MIMF

Setting up to machine the neck tenon on this build, I realized that the blank has developed a #$%*&@!! twist. Grrrr.....

This kiln-dried stock has been "acclimating" in my shop for about a year, so it must be some internal tension that has been released in milling.

Anyway, looking at the pictures below, how serious is this? Hard to measure how much of a twist there is at the nut, but my high school trig says it should be about 0.037", or a bit more than 1/32". If I had more stock to work with, I'd throw this in the trash and start over, but I'll probably need to head out to a distant mill and spend at least another $50 to do so at this point. Maybe there's some way to salvage this that I haven't thought of.

Thanks.

If it’s thick enough, you can hope it’s done all the moving it’s going to do and plane it flat.

I had what I thought was a perfect piece of mahogany. The plank came from the middle of a 12x3 board where the planks on either side made perfect necks. This one was reaction wood. When I cut with the bandsaw down from the peghead to the nut width, I heard a loud crack opening a 3/8” wide at the end 9” split along the length of the neck. It took all my grip strength to close it. I went and picked out another piece of wood. I haven’t been able to figure how all that tension was in that one piece of wood but undetectable anywhere ealse in that large board.

I try to buy my necks as 12/4 flatsawn boards. When I cut out the planks and blocks, I get quartersawn. If I feel wary about a neck piece, it doesn’t become part of a guitar.

Thanks, Bob. I was thinking that might be an option. I'll have to plane the headstock also to keep the line of the break square to the center line. That might be a challenge with the glue line at the headstock.

My last build used a perfectly flat-sawn piece of maple. This build it's all quarter sawn (including the body) so I'm surprised that it twisted.

The most extreme cases of the kind of reaction wood you describe I've had with white oak which is notoriously slow-drying. If the mill rushes it by cranking up the kiln, it "case hardens" where the outer surfaces contract more than wood in the core. Terrible to work with.

This is why I try to sneak up on necks. I mill them to 1/16" oversize at least, usually more like 1/8th", and let them set for days or weeks. The only thing I can think of is to re-mill it.

Guys - thanks for the thoughts.

Bob - I think your point re "If I feel wary about a neck piece, it doesn’t become part of a guitar" is a good one. As you can tell from the picture, my ability to re-mill the neck shaft is pretty limited. I've already cut off the heel stack once (I glued it on aligned with the wrong reference line - Grrrr...) I could hand-plane, but getting both the shaft and headstock right would be a challenge. But will this piece cause problems down the road? It might.

So I bit the bullet and made the trip out to the closest mill to me, and grabbed a new hunk of 4/4 sapele. As with your experience with the reaction wood, I've been cutting these blanks out of the same piece of 8/4 that I used for the body. Liberating a thin 5/8" piece out of a plank that thick might provide more opportunities for movement from stress-relief. Also, the growth rings in the problem piece were running at an angle of about 17* to the face; The new piece I just brought home has growth rings running about 3.5* to the face, so hopefully it will be better behaved. It will only take me a day's work to get back to where I'm at now with this neck, but the hard part is going to be waiting for this stock to acclimate. The mill stores this stuff in unheated buildings, so I'm going to let it acclimate in the shop for a week, then I'll cut the shaft from the plank and skip-plane, and let it sit for another week, following Brian's "sneak up on it" advice. I'll then check for any deformation, then mill it to 3/4", and let it sit for another week. If it's still good, I'll mill it to the final thickness and proceed from there.

I wouldn't be so anxious, but I started this build a year ago. A big furniture project jumped the line, and I'm just getting back to this build. It's gonna be hard to sit on my hands, so maybe I'll start doing some design work on build #3 which will be a solid-body bass.

Thanks again...

I definitely look for what I call 90 degree grain - either quarter sawn or flatsawn I think is OK, rift-sawn I shy away from. I often do what the books suggest, get a 4/4 flatsaw board, dress it, get three equal pieces that end up as a quartersawn three piece glue-up. Have fun finding wood for a bass neck - that's what I'm doing right now, I have a real nice piece of 8/4 by 5" flatsawn cherry that I am going to resaw into two "Fender" neck blanks. BTW, I think that adding a fretboard adds significantly to the twist resistance long term, but you do need to start out straight.

