PM DRO Radius function


Jan 24, 2015
Dear All,

Has anyone here used the Smooth-R function on the PM DRO (or similar DRO) to mill convex or concave radii? The manual that comes with the unit is somewhat difficult to follow. I'm sure it was crystal clear in it's original language.

The first step to set up the smooth R function says: "Move the TOOL to the start point and Clear every axis (make the TOOL setting position to the zero)." OK, sort of, but should the start position be at the midpoint of the arc, the start of the arc, or the center of the arc? Should the start point be set under the center of the spindle, or offset by the end mill radius?

Step 4 reads: "Input the parameter CT POS: CT POS is refer to the position of the center of an arc relative to that of the TOOL at TOOL setting and clearing."

OK, does the center of the arc means: a) the midpoint of the circumference of an arc of radius r and inclusive of angle a, or b) the center point of the circle that the arc is part of?

From the example given, I think they mean b, but the example is pretty difficult to follow.

And what is meant by TOOL setting and clearing?

The manual also refers to planar and arc milling tools. I know not what these terms refer to.

Arg, now I'm writing and translating writing as written with flourish.

Perhaps there is a better manual out there in the intersphere?

Any thoughts will be greatly appreciated.




H-M Supporter Gold Member
Jan 2, 2018
dro pros does a video on the function, might be similar to your unit. Not impressed with the outcome( very rough compared to a rotary table).
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