Wood questions - Public Lumber Company, determining species at the lumberyard

[Corrie]

http://www.publiclumber.com/2x4sitkaspruce.html Anyone had any
dealings with them? They sell "aircraft/spar-grade" 2x4 spruce for
$4.50 / lin.ft. Their prices on marine ply are about what I can get
locally, but the price on spruce beats most I've seen. Of course,
it's only a good deal if the wood is actually high-quality. Or is the
wisest course of action to just suck it up and pay AS&S's prices for
your spars and longerons?

Some plans call for specific species in specific places. At the
lumberyard, how do you tell the difference between pine, spruce, and
fir in dimensional lumber? Are they marked somehow? Guidebooks
aren't very useful - by the time the trees get to where I can buy
them, the bark and needles are long gone. :-)

Corrie

[Ryan Young]

Generally, the wood itself will be stamped or marked on one or both ends
with SOME ID, which may be a little cryptic. "Western Woods" is one common
ID here in Californis, which can be about a half dozen different species.
Luckily, they all have pretty similar mechanical properties.

For a key to wood ID, try "Wood Structure and Identification", Core, Cote,
and Day. Or "What Wood Is That - A Manual of Wood Identification.

Bring a 10X loupe, and a razor knife.

BUT IT JUST DOESN'T MATTER. Read what Veeduber has to say about wood
selection in this group and in the FLY5K yahoo group. Wood selection for
QUALITY is more important than SPECIES. If the grain is OK, the wood will
probably be OK.

Sitka Spruce has lower mechanical properties than just about any commonly
available softwood used for structures - worse than Western Hemlock, Douglas
Fire, etc. But it's lighter than they are, and it's strength/weight ratio
is very high, which is why it's often called for in aircraft work.

You can build a plane just as strong with other woods, it will just weigh a
wee bit more.
--
Ryan R Young
Oakland, CA
http://users.lmi.net/~ryoung

[Eric Miller]

"Flightdeck" > wrote
> Their "marine" ply price is good and we used some in a non-structural
application.

Does marine plywood have any specs regarding voids within intermediate plys?

Eric

[Del Rawlins]

On 08 Sep 2003 10:12 AM, Eric Miller posted the following:
> "Flightdeck" > wrote
>> Their "marine" ply price is good and we used some in a non-structural
> application.
>
> Does marine plywood have any specs regarding voids within intermediate
> plys?

Marine plywood is supposed to not have any voids. There is an excellent
article on the making of marine plywood in the current issue of
Woodenboat magazine.

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

[Corrie]

Thanks for the detailed response. Can you explain more about
compression damage and how to spot it?

