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Greetings OLFers,

I know this is not a new subject, but I would like to hear from those of you that do a mortise and tenon neck joint, what jig or process you use to cut the neck angle and the m and t.
I have been using the J. Simpson plywood jig with marginal results, and am looking for alternatives. My jig is based on the Woolsen plan. I don't know if it's just not stable enough for the weight of my router, but I always seem to get one corner of the mating surface of the heel that cuts deeper and I'm having loads of difficulty getting a good neck fit (it does do a good job of setting the neck angle)

I'd love to see how others are doing it. ( Can not afford $800 for the Luthier Tool version.)

Thanks, Beth

Beth I just finished my first Uke and I dovetailed the neck into the body. Lots of work. I'm starting another here in a day or two and will be bolting the neck on. I just received a commission for my first guitar build. It will be a L2 Martin clone that I have to modify into a tenor guitar. Again no more dovetailing for me. Just bolt on.


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Beth,

FWIW, I have never had that particular problem. I'd take a straight edge to the jig and see how it lays out. Put the router on it and see if it bends anywhere.

Furthermore...

I've abandoned both the dovetail and the m&t joint. Neither have any real valid purpose to me anymore.

In my 17 years at Larrivee I fit I don't even know how many thousands of dovetails. Tens of at least. So I did the same in my own shop.

Then in my own shop I switched to double m&t bolt on necks, but I found that they slipped quite quickly and needed resets within a month or two. Which is fine, as it is so easy to do, except that the average customer is unaware of the mechanics and struggles to play a guitar with .140 action that has slowly crept there so they don't see a sudden change and don't know that their expensive guitar has gradually turned into a POS. And if they live in Florida, it's not like they can just drop by for an adjustment.

So then I started going a bit backwards and returned to glueing the FB extension down for the shear strength.

Then I asked myself, 'What function does the mortise and tenon serve?'

Well, with a dovetail joint it's obvious. A mortise and tenon is mandatory, that is how a dovetail works as a fastener. You can't have a dovetail without an innie and an outie. Granted.

So, when you move to bolts...

What function does the mortise and tenon serve if it is not a dovetail, making it mandatory?

With mechanical fasteners, there is no need for either the mortise or the tenon.

I'm getting a bit long winded here, sorry.

I suggest giving it a bit of a think.

I now use a bolt on butt joint. If you're going to go mechanical, that is the most logical path in my eyes. There is definitely enough strength with threaded inserts to hold the joint fast. There is no need to embed barrel nuts in a tenon.

Anyway, think on it. There's a simpler method at your disposal if you're going mechanical...

Oh, and to answer your question more pointedly...

All I did was switch my stew mac dovetail templates to stew Mac m&t templates. My jig was based off the stew mac plans that they have posted.

Do you have a table saw with a good fence? If so use the Cumpiano method, no jigs needed provided you build the mortise in the head bock, dead accurate

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MK5acoustics.com

For cutaway guitars, it allows the use of low-profile heel shapes so you can keep your thumb on the back of the neck in higher positions. A 12 fret cutaway with low profile heel offers as much reach as a 14 fret cutaway with fat heel. Of course, 14 with low profile is better still...

Without the cutaway, your hand hits the body before your thumb hits the heel, so it's not really an issue.

I will be building my very first bolt on on this baritone Ukelele. So I'm going to need some expert advice. Also I have that Tenor guitar commission coming up as soon as I finish the Uke. So I'll want to be able to do a professional looking job on it. Going to go slow and ask help
before I venture into to deep of water.


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I'm leary of bolt on constructions because I've seen them work loose for no obvious reason. If I have the guitar in the shop it's no problem but in the hands of a customer it causes panic. I've started liking dovetail construction simply because I found it to be more secure, like less joint flexing. It's more work to fit for sure but as long as you know what you're doing they work well. As long as the customer doesn't leave it in a hot car they generally hold together fine.

