I am building a headboard that requires an arched border along the top
edge. The border is 3 1/2 inches tall (the side that faces outward)
and 1 1/2 inches thick (top edge). So it's not the type of arc that
can be bent.
My plan was to piece 5 wide straight segments together with angled
joints then cut the arc from this. The segments would be 22" long for
the center and 2 14" segments on each side. I started worrying,
however about the integrity of the joints. First, they would be end
grain to end grain - I could do a lap joint or a dado to help with
that (I don't think biscuits would be enough). Second, I was worried
about the wood movement. As the segments swelled, on the convex side
of the arc the joints would grow apart, and on the concave side they
would push toward each other. I thought this might make the joint
break.
Does anyone have experience with something like this? Is there any
other way to do it? Should I have smaller segments between joints?
Is there enough movement in 3 1/2 inches to cause any problems?
This is my first commissioned piece for someone else, so I really want
to get it right.
Thanks for any advice you can give.
Jodi
>I am building a headboard that requires an arched border along the top
>edge. The border is 3 1/2 inches tall (the side that faces outward)
>and 1 1/2 inches thick (top edge). So it's not the type of arc that
>can be bent.
>
>My plan was to piece 5 wide straight segments together with angled
>joints then cut the arc from this. The segments would be 22" long for
>the center and 2 14" segments on each side. I started worrying,
>however about the integrity of the joints. First, they would be end
>grain to end grain - I could do a lap joint or a dado to help with
>that (I don't think biscuits would be enough). Second, I was worried
>about the wood movement. As the segments swelled, on the convex side
>of the arc the joints would grow apart, and on the concave side they
>would push toward each other. I thought this might make the joint
>break.
>
>Does anyone have experience with something like this? Is there any
>other way to do it? Should I have smaller segments between joints?
>Is there enough movement in 3 1/2 inches to cause any problems?
>
>This is my first commissioned piece for someone else, so I really want
>to get it right.
>
>Thanks for any advice you can give.
>
>Jodi
>
>
I would stack them long grain to long grain.
If your gonna join end grain to end grain,a finger joint would be the best way
to make the joint. However if the piece is to be finished natural or stained,
it's very hard to make the joints dissapear.
You could do the end grain if you used a
spline joint. You can make a deep spline
cut using the table saw (and a lot of
caution) I wouldn't worry too much about
the joint shrinking apart if the piece is
going to be kept indoors. Clamping
might take a little engineering if you use
aliphatic resin glue (titebond) For joints
where only minimal clamping can be used,
I use a heavy-bodied, 2 part epoxy from
Clearcote Corp. They're in Florida, the
number is 727-898-8611.
On Wed, 13 Aug 2003 03:42:21 GMT, "Lew Hodgett"
<[email protected]> pixelated:
>
>"Jodi" writes:
>
>> If I did a stacked laminate, how much spring back should I expect?
><snip>
>
>I jumped into this late so may have missed something; however. if you are
>considering laminating, go to the library and get Fred Bingham's book,
>"Practical Yacht Joinery".
>
>It is an impossibility to build a decent wooden boat without laminating some
>beams.
>
>Bingham goes into considerable detail including sketches, describing the
>process.
How do you feel about "Yacht Construction" by K. H. C. Jurd?
It's in the local library while Bingham's isn't.
-
Press HERE to arm. (Release to detonate.)
-----------
http://diversify.com Website Application Programming
On 12 Aug 2003 19:52:57 -0700, [email protected] (Jodi) Crawled
out of the shop and said. . .:
snip
>If I did a stacked laminate, how much spring back should I expect?
>The width of the arc end to end is 75" and it has about a 6"
>difference between top of the arc and the bottom. Is it enough to
>need to build the form with more of an arc than I need in the end?
yes
however, with the poly glue, you can eliminate alot of the springback.
make the arc about 10% more aggressive than the final form desired.
M&T joinery will "lock" the final arc so it wont move.
>
>Also, I know the process that you go through to make a form and
>laminate the strips, but I've never done it. I can't picture what the
>final front face would look like when just finished naturally. I'd
>imagine that you could tell that it's a bunch of laminated strips from
>the stuttering of the grain pattern. Is that how it looks or does it
>look pretty much like a single naturally curved piece of wood? In
>other words, would the manner of construction be less obvious than the
>straight segment method?
cut the laminates from a single piece of stock. use the bandsaw to cut
them, and you wont notice much of the seams at all. here are a few
tips for doing just that.
1: after you have all the strips cut, align the grain so it matches
the best, and mark a triangle across the face of the seams.
this helps you to align them without much guesswork when glueing up
the piece.
2: and this one is REAL important. as you cut the strips, mark each
face with a number or letter. first cut, mark a "1" on the faces you
just cut. this helps keep them in order if you mix them up.