"Flightdeck" > wrote in message et>...
> Corrie,
>
> Their "marine" ply price is good and we used some in a non-structural
> application. However, the specification for "aircraft ply" includes a lot
> more than just the "boil" spec. We didn't do the 1/4" strip sectioning to
> look for voids. I have not ordered "Spruce" from them. Before I would buy
> any "spar stock" from a source that does not routinely supply the aircraft
> industry, I would get a sample from them and check it against the specs.
> Here is a link to a Word document file of AC 43.13-1B
> http://av-info.faa.gov/dst/43-13/Ch_01-01.doc This AC gives you some basic
> information.
>
> Each species of wood has some tell-tail characteristics that can be used to
> help identify it after it has been milled. Some of the characteristics are
> so apparent that a visual examination will get you the general species, some
> require specific mechanical tests or examinations. It is fairly easy to
> identify the gross differences between some species, but harder to identify
> the different sub-species. A explanation of some of the more subtle
> characteristics sound like one is describing wine or food... "A soft gold
> sheen with a subtle silken ribbon effect when the face grain is held to the
> light...." Some sub-species identification is made more difficult because of
> the amount of "plantation grown" material on the market. A lot of this
> stuff is cut young and is grown for harvest volume under "fast growth"
> conditions. As a result, some of the more subtle differences in sub-species
> are blurred. Regardless of the species, or sub-species, the faster growth
> and younger stuff makes it difficult to obtain stock that meets the "growth
> rings per inch" specification for spar stock. And, because of the fact that
> it is machine cut and felled for speed and without regard for much "TLC",
> even a lot of the remaining "old-growth" stock ends up with compression
> damage. The trouble with compression damage is that it often takes a
> well-trained eye to spot it.
>
> Some "lumber yards" still have folks who actually know the source
> sub-species of the wood they stock. However, most of them today buy stock
> based upon a fairly wide window of mechanical properties rather than an
> exact sub-species identification. You may see "pine", "spruce", "fir",
> hemlock, etc. listed. However, there can be a big difference in the native
> mechanical properties across the sub-species. In fact, the actual
> properties can be widely different based upon where the tree was grown.
> Some of the best sources for learning to identify milled woods come from the
> older books on cabinet and furniture making.
>
> "There is a bunch of "spruce" on the consumer market, but most of it is not
> suitable for aircraft structural construction. The same thing applies to
> the other species. In a pinch, you might be able to find some longeron
> stock by hand sorting through the entire inventory of a lumber yard and then
> doing some basic moisture content and strength tests. Commercial logs are
> milled in a manner that produces the greatest number of board-feet from the
> bore, but there may be a small portion of the slices that can be classified
> as "straight grain" or "quarter-sawn". You just need to find those slices
> and then count the growth rings, and check for pitch pockets, grain run-out,
> compression wood, moisture content, etc. But, that is a lot of trouble.
> That is why many folks "trust" the aircraft suppliers to have specifications
> in place and just spend the bucks to buy from them. However, there is
> nothing "magical" about Sitka Spruce. In fact, it became a "de-facto"
> standard due more to the original availability (before 90% of the good stuff
> was shipped to the Pacific Rim countries) than anything else.
>
> Aircraft designers specify the species of the wood to be used (given that
> the stock meets the "aircraft use" specifications) because of mechanical
> properties, dimensional, and weight issues. Under ideal A:B comparisons
> between species, each species will have properties that are used to
> calculate for the specific application. In some instances the selection
> will be based upon a specific property versus the dimension needed to meet
> the structural specification. For example, one species may have certain
> mechanical properties in simple bending that is very close to another
> species. However, a specific species is specified because there is a weight
> advantage at a given dimensional size. Some times a species is specified
> because it is better able to handle "shock loads". Some times it comes down
> to the "tool-ability" of the species. For example, Douglas Fir is stronger
> (stiffer) than Spruce in certain load applications. But it is heavier for a
> given volume and can be more difficult to "tool" across the ends of the
> grain.
>
> There have even been a couple of "home-built" (one "ultra-lite" in
> particular) designs that used "Southern White Pine" throughout the
> construction because the kit manufacturer had a "qualified source" and hand
> sorted each piece delivered to the customer. This is a case where the
> original design was plenty strong for its intended use. However, folks
> quickly got in trouble when they stuck too much power on the nose and went
> past the design's intended gross weight and performance envelope.
>
> It is getting more difficult to purchase "aircraft spruce spar specification
> stock" in the dimensions needed for both "certified" and home-built aircraft
> when the spar is a "one piece" design. For a while, it was possible to get
> Western Hemlock "old growth" spar stock in the larger dimensions. In most
> "home built" applications one could do a direct substitution of Hemlock for
> Spruce and actually end up with a better spar because of the native
> properties of the Hemlock and the availability of stock with better "rings
> per inch" than the available Spruce.
>
> At one time there was a fellow up in B.C., Canada with a company called
> "Western Aircraft Spruce" who had access to large, old-growth Hemlock and
> some good Spruce. I bought some Hemlock spar stock from him and it was
> "el-primo" stuff. The main spar stock counted out at about 32 rings per
> inch with so little grain "run-out" that it was not worth mentioning. That
> is old slow-growth stuff! His prices were very reasonable, considering the
> quality, and he had connections to ship via "space available" cargo on some
> of the passenger flights out of B.C. The last telephone number I had for
> him is 250-355-0003.
>
> I guess the one caution I would offer about substitution of one wood species
> for another in aircraft structural application is that there is more to the
> engineering specifications than just the "inspectable" characteristics and
> weight.
>
> J
>
> "Corrie" > wrote in message
> om...
> > http://www.publiclumber.com/2x4sitkaspruce.html Anyone had any
> > dealings with them? They sell "aircraft/spar-grade" 2x4 spruce for
> > $4.50 / lin.ft. Their prices on marine ply are about what I can get
> > locally, but the price on spruce beats most I've seen. Of course,
> > it's only a good deal if the wood is actually high-quality. Or is the
> > wisest course of action to just suck it up and pay AS&S's prices for
> > your spars and longerons?
> >
> > Some plans call for specific species in specific places. At the
> > lumberyard, how do you tell the difference between pine, spruce, and
> > fir in dimensional lumber? Are they marked somehow? Guidebooks
> > aren't very useful - by the time the trees get to where I can buy
> > them, the bark and needles are long gone. :-)
> >
> > Corrie

