Probing and Edge-Finding - Best Tools to Find Your Work

While CNC machines are capable of an awful lot of amazing things, the machine itself is only as capable as its operator and code. That means proper programming and tooling setups are necessary to get the most out of your machine.

What’s more, is making sure your machine knows a couple important measurements - like tool lengths and where the stock is on the machine.

That’s where probing or edge-finding comes into play.

There are a variety of different tools you can use to locate your work on your machine, but not all tools are created equal. It really depends on how much work you want to put in on the front end and how precise you’re hoping to make your part.


Edge Finders

Often called “wiggle edge finders,” these tools are the most economical way to locate your work. While you can certainly dial in the location of your work with these, if you’re looking for precision, these may not be the answer - Wiggle edge finders rely on your line of sight.

The finder is put in your spindle (with a toolholder) and rotated at lower RPM. The center of the tool is off-center in two sections, which is where the term “wiggle” comes from. You set the top section on center and the bottom section off, and slowly jog the tool closer to the edge of your part. As the lower section brushes against the edge, the wiggling is reduced. As you continue (slowly) jogging toward your part, the wiggle will diminish until it goes away completely. At this point, you still have a thou or two to go. When the upper section or head “breaks” from the shaft or just jumps off center, you’ve found your edge.

These edge finders are only capable of finding your edges in X and Y, so you’ll be in need of another tool to find Z. Again, these are a great budget option, but since you are literally eye-balling things (even if it is with a tool), it won’t be as precise or quick as some of the other work-finding options available.


Haimer 3D Sensor

The Haimer 3D Sensor is the go-to for many Tormach users. With an accuracy of +/-0.0005” and a visual display, you can easily find your work in X, Y, and Z. Another thing that makes this tool one of the favorites is that the Haimer tip has a breakaway function, so if you accidentally jog too fast, the tip will break off, rather than destroying the whole tool. 

The Haimer is a split between using something as economical as a wiggle edge finder and the more automated active probe. It is much more accurate than an edge finder since you’re using a dial gauge to measure, but you still have to manually jog your machine. 

Beyond just finding your edges, the Haimer also adds the capability of touching off your part in the Z axis. This enables you to do all of your touch-offs with one tool, rather than calculating your Z-zero elsewhere.

A Haimer 3D Sensor is a great middle-ground measurement tool, and even if you prefer one of the other methods to find your work, it might still be worthwhile to keep one in your toolbox.


Tormach Probes

There are two different Tormach probes, active and passive, but both provide more repeatability and precision because you are relying on the machine to find your offsets for you.

Both probes plug directly into your machine and talk with the PathPilot control system. Essentially, both Tormach probes let the machine do the corner- or center-finding work for you. In fact, it can find the edges in X, Y, and Z, like the Haimer. 

Adding this little touch of automation to your shop might not seem like much, but in the end, the time spent nudging your machine around to find zero adds up. A probe gives you a chance to add a little extra efficiency to your processes.

The passive probe provides a repeatability of 0.0006 in., while the active probe has a 0.00007 in. repeatability. Visit the product pages to see which would be right for your needs.

Active Probe

Passive Probe

While all of these tools will help you find your work, your needs should dictate which tool will work best in your shop. Edge finders are great if you’re not overly concerned about time or super-accurate parts. The Haimer is a great middle-ground, but still requires that you stand at your machine. And the two probes let your machine do some of the tedious work for you.