Official Luthiers Forum!

After completing two solid body electrics I’m in the process of making the the jump to my first acoustic and I have a few random questions…they’re kind of all over the place because I am trying to plan out each step before I attack it.

1) I’m planning on doing a mortise & tenon neck. I have seen some pictures/videos of the mortise already cut in the neck block before they glue it in - is that standard? I figured I would route the neck block mortise once it was glued in & the top & sides were on. Same thing for mortise screw holes - when are those drilled?

2) After I glue the back/top on, how do I flush cut the excess? Won’t the router bit dig into the sides since the back/top are domed?

3) So the neck is attached to the body yet a slight angle upwards to heighten the strings above the bridge & domed body…How does the fingerboard (the part that sits on the body) deal with that? if I just glue it down on the body wont that bend the fingerboard down?

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http://www.Harvestmoonguitars.com

Welcome

I suggest that you get your hands on a couple of acoustic guitar construction publications -- some are better than others, I am sure members will have their favorites. But to your post, I'd start by reading the following, the neck joint can seem like a real mystery if you are not schooled on the basics.

http://www.kennethmichaelguitars.com/neckangle.html

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Ken Cierp

http://www.kennethmichaelguitars.com/

1. Regarding if you cut the mortise before or after the neck block is in, either way is good. It depends on your tooling situation and your inclination. I cut mine first. You didn't ask but this link is excellent for you to read. I strongly recomment doing the bolt on neck like this:
https://www.cumpiano.com/an-improved-neck-body-joint

2.As John suggested, trim it close with a plane then use a flush cut bit on a router to flush it up. Be sure to take small bits. You don't want any chip outs.

3. Glad you mentioned neck angle. You have to carefully plan your guitar geometry every step along the way. What I do is start with straight edges on the tops of the sides. Then I carefully slope the sides from the neck side of the soundhole to the neck attachment area. I slope this down about 3/32" at the neck joint. (goes from zero at the front of the soundhole to 3/32" down at the neck.) I use a plane to cut this slope in. That gives me a basic geometry of my neck angle. Then I set the braced top on the sides and clamp them down and put a straight edge flat against this sloped section where the fingerboard will go and check the clearance from the bottom of the straight edge to the center of where the saddle will be. etc, etc. When you get all done the flat sloped area above the soundhole becomes the plane that the fingerboard sits on. No raises or drop offs. You will notice that the where the end of the neck mates with the body is not 90 degrees from the fingerboard., more like 88-89. But thats just how I do it.

Probably to much info at this time but the point is you have to keep an eye on the big picture all along the way.

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Joe Beaver
Maker of Sawdust

I would recommend a copy of this book.https://books.google.com/books/about/Guitarmaking_Tradition_and_Technology.html?id=aRg5oFhzgEMC
It will answer lots of the questions you will have.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I'm a fan of cutting the tenon after the neckblock is glued due to alignment issues. As long as you have visibly defined center lines and a clamping method that prevents the block from shifting once things are tightened down, it shouldn't be a problem, but I much prefer not having to deal with the fuss. I shift that burden to other parts of the process.

For a new builder, I recommend buying a pre-made neck with neck block cut. It is indeed ideal to be able to cut the tenon and slot after the build. But it also requires a bit of difficult-to-understand tooling (and it can be expensive). Focus on the body. There is plenty to learn there. I know of CNC carvers who will make a standard neck and block for under $200. Well worth it. Andy Birko comes to mind.

My first 4-5 guitars were done this way. Then, when I had a handle on the complex geometries involved, I moved up to doing the cut after. I will tell u I was quite amazed at the skill level required. And the tooling too!

Broken,
Actually you are asking good questions. That leads me to believe you you'll have no problem building a guitar. Mistakes yes, now and then, but none you can't recover from.

As far as buying machined parts or doing it yourself, it is a personal choice . Either way is fine.

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Joe Beaver
Maker of Sawdust

I thought the same thing. These are sophisticated things to think about before you've even started. You can clearly visualize and conceptualize what's going on with the instrument, and I think your first will be a success.

Hi Broken, (It would be nicer if I knew your name.)

Here's how I do it:

1) I am currently doing dovetails on my guitars, before that I was doing butt joint bolt ons but I was doing the bolt on with the tenon for some time.

I cut the mortice after the entire body (including binding) is done. I made a jig to hold the guitar and guide the router to cut the mortice.

I made a jig with hardened steel bushings to drill the holes in the block after it was glued to the body.

I cut the tenon for the neck on the table saw.

2) I use a router with a (sharp) flush cutting bit to trim the edges of the top and back to the sides.
I used to leave 3/16" or so extra, but as of late I am leaving little or nothing to trim-saves time and risk of chip-out. You have the tolerance of the binding thickness as a fudge factor.

3) Getting the neck angle correct is one of the most important parts of guitar making.
I use a flat top and angle the area from the bottom of the soundhole to the heel end of the guitar so that I have the bridge height I want.
In practice I use a plane then sand the angle by shimming the guitar at the bridge location an stroking it on a flat board to which I have glued 36 grit sandpaper to.
You can also make a jig and use a router to "ramp" the sides to the correct angle ala Charlie Hoffman.

I wouild also recommend the book Guitar making tradition and technology by Cumpiano and Natelson

I would also highly recommend Charlie Hoffman's website. He has a step by step outline of building a guitar with photos of each step.

Even after building over 100 instruments, I have a lot to learn-this forum is one of the best. There are others that are great also.

Best of luck.

Brad