Joining soundboard to angled neck (Full Version)

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JasonM -> Joining soundboard to angled neck (Dec. 7 2018 1:43:26)

I thought I remember reading here that some of you guys who use a neck angle of ~2mm don’t bother to compensate for this when cutting the rebate in the neck for the soundboard. Do you guys just plane the underside of the board or do you compensate?

My Luthier mentor suggested I compensate for the angle of the neck when making the rebate. In fact, he thinks I should not even use a neck angle and go with a straight neck since this is how he learned to build. But I tell him this is what we flamenco guitarist need for a proper setup. (I think) you would have to ramp the fretboard so much the frets wouldn’t seat properly right?

I saw an old post from Stephen Eden here shimming up his neck with a ruler to cut an angled rebate on the the router table. So I thought I’d do the same. Here is a picture of what I mean along with all the math I did to set it up for a 2.5mm forward angle:
https://www.instagram.com/p/BrEaJjpl1j8/?utm_source=ig_share_sheet&igshid=1oekz7mlw36jh

Havnt made the cut though.




RobF -> RE: Joining soundboard to angled neck (Dec. 7 2018 2:58:01)

Here is a simple jig for a router table, no math required :)

The white shim taped to the heel end is the same thickness as the rise...





Images are resized automatically to a maximum width of 800px




JasonM -> RE: Joining soundboard to angled neck (Dec. 7 2018 3:35:30)

Well That is just too easy, Rob [:D]. at least I buffed up my math skills for the next time I need to over engineer something. Guess I saw the ruler shim that SEden used and it stuck in my head.




Ricardo -> RE: Joining soundboard to angled neck (Dec. 9 2018 16:03:55)

The Conde secret? Trigonometry




constructordeguitarras -> RE: Joining soundboard to angled neck (Dec. 11 2018 19:01:01)

quote:

I thought I remember reading here that some of you guys who use a neck angle of ~2mm don’t bother to compensate for this when cutting the rebate in the neck for the soundboard. Do you guys just plane the underside of the board or do you compensate?


The neck/soundboard assembly is so flexible that it is not necessary to angle the rebate in the neck that accepts the soundboard. After joining the two (and attaching the tail block, sides and back lining), I clamp the assembly on my solera, which has a ramp for the desired neck angle, and attach the back, which makes the angle between the neck and the soundboard permanent. It may be relevant that I don't glue the ends of the sides into the slots in the neck; they are just inserted.




JasonM -> RE: Joining soundboard to angled neck (Dec. 11 2018 20:16:15)

Thanks for the info Ethan! I just made a jog like the picture Rob posted to add a ramped rebate. Mind as well give it a test.




constructordeguitarras -> RE: Joining soundboard to angled neck (Dec. 12 2018 0:30:48)

You're welcome, Jason.

Looking at your photo, it seems to me that the angle will come out the wrong way around with that jig. I think you want a deeper cut close to the 12th fret line, and less deep on the part of the shelf further from the 12th fret. You want less than 180 degrees (not more) between the soundboard and the neck, right?

SEE BELOW. I WAS MISTAKEN. THE JIG IS FINE.




RobF -> RE: Joining soundboard to angled neck (Dec. 12 2018 1:01:30)

Hi Ethan, I’m not sure if you’re referring to my jig or Jason’s ‘ruler jig’ drawings, but for sure my method will cut deeper at the 12th and less deep further away. I was actually taught the ruler trick in Spain but couldn’t remember how it was done so I just started doing it my own way (like Sinatra, lol).

I’ve seen some people use the ruler trick where the ruler is taped to the router table and the relationship between the ruler and router bit is fixed. To my figuring, depending on how the neck is moved, doing it that way will either result in a flat ramp or a backwards and cupped ramp. (Edit - that should read ‘either a flat, backwards, or cupped ramp’)

But, as you say, the angle is so slight and length of the ramp so short that when coupled with the flexibility of the top this is probably a pretty non-critical operation.




constructordeguitarras -> RE: Joining soundboard to angled neck (Dec. 12 2018 1:06:10)

Hi Rob.

I just realized that I was wrong. The jig is fine.




