need a new batch of spruce

[joehendrick]

Where is everyone buying their spruce for carved tops these days? I am completely out and there don't seem to be many posts on ebay any more. I am looking for mando and mandola sizes. Thanks

[Eddie Sheehy]

Spruce, the woodbutcher is your man.

[Bill Snyder]

Eddie is of course talking about Orcas Island Tonewoods and Bruce Harvie (aka Spruce).

[joehendrick]

Thanks for the translation

[Marty Jacobson]

I get most of my spruce from Bruce as well. He is very easy to work with and the wood he provides is always interesting and of the highest quality. Try some redwood, too, but instead of .100 - 110 at the recurve and .170 - .200 at the crown as you might for spruce, try carving it to .130 at the recurve and .300 or so at the crown. Redwood is lovely stuff.

[mandolirius]

Thanks for the translation

Really. The first reply wasn't much help to the uninitiated.

[Dave Cohen]

Before you plan on any particular thicknesses in your carved plates, measure the density or specific gravity of your wood. I have gotten redwood from "Spruce" with a density of around 0.45 g/cm3, and I have gotten other redwood billets from him with densities around 0.25 g/cm3. The stiffness (actually Young's or elastic modulus) of woods varies approximately linearly with density. Denser stuff is usually stiffer, while less dense wood is usually less stiff. That assumes "average" wood. There are certainly low-density pieces of wood that are fairly stiff, and dense pieces of wood that are not particularly stiff. Nevertheless, in the absence of measurements from your tonewood supplier, density is the easiest rough guideline that you have.

The redwood with a density of 0.45 g/cm3 is about as dense as typical red spruce, and in the case of the billets I got, the wood was about as stiff as typical red spruce. I have seen low density redwood that was as soft and punky as balsa. However, I also got some from "Spruce" with a density of around 0.25 g/cm3 that was very nice wood, quite ringy. Made very nice mandolins.

To measure density, cut a small rectangular chunk from your billet or set. You can cut it from a corner that would be carved away anyway. True it up on a tablesaw so that you can use the length, width and thickness to calculate the volume of the chunk. Measure the mass. A nice balance is helpful, though you could use a simple postal scale if that is all you can find. Be consistent with your units, either grams and centimeters, or kilograms and meters. 0.25 g/cm3 is very low-density wood, while 0.45 g/cm3 is pretty dense for most softwoods. I have seen a few redwood samples as dense as ~0.55 g/cm3, red spruce as dense as ~0.48 - maybe 0.5 g/cm3. Tom Thiel ("Northwind Tonewoods") has been measuring properties of his wood for the last few years, something I would like to see other suppliers do more. Larry Stamm up in BC, does that some, as does Bruce Creps ("Notable Woods"), a neighbor of Bruce Harvie's.

http://www.Cohenmando.com

[joehendrick]

Thanks Marty. Any knowledge of variations using western cedar? I just put an order in with Bruce for my first 2 mandolas

[Steevarino]

Dave (of course) is right. When you consider how tall spruce, and especially redwood trees grow, you have to realize that the wood on the lower portion of the tree us under much more pressure during its lifespan than the wood closer to the top of the tree. I don't know this for a fact, but I would just bet that an equal sized billet cut from near the bottom of the tree would measure in with much more density than the same size piece cut way up higher in the tree. Know what I mean...?

I'd think that it is the luthier's responsibility to carve accordingly, although I do like Dave's suggestion that suppliers do offer this measurement as a guideline. I guess it's the kind of thing where some wood suppliers will offer this service, and others won't.

[Marty Jacobson]

Dave's advice is good.

My recommendations for the specific graduations are a result of my own efforts to make cedar and redwood tops. No luthier that I spoke back in 2002 or since (and I asked quite a few) would give me any kind of concrete information about how much thicker to carve redwood/cedar tops. All I could get was "I don't know how much thicker you should carve it. Just carve it a bit thicker and see how it comes out".

After carving fifteen or so from redwood and cedar that didn't work and which I could not sell (either catastrophic failure or just poor tone), I realized I needed to be roughing them out 50% thicker, not "just a bit" thicker. I hope my advice can save someone else from having to find that out the hard way, as well.

You can always remove more material, but you can never put it back. Also, redwood's tap tone can be very different from that of spruce, and you have to re-learn how to interpret the plate's stiffness and flexibility.

[Dave Cohen]

I just made an octave mandolin top plate from a piece of Engelman spruce with a density of 0.354 g/cm3. Also a mandolin top plate from a piece of Euro spruce with a density of 0.34 g/cm3. Both of those are less dense than the average for their species. By Marty's suggestion, one would have to carve both of those plates considerably thicker than the "average" thickness for those species. In fact, my roughed plates all start out at 0.3" thick, or even thicker, in the center. But then, I am roughing my plates with a pantograph router rather than a cnc router. Otoh, if one followed Marty's advice for some of the dense redwood I mention in my earlier post, (s)he would have a plate that weighed a ton (slight hyperbole), and would be quite unresponsive.