Pardon my ignorance, but could somebody please explain to me why a minor twist such as in the OP would be so detrimental (assuming it's stable). I'd think that the variation in the action could be compensated by saddle height, and I'd think you would have to be a pretty good player (a lot better than me) to detect it while playing. Just askin'.

Depending on exactly where the unevenness is along the neck and on relative strength on the neck along the two sides, it may be hard to get the relief right under each of the strings. If it could be made flat along each of the string paths along the fingerboard, your solution is perfect. But, why build in a potential problem?

Bob Gramann wrote:Depending on exactly where the unevenness is along the neck and on relative strength on the neck along the two sides, it may be hard to get the relief right under each of the strings. If it could be made flat along each of the string paths along the fingerboard, your solution is perfect. But, why build in a potential problem?

That thought process is what made me decide to make the partially-finished neck a "teaching prop" and "test bed" and to start over. I don't know whether gluing on the heel stack did it, but using winding sticks it appears that the twist begins just above the heel stack. It's flat up to that point. So I was thinking if I plane this flat, it would be flat....relative to what? Cutting the tenon relative to the newly-flattened top would probably work out ok, but now the plane of the headstock and the plane of the neck shaft are no longer in the same relationship; correcting the face of the headstock by planing would result in uneven width across the headstock. Enough to make a difference? Enough to have some some effect under string tension? I have no idea, but I'm gonna play this one safe. This build has had it's moments, but so far, everything is coming out really nice, and it makes me all nervous and sweaty to knowingly leave something in the build that has the potential to come back and bite me inna butt down the road.

Brian Evans wrote:I definitely look for what I call 90 degree grain - either quarter sawn or flatsawn I think is OK, rift-sawn I shy away from. I often do what the books suggest, get a 4/4 flatsaw board, dress it, get three equal pieces that end up as a quartersawn three piece glue-up. Have fun finding wood for a bass neck - that's what I'm doing right now, I have a real nice piece of 8/4 by 5" flatsawn cherry that I am going to resaw into two "Fender" neck blanks. BTW, I think that adding a fretboard adds significantly to the twist resistance long term, but you do need to start out straight.

Technically, lumber is classified in 30* increments. Grain at up to 30* relative to the face is quarter-sawn, between 30* and 60* is rift, and 60* to 90* is flat-sawn. This might be fine for furniture, where all the pieces are rigidly glued into an assembly that resist movement, but guitar necks, sticking out into space with nothing external to resist movement have got to be much more sensitive to growth ring orientation.

"it appears that the twist begins just above the heel stack. It's flat up to that point. So I was thinking if I plane this flat, it would be flat....relative to what?"

If you plane the heel area, then it would be flat relative to the rest of the neck and head.

"now the plane of the headstock and the plane of the neck shaft are no longer in the same relationship"

I don't think so; you would simply be making the heel area plane in relationship to the head and neck. (Unless I am misunderstanding what you are saying.)

"correcting the face of the headstock by planing would result in uneven width across the headstock."

Assuming I am understanding what you mean, you wouldn't need to "correct" the face of the headstock, and, even so, it would result in uneven _thickness_, not _width_ across the head.

But, having said all that, if you fear the neck blank will give you future problems then finding another piece of timber would be best.

I think I may have confused things when I said "above" Bill. Sorry.

What I was trying to say was the twist is between the body and the nut, so the planing would have to be done most agressively close to the nut on the treble string side, so the break between the shaft and headstock would no longer be perpindicular to the centerline, and the headstock would need to be planed to compensate.

Very simply, Steve, if I'm not happy with a piece of wood I don't use it. I've got lots of places to use a piece of mahogany or maple or whatever it is - braces, blocks, firewood... - I don't want to loose any sleep over it. Consider saving it for a screw on neck guitar where you can easily replace it if it gets funky.

Another use is to cut it into 1-3/4 wide strips and use it as a laminate center strip in an electric body. Bindings, etc.
There's lots of uses for it, but I hear you about having to travel 50 miles to select another piece.

Sorry I misunderstood, Steve. It being as you have described, I concur with others who advise finding another use for the wood and getting a new, straight piece for your neck.

Maybe it is useful to plane that neck and leave it for a future build if it remains stable?

Beate Ritzert wrote:Maybe it is useful to plane that neck and leave it for a future build if it remains stable?

Being only my second build, and a "first" for many peocesses, this neck will get used to try my hand at many of them before doing the same on the neck that will be actually be put into use.