Clarinet manufacturers spend thousands of dollars to perfect the inside boring of a clarinet joint to make it absolutely smooth. However, when we measured the inside diameter of hundreds of clarinet tuning barrels and compared them to the inside diameters of the top tenon of the first joint we found there was a considerable difference, enough of a difference to make a noticeable "step" in the bore. Quick and easy way to measure clarinet bores. Compare the bore of the top joint with the bore of the barrel that you are using or have just purchased. If the barrel is smaller, you may want to match the bore to the top joint using the G107 Precision Barrel Reamer. You may also want to match the bore of the mouthpiece. We recommend measuring the bottom bore of the barrel first; that way, you can see the difference when you install the probe into the top joint bore. To measure; loosen the set screw slightly and carefully insert the graduated aluminum probe into the bore, slide the brass housing down to where it bottoms out in the socket, lightly tighten the set screw and remove the unit from the bore. The end of the brass housing will be marking where the bore size is. Use your dial calipers or micrometers to measure the aluminum probe at that point. Write down the size and proceed to measure the other parts, similarly.
