RE: [bolger] Re: Wood for Birds'mouth spars
Boy, this thread went places I never expected when I asked the original
question!
One final question along the latest line of discussion - I'm obviously going
to have to scarf whatever staves I make, of whatever wood, to make a 26'
mast. So my question is, should the scarfs be cut 'perpendicular' to the
axis of the mast, or parallel (diagonal scarf lines showing, or just a
horizontal line visible at the scarf)? I seem to remember reading somewhere
that not only should they lay down, but they should 'point downward' like a
shingle so water wouldn't run into the joint - not that that's likely to
happen with a boat that will mostly sit on a trailer with the mast resting
horizontally on braces on the garage wall...
thanks for all the input and great discussion
Paul L.
-----Original Message-----
From:bolger@yahoogroups.com[mailto:bolger@yahoogroups.com]On Behalf Of
Bruce Hallman
Sent: Saturday, March 25, 2006 12:43 PM
To:bolger@yahoogroups.com
Subject: Re: [bolger] Re: Wood for Birds'mouth spars
question!
One final question along the latest line of discussion - I'm obviously going
to have to scarf whatever staves I make, of whatever wood, to make a 26'
mast. So my question is, should the scarfs be cut 'perpendicular' to the
axis of the mast, or parallel (diagonal scarf lines showing, or just a
horizontal line visible at the scarf)? I seem to remember reading somewhere
that not only should they lay down, but they should 'point downward' like a
shingle so water wouldn't run into the joint - not that that's likely to
happen with a boat that will mostly sit on a trailer with the mast resting
horizontally on braces on the garage wall...
thanks for all the input and great discussion
Paul L.
-----Original Message-----
From:bolger@yahoogroups.com[mailto:bolger@yahoogroups.com]On Behalf Of
Bruce Hallman
Sent: Saturday, March 25, 2006 12:43 PM
To:bolger@yahoogroups.com
Subject: Re: [bolger] Re: Wood for Birds'mouth spars
On 3/24/06, Paul Smith <paulnsmith@...> wrote:
> Some years ago I banned the use of finger jointed studs in the city I
worked
Certainly your perogative, but finger jointed 'rated' lumber is
accepted by the LRFD and the ICBO in most jurisdictions.
> I will remain highly suspicious of engineered materials ... for marine
use.
How do you feel about scarf joints?
Bolger rules!!!
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My intuition says that with weaker wood, better fit, and stronger glue, the angle can be
steeper. For instance, I have seen a model airplane wing made of solid balsa wood which
was butt glued, with Titebond, very precisely in the center, which is the part with the
highest loading. When the wing broke, very close to the center, none of the glue joint
failed. Some woods take glue better than others, and I'm sure this is a factor as well. The
guy who designed and built this wing is a brilliant engineer and one of the best craftsmen I
have ever met.
steeper. For instance, I have seen a model airplane wing made of solid balsa wood which
was butt glued, with Titebond, very precisely in the center, which is the part with the
highest loading. When the wing broke, very close to the center, none of the glue joint
failed. Some woods take glue better than others, and I'm sure this is a factor as well. The
guy who designed and built this wing is a brilliant engineer and one of the best craftsmen I
have ever met.
--- Inbolger@yahoogroups.com, stuart crawford <scrawford@...> wrote:
>
> John Guzzwell of Trekka fame, states in his book Modern Cold Molded
> Construction, that scarves should be 12:1. Which is what he learnt working
> for a company building laminated structural beams.
>
> Stuart Crawford.
John Guzzwell of Trekka fame, states in his book Modern Cold Molded
Construction, that scarves should be 12:1. Which is what he learnt working
for a company building laminated structural beams.
Stuart Crawford.
Construction, that scarves should be 12:1. Which is what he learnt working
for a company building laminated structural beams.
Stuart Crawford.
> From: Bruce Hallman <bruce@...>
> Reply-To:bolger@yahoogroups.com
> Date: Sun, 26 Mar 2006 08:09:19 -0800
> To:bolger@yahoogroups.com
> Subject: Re: [bolger] Re: Wood for Birds'mouth spars
>
>> primarily of importance to a strong scarf or finger joint is that the
>> individual components
>> have coefficients of expansion relatively similar.
