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Soundboard Wood From Lumber Vs Split Wood


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I decided to cut a piece of wood to illustrate the benifit of using split wood vs dimensioned lumber for soundboards. This is a subject that comes up, often when people are looking at some of the cheap offerings on Ebay. I have been told by some dealers on Ebay that they do use dimenioned lumber as their source, so it is not an assumption on my part. You should ask them if they could simply sell you raw split bolts instead of cut tops, and they should be willing(it is less work on their part). If they purchase pre-cut soundboards in bulk from one of the mega dealers, they will probably be happy to let you know that(the large dealers, do know what they are doing, so that would not be a problem).

The problem with dimensioned lumber is that it is cut without consideration to runnout, or twists and knots in wood (unless of course they are considered a visable flaw, by softwood grading standards).

This is a billet I cut (it is from my "scrap" pile). It appears to be clean, bright Sitka with high ring counts.

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Nicely quartered

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Visually this would probably be graded reasonably high.

The problem that is harder to detect in cut lumber. (note; there would be a change in the reflectiveness if the wood due to runnout, but you would not be able to judge how extream the runnout is very easily). Most cheap soundboards will not be surfaced, so detecting this would be unlikely. I left a bit of evidense to show where the piece was cut, I could surface all evidence off the billet.

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So the big difference with split wood, cut by someone who is cutting for soundboards specifically, is that they would do as I did and split away wood on the bolt until they reached clean split surfaces (this piece would hit the scrap pile). Milled lumber will not be treated in this manner, it will be cut for optimal yeild and try to achieve "clear" lumber. The problem with extream runnout is that it drastically reduces the strength of a soundboard (one could relate this weakness to runnout issues in necks near the nut area on angled headstocks, although a soundboard is usually less than 1/8" thick, and the issue can REALLY become appearant). I hope the pictures make it easier to visualize why these things are important, and why even a well meaning person selling cheap soundboards may not ever be aware(they couldn't tell the difference) of a severe problem. This type of defect would not be uncommon in sawn lumber, as they are cutting for max clear length and they are bound to pass by limbs or knots (trying to cut clear wood, but certainly close to the knot to capture as much visually clear stock as possible).

Peace,Rich

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Runnout is something that you really want to control as best you can. Runnout up to about 2%(that would be something like 1/2" over about the length of typical soundboard) should have neglagable effects on strength(so no worries). If you are a little higher than that it will effect the strength a bit, but limiting it to say 4% or about 1" over the length of a soundboard although weakening a bit, will not be drastically weaker(at least from what I have found). In the case of a knot like that one pictured you are probably well over 25% runnout and stregth will drop a lot in that area.

It is kinda interesting that curly redwood is used for tops when the figure they have is basically heavy runnout. These soundboards are much weaker in the long grain, however are generally pretty stiff in the cross grain. No doubt they are great looking tops, but you really need to pay attension to your bracing when using them.

With a billet like the one in my pictures. The runnout could be controlled with a bit of cutting, and the area that the knot had existed would be very close to the end of the soundboard(the billet is very long). It could be place high in the upper bout area, that is very heavily braced, and probably pose little issue. Placing it in the lower bout area would be asking for issues. When you do see odd reflectances in a soundboard, it never hurts to try to stratigically locate them to minimise a potential issue. Again the signs of runnout look pretty much like the curly(very broad, wide) figure we are used to seeing. You can pick up on the runnout caused by the slope of the whole board by looking at your bookmatch. One side will reflect differently than the other(appearing a bit darker on one side brighter on the other). You can see these things, but it is hard to quantify exactly how much runnout is present just by looks.

Another thing to note in the pictures os the rays that are visable. Not in the picture of the split face how strongly the rays appear. Also look at the cut face and compair the strength of the rays. The closer to the split surface you can hold the cut the better the rays will be visable. The size and darkness of rays vary with different species, but are always present. If your soundboard has exhibits the rays well you are probably pretty close to the natural split face. Again not an absolute indicator, but a good tool to use.

Peace,Rich

Edited by fryovanni
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Rich,

I've been playing with splitting some quartered pine (not sure what it is - it's recycled from an old door's stiles), and it splits nicely, but doesn't create a flat face. Presumably this wood would be discarded, until a flat cleavage plane occured, and then stock would be jointed and cut parallel to this face?

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Rich,

I've been playing with splitting some quartered pine (not sure what it is - it's recycled from an old door's stiles), and it splits nicely, but doesn't create a flat face. Presumably this wood would be discarded, until a flat cleavage plane occured, and then stock would be jointed and cut parallel to this face?

Setch,

If you mean that the face does not split leaving a smooth flat face, then no you do net need a smooth face. What you are looking for is the line that the wood splits along. You want to cut the face paralleling the direction it wants to split. If the wood splits in a wavy pattern, then you will have runnout issues, but as long as the wood wants to split fairly straight you can just cut referencing the direction it splits. Depending on how you are trying to split the wood you may get a more jagged face. If I split a piece with very little material on one side of the split, it just about never gives a smooth split. If I have about 3/4" worth of wood on each side of the split or better, it will usually split pretty well.

Maybe a picture would be handy to make sure I understand correctly.

Peace,Rich

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