>
>And finally, I don't have enough clamps to do the laminate unless the
>quick clamps have enough pressure to work. Since you say to not use
>too much pressure I'm assuming that they'd be OK. Do you think?
quick clamps should have plenty of force to keep the form tight
enough.
remember, you have 2(two) opposing pieces of bending jig that helps
spread the clamping force over the entire glueup.
use plenty of them. if you don't have enough of them, BUY them BEFORE
you start your glueup. DAMHIKT :((
bar clamps are cheap enough so that no one should be without enough of
those.
i own several of the "el-cheepo" brand sold at menards or HD
>
>Thanks,
never a problem, that's why we do what we do! :)
Traves
You can make it from 3/4" x 3 1/2" pieces, gluing them together side by side
and alternating the joints. Or, you can make a form and glue up enough
strips, say 1/4" x 1 1/2" to make the 3 1/2" high arch. If you do the side
by side, make sure the joints that show are evenly spaced.
Preston
"Jodi" <[email protected]> wrote in message
news:[email protected]...
> I am building a headboard that requires an arched border along the top
> edge. The border is 3 1/2 inches tall (the side that faces outward)
> and 1 1/2 inches thick (top edge). So it's not the type of arc that
> can be bent.
>
> My plan was to piece 5 wide straight segments together with angled
> joints then cut the arc from this. The segments would be 22" long for
> the center and 2 14" segments on each side. I started worrying,
> however about the integrity of the joints. First, they would be end
> grain to end grain - I could do a lap joint or a dado to help with
> that (I don't think biscuits would be enough). Second, I was worried
> about the wood movement. As the segments swelled, on the convex side
> of the arc the joints would grow apart, and on the concave side they
> would push toward each other. I thought this might make the joint
> break.
>
> Does anyone have experience with something like this? Is there any
> other way to do it? Should I have smaller segments between joints?
> Is there enough movement in 3 1/2 inches to cause any problems?
>
> This is my first commissioned piece for someone else, so I really want
> to get it right.
>
> Thanks for any advice you can give.
>
> Jodi
Traves W. Coppock <[email protected]> wrote in message news:<[email protected]>...
> On Sat, 09 Aug 2003 23:38:11 GMT, "Preston Andreas"
> <[email protected]> Crawled out of the shop and said. . .:
>
> >You can make it from 3/4" x 3 1/2" pieces, gluing them together side by side
> >and alternating the joints. Or, you can make a form and glue up enough
> >strips, say 1/4" x 1 1/2" to make the 3 1/2" high arch. If you do the side
> >by side, make sure the joints that show are evenly spaced.
> >
> snip
>
> gotta agree with Preston on this one, lamination bending would be my
> choice here.
> one caveat tho, use a poly urethane glue. it will hold better, and
> produces much less "springback" of the material when released from the
> clamping form. and, as an added bonus, it gives you much more open
> time when stacking the laminations in the form.
> use one clamp for every 5" of length, and do not, i repeat DO NOT
> apply too much clamping pressure. poly urethane glue expands alot!
> DAMHIKT
>
> Traves
If I did a stacked laminate, how much spring back should I expect?
The width of the arc end to end is 75" and it has about a 6"
difference between top of the arc and the bottom. Is it enough to
need to build the form with more of an arc than I need in the end?
Also, I know the process that you go through to make a form and
laminate the strips, but I've never done it. I can't picture what the
final front face would look like when just finished naturally. I'd
imagine that you could tell that it's a bunch of laminated strips from
the stuttering of the grain pattern. Is that how it looks or does it
look pretty much like a single naturally curved piece of wood? In
other words, would the manner of construction be less obvious than the
straight segment method?
And finally, I don't have enough clamps to do the laminate unless the
quick clamps have enough pressure to work. Since you say to not use
too much pressure I'm assuming that they'd be OK. Do you think?
Thanks,
Jodi
On Sat, 09 Aug 2003 23:38:11 GMT, "Preston Andreas"
<[email protected]> Crawled out of the shop and said. . .:
>You can make it from 3/4" x 3 1/2" pieces, gluing them together side by side
>and alternating the joints. Or, you can make a form and glue up enough
>strips, say 1/4" x 1 1/2" to make the 3 1/2" high arch. If you do the side
>by side, make sure the joints that show are evenly spaced.
>
snip
gotta agree with Preston on this one, lamination bending would be my
choice here.
one caveat tho, use a poly urethane glue. it will hold better, and
produces much less "springback" of the material when released from the
clamping form. and, as an added bonus, it gives you much more open
time when stacking the laminations in the form.
use one clamp for every 5" of length, and do not, i repeat DO NOT
apply too much clamping pressure. poly urethane glue expands alot!
DAMHIKT
Traves
"Jodi" writes:
> If I did a stacked laminate, how much spring back should I expect?
<snip>
I jumped into this late so may have missed something; however. if you are
considering laminating, go to the library and get Fred Bingham's book,
"Practical Yacht Joinery".
It is an impossibility to build a decent wooden boat without laminating some
beams.
Bingham goes into considerable detail including sketches, describing the
process.
HTH
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures
"Larry Jaques" writes:
> How do you feel about "Yacht Construction" by K. H. C. Jurd?
> It's in the local library while Bingham's isn't.
I'm not familiar with it but you can buy Bingham's book for about $20 on
Amazon.
IMHO, it's a great reference for someone interested in general woodworking,
not just boat building.
HTH
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures