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Accurate Binding Routing
How to rout accurate ledges on domed surfaces.

Randy Reynolds - 11:08pm Dec 8, 1997
I have trouble routing accurately. I use a laminate trimmer and have "tuned" the base so that it is smooth and of minimum size, but I still have varying materiel left to scrape from the wood bindings. The thought of the router table method leaves me cold also. When you throw in the purfling needs, this is the least satisfactory job in guitar building for me. What's the best way?

Mike Mears - 02:18pm Dec 9, 1997
Randy,
I just use a plain Vanilla Sears router with a Carbide Rabbet bit with a bearing. I adjust the depth of the cut (thickness of the binding) with different bearing diameters fine tuned with aluminum tape. The height of the cut is just the normal router adjustment. This works well as is for the top since it is almost square to the sides. For the back, I account for the arch using a spacer taped to the base plate right next to the bit. A Popsicle stick parallel to the line of the cut works well. then just rout the back normally keeping the spacer aligned with the guitar edge all the time. I've found that the heavier routers give a more even cut. (inertia and all that) This requires very little trimming and you can see the cut as you make it unlike a shaper.

Jonathan Richey - 10:21am Dec 10, 1997 EST
Anybody have any comments on the Schneider/LMI Gramil cutter? Seems like a relatively cheap and graceful little gadget. I suppose that it might be tough to use when binding the top on either side just next to the neck, and also bet it gets tricky to use when there is any kind of arch in the plates. But, I'm too poor to rout and am building a classical, so I think it could be the thing I need (or need to build, I should say). Thanks

Jed Taub - 11:02pm Dec 10, 1997
For cutting binding ledges, archtop or flattop, there's a $15 gadget in Stew-Mac that screws onto a Dremel tool. It comes in two sizes, each having two depths available. The footprint is so small that top shape matters very little. It can also be used from the side for purfling if the purfling butts to the binding. I made a similar gadget, adjustable with tape shims, for the Dremel flex-shaft and it's great.

For purfling channels on a violin top, I used an adjustable-reach leather stitching groover from Tandy Leather--a lot cheaper than a purfling cutter, and works adequately in spruce.

Randy Reynolds - 12:40am Dec 11, 1997
Jed, I have tried the Stew-Mac Dremel set-up and it chattered quite a lot even with their Carbide bit, perhaps I was trying to remove too much materiel at a time.

I have one of the Schnieder Gramil purfling cutters and haven't tried it. I have this image of my chisel slipping it's merry way across the soundboard and ruining a lot of work. I will try it eventually.

Dean Harrington - 03:24am Dec 11, 1997
I've wasted time using the gramil and don't think it's a good purchase. I use it as a simple marking gauge now for various other things but not binding. For guitar building I think a good laminate trimer/router is essential and I prefer the results I get with a spiral down-cut blade. the one time I used regular cutter with two teeth it blew a big chunk of soundboard flying. I'm a big fan of routers and own five, I find that the dremel is too weak for cutting binding. I only use it for cutting rosette channels now.

Jonathan Richey - 10:39am Dec 11, 1997
Randy-- why are you scared a Gramil will slip? From the looks of it it seems pretty foolproof if you keep the pressure straight down over the blade. Then again, I've only seen pictures. Dean-- could you elaborate on your disappointment with the Gramil? I'm trying to do as much work as possible by hand, and the Gramil is the only hand tool I've seen for this task. gracias

Dan MacArthur - 08:36pm Dec 11, 1997
Another option using the router: turn it upside down in a router table, cut a small base out of ply or something for the guitar body to slide along, drill a hole in it for the bit, and mount it with the bit sticking up out of the new smaller base . This keeps the arch of the body from making a difference, gives the router a good solid mounting, but means that you are holding the guitar instead of the router which took me a bit of getting used to.

Dean Harrington - 09:01pm Dec 11, 1997
I'm sure the gramil works fine if you're careful and don't try to make too deep of a cut in one pass. I just like power tools better. This operation is so much faster and cleaner with a router and you can get a used one for about the same price as the gramil.

Jed Taub - 10:26pm Dec 11, 1997
Regarding the Dremel tool binding-cutter attachment: use high speed and a LIGHT touch--also a new #115 bit each time. Make light passes--the sound will tell you if you're trying to take too much. Dremel makes a rabbeting bit that will work--piloted and all--but you'll have to formulate your own router base with a small footprint to use it on archtops. The bit, though, is rare--and costs $17 or so.

Norman DeValliere - 01:17am Dec 15, 1997
I would refer to Benedetto's book for what looks like a really simple way to route binding channels on an archtop. If I could draw it,maybe, but it is too delightfully simple to dishonor with my description. I don't build archtops but I dig that book to the utmost.

