you want to be picky 3.14159 x 3.25 = 10.2101675 also can be rounded off to 10.2 for our purposes.
Let's say 400 ft/min equals (4800 inches/min)(1 revolution/10.2 inches) = inches top and bottom cancel out so you are left with 470.58823594118 rev/min or probably 471 if you want to get really picky.
I'm certainly not a math wizz but that's pretty simple. And oh yeah, css on a real control (I don't know fanuc) runs in sfm not rpm so you'd run up to the part in g97 at s470 (or 471 if you are anal) then kick it to g96 s400 for the 400 ft/min end of things. If you want to be nice you can calcuate the and-of-pass speed and when you drop back to g97, use that speed for an s #.
Is that too difficult ? Even I can do it ... personally, being a NOT g96 fan for roughing passes, I set my rpm at the speed for the cut and leave it there for the pass. Then also leave it until the tool pulls out in x, change speed for the next pass as the slide returns in z, then when you drop down in x to the next pass diameter the spindle is already there, no wackadoodle g96 uppy-downy going on. Makes for a nice program, easier on the lathe. But people can do what they want, eh ?