Cutting scarfs
 

Started working on my Tolman Skiff. I began by cutting the bottom
pieces from 1/2 marine ply but these have to be scarfed together to
make longer pieces. The specified angle is 8.1 degrees and the
directions describe a scarfing jig to be made with a circular saw but
they require a larger saw than mine. However, I did buy a "Sawzall" to
deal with some rot on my house. I tried various ways to do this with
little success. Finally, I simply cut inclined cuts about 2" apart all
along the scarf area angled at the 8 degrees. Then I used the Sawzall
to cut the scarf cutting each of these out. This gave a reasonable
first and second attempt. Then, I used the sander to make it nicer and
make sure the layers of ply formed parallel bands. I think my first
two scarfs are ok.

Cutting scarfs
 

Just a caution. Having made quite a few successful scarfs of 4' wide sheets
of plywood, I managed to screw up the last set badly. My sin was to mix too
much wood flour in the epoxy. The result wasn't fluid enough and I ended up
with voids at the edges of the scarf joint. For scarfing, the mix should be
a fluid, not a paste since there is limited clamping force available, even
with my scheme of driving drywall screws thru the joint into a backup 2x6.
You do want lots of epoxy squeezing out all the edges (and a drop cloth to
protect the stuff underneath your work area.) (I'm working with 3/8"
marine ply sliced into strakes for a lapstrake hull so the voids can't hide
easily.)

I'm fixing the bad areas by playing dentist; cutting the voided area back to
solid wood and epoxy with my 4" grinder and then filling the cavity with
epoxy thickened with milled glass fibers. A layer of fiberglass on the
outside finishes the job with what I think is "good enough." I can lift a
20' long strake at one end and wave it around without it breaking. When the
strake bends, the curve is smooth and uniform thru the scarfed and unscarfed
areas.

8.1 degrees is a 7:1 scarf, while 8:1 is the roughest I've seen
recommended, 7.125 degrees. On the other hand, some people use butt joints
with fiberglass on each side, so ????

Roger

http://home.earthlink.net/~derbyrm

wrote in message
oups.com...
Started working on my Tolman Skiff. I began by cutting the bottom
pieces from 1/2 marine ply but these have to be scarfed together to
make longer pieces. The specified angle is 8.1 degrees and the
directions describe a scarfing jig to be made with a circular saw but
they require a larger saw than mine. However, I did buy a "Sawzall" to
deal with some rot on my house. I tried various ways to do this with
little success. Finally, I simply cut inclined cuts about 2" apart all
along the scarf area angled at the 8 degrees. Then I used the Sawzall
to cut the scarf cutting each of these out. This gave a reasonable
first and second attempt. Then, I used the sander to make it nicer and
make sure the layers of ply formed parallel bands. I think my first
two scarfs are ok.

Cutting scarfs
 

Understand that a plywood scarf should be 12:1.

Cutting scarfs
 

Cutting scarfs
 

OK, I went out and bought a power plane. It is WAAAAAAAY easier with
it and it makes better scarfs.

Cutting scarfs
 

On 15 Oct 2005 16:00:36 -0700, wrote:

OK, I went out and bought a power plane. It is WAAAAAAAY easier with
it and it makes better scarfs.

Now I am getting moody. I looked round town at the last mention of a
power planer - and drew a blank (population 20,000)

There is not meant to be any power tool that I don't own.
That's what my wife says, at least

Brian Whatcott Altus OK

Cutting scarfs
 

Brian Whatcott wrote:
On 15 Oct 2005 16:00:36 -0700, wrote:


OK, I went out and bought a power plane. It is WAAAAAAAY easier with
it and it makes better scarfs.


Now I am getting moody. I looked round town at the last mention of a
power planer - and drew a blank (population 20,000)

There is not meant to be any power tool that I don't own.
That's what my wife says, at least

Brian Whatcott Altus OK


If you can't find one locally, how about:
http://cgi.ebay.com/MAKITA-ELECTRIC-...54745518QQcate
goryZ42283QQrdZ1QQcmdZViewItem

might have to cut and past that url :)

Jonathan


--
I am building my daughter an Argie 10 sailing dinghy, check it out:
http://home.comcast.net/~jonsailr

Cutting scarfs
 

Says Who?
Plywood scarfs (9mm panels) on my boat are 8:1 and I have had no
problem whatsoever with that. Every scarfed offcut I destruction tested
broke elsewhere but the scarf joint.
12:1 scarf is for the strakes to make a hollow mast and other high
load spars.

