A Quick Review of the MAG-ic Probe

At the LINT Masters Class back in February, Liam Snyman introduced to us his new invention the MAG-ic Probe.  The MAG-ic Probe is an electronic thickness measuring device that is capable of taking very accurate measurements of the thickness of plates on finished instruments as well as measuring during the building process.

The MAG-ic Probe uses a magnetic ball (actually, two different sized balls come with the tool) that is placed inside the instrument and is attracted to an electronic probe on the outside of the instrument.  The probe is connected via a cable to the MAG-ic Probe unit which features a digital readout.  The device has a range of 1 to 600 mil and is accurate to within 1 mil.

When I saw the tool demonstrated at the meeting I had to have one and signed up for a unit in the first production run.  It arrived a few weeks later and I have experimented with it some but I got a chance today to do some seriously useful work with it and I thought  would use the opportunity to write a review.

I got a note this week from Matt Jacobs who has a commission to build a tenor ukulele.  Matt knows that I have a fairly large ukulele collection so he asked me for a few measurements.  One of the things he asked for was top thickness.  I whipped out my handy MAG-ic Probe (I love having the right tool for the job) and went to work.

The tool comes in a nicely constructed case with pockets for the main unit, the probe, the ball and the instructions.

The tool itself looks very professional and is solidly built. There is a thorough set of instructions included and the main operating instructions are also printed on the unit for easy reference.

The magnetic ball is simply placed inside the instrument where it is attracted to the probe on the outside while the device shows the thickness. (Normally you would be hanging onto that probe but I was short of hands.)

For this project I just left the instruments hanging on the wall.  I popped the ball inside and took measurements in a few locations.

I had no problem getting the ball to climb over braces to access the lower bout.

And I was surprised to see how much the plate thickness varied in some of the instruments.

And the variance from instrument to instrument.

In all the tool worked great.  I was even able to accurately measure the thickness of the ribs and it was all quick and easy.  Now I am anxious to use it while thicknessing plates.  This is a great tool that belongs in every luthier's tool kit.

There is a short YouTube video at MAG-ic Probe video and you can contact Liam at This e-mail address is being protected from spambots. You need JavaScript enabled to view it.