I’ll probably get in trouble for this one, but here goes. Don’t waste your money on the digital indicators that people strap to their planers, drum sanders, drill presses and routers. They are just silly and useless in most woodworking situations.
I have a couple decades of experience with them. I’ve tried to love them. But they are just not worth the plastic and aluminum they are built with.
Here are some of their problems:
- They aren’t really accurate or precise. When used on machines such as planers or drum sanders they are unable to deal with the wear that occurs with the tooling or the abrasive. Sure, you can measure to .001” with the things, but you really don’t have a true zero reference point. The target is always moving.
- Inexpensive digital indicators don’t deal with the inherent slop of a screw-driven adjustment mechanism. All mechanical screws have play. And these screws wreak havoc with digital indicators. The head might move .006” but the indicator doesn’t register any movement. Or vise versa.
- Most machines have built-in schemes that are more accurate than a digital indicator. Most planers, for example, operate so that when the control wheel is at 12 o’clock or 6 o’clock, you are at an important dimension. For example, every planer I’ve owned hits .75” with the adjuster wheel at 12 o’clock. Plus, after a little use, you will know exactly how much to move a control wheel to remove .05” or whatever. It just takes a little experience, and the digital indicator will lie to you and confuse you as you learn this.
- Most of them eat batteries. And you have to turn them off manually. Or they turn off automatically – right in the middle of a job.
Please note that I’m referring here to the consumer-grade digital gizmos. I’ve worked in industry where the very expensive digital equipment is fully integrated into the machine and really is useful (and smarter than you). But these little add-ons, I’d skip them.
And yes, this is even if you work in a production shop. One of the jobs I do regularly is sand veneered French curves – thousands of them in a year. The veneer is .016” thick, so there’s no room for error. The digital indicator that came on my drum sander is a highly tuned joke. I get better results from moving the head in 30° increments and observing what happens to the veneer. I can compensate for the way the abrasive wears.
The only downside to this approach is I can’t blame the equipment when I make a rare mistake and sand through the veneer.
— Christopher Schwarz