JasonM -> RE: Joining soundboard to angled neck (Dec. 12 2018 1:11:43)

Edit: I see we posted all once!

Rob, that’s what I didn’t like about the ruler taped to the router table. Actually, I don’t see why it’s done that way because the closer the nut end gets to the ruler the steeper the angle. That’s why I did the math to figure out where to place it along the neck and move both together. But like you said it’s so slight...

Ethan, yes I know what you mean




constructordeguitarras -> RE: Joining soundboard to angled neck (Dec. 12 2018 1:12:54)

Right. Sorry, these things confuse me sometimes.




constructordeguitarras -> RE: Joining soundboard to angled neck (Dec. 12 2018 22:19:09)

Something else in this vein: Have you guys noticed that if you rout the shelf so the soundboard fits exactly flush with the neck where the fingerboard will go, when you glue it the glue swells the wood a bit so the SB ends up a little proud? I try to compensate for this by routing a little deeper, but the amount seems to depend on the particular SB or the amount of glue or the phase of the Moon.




RobF -> RE: Joining soundboard to angled neck (Dec. 13 2018 0:42:57)

I’ve noticed that.

In my case, I attributed it more to telegraphing due to excessive clamping pressure rather than glue swell, although I’m sure the glue also has an influence. I had thought my clamping pressure was OK, light actually - one Klemmsia clamp with the cam approaching straight up (parallel to the slide bar) - but it seemed even that was too much, so now I just gently raise the cam until I feel everything is sitting secure and stop.

Even with that I still have to do some fitting...




RobF -> RE: Joining soundboard to angled neck (Dec. 14 2018 15:36:15)

I spent a few hours last night going over old posts in the Luthier section trying to find the ruler trick, just to see if I could somehow remember the setup I had been shown (and then promptly forgot).

I found Stephen Eden’s build pictorials and I’ve got to say they’re top notch, with huge amounts of great information, good pictures, and helpful shots of his techniques. Impressive. Anders, Ethan, Andy, Bananaman and so many others have also posted tons of good stuff. We’re pretty lucky, a lot to be grateful for here...




JasonM -> RE: Joining soundboard to angled neck (Dec. 15 2018 1:46:46)

My neck is now joined to the soundboard! Turned out very well thank you Rob and Ethan. Next time I think I’ll cover the side slots to keep squeeze out glue from running down into the slots. Had a good time chiseling that out.

So much amazing advice and info on the archives here. I’m always digging through them. Another thing I picked up in that thread by SEden was how he used his radiused dish as a caul for gluing the back. The only thing I don’t like about this idea is the dish overhanging along the perimeter making it harder to see what’s going on. But could always cut One to shape.




SEden -> RE: Joining soundboard to angled neck (Dec. 17 2018 10:47:34)

Hey Jason,

Glad to hear that went well. I think the angle I put in to the rebate is an approximate. I figure the neck angle is about 1.5 from the 12th down to the nut. The router table edge is about 2/3 of the that length, so by raising it up by 1mm should give the angle I am after.

The radius dish only works if you use the dish to shape the sides. This doesn't work with a tradition style of back fitting. You can always look under the dish to see what is going on. You have to make sure the back fits well before gluing in any case and with this method you also have to make sure that it doesn't have any wiggle room or the back could be pulled out of alignment. Hope that helps.




JasonM -> RE: Joining soundboard to angled neck (Dec. 17 2018 14:42:44)

Hey Stephen! Thanks for the advice. I sort of realized after cutting the rebate that an estimate is probably ok given that the top flexes and the angle to less than 1 degree. But I was kinda of worried about going to far.

I’m using a 25’ dish for the back. Good to know- If it fits well maybe I’ll give this a go. Otherwise I plan on making a caul with the rubber tube along the perimeter.




David LaPlante -> RE: Joining soundboard to angled neck (Jun. 28 2019 16:53:38)

I do angle the top face of the neck block/foot to accomodate the 1.5mm "lift" of the neck.
Since I'm using the Romanillos double wedge system, the actual width is only about 15 mm
not counting the central spine. A small plane and rasp file are used. I use a razor saw to cut a very small notch at the back of the neck shaft to allow the use of the finger plane.




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