tail and neck block

mjgreenwood

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I'm working on my 2nd body and was curious about neck and tail blocks, concerning grain direction and glue area.

From other threads I gather that I should only glue the blocks with a similar width of the kerfing. That being said should I set a marking gauge and then taper the blocks back slightly from that kerf line? I think that makes sense and would save some rasius sanding? Right or wrong?

Also grain direction was brought up in an earlier thread. My guess was that the grain of the block should be aligned with the grain of the top. This correct?

My first body I radius sanded them but glues the entire face of the blocks to the
To the back and top......
 
I'm sure its been done every way I can imagine............

My tail block goes in perpendicular to the sides such that the end grain touches the top and back.

I bevel the edges with a block plane so that the end grain edge is only as wide as the intended linings.

My neck block is integral with the neck as I do a spanish heel.
 
I use a quality plywood for my tail blocks and in the case of high end instruments I will veneer them with the body material. I may be the only one that ever sees them, but at least I know it's done that way.

Neck is a spanish heel so it's made integral to the neck from Spanish Cedar.

Tail Block 446.jpg
 
I'm sure its been done every way I can imagine..
Right, and there doesn't seem to be a problem with it which ever way.
I make my grain run with the sides, long grain against the top and back.
The argument against end grain touching the top and back says the expansion of the block will show on the thin top wood. I've done it both ways, and I've seen the end block telegraph to the top both ways.
Just use good stable wood for blocks, and don't sweat the direction of grain.
 
I see an advantage in having the blocks of solid wood, with the grain direction the same as the sides; it's easier to shape them together with the sides with a hand plane.

Now I know not everyone uses hand planes as much as I do, but I like them (and collect them, and buy more of them without telling my wife).
 
I see that some of you don't have much repair experience...as in a blow to the butt of the guitar cracking the end block and that crack traveling right around the sides because the grain of the end block is in the same direction as the grain of the sides... I've fixed too many guitars with that crack running right around the body...

I'm with Allen, but I don't hide the 1/2" Baltic birch ply which is 8 ply with no voids. It's great stuff, and you'll build stronger instruments at no penalty if you use it.
 
Ply end block is the only way to go. Period. Especially with a 1/2" hole drilled through it for a pickup jack.

I'll like and will absorb Allen's method of veneering it with the body material. Sexy stuff
 
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Rick, I've only done minor repair on acoustics. I did more electronics work and some setup when I was younger and worked in a shop. Never had to repair split sides. We avoided that and had a couple of real luthiers on call.

I'll try the ply on my #3. Dare I ask about your neck blocks? I've just received my new router gear so ill see how my first two neck joints work out. (I've only done a few resets so huge lack of experiance there).

Thanks for the input
 
Neck block the same as the tail block. 1/2" Baltic birch ply. Strong and light weight. Same as on the acoustic guitars I build.
 
I have always used cedar scraps, with the grain vertical, but I intend to use Baltic birch scraps from this point forward. The arguments in their favor make great sense. Those Spanish cedar blocks with mahogany glued in slots look cunning but also look to be a lot of work.
 
Neck block the same as the tail block. 1/2" Baltic birch ply. Strong and light weight. Same as on the acoustic guitars I build.

I wouldn't have thought a 1/2" (12mm) head block would have given enough support for a uke, and especially a guitar, due to the pivoting action over time. Or do you laminate the ply to a thicker dimension?

Do you saturate the ply's end grain with glue prior to glueing to stop the possibility of a starved joint???
 
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Those Spanish cedar blocks with mahogany glued in slots look cunning but also look to be a lot of work.

I like that, "cunning". I call them "hidden details", and I cut the slots quickly on my drill press set up as a mill, with a cross-slide vise. Poor man's cnc machine.

drill%20bridge.JPG


cross%20slide%20vise%20b.jpg
 
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David- i've been looking at those X/Y milling vices- I was previously spoilt in with access to a $15000 milling machine with digital readout.
Does your Shopfox vice have much play in it??? You recommend it?

cheers
 
1/2" is absolutely adequate for ukes, and on guitars I do a set of flying buttress braces (CF tubing) that transfer the pressure to the sides and back. Works great and allows for the cantilevered fingerboard and hardly any upper bout bracing. The top isn't carrying the neck load.
 
Be aware that there is a potential hazard when putting side loads on a drill press chuck, such as when milling as David's photo shows. The Morse taper arbors that most drill presses have to hold the chuck in place are not supposed to be used with a side load, except those that are held up in the spindle with a draw bar. I've seen draw bar arrangements on metal working mills but never on a drill press, though some may be set up this way for all I know. If the arbor loosens, which can happen due to the vibration induced by milling, the chuck will fly off. My guess is that anyone doing wood routing in this way is going to be using a high speed, so you'd want to duck if it happens. If only you could duck fast enough....but you can't.

This isn't a Chicken Little theory. It has happened to me. Fortunately, the chuck went the other way and the only damage was a trashed bit.
 
Salty, thanks for the caution. My chuck has an allen bolt into the taper, so I can snug it up from time to time. I put very little side load on the machine as it is, cutting saddle slots in bridges, cutting those mortices in end blocks, and such. Slow and steady, as the rpm's are not "router-fast" only about 3200.

Beau, the sliding vise is a Shop Fox from Grizzley and is only one of the two that I've seen available, the other is a cheaper one.
I like it and use it, and recommend it with a warning that it is not "machinist grade". The ways have adjustments, but "it is what it is" so don't expect too much.
 
That allen bolt may help. But it's a double problem. The arbor also has a Morse taper into the spindle. Bad stuff usually doesn't happen and is even less likely to happen if care is taken. In this case, every so often you can run the jaws fully up into the chuck and, holding a block of hardwood against the end of the chuck, tap upwards with a hammer to make sure that both tapers are seated.

Or put some water into both tapers so they rust together for all time. :)
 
A 1/2" thick head block may good enough if you're doing a bolt on neck, but for a tapered dovetail like a Martin style, it ain't going to cut it IMO.
 
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