[bolger] Re: Double Eagle, e-mail , but joints
A 4 and 1/2 inch high speed grinder is my choice. I have used it to make
bevels but the trick is to remember to do it. Clyde Wisner
Lincoln Ross wrote:
Any reason one couldn't bevel the edges of a butt strap with a plane?
If your plane is really sharp this is pretty easy to do. I shaped a
plywood rudder this way. Ought to reduce the stress concentration. Also
ought to make easier to clean, etc. Those with fancy table saw jigs
could probably do it even easier.
david jost <djos-@...> wrote:
snip The internal
> butt straps also work fine, but have tendency to collect dirt and
hold water
> where I don't want it.
>snip
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I've had good luck with the bevels on butt strps, but wonder why the
aversion to scarfs. I rough cut mine with an electic plane and finish them
with a low angle block plane. Before the electric plane I did the whole job
with a block plane. Takes about 30 minutes. I've never had on fail and I'm
no artist ! :)
Rennie
aversion to scarfs. I rough cut mine with an electic plane and finish them
with a low angle block plane. Before the electric plane I did the whole job
with a block plane. Takes about 30 minutes. I've never had on fail and I'm
no artist ! :)
Rennie
>From: "Lincoln Ross" <lincolnr@...>______________________________________________________
>Reply-To:bolger@egroups.com
>To:bolger@...
>Subject: [bolger] Re: Double Eagle, e-mail , but joints
>Date: Sat, 29 Jan 2000 07:38:46 -0800
>
>Any reason one couldn't bevel the edges of a butt strap with a plane?
>If your plane is really sharp this is pretty easy to do. I shaped a
>plywood rudder this way. Ought to reduce the stress concentration. Also
>ought to make easier to clean, etc. Those with fancy table saw jigs
>could probably do it even easier.
>david jost <djos-@...> wrote:
>snip The internal
> > butt straps also work fine, but have tendency to collect dirt and
>hold water
> > where I don't want it.
> >snip
>
>
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yes, the reason I used a disk grinder was that I had temporarily
taped the two pieces of plywood together end to end. Then I ground
out a small cavity. It was pretty brainless but looked good.
No failures after 10 years of hard use.
Lincoln Ross wrote:
Any reason one couldn't bevel the edges of a butt strap with a plane?
If your plane is really sharp this is pretty easy to do. I shaped a
plywood rudder this way. Ought to reduce the stress concentration. Also
ought to make easier to clean, etc. Those with fancy table saw jigs
could probably do it even easier.
david jost <djos-@...> wrote:
snip The internal
> butt straps also work fine, but have tendency to collect dirt and
hold water
> where I don't want it.
>snip
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Any reason one couldn't bevel the edges of a butt strap with a plane?
If your plane is really sharp this is pretty easy to do. I shaped a
plywood rudder this way. Ought to reduce the stress concentration. Also
ought to make easier to clean, etc. Those with fancy table saw jigs
could probably do it even easier.
david jost <djos-@...> wrote:
snip The internal
If your plane is really sharp this is pretty easy to do. I shaped a
plywood rudder this way. Ought to reduce the stress concentration. Also
ought to make easier to clean, etc. Those with fancy table saw jigs
could probably do it even easier.
david jost <djos-@...> wrote:
snip The internal
> butt straps also work fine, but have tendency to collect dirt andhold water
> where I don't want it.
>snip
Phil,
I have built two boats a 10.5 pointy skiff out of Payson's book, and a Diablo from plans. I used the taped scarfs in the Diablo and butt straps in the Pointy Skiff. and they are absolutely as strong as the rest for the boat. I hollowed out the inside slightly with a disk grinder then put on three layers of varying widths on the inside and one on the outside. After I faired the outside and applied a layer of cloth over the entire boat, there is no bump on the outside at all. Very strong and very light. The internal butt straps also work fine, but have tendency to collect dirt and hold water where I don't want it.
I have built two boats a 10.5 pointy skiff out of Payson's book, and a Diablo from plans. I used the taped scarfs in the Diablo and butt straps in the Pointy Skiff. and they are absolutely as strong as the rest for the boat. I hollowed out the inside slightly with a disk grinder then put on three layers of varying widths on the inside and one on the outside. After I faired the outside and applied a layer of cloth over the entire boat, there is no bump on the outside at all. Very strong and very light. The internal butt straps also work fine, but have tendency to collect dirt and hold water where I don't want it.
