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I use the luthierstools neck tool. It's great.

Sometimes I end up with fretboard fall-way (hump after 14th fret). What variables go into eliminating (minimizing) this? I am looking for experienced responses on this. Not theories.

I want to achieve perfect neck angle and minimize fall-away. I did institute John Halls idea of not shaping the front bout (top). Its flat.

Thanks!

Mike

Draw out the side view of yer axe including the neck angle required to achieve your desired string height at bridge with that nice flat fret plane over the upper bout. Then you will see the precise shape the top edge of the sides need to be. Then, before top is glued on make your sides this shape by planing, sanding etc.

Avoid rules of thumb, approximations or someone else’s shortcut techniques which only work for certain designs. If you build multiples of the same design they are useful time-savers. Otherwise they can lead to much tail-chasing and gnashing of teeth.

Better to actually know the side geometry you need to achieve. No one on the internet can tell you this because we aren’t standing at the bench with you looking at your build. Keep in mind that you can dry fit your top to the rims and measure to check the geometry is correct before actually committing to glue. So there should be no surprises after assembly.

I came up with these "guides" a few years back when this question was asked. I probably didn't post it. This seems to help me visualize where things are going to end up . It's just a few sticks glued together to simulate the plane from the neck block to the front edge of the sound hole and with the straightedge on edge the lower bout where the front of the bridge ought to be, the edge should be about 0.100" above the "guide". The little brown square thing is 0.100" thick. I think the actual number with a top having a 25' radius is close to that. If you have the geometry sanded into the sides it will work, or it does for me.

More radius on the upper transverse brace and/or less radius on the X. Sanding some angle into the upper bout of the rim would probably work too, but I've never tried that personally due to my moldless construction style. You've already done the difficult part of building a guitar, so you might as well take the easy route forward and adjust from there instead of drawing up a new design from scratch and risking another failure.

I build integral necks which guarantees no hump, but you could adapt the same techniques to a removable neck: Use a headblock extension butted and glued to the upper transverse brace, and before you close the box, fit the neck so the fingerboard glue surface is coplanar with the upper bout. Then glue the back on with the neck attached, so you can crank it forward or backward to adjust the neck angle to get the right projection at the bridge. This flexes the sides while the super stiff headblock extension prevents the soundboard upper bout from flexing at all so any hump or dip will be past the end of the fretboard extension.

I level the fretboard after it gets installed, then I install the frets and make the bridge.

Entirely depends on your building style. I have totally figured this out and would be happy to share if you build the way I do which is the traditional method of building off the top with a work board.

But if you use a mold and radius dishes it's still similar. You need to bend or cant the top from the top of the soundhole to the neck body joint. I do this with a combination of canting the top and using an arched UTB.

After having these same problems you have one day I sat down with poster boards and drafted the whole thing out. It took me hours but it was so well worth it. Today when I am done with the finish on a guitar and it's ready to set up I can pretty much just make a saddle so that it is just over 1/8th in protruding out of the bridge and string the guitar up and it's near perfect an the neck is dead flat from nut to the last fret.

So that's my suggestion, sit down at a big drafting table with poster boards, straight edges and pencils and dedicate a day to figuring htis out based on your building method.

Many of us have our own methods of setting the neck angle and you will be offered many of these methods here.

I wanted to offer you something else Mike that is lacking in most small builder guitars and that is the notion and reality that the fret plane can and should be shaped and dialed in after the neck is installed at the correct angle.

The body hump that you cite can be and is eliminated if present if you shape your fretboard on the guitar with the neck installed. Fall-away can be milled in, etc. I am speaking of fretting the guitar with the neck installed. Much of the problems we see from small builders is they fret the board off the guitar, slap it on the guitar and call it good. It's not....

It's an opportunity to take that neck angle to the last step and get it perfect.

I have a tutorial here on neck angle and how I set it using the Martin method of flattening the upper bout. I think I called it "Flattening the upper bout." John and I use the same method and we got it from Martin.

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Ann Arbor Guitars

I have used this method on the last four guitars I made and every one came out great with very little fret levelling required. No hump and nice low action. Also check Hesh's method for shaping the nut and cutting the slots. Thanks again Hesh.

Hesh I couldn't find your toot. Do you have link?

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Flattening Upper Bout (Pics..)
https://r.tapatalk.com/shareLink/topic? ... source=app

Hope that link works.


Sent from my iPhone using Tapatalk Pro

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Sure thing David and Brad's link does work, here's another one: http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=25931&hilit=flattening

Thanks guys!

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Ann Arbor Guitars

Read the tutorial. Curious, wha the entire top radiused to 25 ft before then flattening? Can just the lower bout be radiused then the upper flattened?

Mike

Radius the rims first and then flatten just the top. Hesh mentioned in the article that he also radiused to 25' first. I use 30' radius and flattening goes super fast.

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Yep the entire top (of the rim only) was radiused to 25' and then only the upper bout has the radius flattened back out. This is all done with the rim and then my upper transverse brace is flat and glued on the top with a flat backing board. Smash and glue it all together and you have a flat upper bout, a much more predictable place for a neck and extension to land and a radiused lower bout.

I have not looked at the toot in over a decade but one other light bulb moment for me was when "driving the bus" or doing the rim in the radius dish do it first with no linings.... duuuuh and then glue the linings in place minimally proud and it's far easier. I did not do this the first ten or so and had to sand my way through lots of lining needlessly.

Now I always used 25' top radius and this toot and the numbers provided worked great for me. It could be done with any top radius likely but you will have to experiment with things such as the shim stick thickness, etc.

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Ann Arbor Guitars

This helped me.

https://obrienguitars.com/courses/perfect-neck-set