Plans for a jig for cutting a binding ledge

Hello All,

I few weeks ago, I commented in a discussion that I had a binding cutting jig which worked well for me. Several people were interested in pictures of it, so I sent them copies. Deb suggested that I send her the pictures so that everyone can see them. Well, here we go ...

The pictures are big (had to leave them that way or the text got too hard to read) but the files are small.

James, thanks.

On IBM compatible and using Netscape I got a pretty good print out by right clicking each image, clicking the view image option and then printing that in landscape.

Thanks James, Is one screw enough to hold the dowel to the place? how long should the screw be. About the sloped surface of the router base, does it ride on the guitar in some places or just touch on the edge of the guitar?

Do you cut the groove in one pass? I know some recommend a couple light passes, but If the bit is sharp one pass leaves a better surface, (no steps or variation).

Thanks again for going to the trouble of drafting it for us.

James, Thanks for the plans. The thing I like about it is that it's designed to register off of the guitar side which I believe is the only way to get accurate cuts on the arched back. I modified my Dremel router base using Teeter's book to do the same thing with a couple of ball bearings, but, of course, have never been happy with the limited power of the motor.

I've got a couple of questions about your design. What brand of laminate trimmer did you use, or would recommend? How easy is it to set the horizontal adjustment? Also, when you use the jig, how do you hold it? Do you have one hand on the laminate trimmer and one on the 1-1/2" dowel?

Hello All:

I'll try and answer all the questions:

1. I used only glue (Titebond) on my jig: it's plenty strong and stiff. (The only screws are used to hold the trimmer to the jig.)

2. The jig is only designed to touch the very edge of the guitar. I use 15-foot radius for the back of all my guitars; but the slope is different at different points along the edge of the guitar, so you can't match except at one point. Since you are intending to fit exactly at the edge, I register off the very edge, only.

3. This is really important: I make a minimum of three passes. Because the cutter must press into the wood to cut it (physics) it will ALWAYS deflect away from the work (when you press on the end of a cantilevered beam, it deflects). This deflection will VARY depending on how fast you move along the edge. Therefore, my solution is to make one heavy cut (lot's of deflection) and then several more cuts until the deflection is negligible. At this point - after several passes - the cutter is no longer touching the wood as it passes, and you can hear that little or no cutting is happening. This method has given me very consistent rabbetts with ~ no gaps.

Ken, I find it interesting that your experience shows a more even surface with a single pass. My experience is just the opposite. Once I solved my problems of correctly registering against the sides and back/top of the guitar, I can make as many passes as I like, with very consistent results. When I "connect" the ends of the rabbett, there is no discernable mismatch whatever.

4. I don't think Dremels have enough horsepower to cut binding. I am using a Skil laminate trimmer which I bought because it was the cheapest available and had vertical adjustment. I would go for the smallest, lightest one you can get, other things being equal. One luthier I know has a Hitachi trimmer which he really likes. I haven't tried it.

5. The horizontal adjustment is very simple and easy. Loosen the wing-nuts and nudge the trimmer a little. When I eventually retire this tool and make a new one, I'll put thin metal plates under the screw-heads that hold the new jig to the trimmer -- they dig in a little.

6. When I use the jig, I hold the trimmer lightly in my right hand: this controls the orientation of the trimmer (twisting) and keeps it square to the work. With a firmer grip, I press the dowel into the side of the guitar, about midway down the side. Keep at least one finger on the left of the dowel, to keep it from running left suddenly. I always work from right to left to prevent tear-out. (My trimmer spins clockwise as you look down on the work and therefore tends to run leftwards.)

Just in case: WEAR SAFETY GLASSES AND EAR PROTECTION!!! A 20,000 rpm trimmer whacking away at a complete guitar body (resonator!) makes an infernal racket.

There was some other comment I was going to make but my short term memory is ... I forget. Maybe I'll remember it later!

Oh yeah, now I remember: I do a very careful job of smoothing the sides (and back and top) of the guitar body before I cut the binding rabbetts. This is critical to a good, smooth cut. I smooth mine on a flatbed belt sander with a fine grit belt and light touch. It gives excellent results. After cutting and gluing on the binding, I smooth the works again on the belt sander and then by hand.

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