David Jost
Giuseppe 'Pippo' Bianco wrote:
Phil,
I made a test fiberglass/epoxy butt joint with 10 mm (3/8") plywood for
my Micro. I used biaxial cloth: 400 g/m^2 (12 oz) outside and 300 g/m^2
(9 oz) inside. In such an arrangement, the biaxial tape is stronger with
respect to normal cloth by a factor of 1.4. Actually there is no glass
thread that runs at 0 degress nor ar 90 degrees, except a light
longitudinal stitching to avoid unraveling. This cloth though is a
little bulkier that an equal weight normal cloth. I don't expect this to
be a problem though and imagine a bit of light putty and sanding would
make the joint invisible.
By the way, such a joint resulted to me both stronger and more flexible
than the plywood butt block. I used the Carnell/Payson method, i.e. I
did both sides in one time.
Best, Pippo
Phillip Lea ha scritto:
>
> Justin Pipkorn of Thousand Oaks, California uses a biaxial glass
tape
> for strength at butt joints. The tape is made with heavier
threads
> that go across the width of the tape and the joint for tensile
> strength. There are only very light threads that run the length
of the
> tape, which once on the boat provide only useless bulk. One could
use
> glass cloth cut in diagonal strips so that each of the fibers would
> contribute to the strength of the joint while minimizing bulk.
I have
> done this with 4 oz. cloth and it makes a very low buildup.
Total
> strength of the joint will also depend on location of skids, etc.
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Phil,
I made a test fiberglass/epoxy butt joint with 10 mm (3/8") plywood for
my Micro. I used biaxial cloth: 400 g/m^2 (12 oz) outside and 300 g/m^2
(9 oz) inside. In such an arrangement, the biaxial tape is stronger with
respect to normal cloth by a factor of 1.4. Actually there is no glass
thread that runs at 0 degress nor ar 90 degrees, except a light
longitudinal stitching to avoid unraveling. This cloth though is a
little bulkier that an equal weight normal cloth. I don't expect this to
be a problem though and imagine a bit of light putty and sanding would
make the joint invisible.
By the way, such a joint resulted to me both stronger and more flexible
than the plywood butt block. I used the Carnell/Payson method, i.e. I
did both sides in one time.
Best, Pippo
Phillip Lea ha scritto:
I made a test fiberglass/epoxy butt joint with 10 mm (3/8") plywood for
my Micro. I used biaxial cloth: 400 g/m^2 (12 oz) outside and 300 g/m^2
(9 oz) inside. In such an arrangement, the biaxial tape is stronger with
respect to normal cloth by a factor of 1.4. Actually there is no glass
thread that runs at 0 degress nor ar 90 degrees, except a light
longitudinal stitching to avoid unraveling. This cloth though is a
little bulkier that an equal weight normal cloth. I don't expect this to
be a problem though and imagine a bit of light putty and sanding would
make the joint invisible.
By the way, such a joint resulted to me both stronger and more flexible
than the plywood butt block. I used the Carnell/Payson method, i.e. I
did both sides in one time.
Best, Pippo
Phillip Lea ha scritto:
>
> Justin Pipkorn of Thousand Oaks, California uses a biaxial glass tape
> for strength at butt joints. The tape is made with heavier threads
> that go across the width of the tape and the joint for tensile
> strength. There are only very light threads that run the length of the
> tape, which once on the boat provide only useless bulk. One could use
> glass cloth cut in diagonal strips so that each of the fibers would
> contribute to the strength of the joint while minimizing bulk. I have
> done this with 4 oz. cloth and it makes a very low buildup. Total
> strength of the joint will also depend on location of skids, etc.
Justin Pipkorn of Thousand Oaks, California uses a biaxial glass tape
for strength at butt joints. The tape is made with heavier threads
that go across the width of the tape and the joint for tensile
strength. There are only very light threads that run the length of the
tape, which once on the boat provide only useless bulk. One could use
glass cloth cut in diagonal strips so that each of the fibers would
contribute to the strength of the joint while minimizing bulk. I have
done this with 4 oz. cloth and it makes a very low buildup. Total
strength of the joint will also depend on location of skids, etc.
