G96 on a Cincinnati

[cdlenterprises]

I have an old Cincinnati lathe that I'm programming. Some of the existing programs have this in them :G96 R5.862 S0350. I know what G96 does and why the S0350 is there but what is the R5.862 for? I've never seen this....

[Eurisko]

Please bear with me, first some background info, then I'll get to the answer.

Years and years ago, our shop had a Cincinnati Milacron lathe.

The lathe had two turrets, an ID turret for boring and an OD (crown) turret for turning.

The OD turret X zero point was on the spindle center line. I believe that the ID turret X zero point was six inches above the OD turret X zero point.

For example, when moving to an outside diameter of 10 inches with OD turret,
G00 X+5.000 (the distance is radial, diameter = X times 2)
G96 R+5.000 S800

But when moving to an INSIDE diameter of 10 inches with the ID turret,
G00 X-1.000 ( diameter = (X+6) times 2 )
G96 R+5.000 S800

In answer to your question, the control used the 'R' parameter to determine the actual distance from the tool point to the spindle centerline. Even though an ID tool was positioned at X-1.000, the 'R' parameter of 5.000 allowed the G96 command to calculate the constant surface speed correctly.

Whew!