(11C) (15C) Convert German Units of Area Measurement

[asevenson]

Thanks for this nice technique! It may not be new but works well and I've used it to combine two existing programs I've kept in my 11-C for years as a machinist/programmer - saving two program lines and 1 (precious) label in the process.

I calculate spindle RPM (rotations per minute) from SFPM (Surface feet per minute) and tool Diameter using RPM = (SFPM * 12) / (PI * DIA)

And occasionally, given the RPM and Tool Diameter calculate SFPM using
SFPM = (PI * DIA * RPM)/12

For the updated program I enter SFPM as positive and RPM as negative, followed by DIA (always pos):

Code:


LBL A
PI
*
X><Y
X<0?
1/x
/
1
2
/
X>0?
1/X
CHS
RTN

Example: what RPM do you run a 2.0 dia tool at 3000 SFPM?
3000 ENTER 2 A yields: -5730 RPM (rounded to nearest integer)

Example: what SFPM is a .50 dia tool at 6000 RPM?
6000 CHS ENTER .5 A yields: 785 SFPM (to nearest integer)

Note: Interestingly, I had to change the 2nd test to X>0? to get things to come out right - probably due to using division after the constant 12 (feet to inches). One could probably rewrite to make the tests the same but the program works as is and made sense to me when tracing the program and stack contents.

Thanks again!

Allen