The only reason that density is any help to the luthier is the rough linear relationship I mentioned between density and Young's (elastic) modulus. But even that is a bit tenuous. David Hurd wrote an article some time ago in American Lutherie. I would have to look up the reference. He included a graph of some Young's modulus vs density data for his wood samples. There was a similar plot and tables of data in a few articles by Daniel Haines in CAS Journal (= Catgut Acoustical Society Journal). Anyway those plots showed lots of scatter. There were points all over the graph, and a best-fit straight line through the data points. The density of points was greater closer to the line, but there were still points that were far away from the line. What that means is that if you have a dense piece of wood, there is a good chance that it is also relatively stiff, and if you have a low-density piece of wood, there is a good chance that it is relatively less stiff. But, the scatter tells us that you also have a chance of buying low density wood that is surprisingly stiff, and also dense wood that is not particularly stiff. Now, most of the wood has the potential to make "good" instruments, but the stuff that is dense and not particularly stiff is probably the least desirable. No matter how you carve it, it will result in a plate that is heavy for its' final stiffness. By any measure, a heavy plate will be less responsive than a lighter plate of the same stiffness. The criterion that Haines used for "goodness" of wood was the product of the parallel and perpendicular Young's moduli divided by the density. Iirc, he called that the "acoustic merit". There is a lot more detail on this in Howard Wright's dissertation under Bernard Richardson, also in the new Gore-Gilet book.

All of the above was intended to convey that not only stiffness, but also density matters, and there is a tremendous amount of variability in the wood you buy. Tonewood suppliers traditionally left it to the luthier to figure out what to do with the wood they bought. It is possible to measure the properties of the wood, and if the suppliers did that, at least the luthier would have an idea of what was coming. It would be nice to know the parallel and perpendicular Young's moduli, but even knowing the density would be a help.

http://www.Cohenmando.com

[j. condino]

Dave's advice is good.

My recommendations for the specific graduations are a result of my own efforts to make cedar and redwood tops. No luthier that I spoke back in 2002 or since (and I asked quite a few) would give me any kind of concrete information about how much thicker to carve redwood/cedar tops. All I could get was "I don't know how much thicker you should carve it. Just carve it a bit thicker and see how it comes out". .

Having formerly lived and built a lot of instruments in the land of redwoods and wester red cedars for about 20 years, the variability is profound. I've seen a lot of the so called "sinker" redwood for sale that, to my hands, is basically soggy rust colored wet carboard. On the other end of the spectrum I looked through thousands of sets from the "Lucky Strike" tree cut by the Carters back in the day that was like some of the stiffest rust colored red spruce you could imagine. It is just too variable to offer solid advice strictly by the numbers.

I measure the density; I crunch the speed of sound with a fancy Lucci meter (What else would you expect from an Italian mandolin builder????), I make up graphs with the radiation ratios; I have my own funky deflection gadgets....but.....

When the numbers seem to be against you...follow your heart and your ears. Carve a little bit, and then save some. String it up in the white with no soundholes. Play a little Salt Creek; carve a little more. Play a little Django; open up the sound hole apertures a bit. Play a little Monroe; tweek it a little more. Miles, Duke, Jerry, Bach, Zappa, Chris, cross tune the thing and play Michael Hedges covers...whatever it is that moves you...play it.

At the end of the day (and the start for many of us!), what matters most making great music from the instrument. If you have a matched set of two identical tops, don't be afraid to carve one into oblivion. Somewhere during the process, you'll know what worked well and when you crossed the threshold. Better to maximize one top than to have two that are nothing but pretty wall art. It is not a perfect science, but it will give you more insight than we can offer for your specific wood. Then tell us all what your results were and remember that when just when you get it down with one set of wood, the next will be different and challenge you in new ways.

j.
www.condino.com

[John Arnold]

I don't know this for a fact, but I would just bet that an equal sized billet cut from near the bottom of the tree would measure in with much more density than the same size piece cut way up higher in the tree. Know what I mean...?

After cutting red spruce for 23+ years, I have not found that to be true. The densest wood in a given tree is the compression wood, which is usually a good distance from the butt. A false notion is that compression wood comes from the weight of the tree. It does not. It comes from the side forces generated when a tree leans. In other words, the tree will straighten itself by growing faster on the downhill side, making a curved trunk. Compression wood forms on the convex side of this curve.
Violin makers traditionally have avoided the first few feet at the butt of the log, but that is for a different reason. That is the area that often displays interlocked grain, which can be more difficult to carve. OTOH, some of the best instruments I have ever played (including my 1937 D-28) have some interlock in them.
In the last few years I have included density measurements when selling red spruce violin tops.

[Charles E.]

The OP should contact John for some spruce. I have bought some nice pieces from him over the years.

[Clicker]

Best regards to the OP and to those who made such good suggestions. Our observations as to how a tree grows though would tell us that there may not be a denser material at the base of a tree but that there would be more wood there to help hold it up. And, as far as density goes, why wouldn't one check for moisture content before weighing? We might surmise wrongly that a 3% difference in moisture content would make a more suitable instrument when in fact, it wouldn't. Would two samples of Picea engelmannii be that much different no matter where they came from, given their equivalent moisture content and grown under similar conditions of moisture availability and temperature? I am not convinced that they would be.

[Spruce]

Would two samples of Picea engelmannii be that much different no matter where they came from, given their equivalent moisture content and grown under similar conditions of moisture availability and temperature?

Yes, and drastically so...
I've milled Engelmann that grew 30 feet apart from one another--one light in weight and soft to the fingernail, and one hard and heavy...
Go figure...

[John Arnold]

In 1994, I bought two red spruce logs from a sawmill. These were cut on WV National Forest land, in preparation for a scenic highway (Senator Robert Byrd pet project). These trees came from the same area, and the wood looked the same....same grain count and spread). But they were as different as any red spruce I have cut. One as dense and stiff as Doug fir, the other indistinguishable from Engelmann.
Like Bruce, my long experience in cutting spruce has taught me that a lot of the assumptions we take for granted are just dead wrong.

And, as far as density goes, why wouldn't one check for moisture content before weighing?

Of course, I always measured the moisture content when doing the density calculations. IMHO, as a wood seller, ignorance about the MC of the wood is just plain negligence.