6" of snow outside -- first snow in three years. Nothing like mountain
biking in fresh snow! A little snow on the ground (6" is a little
deep) lets a mountain bike climb these Ozark hills better than the
4-wheel drives.
Phil Lea, Russellville, Arkansas
"fritz koschmann" <fritzdf-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2070
for strength at butt joints. The tape is made with heavier threads
that go across the width of the tape and the joint for tensile
strength. There are only very light threads that run the length of the
tape, which once on the boat provide only useless bulk. One could use
glass cloth cut in diagonal strips so that each of the fibers would
contribute to the strength of the joint while minimizing bulk. I have
done this with 4 oz. cloth and it makes a very low buildup. Total
strength of the joint will also depend on location of skids, etc.
6" of snow outside -- first snow in three years. Nothing like mountain
biking in fresh snow! A little snow on the ground (6" is a little
deep) lets a mountain bike climb these Ozark hills better than the
4-wheel drives.
Phil Lea, Russellville, Arkansas
"fritz koschmann" <fritzdf-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2070
> Yes there is a "lump" and it is approximately .025 inch at the highestThe
> point, with 6 oz cloth, and nicely tapered to zero at each edge of the
> joint because of the increasingly wider cloth strip in each layer.
> first layer is 2-3" the second 4-5" and the third 6-7". On the outside
> of the hull at least one more layer is applied overall. Regular tape
> does not work because of the selvage edge. This joint is basically
> invisible especially if you want to extend the taper a little further
> with an epoxy fairing compound but I don't think it is necessary.I
> might also mention that I saturate the end grain with resin and use
> well thickened epoxy between the butting edges when assembling the
> joint.
>
That sounds like the strongest option. A few years ago my daughter did a
technical project at school, testing the various ways of joining sheets of
ply - Your method was WAY stronger than scarfing or butt blocks.
Regarding the lump - It's safe to say that after you've faired and sanded
everything, the best 'lump test' is to run your fingertips along the
surface. If you can't feel any lump, then it won't show even with gloss
paint. A French polisher showed me this trick - the fingertips are very
sensitive to the smallest irregularities.
Bill
technical project at school, testing the various ways of joining sheets of
ply - Your method was WAY stronger than scarfing or butt blocks.
Regarding the lump - It's safe to say that after you've faired and sanded
everything, the best 'lump test' is to run your fingertips along the
surface. If you can't feel any lump, then it won't show even with gloss
paint. A French polisher showed me this trick - the fingertips are very
sensitive to the smallest irregularities.
Bill
>From: "Fritz Koschmann" <fritzdfk@...>______________________________________________________
>Reply-To:bolger@egroups.com
>To:bolger@...
>Subject: [bolger] Re: Double Eagle, e-mail , but joints
>Date: Thu, 27 Jan 2000 23:28:40 -0800
>
>Yes there is a "lump" and it is approximately .025 inch at the highest
>point, with 6 oz cloth, and nicely tapered to zero at each edge of the
>joint because of the increasingly wider cloth strip in each layer. The
>first layer is 2-3" the second 4-5" and the third 6-7". On the outside
>of the hull at least one more layer is applied overall. Regular tape
>does not work because of the selvage edge. This joint is basically
>invisible especially if you want to extend the taper a little further
>with an epoxy fairing compound but I don't think it is necessary.I
>might also mention that I saturate the end grain with resin and use
>well thickened epoxy between the butting edges when assembling the
>joint.
>
>
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Yes there is a "lump" and it is approximately .025 inch at the highest
point, with 6 oz cloth, and nicely tapered to zero at each edge of the
joint because of the increasingly wider cloth strip in each layer. The
first layer is 2-3" the second 4-5" and the third 6-7". On the outside
of the hull at least one more layer is applied overall. Regular tape
does not work because of the selvage edge. This joint is basically
invisible especially if you want to extend the taper a little further
with an epoxy fairing compound but I don't think it is necessary.I
might also mention that I saturate the end grain with resin and use
well thickened epoxy between the butting edges when assembling the
joint.
point, with 6 oz cloth, and nicely tapered to zero at each edge of the
joint because of the increasingly wider cloth strip in each layer. The
first layer is 2-3" the second 4-5" and the third 6-7". On the outside
of the hull at least one more layer is applied overall. Regular tape
does not work because of the selvage edge. This joint is basically
invisible especially if you want to extend the taper a little further
with an epoxy fairing compound but I don't think it is necessary.I
might also mention that I saturate the end grain with resin and use
well thickened epoxy between the butting edges when assembling the
joint.