>
> That is probably true, though another very important thing is the
> slope of the scarf to the direction of the grain. All things equal, a
> 10:1 scarf is stronger than a 6:1. Similar for finger joints, if the
> fingers are 10 times longer than the width they would be stronger than
> if the fingers are 6 times longer than the width.
>
>> The finger jointed material we observed on the gulf coast
>
> Do you recall what the finger joint rating was?
>
>> The rotting we observed ...NFPA
>
> Well, good point, it it pretty likely that if you read the rating
> agency 'fine print' for most of the finger joint ratings you will find
> them limited to dry use conditions.
>
>
> Bolger rules!!!
> - NO "GO AWAY SPAMMER!" posts!!! Please!
> - no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
> (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> Yahoo! Groups Links
>
>
>
>
>
>
>
--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
and application. I'm sure that the rating agencies did not factor in that a framed building
on the gulf coast can get "rained out" for 3 or 4 weeks in a row during the winter time.
This points up the fact that such use is probably not technically approved by the codes.
They would be appropriate for "build-out" studs in closed-in buildings...
>I agree. My recollection is that they were probably closer to 6::1 than 10::1...
> That is probably true, though another very important thing is the
> slope of the scarf to the direction of the grain. All things equal, a
> 10:1 scarf is stronger than a 6:1. Similar for finger joints, if the
> fingers are 10 times longer than the width they would be stronger than
> if the fingers are 6 times longer than the width.
>
> Do you recall what the finger joint rating was?Sorry I don't. This occured 10 years ago. > >The rotting we observed ...NFPA
> Well, good point, it it pretty likely that if you read the ratingI'm sure you are correct. Which points out the gap that exists on occassion between theory
> agency 'fine print' for most of the finger joint ratings you will find
> them limited to dry use conditions.
and application. I'm sure that the rating agencies did not factor in that a framed building
on the gulf coast can get "rained out" for 3 or 4 weeks in a row during the winter time.
This points up the fact that such use is probably not technically approved by the codes.
They would be appropriate for "build-out" studs in closed-in buildings...
> primarily of importance to a strong scarf or finger joint is that the individual componentsThat is probably true, though another very important thing is the
> have coefficients of expansion relatively similar.
slope of the scarf to the direction of the grain. All things equal, a
10:1 scarf is stronger than a 6:1. Similar for finger joints, if the
fingers are 10 times longer than the width they would be stronger than
if the fingers are 6 times longer than the width.
> The finger jointed material we observed on the gulf coastDo you recall what the finger joint rating was?
>The rotting we observed ...NFPAWell, good point, it it pretty likely that if you read the rating
agency 'fine print' for most of the finger joint ratings you will find
them limited to dry use conditions.
--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
lumber industry and building code approval process. Suffice it to say that I believe in the
concept of materials utilization as represented by finger jointed construction lumber, just
not in the uncritical either/or application required in the administration of the various
national building codes. Having put that aside...
Scarf joints are different than the joints in construction grade lumber in two ways:
construction lumber uses relatively short, narrow "V" shaped fingers and the fingers run
cross grain to the blocks comprising the member. Because wood typically has a greater
expansion coefficient perpindicular to the grain than parallel the glue joint comes under
greater strain IMO. Whereas a scarf runs more parallel with the grain. To some extent this
statement begs the question because both joints are subject to cross-grain shear. What is
primarily of importance to a strong scarf or finger joint is that the individual components
have coefficients of expansion relatively similar. Boat building lumber is (hopefully) of a
better quality than construction lumber and therefore more uniform in structural
characteristics from component to component.
The finger jointed material we observed on the gulf coast exhibited stair stepping at the
joints of 1/16" to 1/8" difference between adjacent components (across the 1 1/2"
dimension). This indicates to me that the scrap pile from which the components were
milled contained lumber with drastically differing structural characteristics. The rotting we
observed was highly unusual for construction lumber and there are two opinions as to its
cause: improper storage of the finished lumber (according to the NFPA) and too much
time in the scrap pile before processing (my opinion). By the way, none of my comments
apply to fingerjointed joists and rafters that use finger joints to increase length beyond
that available from current forests. These members are not typically made up of short
blocks like the studs.