I think the neck bolt working loose has to do with wood contraction over time, so that becomes really iffy especially if the customer is on the other side of the world. I am concerned about too little wood remaining in a butt jointed guitar that the heel could fail prematurely, and also threaded inserts could fail too. Barrel nuts aren't perfect but it has a more secure bond than threaded inserts. Wood failure isn't an issue with dovetails because the entire length of the heel is supported by the dovetail, whereas with threaded inserts it's only supported by the wood between the threads in the insert. I've smashed butt jointed guitars before... the inserts blew out easily.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

I cut the mortise with my table saw into a long blank of mahogany. When I need a new block I just cut one to length and carefully glue it in place. Once the binding is complete I simply cut away the sides where they extend over the mortise. Simple, easy, quick.

_________________
Doug

Don't let fear or common sense stop you from trying to build something

Thanks all! Meddlin', your choice of butt joint is one I am considering. I made my first guitar that way in 2009 and it is still rock solid. I do all my ukes this way. I have experienced some difficulty matching up the neck block bolt holes with the insert holes no matter how careful I am about placing the inserts and drilling the neck bolt holes. As a result, I sometimes have had to increase the size of the neck bolt holes to match and then the washers don't fit properly in the counterbore ledge (because now the hole is not necessarily centered in the counterbore anymore.
When you use the butt joint, do you just figure out the neck angle using a sliding bevel against the body and then reverse it to draw the angle on the neck or do you use a jig?

Wes, I have a craptastic table saw that I use for as few things as possible and wouldn't use on a neck blank, but great idea, thanks.

Dennis, good point about the diff between cutaway and non. I am finishing the neck on a cutaway right now and am carving a low profile heel for it. It still seems like it would be functional as a butt joint because I think the inserts would fit into the depth at the apex, and the neck mating surface is wide enough to give support, I think. I did do the M/T on this one though, and a really low profile neck probably wouldn't allow for enough depth to properly use the inserts. Thanks for that.

Doug, if I had a better table saw I might do that too, though the one pre-mortised block I used ended up being just a bit off square to the rims and so the pre-carved neck didn't sit right and needed some tweaking…seems like you better be darn sure you've got the block straight if pre-mortising.

I flood the area around the inserts with CA. They prove impossible to remove and re use. Unless you wanted to chip the neck off around it and use CA solvent which doesn't seem like a good trade for a bucks worth of insert. I've tried.

What I mean is, (I know this is not proper for a guitar) how easily the neck detached from the body when smashed against the wall or other hard objects. Perhaps it is of little consequence since no one would ever do that to their guitar, but on a dovetail neck you'll destroy the body before you can do anything to the neck joint itself. However once the inserts rip out of the neck heel, there is very little that can be done to reattach it. I suspect the quality of the inserts matter too... on that note the LMI set for bolt on neck costs too much, and while McMaster Carr sells the same set of hardware for about a dollar for the set of hardware needed (2 brass inserts, 2 bevelle washers, and 2 bolts) McMaster Carr won't ship outside of the US, so I was forced to use inferior hardware available locally.

Dovetail on the other hand is free and effective.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

This is what I've learned to do too…no failures yet

Basically, my OP was about how to get the neck to fit better. I think that the recommendation to figure out where the apparent instability is in my jig that is causing the poor leveling of the initial rout is going to be key if I keep using the Simpson jig. The M/T issue is really a separate issue for me, because the problem is actually arising with the initial rout which is to set the neck angle on the neck block (which then, if doing M/T, subsequently gets the tenon routed after, leaving the same, non-level surface, which in turn requires an unacceptable amount of adjustment to get a good fit neck to body (cosmetically).
This step still needs to be done whether I use M/T, Dovetail or Butt joint and I should have asked the question in a better way.
So maybe I should ask…without regard to how you fasten the neck on, what jig or process do you use to create the neck angle on the heel block (I know some use a technique that shims the body so the rims are perpendicular with the table, and do the math so there's no neck angle, but that's not how I want to do it).

Hmmm...

So many words. Here's some pictures of the process I use.

back and forth angle is set using the edge sander and miter guage, using the actual FB, bridge, and a straight edge.

Side to side is set after back and forth. I use shims of 100 grit facedown so they don't slide around. Tilt right, sandpaper towards neck. Tilt righ sandpaper towards heel.

Centerline jig references the truss rod slot.



