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Doing bloodwood binding on an instrument. I have the wood bent nice and pretty (remember to buy extras if you decide to use it. It enjoys breaking) but I have a problem towards the neck block. The instrument is teardrop shaped and the top of the body where the neck joins is flat. Due to the radius of the top, the channel slopes down sharply in that area, so if I want the binding to follow the channel, it has to be bent on that axis as well as the usual one so that it wraps around the top.



To get it to conform to that curve, I plan on using force and heat. I'm wondering how titebond will react to heat, as well as the painter's tape I hope to attach it with. No problem with using hide glue if it's required but I do prefer a longer open time for operations like this, and excessive heat may also mess with the side to top joint.

Think I may have this. If I tape down the binding at the neck block, the taper is more gradual going the other way. I think I need stronger tape if nothing else though. This topic is still up for discussion if anyone can think of anything else I may need to know.

As Howard Klepper suggests, scotch 223+. Best binding tape there is.

Or that could work too..........

Ian: That looks like extra high binding. Makes it that much harder to bend to the ups and downs.I generally rope mine but have never used this size binding.
Tom

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A person who has never made a mistake has never made anything!!!

I think the binding is .025". Definitely have to remember to shorten it for next time. This is hard to do, which is odd, because I did a similar shape last time and don't remember having so much difficulty. The binding is in fact shorter than the channel by about .3mm. I can work that out though. Did a test run with the blue tape and it's holding together nicely. Got some stronger stuff on the way. Not looking great at the moment but it should be fine.

So what kind of instrument is it?

That really isn't "the way" to do it. For florentines and tight areas where you have both a tight bend and movement in the "z" plane --- make the binding taller. Then put sandpaper with adhesive backing on the area you are going to put the binding and sand the bottom of the binding to conform to the area. With a 15' radius back, I don't think there is any way to get binding to fit perfectly without doing this. Maybe there is an alternative method but none comes to mind.

Sometimes the binding has a natural bend that can be used to advantage when bending so that it will conform to the radiused shape. Also thinner binding can bend in the z plane more easily. You can make a scarf joint if you need to that will not be that visible. Todd's rubber band technique usually works though. I've had some success bending the binding at an angle across the pipe so that when it is taped in place the twist comes out and the lining fits better in the slot. Like Todd, over the years I have gone to shorter bindings.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Ah screw it. The channel is way too big on both fronts and I'm getting gaps from the angle that the gramil created when it was flush to the top. It's hopeless. The only hope that I have left in fact is that I can remove the top, make the rim more shallow, and redo it. The thickness is fine, but the channel needs to be shorter, much shorter. This was going so well.....

It's an octave mandolin by the way. Same one I've been yammering on about for a month or two

There's a cool trick in the second Somogyi book for situations like this. Rather than bending straight binding strips and trying to get them to conform to curves in the tall direction, get an extra set of sides in whatever wood you want, bend them, and then cut binding strips from them following the curves of the back arch. Requires a form of some sort to hold the sides while you cut them with a dremel cutoff wheel or whatever. Ervin's outside molds have their surface arched to the same amount as his backs, so they double as holders and a bearing surface for the router with cutting wheel.

Oh, and about registering the gramil on the top... I came up with an improvement for that on my current guitar. Mainly out of necessity, given that it's a Manzer wedge, so on the narrow side of the back, scoring into the ribs, the gramil registers quite a lot higher than the actual corner, due to the back sloping upward. I ended up taping a small wood block to the gramil that rides about 1/8"-1/4" in from the edge, where the slope hasn't made a significant difference yet. Turns out it also makes it easier to keep the bottom of the channel perpendicular to the rib surface, rather than having it angled like the dome of the back. The wood block doesn't lock the tilt of the gramil at all, but makes it easier to hold it vertical yourself, as you can see the tilt more clearly. Also keeps any indentation in the plate right at the edge, where it will get sanded out when rounding it over. The corners of the gramil bearing surface tend to leave marks ~3/4" inward from the edge using the normal style.

^ that paragraph would make a lot more sense with pictures. Let me know if I should bother taking any.

Yeah I'd appreciate that.

Ok, here is my high tech little snippet of wood:


And here is the troublesome gap created by the angled back of the Manzer wedge, and how the block solves it. Obviously the binding is already installed now, and I don't have the depth set exactly the same, but you get the idea. Also, I would normally be holding it with both hands, but one was busy taking the picture.


The block could be a more pointy triangle than that. Sort of coincidence that the angle of it lays nicely on the back in that shot. On the top and the other side of the back, it only rides on the peak of the guide block, very close to the edge of the guitar.