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#1
03-24-2015, 07:17 PM
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A question about binding the back of the guitar
So, I've been struggling (as many do, it seems!) with routing the channel for the binding on the back of my guitars (because of the radius). I recently went ahead and bought the router attachment from KMG:
http://www.kennethmichaelguitars.com/portattach.html Long story short, the channel is now consistent in thickness and is square with the sides. However, I noticed that because of the relatively steep angle starting at the upper bout and going toward the center point (where the heel of the neck will be), the height of the channel is almost 1.5 mm less there than around the rest of the body (there is a bit more binding sticking up above the back of the guitar there). Is this always the case, and you just end up scraping a bit more of the binding in that area, which results in a binding that is a tiny bit shorter in height than at the lower bout or are you supposed to mess with the bit depth in the router and try to average out the difference somewhere in between? Hope I'm explaining myself clearly enough. Thanks for any and all input! P Last edited by PhilQ; 03-24-2015 at 07:26 PM. 
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#2
03-24-2015, 07:49 PM
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Yes.
You can do it either of the ways you suggested, but most people would find an even depth binding to be the most pleasing. Many of us have made our own hand-made attachments to route binding channels effeciently and effectively. That said, a bit of touch up with a chisel and/or file can help. Then you enter the realm of craftsmanship, where individuals' skills will become apparent. When you are just using power tools and purchased jigs, then you are still mostly in the realm of manufacturing.
__________________
---- Ned Milburn NSDCC Master Artisan Dartmouth, Nova Scotia
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#3
03-24-2015, 07:56 PM
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You've explained it clearly.
Short answer, no. A good jig, used correctly, will ensure that the channels are square to the side, uniform depth and uniform height. The whole purpose of using a jig is to ensure that. If the jig doesn't you either don't have it setup correctly, haven't used it correctly or the jig isn't a very good design. With a good jig, used well, very, very little hand work is required to fit the bindings. I'm okay with that and don't see that as a negative or as "manufacturing". Craftsmanship is not defined by whether or not hand tools or machine tools are used. I'd contact the designer/maker of the jig for trouble-shooting the use of his jig. Last edited by charles Tauber; 03-24-2015 at 08:02 PM.
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#4
03-24-2015, 08:10 PM
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Thank you both. I agree, Ned. I didn't start building very long ago. I've built a few already, and am striving to get better and get a better finished result. I agree there's much experience to gain and things to learn. I really do appreciate the wisdom and tips of all you builders on here. I don't use too many power tools, actually. I'm not so much relying on a gadget as I am trying to find a reliable way to do this that works for me. I started out doing them entirely by hand...
I guess the reason I am asking is that after routing the channel, and looking at it, I wondered how you could have a channel that is equal in height the whole way around, and yet manage to have the piece of binding (that is straight) follow that steep curve down from the upper bout to the center point at the top of the back. When I tried to use a chisel to even out the height, I end up with a bit of a gap under the piece of binding... Doing a mock up with a piece of tape instead of binding, I still end up with some of it sticking up over the back of the guitar in that same area unless I bend the tape down. Which is why I was wondering... I'm using wood (ebony) BTW. Not plastic. Thanks again
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#5
03-24-2015, 08:42 PM
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Wood binding will bend on edge sufficiently to follow the contour of a uniform depth channel that follows the curves of the back. It is a smooth curvature, without abrupt changes. If need be, you can use rope, masking tape or clamps to pull it down to the bottom of the channel.
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#6
03-24-2015, 08:52 PM
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What back radius are you using? The lower the number i.e. 12' compared to 15', the HIGHER the binding will be sticking up. What is happening is the tongue slides up higher on the back radius lifting the router bit up causing the channel to be narrower. If you shorten that tongue there will be less/no difference. You only need the router to ride just enough on the edge of the guitar to keep it from slipping off. Does that make sense?
__________________
Tim B
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#7
03-24-2015, 09:11 PM
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#8
03-24-2015, 09:11 PM
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#9
03-24-2015, 09:22 PM
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#10
03-24-2015, 10:21 PM
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The jig design you purchased uses a larger contact surface area that is flexible. It's the first that I've seen of that design. All other jigs I've seen rely upon a small surface area - in fact, they minimize the contact area so as to eliminate the very problem you are encountering. The maker of the jig you purchased claims it is the "Taylor factory work alike". I don't know what Taylor does and can't comment on that. Having not used that jig, I can't comment much on it or its use. I have tried a number of other jigs - as well as hand cutting the channels. Each is different, but relies upon the same principle: keep the cutter parallel to the sides and govern depth of cut by having a small reference surface in contact with the back. My previous suggestion is to contact the maker of the jig you purchased. Presumably, he knows how to make it work and can make suggestions for its setup and use. Otherwise, I'd use a different jig: there are many proven ones from which to choose, and at all price ranges.
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#11
03-25-2015, 05:53 AM
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Hi Charles and thank you for your reply. I did write to the manufacturer and will see what he says.
But actually, my understanding of the jig isn't exactly the same as yours. There is a rigid cross that is just in front of the bit and doesn't bend at all. That cross (see the blue circle on the picture) is what registers on the top or back of the guitar and remains at 90 deg to the jig no matter what. It has a very small footprint. The stiff, flexible tongue (my understanding of it anyway) is just an additional safety feature. Anyway. I'll see what he says. Thanks. 
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#12
03-25-2015, 07:24 AM
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I have modified that exact jig and mounted it in a tower. I will take a close up pic of it if you are interested. I modified it before I mounted it in the tower as I mentioned and further modified it for the tower.
__________________
Tim B
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#13
03-25-2015, 07:45 AM
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#15
03-25-2015, 09:13 AM
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If the contact area with the back is as shown in the picture below - next to his index finger in the top right of the photo - then it is much too large, extending too far over the back to give a consistent depth of cut: the router will rise and fall with the curvature, not what you want.
Shorten that to 1/4" or 3/8" and you'll get much better results. 
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