[Eric Miller]

"Corrie" > wrote in message
om...
> Thanks for the detailed response. Can you explain more about
> compression damage and how to spot it?

I've seen more extensive articles on this that I can't find/recall right
now, but I know Ron Alexander covered it in Sport Aviation Feb '99.

Eric

[Ed Sullivan]

(Corrie) wrote in message >...
> Thanks, Ryan. Veeduber is indeed generous with his wisdom. Fly5k has
> been rather terribly OT of late, but I suspect there are gems in the
> archives.
>
> What you say makes a good deal of sense as well. I'd hesitate to
> substitute fir for spruce in spars or longerons, as fir is reputed to
> be stiffer. The expected amount of 'give' of the beam is likely to
> have been designed into the structure. But for other parts, I suppose
> it doesn't matter all that much. It struck me as odd, though, that
> the Evans VP front spar bulkhead (carries the instrument panel, and
> your legs stick through a big opening in the middle) calls for Douglas
> Fir for the spar and strut carry-through, spruce for the vertical
> members, and pine for a transverse member. I've asked on the vp group
> on yahoo, but haven't gotten a definitive answer.
>
> Spent a little while at the local Huge Orange Store tonight looking at
> lumber. Lotsa knots and center cuts from little trees. :-(
>
>
>
> Ryan Young > wrote in message >...
> > Generally, the wood itself will be stamped or marked on one or both ends
> > with SOME ID, which may be a little cryptic. "Western Woods" is one common
> > ID here in Californis, which can be about a half dozen different species.
> > Luckily, they all have pretty similar mechanical properties.
> >
> > For a key to wood ID, try "Wood Structure and Identification", Core, Cote,
> > and Day. Or "What Wood Is That - A Manual of Wood Identification.
> >
> > Bring a 10X loupe, and a razor knife.
> >
> > BUT IT JUST DOESN'T MATTER. Read what Veeduber has to say about wood
> > selection in this group and in the FLY5K yahoo group. Wood selection for
> > QUALITY is more important than SPECIES. If the grain is OK, the wood will
> > probably be OK.
> >
> > Sitka Spruce has lower mechanical properties than just about any commonly
> > available softwood used for structures - worse than Western Hemlock, Douglas
> > Fire, etc. But it's lighter than they are, and it's strength/weight ratio
> > is very high, which is why it's often called for in aircraft work.
> >
> > You can build a plane just as strong with other woods, it will just weigh a
> > wee bit more.

The EAA has a book available on aircraft woodwork, but I don't know if
it has some of the same stuff on selecting and grading wood that is in
an old publication of theirs that I bought 20 years ago. The selection
process and the moisture content of the lumber is pretty critical. I
chose to use Spruce in my Jungster II because I could obtain stock
that was graded for aircraft and the quantity of wood in an aircraft
is so little that the price difference was not as important as the
peace of mind. Also Spruce is much easier to work with than Douglas
Fir for instance. There are other wood as good or better than spruce,
but they are scarce, such as Port Orford Cedar. Most of the wood
expense on my project was in the plywood and the metal wing struts
cost almost as much as all the other material.

