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Thoughts On Tip Of The Day

Keith Foor

Active Member
Active Member
I was just thinking that a TOD (tip of the day) would be a good addition in here for the beginners (and us salty old farts too)

Things like cutting with a mill and how to figure distance.

If I have a tool that has .5 inch diameter, and I need to come 12 inches off an edge. I zero my machine to that edge and then come over 11.75 inches to start the cut. The reason is half the tool diameter. Then I only cut 11.75 inches back on my DRO. Again, half the tool diameter needs to be accounted for because the DRO is measuring the center line of the machine and not taking into account the diameter of the tool..

Input is welcome on this.
If it's already here and I missed it, let me know.
If it's in the wrong place please move


Active Member
Active Member
Great point. But does the DRO measure from the tools edge or the tools center.? If from the center it would be .25 inch. If the DRO has an accuracy of .0001 do you add or subtract .00005. Ah! Just playing with you!! Tom

Keith Foor

Active Member
Active Member
Some DRO's can be programmed with the tool diameter. Mine can't that I have found and a lot of my tooling came home dull in a bucket so it was cleaned up and sharpened by me on a T&C grinder, so it's actual diameter isn't always correct. The other thing I worry about is I swap tooling a good bit and if I forget I will lunch a project if I go from little to big and don't get it in there.


Active User
H-M Supporter-Premium
The same exact principles apply to handwheels. You merely need to consider backlash and count rotations.