One last thought -a stud is loaded primarily in compression whereas joist, rafters and
especially scarf joints in boat building are loaded in both compression and tension in
addition to bending and so the latter must meet a higher standard. Sorry for the long
winded opinion...
>This is probably not the forum to discuss the policies, procedures and politics of the
> On 3/24/06, Paul Smith <paulnsmith@...> wrote:
> > Some years ago I banned the use of finger jointed studs in the city I worked
>
> Certainly your perogative, but finger jointed 'rated' lumber is
> accepted by the LRFD and the ICBO in most jurisdictions.
>
> > I will remain highly suspicious of engineered materials ... for marine use.
>
> How do you feel about scarf joints?
>
lumber industry and building code approval process. Suffice it to say that I believe in the
concept of materials utilization as represented by finger jointed construction lumber, just
not in the uncritical either/or application required in the administration of the various
national building codes. Having put that aside...
Scarf joints are different than the joints in construction grade lumber in two ways:
construction lumber uses relatively short, narrow "V" shaped fingers and the fingers run
cross grain to the blocks comprising the member. Because wood typically has a greater
expansion coefficient perpindicular to the grain than parallel the glue joint comes under
greater strain IMO. Whereas a scarf runs more parallel with the grain. To some extent this
statement begs the question because both joints are subject to cross-grain shear. What is
primarily of importance to a strong scarf or finger joint is that the individual components
have coefficients of expansion relatively similar. Boat building lumber is (hopefully) of a
better quality than construction lumber and therefore more uniform in structural
characteristics from component to component.
The finger jointed material we observed on the gulf coast exhibited stair stepping at the
joints of 1/16" to 1/8" difference between adjacent components (across the 1 1/2"
dimension). This indicates to me that the scrap pile from which the components were
milled contained lumber with drastically differing structural characteristics. The rotting we
observed was highly unusual for construction lumber and there are two opinions as to its
cause: improper storage of the finished lumber (according to the NFPA) and too much
time in the scrap pile before processing (my opinion). By the way, none of my comments
apply to fingerjointed joists and rafters that use finger joints to increase length beyond
that available from current forests. These members are not typically made up of short
blocks like the studs.
One last thought -a stud is loaded primarily in compression whereas joist, rafters and
especially scarf joints in boat building are loaded in both compression and tension in
addition to bending and so the latter must meet a higher standard. Sorry for the long
winded opinion...
On 3/24/06, Paul Smith <paulnsmith@...> wrote:
accepted by the LRFD and the ICBO in most jurisdictions.
> Some years ago I banned the use of finger jointed studs in the city I workedCertainly your perogative, but finger jointed 'rated' lumber is
accepted by the LRFD and the ICBO in most jurisdictions.
> I will remain highly suspicious of engineered materials ... for marine use.How do you feel about scarf joints?
Some years ago I banned the use of finger jointed studs in the city I worked for because of
the substandard nature of the material. Our observation was that when the studs were
exposed to continuous moisture for about 30 days (Gulf Coast, Texas, rainy season) the
individual components reacted with different coefficients of expansion resulting in a
shearing of the joints. The individual pieces stair stepped at the joints. It wasn't clear
whether the glue failed in addition to the shear damage. As noted in an earlier post they
are intrinsically weaker as some can be literally kicked out of the framed wall -something I
wouldn't try with even the poorest conventional stud. Some of the components were
apparently pre-rotted as after 30 days some of the studs had almost totally disintegrated,
rate varying from component to component. I will remain highly suspicious of engineered
materials from the building construction industry for marine use.
the substandard nature of the material. Our observation was that when the studs were
exposed to continuous moisture for about 30 days (Gulf Coast, Texas, rainy season) the
individual components reacted with different coefficients of expansion resulting in a
shearing of the joints. The individual pieces stair stepped at the joints. It wasn't clear
whether the glue failed in addition to the shear damage. As noted in an earlier post they
are intrinsically weaker as some can be literally kicked out of the framed wall -something I
wouldn't try with even the poorest conventional stud. Some of the components were
apparently pre-rotted as after 30 days some of the studs had almost totally disintegrated,
rate varying from component to component. I will remain highly suspicious of engineered
materials from the building construction industry for marine use.
