Official Luthiers Forum!

Just a quick musing really.

I was thinking about the best ways to align neck blocks when gluing them to the sides (thinking about using pre mortised neck blocks you see).
If I were going to use a bolt on neck it seems to make sense to me to use those bolt holes in the block to line things up. I could drill out my molds for bolts, centering these holes exactly, then slot on my pre drilled and mortised neck block and crank down some nuts on the inside of the block. Both aligning and clamping the block while the glue dries.

Any potential problems anyone can spot? I think this may be a nice 2 birds with one stone solution...

I thought of that too! Lately I have been making a little spruce piece about .09 thick that fits tight in the mortise and I superglue that across the center line. That holds the neck block perfect side to side and gets routed out when you open up the pocket. I would have done the bolt holes, but there is always a slight bit of play and the patch is pretty tight. Probably combining the two is the way to go, the bolts would be a great clamp!

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Burton
http://www.legeytinstruments.com
Brookline, MA.

use tefton tape on the bolts to avoid glueing them in place

Well bolt holes are not the best method to control the block in all 3 axis. Bot hole are typically 1/32 over sized for 1/4" bolts so they are to small for 5/16 bolts and allow to much rotation because of the oversized hole wit 1/4" bolt.

When I build my rim my mold is pinned to a 24" x 20" sheet of 3/4" MDF this has a centerline scribed and a neck block guide blocks that fits the width of my neck block and maintains the block in vertical plane squareness to the center line and allows me to press via a turnbuckle as screw press, the block into the side material and thus both into the wall of the mold. This insures the block is both square to the centerline and the the side with zero though given to it. Once the blocks and sides are glued up I no longer use this piece of MDF.

Original design sketch



Besides you would have to cut some sort of bolt access in to the sides at the location of the bolt holes and this is on the center line of the joint prior to glue up so you would be providing a point for possible crack to start

By the way the two 3/8" threaded studs glued into the 3/4" MDF base and a slot in the block guides are to keep the guides flat to the base but just loos enough that the turn buckel will move the guides. The guides must be built good a square but that really easy to do.

Michael, I like your jig a lot! But I would reuse the platform by making it out of melamine clad particleboard instead of MDF, or by putting a small piece of waxed paper beneath each block during gluing.

Yep, I think I'm gonna use this idea. Thanks!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Lying in bed at night, next to my wife, guitars are NOT what I'm thinking about!

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

Yet another way to do this is to cut a centered mortise in the mold that has the same size as the one in the neck block, and use a piece of wood that fits tightly in them both as a temporary ‘tenon’ to align the two.

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Rian Gitar og Mandolin

I've kept it pretty simple. I have a centerline on my Fox mold and put the half template on it to set the posts so it really is in the center.
I mark the neck block based on the center of the mortise rather than the center of the block and just line it up with the centerline of the mold and clamp. It's worked fine for me. You do have to be a little careful that it does not shift from clamp pressure but that's not too hard.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Oh yeah, as long as we are talking about gluing end blocks don't forget the waxed paper!! I bet most of us have glued our rims to the mold at least once.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Dennis. When I said I no longer is the the MDF I meant after this process. I use the fixture to do the initial glue up of the rim on every guitar

Actually after the first dry run I figured that squeeze out would be an issue so I covered the MDF with a 2' x 2' sheet of .01" thick UHMF PS film. I forgot to mention this. The inside of my molds also have a .005" thick lining of this film. The film is really cheap at these thicknesses about $3.00 for a 2'x2' piece and wears well. I got mine through McMaster-Carr

One thing to keep in mind as I mentioned there are two thread studs with nuts and washers that are glued to the MDF (the studs) and a slot in the guide block the nuts and washer keep the block flat level and running square as you apply pressure. With out the studs and slots the guides cam wander and the bottom of the guide will want to kick up as the guide adds clamping force. I tighten the nuts just tight enough to hold the guide down but move with the force of the turnbuckle.

I have been thinking of replacing the turnbuckle with a push rod toggle clamp like #4 in this picture but just have no got around to it.

Todd -
You must have taken a great amount of notes when you were at my shop! As you mentioned I don't pre-cut my mortises any more but when I did I used a very simple way to align it perfectly. Remember Mario's mantra--keep it simple! If your mortise is 3/4" as mine is simply cut two 3/8" pieces of plywood and glue a .010" shim stock in between. Then the shim stock fits the joint of your mold and the now 3/4" piece fits your pre-cut 3/4" mortise perfectly aligning it with all planes. Here are a couple of photos of the real jig as Todd has drawn it....

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Sylvan
http://www.wellsguitars.com