Construction:body:Installing FlexiFrets

Installing FlexiFrets®

Bear Meadow Dulcimers-Click to see full size

FlexiFrets® were invented here at Bear Meadow to give musicians a way to partially or wholly modify the diatonic fretboard of the Appalachian dulcimer. The FlexiFret is a conventional fret, but instead of being pressed into a slot sawn in the fretboard, it rides in a little channel.

Because each fret rides in a channel, the installation has to be very precise, so that each channel is the same height as all the others, and placed very accurately on the fretboard. No "fret leveling" can be done, because you have to be able to pull a FlexiFret out and re-install it without worrying which position it came out of. The frets can't be shaved to cure a buzz. Also, the slot has to be cut into the fretboard with no chipping, since the wood has already been finished, and the brass channels oxidized to a nice matching brown tone.

The process begins with a very accurate measurement (+-.00025") from the nut to the center of the slot of the channel. This measurement is made with a 24" digital caliper, quite a fancy too. Of course, no one could hear a pitch difference arising from such a small measurement error. We just don't want errors stacking up (or multiplying!). The actual measurement is 7/8" longer, to accommodate the distance from the edge of the router base to the center of the cutter. It helps a lot here to have the digital caliper, since I can simply zero the calipers at 7/8", then read measurements directly off my fretting chart.

The setup for cutting the slot is pretty simple (anything complex at this point would drive me bats!). A specially made square is clamped onto the fretboard. It is left loose while the distance from the nut is being set, then clamped tight.

The slot for the channel is cut into the fretboard with a Dremel variable speed Moto-Tool, held in a special high-precision router base. The tool used is a carbide end mill, .090" The slot cut turns out to be just a few thousandths shy of the final .093", which is hand-dressed with a fine machinist hand file. Here's another view of the operation, at right. The biggest trick is getting the channel flush with the top of the fretboard. Use a true flat tool (a ground lathe tool bit is perfect) pressed to the top surface of the fretboard. If the FlexiFret channel is truly flush with the top, there will be a nice slip fit of the channel under the bottom of the tool bit.

Here's a closeup of the channels after the installation is complete. They are actually held in with cyano-acrylate glue ("crazy glue") applied to the bottom of the slot.

The question sometimes comes up, "Can I just buy the FlexiFrets and install myself?". As you can see, the installation currently requires some pretty specialized equipment. If there is a dulcimer maker or music shop which does repairs near you, they can arrange to get the materials and install on your dulcimer. And other dulcimer makers can install them on their own dulcimers. That will require some detailed descriptions, so they avoid a lot of the headaches I had (I'm not going to tell you about them!) getting the process just right. But I don't think it will ever be something someone could do without a shop.

Dwain Wilder

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