CNC machines are used for all kinds of applications; this makes CNC users quite a diverse group. What is obvious and important for one user will have no meaning or value for another. Combine this usage diversity with a CNC control manufacturer’s desire to please everyone and you end up with a lot of CNC features that are not appropriate for everyone. In this blog, we cover a few of those lesser-known CNC features.

Understanding Least Input Increment and Sizing Adjustments

Many years ago, a CNC machine’s least input increment (the smallest value the CNC could display, or that you could enter or program) was the same as its resolution (smallest motion departure amount for each axis). When working in the imperial measurement system, each was 0.0001 in. With today’s machines, resolution is measured in milometers; 0.0001-mm to be exact. 

This is acceptable for most applications, but there are times when very small tolerances are involved, requiring smaller least input increments. Though it is not common knowledge, today’s CNCs allow you to program values smaller than the least input increment, even though the CNC cannot display them. And when making sizing adjustments, you can also enter imperial measurement system values into offset registers out to five places. 

Rapid Motion (Linear or Nonlinear)

Traditionally, when more than one axis is fed a rapid motion command, all axes will move at their rapid rates. If one axis must move further than another, it will take longer to reach its destination and the motion will not be along a straight line. If you are not careful, this can result in a collision. Newer CNCs allow you to specify with a parameter setting that you want rapid motion to occur in a linear or nonlinear manner. 

Machine Locks

There was a time when most operation panels included an on/off switch labeled “Machine Lock”. If turned on, axes would be kept from moving — all axes with Machine Lock or just the Z-axis with Z Axis Feed Neglect. While this could be helpful during a program’s verification to test a program for syntax errors, it’s also the cause of crashes if not used properly.

When this switch is on, the CNC thinks the axes are moving even though they are not. If the axes are not left at the same position where they started, the coordinate system will be out of sync with the CNC. In essence, the machine loses position. Older machines actually required cycling the power to reset the coordinate system. Newer CNCs do so when you perform a manual reference return. 

Optimizing CNC Features for Your Needs

CNC machines come packed with features designed to accommodate a wide range of users, but not all of them will be beneficial for every application. Understanding how lesser-known functions—like least input increment adjustments, rapid motion settings, and machine locks—affect your machining process can help you optimize performance while avoiding costly mistakes.

Whether you’re fine-tuning precision, improving motion control, or ensuring accurate program verification, taking the time to understand and configure these settings properly can make a significant difference in your efficiency and results. By leveraging the right CNC features for your specific needs, you can maximize productivity and minimize errors in your operations.