Tuesday, April 13, 2010

Forms, Patterns and Helpful Tools, Part 3

Router Table Jig for the Binding Ledge
One of the things I've had a lot of trouble with in the past is routing the binding ledge. It can be (and still is . . . at least for me!) pretty tricky and a little more than nerve racking. When I built an Irish bouzouki a couple of years ago I used a flush-cut (aka, flush trim) bit with a couple of bearings that were just a skosh smaller than the actual bit diameter. I also free-handed the channel. Well, long story short, I blew out part of the side. I've experimented with other methods since. I would like to buy one of those nice routing jigs from Stew-Mac or Luthier's Merc but I don't have the cash right now. Thanks to the helpful folks on Mandolin Cafe I was directed to Lynn Dudenbostel's site (documenting a build for, no less than, Chris Thile!), and Stan Miller's webpage. On each I saw their set-ups for routing bindings. I decided to try and construct something similar. So, here goes . . .

First, I cut a piece of 1"x4" pine a few inches strong of the actual length that I needed (just measure your router table to find this length). Next, using a keyhole bit I routed a channel in the center of the 1"x4" large enough to insert a couple of hex head bolts. I made one complete pass, and then moved the router table fence about 1/8" and made another pass. Again, this was done to be able to slide the hex head bolts in the channel . . . that is why it looks a hair off center. Here is a picture:

Next, I cut another piece of 1"x4" about half the lenght of the first, marked a centerline, and drilled two holes to accept the bolts.

Then, on the bottom side of the top piece, using a straight router bit (if you are unfamiliar with router bits, here is a basic, but good tutorial), I cut a channel about 2" long. When that was complete, I cut the angles on the top and bottom pieces, sanded them smooth, and added a washer and wing nut each to the bolts. I also drilled a hole in the channel on the bottom piece about 3/4" in from the end to accept the router table bit when cutting the binding channel. Here are a few pics:

Clamp it down, and you are good to go:

When you use this set-up, the sides of the box simply ride along the lower piece of pine. The top piece of pine is used to set the thickness of cut. By moving the router up and/or down in the table you can control the depth of cut. I've found that one of the keys to making this work properly is to hold the back of the box being routed (the part of the mandolin closest to your belly while standing at the table) at a slight angle down from the bit. In other words, the box should slope downwards from the router bit to you. If you raise the back of the box you will cut too far into the back and/or soundboard. Overall, with a little practice this seems to work like a charm. I'm still a long, long way from getting my binding routes 'perfect' . . . but is there really such a thing in this life anyway? :) I hope this is helpful.

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