1/4" holes through the body are enlarged to 9/32" for a bit of wiggle room.

Chuck a pencil in your drill and push it through your drill bit holder to make it round.



Place neck where it will be using the centerline jig, making sure it's where it will be, as in make sure the neck surface is flush to the top. This pic again...

Hold neck in place and push your 'Super Mod High Tech Artisan Hand Crafted Luthiers Pencil' through the neck block from inside.

Twist the pencil in a circle a few times to mark on the neck where the inserts need to be. Drill accordingly.

There are certainly some drawbacks to threaded inserts, the foremost being that they can have a tendency to slip sideways as they go in, pushing your neck out of alignment sideways. The solve for this is to drill a hole in scrap wood just large enough for them to fit in, then clamp the crap wood over the hole and thread them in. This prevents sideways motion.

Anyway, a butt joint is no easier or harder than any other method, it just has it's own particular caveats. In fact (well ok, IMO) the dovetail is the easiest and fastest which is how it found predominance in a mass production environment. Sure, a pair of bolts and inserts only costs two bucks, but if you make 100,000 guitars a year, well, it adds up...

Also, though I've never had to put it to the test yet, I believe to reset the neck with a butt joint, all you'd need to do is remove the bolts, slip in some sandpaper, and floss, without even needing to worry about side to side action....

Ah, you posted while I was typing...

With any neck joint, the angling happens in the heel portion of the neck. I mean to say that the neck block in the guitar can be a little this way or a little that way, both left to right and back and forth. The angle for the neck, both left to right and back and forth, is correspondingly placed into the neck heel area which you would place your inserts or cut a dovetail. Not sure how to describe that better...

Also, you need to assure that the body surface where the neck will rest is flat and square...

Though of course that area can in fact be round butt he principle is the same...

Meddling fool you said that your bolt on's come loose and slip around? This something I wouldn't want to happen. I see you used a dowel type thingy as well as the bolt thru. How does that slip around? Does your bolt loosen? Would locktite prevent that? Just not wanting to do more dovetails. I have an old Mandolin I made in 1990 used a dovetail it fit so tight I didn't bother to glue it. Of course the fretboard is glued to the top but it's still on there hasn't moved at all.


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Only the bolt ons that used bolts for the tongue as well. So I stopped using it, because the shear strength of a glued FB extension prevents forward motion.

Not sure why you see dowels, there aren't any in my necks anywhere...

Perhaps you're thinking of the pencil?

I use a bolt m&t. I use the tenon to shim for center line then set the neck after the FB is on like you would in a re set situation.

I use one I built from Robbie O'Briens plans that works great and gives me a dead on accurate neck angle. You rout the body mortise then the Neck heel (you can make a M&T or DT joint). Similar to the Simpson but I thought it was more accurate looking so went with it.

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"I've been had again"
Tim Benware
Creedmoor, NC

Thanks so much for the picture tut, Meddling….very nice and I can adopt some of those processes easily.
Thanks for the input uvsam and Tim.
Tim, that's a beautiful painting on that spruce top (looks like Adi)…did you do it?

Meddling I do see something sticking out of that bottom hole. So that's a pencil? So you use two bolts. They shouldn't move around.


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I do not know if Brune still uses this method that he demonstrated, but I will explain as best I can. He had a belt sander for which the entire guitar body fit inside, and the back of the belt was supported by the area to which the neck would attach. The neck was sanded to exactly fit the body in a few seconds. The neck was then attached with a glued spline. At least that is what I understood. If I were doing this, I would use a chunk shaped like the contact surface to the upper bought for the belt backing.

I cut the mortise on my table saw prior to installing the heel block, sometimes a router table, straight forward no jigs required. Here are a few pictures of my tenon jig. I establish the neck angle using an appropriate shim at the bridge location and an adjust bevel gauge to pick up the angle and transfer that to jig.

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Jim Watts
http://jameswattsguitars.com

Thank you. It's an Adi top and a scene of Adirondack Spruce trees. I had my brother-in-law put it on for me, he is a professional artist and uses ink and watercolor for his drawings (aksdalart.com)

_________________
"I've been had again"
Tim Benware
Creedmoor, NC