Why don't more builders do 2-piece necks since they're more stable?

lightningsmith

Silver Supporting Member
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999
I may be naive since I'm not a builder but the process seems straightforward and even converts flatsawn wood to quartersawn, somehow.

Any technical or tonal drawback to doing this?
 

Terry McInturff

40th Anniversary of guitar building!
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I may be naive since I'm not a builder but the process seems straightforward and even converts flatsawn wood to quartersawn, somehow.

Any technical or tonal drawback to doing this?
1) A two piece neck is not inherently more stable than a one piece, a three piece, etc.

The idea behind a two piece neck being that the tendency of one side to move in a direction is "cancelled" by the opposite piece wanting to move in the opposite direction. It's a valid idea and in practice can work, but each piece needs to have exactly the same properties and this is seldom the case.

What makes for a rock-stable neck is a huge topic! Having said that, one of the key elements resides in what sort of stored energy (stress) resides in the neck. There are two types: a) Intentional (good) and b. Unintentional (very bad).
A neck made of any number of elements can carry with it either "good" or "bad" stored energy.

2) Vertical grain and true quarter sawn wood are not the same thing. This is because flat sawn wood can be laid on edge, thus presenting vertical grain..but it is still flat sawn wood and will act as such. If vertical grain is desirable true quarter sawn wood reigns supreme.
 

lightningsmith

Silver Supporting Member
Messages
999
1) A two piece neck is not inherently more stable than a one piece, a three piece, etc.

The idea behind a two piece neck being that the tendency of one side to move in a direction is "cancelled" by the opposite piece wanting to move in the opposite direction. It's a valid idea and in practice can work, but each piece needs to have exactly the same properties and this is seldom the case.

What makes for a rock-stable neck is a huge topic! Having said that, one of the key elements resides in what sort of stored energy (stress) resides in the neck. There are two types: a) Intentional (good) and b. Unintentional (very bad).
A neck made of any number of elements can carry with it either "good" or "bad" stored energy.

2) Vertical grain and true quarter sawn wood are not the same thing. This is because flat sawn wood can be laid on edge, thus presenting vertical grain..but it is still flat sawn wood and will act as such. If vertical grain is desirable true quarter sawn wood reigns supreme.
Insightful stuff Terry, thanks. I'm curious, how do you make stored energy intentional or unintentional?
 

Terry McInturff

40th Anniversary of guitar building!
Platinum Supporting Member
Messages
7,046
Insightful stuff Terry, thanks. I'm curious, how do you make stored energy intentional or unintentional?
1) Unintentional stored energy= internal stress that has not been allowed to relieve itself during the course of the neck build. This will come from unrelieved stress that occurs naturally...to some degree..in virtually every piece of wood. The cure for this involves the neck recipe and the exacting nature of the build process....and of course the use of the proper materials. I think that Ive discussed this here in the past to greater length.
Unintentional stresses can be the result of certain rather traditional build schedules as well; to a large degree, the double-action truss rod designs are a result of this.
2) Intentional stored energy= just that; a focussed type of stress that is introduced at a specific stage in the neck build schedule.
I'm sorry to say that I cannot discuss this at this time publicly, as it is a part of the proprietary TCM neck design...but at some point in the future it may well be described in my book.
Thanks for asking!
 

Killed_by_Death

Senior Member
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Weren't TCM guitars featured on a game show at one time?
You're doing something correctly, I found this:

 

Terry McInturff

40th Anniversary of guitar building!
Platinum Supporting Member
Messages
7,046
Weren't TCM guitars featured on a game show at one time?
You're doing something correctly, I found this:

I haven't heard about a game show involvement, but who knows.
The closest thing that I do know, is that a criminal character in the crime drama series "The Fall" was named after me; the writer of the show, an Allen Cubitt, was apparently a fan of the guitars. The character "Terry McInturff" was a very unsavory murderer as I recall. There was also a character named "Paul Reed Smith"!
 

georgf

Member
Messages
10
well, there are a lot of 3P necks, where the middle piece usually has the wood grain in the opposite direction as the left and right pieces.

Maybe, if not making a 1P neck, luthiers skipped the 2P and go straight to a 3P construction.
 

PB Wilson

Member
Messages
830
It seems to me that tradition and extra steps (prepping pieces for gluing, matching wood grain) get in the way of many builders choosing to build with multiple-piece necks.

Seems that they are willing to pay the price for larger pieces of wood.

I have seen many acoustic guitar makers using separate pieces for the heel and the tilted-back headstock. Big chunks of Mahogany are pretty expensive these days.

I'd like to hear more about the difference between flatsawn wood laid on edge vs. true quartersawn in neck applications. I've milled a decent amount of wood and used flatsawn pieces on their edge and glued up into larger pieces and they've behaved like quartered pieces. They seem to expand and contract with the seasons in the same direction and maybe moved a little less than flatsawn pieces. When exposed to moisture, these vertically oriented glue ups didn't have a tendency to twist like larger flatsawn pieces. Granted, I didn't take a micrometer to them to measure or take notes over time, but in observations over the years I've noticed these trends.
 

jvin248

Member
Messages
5,974
.

Build necks from the same wood ... or get instability.
I also like maple fretboards because they get a finish that further retards humidity effects.



Be sure to research the Peavey guitar neck process of splitting a neck blank, flipping one side end for end to counteract stresses, machining the truss rod groove in each side of a neck blank that then gets glued together. They also used gun-stock duplicator machines as an early 'CNC'-type of neck carving technique. They had great neck stability due to this method.


 

lightningsmith

Silver Supporting Member
Messages
999
I posted another thread about plant-based composite materials and I wonder; if you glued a thin strip of stiff and stable material that sounds like Ebony without any of its issues in the middle of the neck between the two halved woods, would that make it more stable?
 

wraub

Member
Messages
300
[snip]

I have seen many acoustic guitar makers using separate pieces for the heel and the tilted-back headstock. Big chunks of Mahogany are pretty expensive these days.

[snip]
I've seen this on some inexpensive electric guitars, too. Might not be a good aesthetic choice, but seems structurally sound.
 




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