Flat sawn wood?

Sawdust · Nov 6, 2019

Does everyone use quarter sawn wood for top, back and sides?

I have a good supply of wood but it is not quarter sawn, I have used it to build small instruments in the past with no problem.

I would like everyone's thoughts on using flat sawn wood instead of quarter sawn.

Thinks!

bazuku · Nov 6, 2019

Sawdust,

This just one isolated personal opinion:
Flat sawn wood can be used for back and sides but this is usually 'piece dependent'. When we speak of flat sawn, we are not speaking of flat grained. The grain of most flat sawn pieces is usually in a shallow 'u' or an inverted shallow 'u' configuration, depending on the builder's preference for the face surface. When this configuration is perfectly symmetrical, some very attractive patterns can result, but when it is not symmetrical, the resultant patterns (in figured woods) can prove difficult to book match and are best utilised as one piece.
Adequately braced backs are rarely problematic, and the bending of sides can go well if the piece has little run out, but is prone to diagonal splits if significant run out is present. Vertical side 'splints' around the levels of the upper and lower bouts are good insurance. The species of wood is a big factor.... finer grained varieties usually behave better than the very coarse grained.
Some (typically high end) luthiers use quarter sawn wood exclusively. They see flat sawn wood as risky from both the stability point of view and the fact that flat sawn pieces are often associated with instruments built to a budget. This is not even considering the endless discussion and arguments of sound characteristics from different wood types and cuts.
Historically, some very fine looking and sounding stringed instruments have been built from flat sawn lumber.
Personally, I have not made an Ukulele from flat sawn stock (and have no plans to), but I imagine that it would not be as risky a proposition as with larger instruments.
I would use quarter sawn stock for all soundboards and bracing.
This has always been a contentious issue and this thread will likely perpetuate that theme.
I suggest that you go with the majority.

turf3 · Nov 6, 2019

bazuku said:
Sawdust,

This just one isolated personal opinion:
Flat sawn wood can be used for back and sides but this is usually 'piece dependent'. When we speak of flat sawn, we are not speaking of flat grained. The grain of most flat sawn pieces is usually in a shallow 'u' or an inverted shallow 'u' configuration, depending on the builder's preference for the face surface. When this configuration is perfectly symmetrical, some very attractive patterns can result, but when it is not symmetrical, the resultant patterns (in figured woods) can prove difficult to book match and are best utilised as one piece.
Adequately braced backs are rarely problematic, and the bending of sides can go well if the piece has little run out, but is prone to diagonal splits if significant run out is present. Vertical side 'splints' around the levels of the upper and lower bouts are good insurance. The species of wood is a big factor.... finer grained varieties usually behave better than the very coarse grained.
Some (typically high end) luthiers use quarter sawn wood exclusively. They see flat sawn wood as risky from both the stability point of view and the fact that flat sawn pieces are often associated with instruments built to a budget. This is not even considering the endless discussion and arguments of sound characteristics from different wood types and cuts.
Historically, some very fine looking and sounding stringed instruments have been built from flat sawn lumber.
Personally, I have not made an Ukulele from flat sawn stock (and have no plans to), but I imagine that it would not be as risky a proposition as with larger instruments.
I would use quarter sawn stock for all soundboards and bracing.
This has always been a contentious issue and this thread will likely perpetuate that theme.
I suggest that you go with the majority.

I have seen some very fine double basses made with flat sawn tops. Can't get much bigger than that. Cannot speak to things like seasonal variation or warpage. Most DB are made with quartersawn tops.

Brett S. · Nov 6, 2019

bazuku said:
Sawdust,

This just one isolated personal opinion:
Flat sawn wood can be used for back and sides but this is usually 'piece dependent'. When we speak of flat sawn, we are not speaking of flat grained. The grain of most flat sawn pieces is usually in a shallow 'u' or an inverted shallow 'u' configuration, depending on the builder's preference for the face surface. When this configuration is perfectly symmetrical, some very attractive patterns can result, but when it is not symmetrical, the resultant patterns (in figured woods) can prove difficult to book match and are best utilised as one piece.
Adequately braced backs are rarely problematic, and the bending of sides can go well if the piece has little run out, but is prone to diagonal splits if significant run out is present. Vertical side 'splints' around the levels of the upper and lower bouts are good insurance. The species of wood is a big factor.... finer grained varieties usually behave better than the very coarse grained.
Some (typically high end) luthiers use quarter sawn wood exclusively. They see flat sawn wood as risky from both the stability point of view and the fact that flat sawn pieces are often associated with instruments built to a budget. This is not even considering the endless discussion and arguments of sound characteristics from different wood types and cuts.
Historically, some very fine looking and sounding stringed instruments have been built from flat sawn lumber.
Personally, I have not made an Ukulele from flat sawn stock (and have no plans to), but I imagine that it would not be as risky a proposition as with larger instruments.
I would use quarter sawn stock for all soundboards and bracing.
This has always been a contentious issue and this thread will likely perpetuate that theme.
I suggest that you go with the majority.

This answer covers it as I see, but I'll re-iterate that certain woods are more stable than others so there is little risk.

printer2 · Nov 6, 2019

A double bass is built like a violin where the bridge is floating and any top shrinking can be compensated for by using a different size bridge. Same goes with archtops. It is stability that is the difference between quartered and non-quartered wood. I am on forums where some of the top guitar makers acknowledge there is not much difference in tone between the different cuts. I built a walnut guitar out of scrap, I was setting up to resaw wood and used some flat sawn wood. The question was asked what an all walnut guitar sounded like and since I had some wood just sitting about I built with it. It is about 5 years old and no crack yet. Because it was only a test guitar I did not make it look pretty.

Sawdust · Nov 7, 2019

The wood I have is not actually flat sawn, but is more like riff sawn.

ProfChris · Nov 7, 2019

There are two issues here:

1. Reaction to humidity changes in the atmosphere. All wood moves because of this (mainly in the cross-grain direction), but flat sawn wood moves about twice as much as quarter sawn. This is usually OK for sides, because there is nothing stopping them expanding and shrinking cross-grain other than the head and tail blocks. Backs and tops, if flat, will be more likely to split (shrinking) or pop their braces (expanding). You can build in enough doming to allow for this.

2. Flat sawn wood has less cross-grain stiffness than quarter-sawn, quite a lot less. It's instructive to thin two small board to the thickness of a uke top and then flex them - the difference is very noticeable. This may mean that you need to make a flat-sawn top rather thicker than a quarter sawn, or to brace it more strongly. Either adds weight to the soundboard, which is generally undesirable and makes the instrument quieter. Again, careful design with the right arching to allow both for humidity change and to add stiffness (even a piece of paper curved lengthways is stiffer than a flat sheet) can cope with the problem.

So the answer is that you can use flat sawn wood, but you need to know how to build to accommodate the ways it differs from quarter sawn.

sequoia · Nov 7, 2019

As usual ProfChris sums it up beautifully... Below some diagrams showing how logs are cut using the three different methods (from Fine Homebuilding magazine). Sorry the graphic is so small.

To see the original article, go here:

https://www.finehomebuilding.com/2018/07/10/quartersawn-wood-rift-sawn-wood-explained

Flat sawn wood?

Sawdust

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bazuku

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turf3

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Brett S.

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printer2

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Sawdust

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ProfChris

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sequoia

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