RE: [bolger] Re: scarfing plywood using lap joint
Actually.... Most of the Bolger boats call for butt-blocking the sheets, not
scarfing them.
-----Original Message-----
From: Nels [mailto:arvent@...]
Sent: Sunday, February 06, 2005 1:01 PM
To:bolger@yahoogroups.com
Subject: [bolger] Re: scarfing plywood using lap joint
--- Inbolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...>
wrote:
scarfing the plywood?
Of the plans I have, if you used 12:1 scarfs all the boats would end up
shorter than designed unless you scarf on some extra which of course negates
one of Bolgers greatest gifts - making the best usage of standard 8'X 4'
sheet sizes.
As mentioned earlier, the Birdwatcher calles for 3 sheets joined into one 24
foot length and ripped down the middle. How does one do this with 12:1
scarfs?
I also don't quite understand another comment that with decks, there is not
other option than scarfing. Yet none of my plans ever said that.
Curious,
Nels
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scarfing them.
-----Original Message-----
From: Nels [mailto:arvent@...]
Sent: Sunday, February 06, 2005 1:01 PM
To:bolger@yahoogroups.com
Subject: [bolger] Re: scarfing plywood using lap joint
--- Inbolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...>
wrote:
> Hi Robert,Of all the Bolger plywood plans published so far, I wonder how many call for
>
> Straight forward 12:1 scarfs are easy in plywood with nothing more
> then a SHARP hand plane.
scarfing the plywood?
Of the plans I have, if you used 12:1 scarfs all the boats would end up
shorter than designed unless you scarf on some extra which of course negates
one of Bolgers greatest gifts - making the best usage of standard 8'X 4'
sheet sizes.
As mentioned earlier, the Birdwatcher calles for 3 sheets joined into one 24
foot length and ripped down the middle. How does one do this with 12:1
scarfs?
I also don't quite understand another comment that with decks, there is not
other option than scarfing. Yet none of my plans ever said that.
Curious,
Nels
------------------------ Yahoo! Groups Sponsor --------------------~--> Help
save the life of a child. Support St. Jude Children's Research Hospital's
'Thanks & Giving.'
http://us.click.yahoo.com/6iY7fA/5WnJAA/Y3ZIAA/_0TolB/TM
--------------------------------------------------------------------~->
Bolger rules!!!
- no cursing, flaming, trolling, spamming, 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, "Peter Lenihan" <peterlenihan@h...>
wrote:
call for scarfing the plywood?
Of the plans I have, if you used 12:1 scarfs all the boats would end
up shorter than designed unless you scarf on some extra which of
course negates one of Bolgers greatest gifts - making the best usage
of standard 8'X 4' sheet sizes.
As mentioned earlier, the Birdwatcher calles for 3 sheets joined into
one 24 foot length and ripped down the middle. How does one do this
with 12:1 scarfs?
I also don't quite understand another comment that with decks, there
is not other option than scarfing. Yet none of my plans ever said
that.
Curious,
Nels
wrote:
> Hi Robert,Of all the Bolger plywood plans published so far, I wonder how many
>
> Straight forward 12:1 scarfs are easy in plywood with nothing
> more then a SHARP hand plane.
call for scarfing the plywood?
Of the plans I have, if you used 12:1 scarfs all the boats would end
up shorter than designed unless you scarf on some extra which of
course negates one of Bolgers greatest gifts - making the best usage
of standard 8'X 4' sheet sizes.
As mentioned earlier, the Birdwatcher calles for 3 sheets joined into
one 24 foot length and ripped down the middle. How does one do this
with 12:1 scarfs?
I also don't quite understand another comment that with decks, there
is not other option than scarfing. Yet none of my plans ever said
that.
Curious,
Nels
--- Inbolger@yahoogroups.com, "Robert Paquette"
<robertpaquette@o...> wrote:
used my table saw (lots of fiddling with scrap to get the depth of
cut right) to cut down the material. The joint was quite weak at
each end of the lap where the actual material thickness was only 1/8"
but once installed on the boat it was fine.
Since then I've use butt joints with a plywood backer block and been
happier with the results although they aren't quite as pretty.
Andrew Butchart
andrew@...
