Making Kerfing Quickly
This week I had to replenish my stash of kerfing. Kerfing or lining is the material that is glued to the top and bottom of the sides to allow more surface area to glue both the top and back plates. The kerfing also stiffens up the rims and is another important ingredient in the overall sound of an instrument. I use a ‘reverse’ kerfing, where the surface facing the inside of the guitar is uncut and the teeth of the kerfing are glued against the side. This leaves a smooth surface to reflect sound quicker instead of absorbing more sound like little sound baffles. It’s a minuscule difference, I’m sure. I’ve also been thinking about making some solid linings like those seen in string instruments (but that’s the topic for a whole other conversation!).
I like using Basswood for the kerfings. It is light, flexible, and soft. I french polish the insides of my instruments so it will get a harder shell when finished. I’ve used Mahogany too, but Basswood is generally lighter in weight.
This is a setup I use that I can make about 50-60 14″ strips an hour. Like anything else with lots of repetition it is easy to loose concentration, but focus is THE most important thing here when working with power tools.
Resawing Basswood sheets
After a quick pass in the drum sander the boards are kerfed on a radial arm saw with a fine tooth fretting blade and a pin in the fence. With the saw cutting almost through the material, it is important to keep firm pressure on the sheet.
I run them in reverse, against the rotation of the 1/4″ roundover bit to avoid ripping all the teeth out (if you don’t do this, you’ll learn pretty quickly that it doesn’t work the other way)
I’ll run both edges of the sheet against the bit, then over to the band saw to cut the strips off. Then repeat…
When your material is running down to the last strip, make sure to use a push block to keep your fingers clear and safe. Even when run in reverse, teeth can still chip away and create a surprising chatter. So be careful and work smart!
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