HSMWorks Cutter Compensation

Cutter Diameter Compensation (CDC) is a key to holding extremely tight tolerances. CNC provides a way for toolpaths to be adjusted to compensate for tool wear and deflection. We get a lot of questions from those new to CNC about how to use compensation. Part of whay makes it so confusing is there are so many options: In Computer, In Control, Wear, Inverse Wear and Off.


Figure 1: HSMWorks Diameter Compensation Options

To make matters worse, the seeing in HSMWorks, Tool Diameter and Wear registers on your machine have to be selected in harmony. If not, compensation will not work al all or the tool can be double-compensated (offset by twice the desired amount).

Let's simplify things considerably, 99% of people use cutter compensation as follows:

  1. In HSMWorks, select Wear.
  2. On the CNC control, set Tool Diameter value to 0.0 (always*).
  3. On the CNC control, set Tool Wear value to 0.0 (typical).

*Note the exception below.

Machine a feature on the part, and then measure this feature or use a Tool Probe to find the actual diamter of the tool. For example, let's say there is a 1.000in OD feature on the part, but when you measure it's acutally 1.004in. In this case, the feature is slightly larger than desired so you would enter .004in in the Wear register for that tool (1.000-1.004= -.004).

This will cause the CNC to make the tool veer .004in closer to the wall, effectively compensating for the tool wear (and/or deflection).

Exception: Unlike the Haas, some controls do not have a separate Wear register. In that case, put the wear value in the Tool Diameter register.

"Why do almost all CNC users choose this method? Because CNC control diameter compensation errors are virtually eliminated by having HSMWorks handle the majority of compensation. We do the complex offset required to get the tool centerline path. All the control has to calculate is a relatively small course correction.

Tip: Always use a Line and Arc lead-in/out when using Compensation. The length of the lead in should be more than the maximum value of offset you expect to enter in the Wear register on your control (example: .01in). Most CNC machines will error if you try to turn CDC on (G41/G42) or off (G40) on an arc (G2/G3) move."

If you want to learn more about Cutter Compensation, including how to change Wear Offsets on a Haas control, refer to the CNC for Engineers and Makers book found on our website, specifically pages 6-27, 6-28, 7-11 and 7-12.


Figure 2: Effect of Cutter Diameter Compensation

  • Tags: Cutter Compensation, HSMWorks, HSMWorks Basics

Categories: HSM Tips and Tricks

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