Cutting bridge string slots

[Kary Karahadian]

After 10+ years of classicals I decided to try a steel string (Weissenborn). I've read that some use a jig saw blade to cut the string slots. Are the slot widths customized to the individual string gauges or do most slot each hole with the same blade? (I'm using 3 degree slotless pins).

[Bob Gramann]

I picked a jig saw blade that fits in the hole and makes a kerf about as wide as I want for the small e string. As I cut, I move it sideways back and forth to enlarge the slot to the correct width for each string. I made a handle for the blade out of an appropriately-sized dowel. When necessary, I polish the slot with a small file. It's pretty easy to adjust the kerf of the blade but either flattening the teeth a bit with a hammer or bending them out a bit (alternately) with small pliers. Cutting pin hole slots is not hard work for the blade--mine has lasted years without sharpening.

[Paul Breen]

I start my string slots with a jig saw blade and use Bosch's sharpened blades that are alternating teeth with no set to them. They are glued into dowel rod handles. I follow up with a tapered, round needle file to final depth and diameter.

I used to do them start to finish with the needle files only but it's too slow with them alone. The jig saw blade creates the slot quickly and I stop when the depth is close. Using different areas alone the length of the needle file, I can create different diameter slots. You will want a round tapered needle file with some tooth that can cut reasonably fast. Stew Mac sells modified nut files in different widths for bridge pin slots. I have been tempted to buy them and may yet succumb but the jig saw blade and needle file do a pretty decent job of it

The slots are done individually, trial and error until a fit is achieved. The windings at the ball end must have room in the finished slot so that the ball end will pull down tight onto the bridge plate with the bridge pins turned with the flute AWAY from the string.

When I lay them out before cutting, I draw a line on the bridge that is parallel to the saddle. The slots are rounded over as they exit the pin hole and stop along the line I have drawn on the bridge. Makes for a bit tidier job when yo u do this and also helps to achieve better balance with an under saddle pick-up.

[Bob Gramann]

One thing I forgot to say: put some cardboard or some other protecting surface on both sides of the bridge to protect the top. When you hit it, you'll know why you put it there.

[Kary Karahadian]

Bob and Paul, thanks for the advice. really appreciate it.

[Todd Stock]

Guard: Formica backed with cork for a guard...put it between bridge and sound hole, and tape in place (usually to the bridge and PG). Mat board is good, as is double weight cardboard, but don't expect a single thickness of shirt cardboard or bristol board to stop a slotting saw from punching through and damaging the top.

Blade: U101BR or T 101AO Bosch 20 TPI jig saw blade superglued into file handle...grind a bit off the back and tip of the blade if necessary to fit the pin hole...widen bass slots by sawing at angle to slot once the slot is established.

Tips: A sheet of white paper or paper towel and a flashlight inside the body aids in seeing depth/width of slots at bridge plate. The StewMac bridge pin slot files work well for smoothing things out, but a set of needle files can do it. Buy a couple extra round needle files and going one of them a bit narrower...will do a cleaner job of finishing off the ramps. The last three inches of string with ball ends of an old, dead, medium gauge set are handy as a tool for fitting pins and ramping and slotting...a little strapping tape holds then in order and at correct spacing.

[Barry Daniels]

In the past I used a jig saw blade but always felt that it was a bit too aggressive and coarse and it was difficult to keep it under control. The new Stew-Mac saws cut fairly quickly but are a whole lot smoother and easier to control. The files are cool but not as useful as the saws.

http://www.stewmac.com/Luthier_Tools/To ... Files.html

[Bob Gramann]

Ooh! The free shipping option ($40) is evil. I already have two of these new saws on the way. Use to be, I'd load up my cart until I had enough in it to make the shipping worthwhile or until I had an urgent need for something. Then, I'd edit it down to save money. Now, the impulse reigns. Good for StewMac.