<robertpaquette@o...> wrote:
>the
> Every article I've read on scarfing plywood, the method used is by
> bevelling of two edges at at least a 1:8 ratio, thickness ofplywood :
> width of bevel. Why couldn't a lap joint be done (at the sameinch
> ratio), and then with a shallow countersink to accomodate a three
> fibreglass tape on both sides where the two edges meet? Let's facescarf
> it, unless you are very well equipted with machinery, a bevelled
> joint is a pretty tricky situation with a limited number of tools.procedure.
> But a lap joint, using a router would be a relatively easy
> I seen this method used in a magazine where a bulkhead in a largerI did this a few years ago on 1/4" plywood and it worked out OK. I
> sailing vessel needed to be replaced. It won't be long I'll have to
> join some plywood for my Scram Pram. Has anyone tried this method?
>
> Robert, Boatless in Niagara Falls
used my table saw (lots of fiddling with scrap to get the depth of
cut right) to cut down the material. The joint was quite weak at
each end of the lap where the actual material thickness was only 1/8"
but once installed on the boat it was fine.
Since then I've use butt joints with a plywood backer block and been
happier with the results although they aren't quite as pretty.
Andrew Butchart
andrew@...
> Add one right angle grinderWhich size and brand name to you prefer?
> Peter Lenihan
--- Inbolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...> wrote:
Robert
PS: yes, it is quite mild... it's really nice to able to go and walk
on sidewalks again. Our sidewalks had been iced up for about three weeks.
> Hi Robert,sounds exciting... would you expand and explain your system?
>
> Straight forward 12:1 scarfs are easy in plywood with nothing
> more then a SHARP hand plane.Add one right angle grinder to the kit
> and you're popping out scarfs fast...really fast.
Robert
PS: yes, it is quite mild... it's really nice to able to go and walk
on sidewalks again. Our sidewalks had been iced up for about three weeks.
In some situations you don't have the choice but bevel scarphing, for
example on laying a plywood deck on deck beams scarphed in place. You
can't rout out the countersink from below as your laps will lie on the
beams.
I do my scarphing with a power plane and finish them with a block
plane. I don't own a router and that tool is still very low on my list
of tools to get because of the cost of bits. Keep it simple.
Scarphing ply is easier than scarphing lumber because the lines of the
plies tell you if you scarph is perfectly plane.
Thierry
example on laying a plywood deck on deck beams scarphed in place. You
can't rout out the countersink from below as your laps will lie on the
beams.
I do my scarphing with a power plane and finish them with a block
plane. I don't own a router and that tool is still very low on my list
of tools to get because of the cost of bits. Keep it simple.
Scarphing ply is easier than scarphing lumber because the lines of the
plies tell you if you scarph is perfectly plane.
Thierry
> Every article I've read on scarfing plywood, the method used is by the
> bevelling of two edges at at least a 1:8 ratio, thickness of plywood :
> width of bevel. Why couldn't a lap joint be done (at the same
> ratio), and then with a shallow countersink to accomodate a three inch
> fibreglass tape on both sides where the two edges meet? Let's face
> it, unless you are very well equipted with machinery, a bevelled scarf
> joint is a pretty tricky situation with a limited number of tools.
> But a lap joint, using a router would be a relatively easy procedure.
> I seen this method used in a magazine where a bulkhead in a larger
> sailing vessel needed to be replaced. It won't be long I'll have to
> join some plywood for my Scram Pram. Has anyone tried this method?
>
> Robert, Boatless in Niagara Falls
I replaced the bulkhead in my boat and it may well have been one of my
articles. The reason for using a stepped lap in that situation was that
there simply wasn't room to cut a normal scarf - room for the plane to cut
the scarf.
Chesapeake light craft uses a stepped scarf, with about three steps per
scarf, I think. they cut them on their CNC mill with great accuracy.
In normal scarfing, I think the 12 to 1 taper is still easier to do - with
sharp tools.
Just my $.02
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
Published in Small Craft Advisor, SAIL,
Living Aboard, Boatbuilder, Good Old
Boat, Blue Water Sailing, Nor'easter
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
articles. The reason for using a stepped lap in that situation was that
there simply wasn't room to cut a normal scarf - room for the plane to cut
the scarf.