Eduardo Brito - 08:01am Dec 21, 1997
Classical, Steel string and Solidbody guitar builder
In my opinion, the important thing is not how you carve the binding channel, but, how many times you do it, you cannot expect to try a technique once and do everything right, all of them work great if you stick to them and improve. There was a guy in one of the previous issues of American Lutherie who claimed to have built an entire guitar using only a swiss army knife. In my guitars I use the stew-mac dremel attachment and a # 115 bit for the binding and it has been working for me. I can see on every guitar I've made, though, a little improvement in that area, I learned how to sharpen the bit before every job, how to rout a little bit at a time so you don't bite chunks off the soundboard, how to improve on the precision of the rout with a square file and a square stick with sandpaper, how to aply pressure on the bindings during the glueing with inner tube bands. Nowadays the job comes out perfect.

Bruce Calder - 04:02pm Jan 13, 1998
Has anyone used that other Stew- Mac binding router, the brass one designed to be used w/ their precision router base?

Mike Mears - 09:41am Jan 20, 1998
Jim Olson gave a talk at the last ASIA Symposium with a slide tour of his shop. One remarkable thing, aside from making all his guitars by himself, was that he used 30-plus routers. He claimed it was because he hated setting them up but we thought maybe he owned stock in Sears.

Bob Gleason - 03:23am Jan 23, 1998
Friends-The best trick I ever learned about the binding rabbit had to do with the binding itself (I'm talking about wood bindings here because you really gotta twist my arm to make me use the gooey plastic stuff). I think that most of us cut those rabbits with routers of some sort. The problem is that no technique guarantees a right angle at the inside back edge of the cut all the way around. Some years ago a great luthier in Wash. showed me that scraping that bottom inside edge of the binding that you are applying into a slightly rounded shape really helps eliminate gaps where the binding meets the sides. I suppose you're all doing that already, but if not try it, it's a minor miracle!

David Berkowitz - 10:34pm Jan 26, 1998
There are several set-ups for routing binding that I've seen. I saw a machined aluminum laminant trimmer jig at Breedlove that consisted of a housing to hold a Bosch 1608 Laminant trimmer horizontally, and a pair of sealed bearings running parallel to the bit. The bit feeds through the housing where the surface has bee domed back to allow for the curvature of the back. The bearings consist of a armature holding a pair of sealed bearings which is attached to a bracket mounted below the domed face. The height of the cut is adjusted by moving the trimmer in and out, and the depth by adjusting the height of the bearing armature relative to the bit. Just ride the body on the bearings and into the bit. I made one out of maple and it worked fine.

Another option is a parallelogram set-up which Harry Fleischmann has used made out of wood, and that Dana Bourgeois purchased an industrial version from Grainger (~$600.00 just for this armature, plus the cost of a die grinder and, and and....). It essentially consists of a post on which a arm is free to rotate,and at the end of that arm is a parallelogram type of thing, kinda like an architect's lamp. With the parallelogram ends being parallel to the post, and a laminant trimmer (or die grinder in Dana's case) attached to the other, the trimmer is always 90 degrees to the table no matter where it is moved. With a carriage to sit the body in so that it's sides are perpendicular to the table, one gets perfect binding ledges with no cleanup.

peter rosenthal - 12:25am Jan 28, 1998 EST
In 1970 I bought Sloanes classical guitar constructon book and gallantly attempted to make my own guitar. Everything went well until... THE BINDING CHANNEL!!! NOT THE BINDING CHANNEL??!! I tried to fabricate my own purfling channel cutter and to be honest it looked as if beavers with bad teeth got ahold of the thing. That was it for me. I didn't touch guitarmaking until.... I stumbled upon a picture of LMI's channel cutter behemoth. It took a while to make but let me tell you, it worked great. I mean great!! It routed a perfect two step channel in 3 minutes. I think the term is anticlimactic. I have a small lathe at work and I turned bearing bushings for the trim bit bearing to cut a very precise depth so when I glued the herringbone and binding on it fit to within a thousandth or two. Yup, I'm a believer. A truly religious experience.

Wayne Kelly - 01:22pm Feb 19, 1998
I made myself a gramil out of scrap, using the photos in the LMI catalog as a guide. I used a small chunk of maple for the piece that bears against the instrument. The rod part is a short piece of 1/2" aluminum rod. Aluminum is quite easy to work with a drill press and hand files. The blade is a short piece of used sabre-saw blade that I reground to a single-bevel knife edge. I tapped a hole in the end of the rod for a 1/4" threaded insert. A short bolt in the insert clamps the blade securely against the shoulder of a square hole filed across the rod. Another threaded insert in the maple block clamps the rod, allowing me to adjust the depth of cut. I also made a simple little miniature honing jig to sharpen the blade, because a keen blade seems necessary for these things to work well .

I realize this is difficult to follow without a picture - if you have a copy of the LMI catalog take a look at the photos of the gramil.

David C. Hurd - 11:45am Feb 22, 1998
When putting in the binding, I make it so that the sides are a little "proud" (the binding is inset slightly). But how to smooth it? I've used scrapers before but now use a Sears (Ryobi) oscillating drum sander. This is an excellent tool and has many other uses including neck heel shaping, headstock trimming, bridge shaping and so forth.

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