Klaus

Cutting scarfs
 

A belt sander will do this job just as well and is much more widely useful
than a power plane.
In either case, finish the scarph surfaces with a sharp handplane. Check
with a straightedge.


"Jonathan W." wrote in message
...
Brian Whatcott wrote:
On 15 Oct 2005 16:00:36 -0700, wrote:


OK, I went out and bought a power plane. It is WAAAAAAAY easier with
it and it makes better scarfs.


Now I am getting moody. I looked round town at the last mention of a
power planer - and drew a blank (population 20,000)

There is not meant to be any power tool that I don't own.
That's what my wife says, at least

Brian Whatcott Altus OK


If you can't find one locally, how about:

http://cgi.ebay.com/MAKITA-ELECTRIC-...54745518QQcate
goryZ42283QQrdZ1QQcmdZViewItem

might have to cut and past that url :)

Jonathan


--
I am building my daughter an Argie 10 sailing dinghy, check it out:
http://home.comcast.net/~jonsailr

Cutting scarfs
 

Jim Conlin wrote:
A belt sander will do this job just as well and is much more widely useful
than a power plane.
In either case, finish the scarph surfaces with a sharp handplane. Check
with a straightedge.

The problem with using an edged tool on any surface that's been sanded
is that the inevitable grit that's left behind does a number on the
cutting edge. That's one major advantage of using a power planer rather
than a belt sander. The others are reduced sawdust and greater ease in
maintaining a flat surface. Belt sanders are great for rounding things
over. ;-)

Cutting scarfs
 

Subject

Tool chosen depends on the size of the scarf.

I've use both a router and a power plane, each with it's own jig to make
a lot of scarfs on pieces less than about 6" wide.

If sheet goods are involved, then the Gougeon Bros have a neat
attachment for a circular saw.

I would do most anything to avoid a belt sander, they are strictly a
PITA except as an abrasive stock removal tool, IMHO.

Lew

Cutting scarfs
 

My reaction to belt sanders was the same as yours. I'd borrowed a
neighbor's contractor grade unit made it the 1960s and it was vicious.
Then, a few years ago, I bought a Ryobi BE-321 and it's one of my favorite
tools. Variable speed and a case that lets it be set down on the bench
upside down for use as a fixed sander.
http://www.ryobitools.com/index.php/.../tool/be321vs/

I prefer the electric block plane for making scarfs in plywood, primarily
because I think it leaves the pores open, but the belt sander is a must
have. Yes, by definition it is an abrasive stock removal tool, but the flat
sole and the variable speed allow quite small amounts to be removed.

Roger

http://home.earthlink.net/~derbyrm

"Lew Hodgett" wrote in message
ink.net...
Subject

Tool chosen depends on the size of the scarf.

I've use both a router and a power plane, each with it's own jig to make a
lot of scarfs on pieces less than about 6" wide.

If sheet goods are involved, then the Gougeon Bros have a neat attachment
for a circular saw.

I would do most anything to avoid a belt sander, they are strictly a PITA
except as an abrasive stock removal tool, IMHO.

Lew

Cutting scarfs
 

Roger Derby wrote:
My reaction to belt sanders was the same as yours. I'd borrowed a
neighbor's contractor grade unit made it the 1960s and it was vicious.
Then, a few years ago, I bought a Ryobi BE-321 and it's one of my favorite
tools. Variable speed and a case that lets it be set down on the bench
upside down for use as a fixed sander.
http://www.ryobitools.com/index.php/.../tool/be321vs/

I prefer the electric block plane for making scarfs in plywood, primarily
because I think it leaves the pores open, but the belt sander is a must
have. Yes, by definition it is an abrasive stock removal tool, but the flat
sole and the variable speed allow quite small amounts to be removed.

I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for
making scarfs.

Cutting scarfs
 

I was suggesting that the belt sander will do a good job and if your tool
budget is limited it's more generally useful than a power plane.
I've not been aware of belt sanders leaving grit in the victim and if used
with a fresh belt, they don't close pores badly.
If you worry about nasty stuff a block plane iron might encounter, you can't
build boats. You'll be planing the edge of a glass-sheathed panel soon
enough. Keep the stone handy.

