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Binding an Arm Bevel


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I'm working on an instrument right now where I carved the arm bevel, bent a top over it, and would now like to bind the instrument in some plastic binding. The only issue? Cutting the binding channel on the bevel. Obviously the router table is out for that section... And the router jig used for binding stuff like acoustics isn't working either as the angle on the arm bevel is greater than the angle on the donut that sits on the top.

So, how would you guys go about cutting this channel as I'd LIKE to avoid doing the old fashion gramel technique and chisels.

Chris

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I've never done it before, but I would imagine a dremel with base could be made to work pretty well, though I would keep the channel slightly undersize for the first go just in case.

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Small palm router with a rabetting bit plus bearing would be my guess. Might need to finesse the channel by hand at the transistion of the flat section of body and the arm rest.

The router table probably could work too. You'd just need to tip the body into the cutter so that the face of the arm rest remains flat to the table as it goes around.

Both methods above would require that the bevelled section is as level as possible, otherwise your binding channel could end up a bit wavy. A shallow setions in the channel are OK as they can easily be adjusted by hand to the correct depth later on. Deep spots in the channel will be difficult to recover from.

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Thought about those too... sadly, they won't work either. If you have an arm bevel, then by definition the sides in that area are not perpendicular to the bevel, they're perpendicular to the back. Which means they're obtuse to the bevel's top. This means when the bearing follows the side there it's following too far out. So for instance instead of getting a say, .070" thick binding ledge, you'd get much less. The trick is to somehow keep the bearing parallel with the sides (which is what my router jig does) but while also getting it down to the right depth!

My latest idea is to use that jig, but to then keep the bit out really far. My issue right now is it's not cutting deep enough with that method... so why not set it super deep to make it cut CLOSE to what I need, the finish up with a chisel/gramel?

Chris

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If you look hard you can almost see the doughnut from the LMI jig in this picture from my review of that jig. :

gallery_3898_71_1289716.jpg

I don't think it is totally impossible to use something like that. You might need to set the bit to a greater depth than on the sides, but if you have a flat arm bevel (myself I cut them in a smooth curved shape) the offset in cutting depth is constant and you should be able to do it with only minor touchups in the transition area.

You might get a better view in this video

At around 1.00 you get a good look at the rub collar/doughnut

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Meh. Just went ahead and did it by hand. Fun little exercise in hand tools:

86363B60-EF8A-4084-A001-367F5740F973_zps

Chris

Nice job!

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