Ed Sullivan

[Corrie]

Thanks, Eric. A bit of googling turned up some information - it's
hard-to-spot damage that can come from a tree growing at an angle,
being felled onto a slope, a whole range of things. I was actually
looking for something on the compression *strength* of hoop pine vs
birch to respond to a post elsewhere, but "compression damage" kept
coming up in the list.

I also just received the 1994 EAA publication on wood building
techniques - appears to be a collection of reprinted articles. On
page 11 is a reprint of an article by Volksplane designer W.S. Evans
that goes into some detail on the subject, with the conclusion that
it's not worth the risk for spars and longerons to use
non-certificated (and possibly compression-damaged) wood. Even so, he
advocates cutting off 2" of each end of the stock and inspecting it
for obvious fiber damage. THAT could get expensive!

Corrie

"Eric Miller" > wrote in message >...
> "Corrie" > wrote in message
> om...
> > Thanks for the detailed response. Can you explain more about
> > compression damage and how to spot it?
>
> I've seen more extensive articles on this that I can't find/recall right
> now, but I know Ron Alexander covered it in Sport Aviation Feb '99.
>
> Eric

[Corrie]

AHA! It's all in the wrist, or in getting the correct search terms in
google. Depends what you want to do. Anyway, here are a couple of
links to info:

http://www.lsuagcenter.com/Communications/news/NewsArchive/3nws0806.htm
http://www.safnet.org/archive/0703_howtointerpret.cfm

From that second site, here's some interesting info:

"...species groups ... are denoted by these abbreviations:
Spruce-Pine-Fir S-P-F
...."

I saw a *lot* of lumber at the yard stamped S-P-F. Spruce-pine-fir,
doesn't matter for wall studs. Oh joy, or rupture.

THIS is interesting, though:
http://www.wclib.org/results2.asp?mnuLocation=%25&mnuSpecies=Sitka+Spruce&mnuProducts=Boards&mnuMoisture=Dry&mnuHeat=%25&mnuShipping=Truck&Submit=Search

No idea if they'd sell in less than truckload quantities. Worth a
call, maybe.


(Corrie) wrote in message >...
> Thanks, Ryan. Veeduber is indeed generous with his wisdom. Fly5k has
> been rather terribly OT of late, but I suspect there are gems in the
> archives.
>
> What you say makes a good deal of sense as well. I'd hesitate to
> substitute fir for spruce in spars or longerons, as fir is reputed to
> be stiffer. The expected amount of 'give' of the beam is likely to
> have been designed into the structure. But for other parts, I suppose
> it doesn't matter all that much. It struck me as odd, though, that
> the Evans VP front spar bulkhead (carries the instrument panel, and
> your legs stick through a big opening in the middle) calls for Douglas
> Fir for the spar and strut carry-through, spruce for the vertical
> members, and pine for a transverse member. I've asked on the vp group
> on yahoo, but haven't gotten a definitive answer.
>
> Spent a little while at the local Huge Orange Store tonight looking at
> lumber. Lotsa knots and center cuts from little trees. :-(
>
>
>
> Ryan Young > wrote in message >...
> > Generally, the wood itself will be stamped or marked on one or both ends
> > with SOME ID, which may be a little cryptic. "Western Woods" is one common
> > ID here in Californis, which can be about a half dozen different species.
> > Luckily, they all have pretty similar mechanical properties.
> >
> > For a key to wood ID, try "Wood Structure and Identification", Core, Cote,
> > and Day. Or "What Wood Is That - A Manual of Wood Identification.
> >
> > Bring a 10X loupe, and a razor knife.
> >
> > BUT IT JUST DOESN'T MATTER. Read what Veeduber has to say about wood
> > selection in this group and in the FLY5K yahoo group. Wood selection for
> > QUALITY is more important than SPECIES. If the grain is OK, the wood will
> > probably be OK.
> >
> > Sitka Spruce has lower mechanical properties than just about any commonly
> > available softwood used for structures - worse than Western Hemlock, Douglas
> > Fire, etc. But it's lighter than they are, and it's strength/weight ratio
> > is very high, which is why it's often called for in aircraft work.
> >
> > You can build a plane just as strong with other woods, it will just weigh a
> > wee bit more.