Chesapeake light craft uses a stepped scarf, with about three steps per
scarf, I think. they cut them on their CNC mill with great accuracy.
In normal scarfing, I think the 12 to 1 taper is still easier to do - with
sharp tools.
Just my $.02
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
Published in Small Craft Advisor, SAIL,
Living Aboard, Boatbuilder, Good Old
Boat, Blue Water Sailing, Nor'easter
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
--- Inbolger@yahoogroups.com, "Robert Paquette"
<robertpaquette@o...> wrote:
Straight forward 12:1 scarfs are easy in plywood with nothing
more then a SHARP hand plane.Add one right angle grinder to the kit
and you're popping out scarfs fast...really fast.Things can go fast
too since you can stack many sheets of ply together to go at all at
once.The laminations or glue lines make perfect self aligning
indicaters of how your work is progressing.
Can't help with comments on your idea for a lap joint as I don't
own a router.......
Has it been as mild in your neck of the woods as it has been
further downstream from you? Can you Spring has sprung? HEEEHAWWW!!!
Sincerely,
Peter Lenihan
<robertpaquette@o...> wrote:
>Let's face
> it, unless you are very well equipted with machinery, a bevelledscarf
> joint is a pretty tricky situation with a limited number of tools.procedure.
> But a lap joint, using a router would be a relatively easy
> I seen this method used in a magazine where a bulkhead in a largerto
> sailing vessel needed to be replaced. It won't be long I'll have
> join some plywood for my Scram Pram. Has anyone tried this method?Hi Robert,
>
> Robert, Boatless in Niagara Falls
Straight forward 12:1 scarfs are easy in plywood with nothing
more then a SHARP hand plane.Add one right angle grinder to the kit
and you're popping out scarfs fast...really fast.Things can go fast
too since you can stack many sheets of ply together to go at all at
once.The laminations or glue lines make perfect self aligning
indicaters of how your work is progressing.
Can't help with comments on your idea for a lap joint as I don't
own a router.......
Has it been as mild in your neck of the woods as it has been
further downstream from you? Can you Spring has sprung? HEEEHAWWW!!!
Sincerely,
Peter Lenihan
--- Inbolger@yahoogroups.com, "Robert Paquette"
<robertpaquette@o...> wrote:
will have to be perfect on both pieces of plywood to get a smooth
sheet. Likely not much harder to get right than a scarf but the
scarf would be stronger.
A butt joint with two layers of 9 oz cloth on both sides should be
as strong as the plywood. The router may be used to counter sink
the figerglass to ensure a smooth panel unless the sheets are too
thin to allow the loss of thickness.
Another option is to cut a "keyed" pattern on the end of one sheet,
lay the keyed end on top of the uncut sheet and mark the inverse
pattern on that sheet. Cut the pattern on the second sheet and the
two should interlock like a picture puzzle. After checking for fit,
wet out both ends, lay on a sheet of plastic, butter the keyed areas
with epoxy putty and lay the two together interlocked. A second
sheet of plastic is placed on top, a piece of scrap lumber and then
a weight to hold the sheets in alignment until the expoy sets.
The key width needs to be at least 8 X tickness of the plywood with
at least 2 or 3 "keyed" patterns per foot.
The keyed joint may also be glassed if need be. The top layer of
glass could go on under the plastic and weights.
A simple wooden jig that will support your router can be made with a
slope that matches the desired scarf angle. I use a jig with one end
off the plywood on a level work surface and the other end on the
wood with the reqired difference in height to get the desired angle
to yeild a 8 X thickness scarf length. A slot is cut in the jig to
allow the router to travel the 2 to 6 inches needed for your plywood
thickness. Just move the jig over the width of your cutting tool
for each stroke until the width is completed. The off sheet cross
piece on the jig "hooks" on the end of the plywood sheet being cut
so the cut will be uniform across the entire end of the sheet. The
cross piece on the other end of the jig (the one that sits on top of
the plywood sheet)may be made adjustable with a couple bolts with
locking nut to act as "feet" to slide on the work. I adjust
the "feet" until I get the desired cut on a piece of scrap wood the
same thickness of the work being done.