--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
>
> > The finger joint
>
> Google 'structural finger joint'.
>
> There are architectural finger joints, with a shallow 'scarf', which
> we are most familiar with with the modern wood molding you can buy at
> the lumber stores, and yes they do fail easily. Those fingers look to
> be perhaps a 4:1 slope to me, and I would not trust a 4:1 scarf joint
> either. 'Stud use' finger joints are too shallow for use in bending
> also.
>
> There are also the "structural finger joints", with very long
> 'fingers', and they are much stronger but we rarely see them for sale
> in retail stores. In short, if you can trust an 10:1 scarf joint, you
> can trust an 10:1 finger joint.
>
>http://www.fpl.fs.fed.us/documnts/pdf1998/herna98b.pdf
> etc.
>
> The finger jointGoogle 'structural finger joint'.
There are architectural finger joints, with a shallow 'scarf', which
we are most familiar with with the modern wood molding you can buy at
the lumber stores, and yes they do fail easily. Those fingers look to
be perhaps a 4:1 slope to me, and I would not trust a 4:1 scarf joint
either. 'Stud use' finger joints are too shallow for use in bending
also.
There are also the "structural finger joints", with very long
'fingers', and they are much stronger but we rarely see them for sale
in retail stores. In short, if you can trust an 10:1 scarf joint, you
can trust an 10:1 finger joint.
http://www.fpl.fs.fed.us/documnts/pdf1998/herna98b.pdf
etc.
We will have some type of engineered wood. That is chips of wood or
bamboo glued together into any number of shapes just as plywood and the
various flake boards are today. They will be improved and in various
grades intended for the different uses that we have today. My crystal
ball is getting cloudy, too cloudy. That is all today folks.
The finger joint wood would be a good product if they would use good glue
and enough that the joint is not starved. Imagine the joint properly
done with a good epoxy!
On Fri, 24 Mar 2006 20:23:20 -0000 "saillips" <saillips@...>
writes:
bamboo glued together into any number of shapes just as plywood and the
various flake boards are today. They will be improved and in various
grades intended for the different uses that we have today. My crystal
ball is getting cloudy, too cloudy. That is all today folks.
The finger joint wood would be a good product if they would use good glue
and enough that the joint is not starved. Imagine the joint properly
done with a good epoxy!
On Fri, 24 Mar 2006 20:23:20 -0000 "saillips" <saillips@...>
writes:
> --- Inbolger@yahoogroups.com, "Nels" <arvent@...> wrote:
> >Any thoughts on the stuff that is
> > scarfed into longer lengths with finger joints? I mean as far as
> using
> > it in a smaller sized birdsmouth mast such as those in the
> > Bolger/Payson line of Instant boats as well as for the mizzen on
> > larger ones.
> >
> > I guess the obvious answer is to build one and test it eh?
> >
> > Nels
> >
> Hi Nels,
> In my business (home building and remodeling) more and more
> mouldings
> that used to be solid (stain grade) are now being produced with
> shorter pieces finger jointed together ( or even extruded
> plastic!).
> The finger joint is designed to increase the surface area for a
> stronger glue joint. I can't begin to tell you how many times those
> joints have failed. Sometimes just when trying to load the stuff on
> the truck in the parking lot of the store I just purchased it in!
> Sticks of clear douglas fir used to be available at Home depot for
> a
> decent price. They haven't carried it in three years now, so in
> spite
> of warnings about rot, I've used a lot of Hemlock for my shade-tree
> boatbuilding. IMHO, stay away from the finger jointed material. The
> other question is, what will we use when the Hemlock has been
> depleted?
> David
>
>
>
>
>
> Bolger rules!!!
> - NO "GO AWAY SPAMMER!" posts!!! Please!