[Daniel]

Corrie wrote ...
> ... an article by Volksplane designer W.S. Evans
> ... with the conclusion that
> it's not worth the risk for spars and longerons to use
> non-certificated (and possibly compression-damaged) wood.


Certificated by whom? Anybody with a chainsaw & a porta-mill can
declare whatever grade they wish on any lumber they produce. Heck,
take the basic quality designations for #2 construction lumber & see
what percentage of the ordinary wall studs at Big Orange even meet the
specs stamped on them. I think a plane builder is far better off
performing his/her own pass/fail inspections than trusting Larry the
Lumberjack to have done so correctly at the mill.

Daniel

[Rich S.]

"Corrie" > wrote in message
om...
> AHA! It's all in the wrist, or in getting the correct search terms in
> google. Depends what you want to do. Anyway, here are a couple of
> links to info:
>
> http://www.lsuagcenter.com/Communications/news/NewsArchive/3nws0806.htm
> http://www.safnet.org/archive/0703_howtointerpret.cfm
>
> From that second site, here's some interesting info:
>
> "...species groups ... are denoted by these abbreviations:
> Spruce-Pine-Fir S-P-F
> ..."
>
> I saw a *lot* of lumber at the yard stamped S-P-F. Spruce-pine-fir,
> doesn't matter for wall studs. Oh joy, or rupture.

The wood you find at the Borg* may have the word "Fir" but you will notice
the absence of the modifier "Douglas". I'm about the open up a wall in my
living room and install a couple more windows. You can bet I'll be going to
a real lumber yard and buying kiln-dried Douglas Fir studs and headers. That
wet sub-species crap at the Borg will twist and turn like a stick of red
licorice as it cures.

*Borg: Aliens who operation out of a cube-shaped ship (may be disguised as a
building).

Rich S.

[Rich S.]

"Daniel" > wrote in message
om...
>
> Certificated by whom? Anybody with a chainsaw & a porta-mill can
> declare whatever grade they wish on any lumber they produce. Heck,
> take the basic quality designations for #2 construction lumber & see
> what percentage of the ordinary wall studs at Big Orange even meet the
> specs stamped on them. I think a plane builder is far better off
> performing his/her own pass/fail inspections than trusting Larry the
> Lumberjack to have done so correctly at the mill.

Just like adhesives.

Rich S.

[Jerry Wass]

Corrie wrote:

> "Rich S." > wrote in message >...
> > "Corrie" > wrote in message
> > om...
> > > AHA! It's all in the wrist, or in getting the correct search terms in
> > > google. Depends what you want to do. Anyway, here are a couple of
> > > links to info:
> > >
> > > http://www.lsuagcenter.com/Communications/news/NewsArchive/3nws0806.htm
> > > http://www.safnet.org/archive/0703_howtointerpret.cfm
> > >
> > > From that second site, here's some interesting info:
> > >
> > > "...species groups ... are denoted by these abbreviations:
> > > Spruce-Pine-Fir S-P-F
> > > ..."
> > >
> > > I saw a *lot* of lumber at the yard stamped S-P-F. Spruce-pine-fir,
> > > doesn't matter for wall studs. Oh joy, or rupture.
> >
> > The wood you find at the Borg* may have the word "Fir" but you will notice
> > the absence of the modifier "Douglas". I'm about the open up a wall in my
> > living room and install a couple more windows. You can bet I'll be going to
> > a real lumber yard and buying kiln-dried Douglas Fir studs and headers. That
> > wet sub-species crap at the Borg will twist and turn like a stick of red
> > licorice as it cures.
>
> No doubt. According to the forest-products trade association stuff I
> found, there IS a stamp for Douglas fir, though - the letters 'DF'
> inside a triangle. Just didn't see any the other night. Short of
> sending a swatch to the local forestry lab, knowing what the markings
> mean is likely to get you better results than asking a guy in an
> apron.Oh, But last week he was probably helping customers

by asking--You want fries with that ,sir ???