> Doesn't that leave a lump on the hull?Seems to me it would. Last time around, I used an angle grinder with a
sanding disk and sanded a shallow cove about 1/8" deep and 5" wide. Cover
with a couple of layers of glass tape and resin, belt sand flush, turn
over, and repeat. I'm happy.
Chuck
"fritz koschmann" <fritzdf-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2062
original article:http://www.egroups.com/group/bolger/?start=2062
> Robert Norris requested my correct e-mail address, it is:might
>fritzdfk@.... I would be glad to answer any questions anyone
> have.is
>
> There was a scarfing thread a while ago and I thought I might add my
> two cents.
> I started with Payson joints as described in my building guide. That
> basically butting the plywood together, running a power planer downthe
> joint and filling the "valley" with three layers of tape and epoxy.three
> This worked fairly well but the planer always left a very ragged
> surface in the 1/2" fir ply I am using. The added time fairing the
> surface before tapeing was annoying and I noticed that when breaking
> test joints they usually broke along the edge of the planed valley.
> When my planer died while shapeing the second outside bow stem I
> decided to do away with the valleys and lay up the butjoints with
> layers of cut strips (not tape) of cloth all at once starting with theDoesn't that leave a lump on the hull?
> narrowest first. This is basically the method described by David
> Carnell. The joints when finished are very hard or impossible to tell
> from the others and though I have not tested them I feel better not
> removing wood and I think the stresses are more spread out. I do one
> side at a time and then flip the panel for the other side, even on the
> fourty foot panels this isn't a problem if you have some help. PS, I
> got a new Dewalt planer for Christmas.
Robert Norris requested my correct e-mail address, it is:
fritzdfk@.... I would be glad to answer any questions anyone might
have.
There was a scarfing thread a while ago and I thought I might add my
two cents.
I started with Payson joints as described in my building guide. That is
basically butting the plywood together, running a power planer down the
joint and filling the "valley" with three layers of tape and epoxy.
This worked fairly well but the planer always left a very ragged
surface in the 1/2" fir ply I am using. The added time fairing the
surface before tapeing was annoying and I noticed that when breaking
test joints they usually broke along the edge of the planed valley.
When my planer died while shapeing the second outside bow stem I
decided to do away with the valleys and lay up the butjoints with three
layers of cut strips (not tape) of cloth all at once starting with the
narrowest first. This is basically the method described by David
Carnell. The joints when finished are very hard or impossible to tell
from the others and though I have not tested them I feel better not
removing wood and I think the stresses are more spread out. I do one
side at a time and then flip the panel for the other side, even on the
fourty foot panels this isn't a problem if you have some help. PS, I
got a new Dewalt planer for Christmas.
fritzdfk@.... I would be glad to answer any questions anyone might
have.
There was a scarfing thread a while ago and I thought I might add my
two cents.
I started with Payson joints as described in my building guide. That is
basically butting the plywood together, running a power planer down the
joint and filling the "valley" with three layers of tape and epoxy.
This worked fairly well but the planer always left a very ragged
surface in the 1/2" fir ply I am using. The added time fairing the
surface before tapeing was annoying and I noticed that when breaking
test joints they usually broke along the edge of the planed valley.
When my planer died while shapeing the second outside bow stem I
decided to do away with the valleys and lay up the butjoints with three
layers of cut strips (not tape) of cloth all at once starting with the
narrowest first. This is basically the method described by David
Carnell. The joints when finished are very hard or impossible to tell
from the others and though I have not tested them I feel better not
removing wood and I think the stresses are more spread out. I do one
side at a time and then flip the panel for the other side, even on the
fourty foot panels this isn't a problem if you have some help. PS, I
got a new Dewalt planer for Christmas.