> - no cursing, flaming, trolling, spamming, respamming, or flogging
> dead horses
> - stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred'
> posts
> - Pls add your comments at the TOP, SIGN your posts, and snip away
> - Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930,
> Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
> - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
--- Inbolger@yahoogroups.com, "Nels" <arvent@...> wrote:
In my business (home building and remodeling) more and more mouldings
that used to be solid (stain grade) are now being produced with
shorter pieces finger jointed together ( or even extruded plastic!).
The finger joint is designed to increase the surface area for a
stronger glue joint. I can't begin to tell you how many times those
joints have failed. Sometimes just when trying to load the stuff on
the truck in the parking lot of the store I just purchased it in!
Sticks of clear douglas fir used to be available at Home depot for a
decent price. They haven't carried it in three years now, so in spite
of warnings about rot, I've used a lot of Hemlock for my shade-tree
boatbuilding. IMHO, stay away from the finger jointed material. The
other question is, what will we use when the Hemlock has been depleted?
David
>Any thoughts on the stuff that isHi Nels,
> scarfed into longer lengths with finger joints? I mean as far as using
> it in a smaller sized birdsmouth mast such as those in the
> Bolger/Payson line of Instant boats as well as for the mizzen on
> larger ones.
>
> I guess the obvious answer is to build one and test it eh?
>
> Nels
>
In my business (home building and remodeling) more and more mouldings
that used to be solid (stain grade) are now being produced with
shorter pieces finger jointed together ( or even extruded plastic!).
The finger joint is designed to increase the surface area for a
stronger glue joint. I can't begin to tell you how many times those
joints have failed. Sometimes just when trying to load the stuff on
the truck in the parking lot of the store I just purchased it in!
Sticks of clear douglas fir used to be available at Home depot for a
decent price. They haven't carried it in three years now, so in spite
of warnings about rot, I've used a lot of Hemlock for my shade-tree
boatbuilding. IMHO, stay away from the finger jointed material. The
other question is, what will we use when the Hemlock has been depleted?
David
--- Inbolger@yahoogroups.com, "J. R. Sloan" <jr_sloan@...> wrote:
that at Windsor Plywood as well.Any thoughts on the stuff that is
scarfed into longer lengths with finger joints? I mean as far as using
it in a smaller sized birdsmouth mast such as those in the
Bolger/Payson line of Instant boats as well as for the mizzen on
larger ones.
I guess the obvious answer is to build one and test it eh?
Nels
>nominal
>
> I have used both clear douglas fir and hemlock molding stock in
> 1" thicknesses. I scarfed up the appropriate lengths in the fir, buttable
> the hemlock molding stock came in 14' & 16' lengths. I used the
> saw, too, and set up a jig so the angle for the cut allowed me a 6-sided
> mast. These were both shorter masts, one for a Windsprint using theGreat to hear about the success with the hemlock as I was looking at
> balanced lug, and the other a replacement to use a jib-spritsail
> combination.
>
> JR
>
that at Windsor Plywood as well.Any thoughts on the stuff that is
scarfed into longer lengths with finger joints? I mean as far as using
it in a smaller sized birdsmouth mast such as those in the
Bolger/Payson line of Instant boats as well as for the mizzen on
larger ones.
I guess the obvious answer is to build one and test it eh?
Nels
I have used both clear douglas fir and hemlock molding stock in nominal
1" thicknesses. I scarfed up the appropriate lengths in the fir, but
the hemlock molding stock came in 14' & 16' lengths. I used the table
saw, too, and set up a jig so the angle for the cut allowed me a 6-sided
mast. These were both shorter masts, one for a Windsprint using the
balanced lug, and the other a replacement to use a jib-spritsail
combination.
JR
1" thicknesses. I scarfed up the appropriate lengths in the fir, but
the hemlock molding stock came in 14' & 16' lengths. I used the table
saw, too, and set up a jig so the angle for the cut allowed me a 6-sided
mast. These were both shorter masts, one for a Windsprint using the
balanced lug, and the other a replacement to use a jib-spritsail
combination.
JR