[Fred the Red Shirt]

"Rich S." > wrote in message >...
>
> The wood you find at the Borg* may have the word "Fir" but you will notice
> the absence of the modifier "Douglas".

Much to my surprise about six months ago in Pasadena CA or therabouts
I found some bords at the borg (aka Home Depot) that were stamped
by HD 'Green Fir' and 'Doug Fir' in another place by the supplier.
They were in fact green Douglas Fir.

It just goes to show you that it isn;t only the guys working retail
at HD who don;t know wood.

Douglas Fir is not fir. It is not even the same genus as fir. It
more closely resembles Larch and can be grouped by the American Software
Lumber Association with Larch in terms of properties but it isn't a
Larch either. Doug Fir is its own genus.

Anyhow, for structural lumber the common species groups in ascending
order by tensile strength are SPF (spruce or pine or fir) Hem-Fir
(Hemlock or Fir), Doug Fir or Larch, and Southern Yellow Pine.

Doug Fir and Southern Yellow Pine are about equal in strength and
stiffness, SYP is denser.


> I'm about the open up a wall in my
> living room and install a couple more windows. You can bet I'll be going to
> a real lumber yard and buying kiln-dried Douglas Fir studs and headers. That
> wet sub-species crap at the Borg will twist and turn like a stick of red
> licorice as it cures.
>

Doug Fir supposedly has the unique property of maintaining dimensional
stability as it dries. I suspect that property was observed in the
Old growth wood and question if it it is still true for the plantation
grown stuff.

If I build an aircraft, you can be damn sure that I'll be getting my
wood from a bona-fide lumber dealer or direct from a sawyer and not
from a home center.

--


FF

[Gregg Germain]

Fred the Red Shirt > wrote:

: If I build an aircraft, you can be damn sure that I'll be getting my
: wood from a bona-fide lumber dealer or direct from a sawyer and not
: from a home center.

If you get it from a sawyer, you are buying green wood (I suspect
you know that). So stack the flitches and sticker them and let them
air dry. Then rough out the stock, bring it into the shop and let
it air dry for a week. Then work it to final dimension.


--- Gregg

My woodworking projects:


Replicas of 15th-19th century nautical navigational instruments:

http://home.comcast.net/~saville/backstaffhome.html

Restoration of my 82 year old Herreshoff S-Boat sailboat:

http://home.comcast.net/~saville/SBOATrestore.htm

Steambending FAQ with photos:

http://home.comcast.net/~saville/Steambend.htm


"Improvise, adapt, overcome."

Smithsonian Center for Astrophysics
Phone: (617) 496-1558

[Fred the Red Shirt]

Gregg Germain > wrote in message >...
> Fred the Red Shirt > wrote:
>
> : If I build an aircraft, you can be damn sure that I'll be getting my
> : wood from a bona-fide lumber dealer or direct from a sawyer and not
> : from a home center.
>
> If you get it from a sawyer, you are buying green wood (I suspect
> you know that).

Some sawyers have kilns. One I know in Southern MD has a Solar kiln.


> So stack the flitches and sticker them and let them
> air dry.

The rule of thumb is one year for each inch of thickness of the stock.

> Then rough out the stock, bring it into the shop and let
> it air dry for a week. Then work it to final dimension.

--

FF

[Fred the Red Shirt]

(Corrie) wrote in message >...
> Quite right, I'm not so foolish as to trust my life to a stick I
> haven't looked at *closely*. "The stamp isn't load-bearing" - good
> point. But the stamp is at least a starting place. And unless you
> own a timber stand in the pacific Northwest (or know someone who
> does), you have to buy the wood from somewhere. Hence my
> (still-unanswered) question about PLC.
>

Honestly, I never heard of them before. I suggest you ask over on
rec.woodworking, and maybe over on the lutherie (stringed musical
instrument making) group--rec.crafts.something or another.

--

FF

[Corrie]

(Fred the Red Shirt) wrote in message >...

> Honestly, I never heard of them before. I suggest you ask over on
> rec.woodworking, and maybe over on the lutherie (stringed musical
> instrument making) group--rec.crafts.something or another.

Good idea. Thanks.