CNC machining with feeling… or, probing your workpiece like a pro

August 16, 2017  


Feeler; Merriam-Webster’s definition, noun feel·er \ˈfē-lər\: “an animal organ such as an antenna or palp that is used for testing things by touch or for searching for food.”  In essence, feelers are a type of antenna that probe physical conditions for useful information.  Not to be outdone by simple bugs, FERMAT also encourages its customers to thoroughly probe their workpiece, testing it for any offsets that need to be corrected before chewing into it with their top-of-the-line CNC horizontal boring mill.

How it works

An extremely ‘touchy-feely’ probe with a long, thin, hypersensitive stylus is mounted on the machine’s spindle, then moved in direction of the workpiece.  When the stylus contacts the workpiece, it triggers a switch sending a signal to a wireless interface receiver capturing the position and feeding the coordinates into the CNC control system.  Then, the measurement of that particular feature of the workpiece is compared with its theoretical perfect equivalent, e.g., a circle or 3D corner, and deviations calculated.  Through repeatedly probing the workpiece at different positions and directions, all the measurements are taken to create a mathematical picture of the actual workpiece and any problems found are fixed.

workpiece probe

Heidenhain workpiece probe getting up close and personal with a workpiece.

As long as there’s a CNC axis that can be adjusted to compensate for the offset, the axis will be moved, fixing the error automatically via the CNC machining process.  If not, e.g., when the workpiece has been tipped, tilted or canted while being set, the workpiece must be manually reset before machining can begin.

Although it’s up to you which type of probe you’d like to have, we recommend a radio probe due to two distinct advantages.  First, the signal sent from the probe to the receiver will not be interrupted by coolant and cutting chips.  Second, the signal isn’t interrupted by the obstacle of the workpiece itself, especially when measuring inside the workpiece.  That’s handy.

Workpiece and Tool Probes

By probing the workpiece before machining, and inspecting it along stages of production, costly mistakes can be avoided.  Measure twice and cut once always pays off, whether in carpentry, surgery or CNC machining.

Please visit,, for information on the different FERMAT machine tools and accessories that can improve your manufacturing business. Also, try to Build Your Own machine using our on-line configurator found on our homepage, Should you have any enquiries, please send us an e-mail:, or for the U.S. market, e-mail Lucas Precision, a FERMAT Group company:, or call toll-free: 1-800-336-1262, or telephone in the U.S.: (216) 451-5588, or send us a fax (216) 451-5174.