I have used this method to help shape a large leeboard with good
results.
David Davis
<robertpaquette@o...> wrote:
>the
> Every article I've read on scarfing plywood, the method used is by
> bevelling of two edges at at least a 1:8 ratio, thickness ofplywood :
> width of bevel. Why couldn't a lap joint be done (at the sameinch
> ratio), and then with a shallow countersink to accomodate a three
> fibreglass tape on both sides where the two edges meet? Let's facescarf
> it, unless you are very well equipted with machinery, a bevelled
> joint is a pretty tricky situation with a limited number of tools.procedure.
> But a lap joint, using a router would be a relatively easy
> I seen this method used in a magazine where a bulkhead in a largerto
> sailing vessel needed to be replaced. It won't be long I'll have
> join some plywood for my Scram Pram. Has anyone tried this method?Robert the lap joint is not often seen because the depth of the cut
will have to be perfect on both pieces of plywood to get a smooth
sheet. Likely not much harder to get right than a scarf but the
scarf would be stronger.
A butt joint with two layers of 9 oz cloth on both sides should be
as strong as the plywood. The router may be used to counter sink
the figerglass to ensure a smooth panel unless the sheets are too
thin to allow the loss of thickness.
Another option is to cut a "keyed" pattern on the end of one sheet,
lay the keyed end on top of the uncut sheet and mark the inverse
pattern on that sheet. Cut the pattern on the second sheet and the
two should interlock like a picture puzzle. After checking for fit,
wet out both ends, lay on a sheet of plastic, butter the keyed areas
with epoxy putty and lay the two together interlocked. A second
sheet of plastic is placed on top, a piece of scrap lumber and then
a weight to hold the sheets in alignment until the expoy sets.
The key width needs to be at least 8 X tickness of the plywood with
at least 2 or 3 "keyed" patterns per foot.
The keyed joint may also be glassed if need be. The top layer of
glass could go on under the plastic and weights.
A simple wooden jig that will support your router can be made with a
slope that matches the desired scarf angle. I use a jig with one end
off the plywood on a level work surface and the other end on the
wood with the reqired difference in height to get the desired angle
to yeild a 8 X thickness scarf length. A slot is cut in the jig to
allow the router to travel the 2 to 6 inches needed for your plywood
thickness. Just move the jig over the width of your cutting tool
for each stroke until the width is completed. The off sheet cross
piece on the jig "hooks" on the end of the plywood sheet being cut
so the cut will be uniform across the entire end of the sheet. The
cross piece on the other end of the jig (the one that sits on top of
the plywood sheet)may be made adjustable with a couple bolts with
locking nut to act as "feet" to slide on the work. I adjust
the "feet" until I get the desired cut on a piece of scrap wood the
same thickness of the work being done.
I have used this method to help shape a large leeboard with good
results.
David Davis
Every article I've read on scarfing plywood, the method used is by the
bevelling of two edges at at least a 1:8 ratio, thickness of plywood :
width of bevel. Why couldn't a lap joint be done (at the same
ratio), and then with a shallow countersink to accomodate a three inch
fibreglass tape on both sides where the two edges meet? Let's face
it, unless you are very well equipted with machinery, a bevelled scarf
joint is a pretty tricky situation with a limited number of tools.
But a lap joint, using a router would be a relatively easy procedure.
I seen this method used in a magazine where a bulkhead in a larger
sailing vessel needed to be replaced. It won't be long I'll have to
join some plywood for my Scram Pram. Has anyone tried this method?
Robert, Boatless in Niagara Falls
bevelling of two edges at at least a 1:8 ratio, thickness of plywood :
width of bevel. Why couldn't a lap joint be done (at the same
ratio), and then with a shallow countersink to accomodate a three inch
fibreglass tape on both sides where the two edges meet? Let's face
it, unless you are very well equipted with machinery, a bevelled scarf
joint is a pretty tricky situation with a limited number of tools.
But a lap joint, using a router would be a relatively easy procedure.
I seen this method used in a magazine where a bulkhead in a larger
sailing vessel needed to be replaced. It won't be long I'll have to
join some plywood for my Scram Pram. Has anyone tried this method?
Robert, Boatless in Niagara Falls