"Brian Nystrom" wrote in message
news:lcpaf.3490$5F3.808@trndny03...
Roger Derby wrote:
My reaction to belt sanders was the same as yours. I'd borrowed a
neighbor's contractor grade unit made it the 1960s and it was vicious.
Then, a few years ago, I bought a Ryobi BE-321 and it's one of my
favorite
tools. Variable speed and a case that lets it be set down on the bench
upside down for use as a fixed sander.
http://www.ryobitools.com/index.php/.../tool/be321vs/

I prefer the electric block plane for making scarfs in plywood,
primarily
because I think it leaves the pores open, but the belt sander is a must
have. Yes, by definition it is an abrasive stock removal tool, but the
flat
sole and the variable speed allow quite small amounts to be removed.

I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for
making scarfs.

Cutting scarfs
 

I've not been aware of belt sanders leaving grit in the victim and if used
with a fresh belt, they don't close pores badly.

I brush sanded wood. Seems to clean it up.
Also brush sand paper to clean it.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned

Cutting scarfs
 

On Thu, 03 Nov 2005 14:32:49 GMT, Brian Nystrom
wrote:

I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for
making scarfs.

Brian, you can't blow out the sanded area with a high pressure air
gun? I can't imagine ANY sand or grit being left in a sanded area
after a thorough blasting with an air gun using 100+ psi.

Corky Scott

Cutting scarfs
 

Cutting scarfs
 

People always say that having a belt sander is a good idea, but I have a
good Bosch one that's been sitting on the shelf for years and years, just
collecting dust. I find that with my Bosch power hand plane, low-angle
block plane, 5" random orbital sander, and 7" random orbital angle sander,
that I just don't need anything else. It's very difficult to do a nice job
of anything with a belt sander ...very easy to get non-level in one
direction or the other and you can't see it happening. Maybe I haven't
found the right wood working project to match up with the belt sander?

Brian D



"Brian Nystrom" wrote in message
news:lcpaf.3490$5F3.808@trndny03...
Roger Derby wrote:
My reaction to belt sanders was the same as yours. I'd borrowed a
neighbor's contractor grade unit made it the 1960s and it was vicious.
Then, a few years ago, I bought a Ryobi BE-321 and it's one of my
favorite tools. Variable speed and a case that lets it be set down on
the bench upside down for use as a fixed sander.
http://www.ryobitools.com/index.php/.../tool/be321vs/

I prefer the electric block plane for making scarfs in plywood, primarily
because I think it leaves the pores open, but the belt sander is a must
have. Yes, by definition it is an abrasive stock removal tool, but the
flat sole and the variable speed allow quite small amounts to be removed.

I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for making
scarfs.

Cutting scarfs
 

I agree that both are equally likely. Both likelihoods are about zero.

"Brian Nystrom" wrote in message
news:%D2bf.233$SV1.39@trndny01...
wrote:
On Thu, 03 Nov 2005 14:32:49 GMT, Brian Nystrom
wrote:


I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for
making scarfs.


Brian, you can't blow out the sanded area with a high pressure air
gun? I can't imagine ANY sand or grit being left in a sanded area
after a thorough blasting with an air gun using 100+ psi.

Actually, you're as likely to blow grit INTO the pores in the wood as
out of them.

Cutting scarfs
 

Here's a free opinion (and I've made a lot of scarfs ...never a failure
either);

- I prefer cut pores, not pores sanded and smooshed flat. Use of a circular
saw attachment (followed by a low-angle block plane finish) or a power hand
plane is what I do in my shop. I want the epoxy to suck as deeply in the
wood as possible, and judging by how many coats it takes to keep the cut
edges looking wet (3 coats, sometimes a 4th), I'd say that the epoxy is
going SOMEWHERE where it's doing some good for the strength of the joint.
Right into the pores.

- I vacuum scarf joints with a ShopVac prior to gluing. Then I wipe down
with a damp hand towel and let it dry for 20 minutes. Then I pre-wet with 3
or 4 coats of clear epoxy, then glue it up with a mix appropriate to the
task ...straight silica thickener, or silica plus milled glass fiber.

Just my 2-bits. When it comes to scarfing, there are a lot of ways to skin
the cat. I've heard of others having scarfs pop open when bending wood
around a boat, and wonder how many scarfs 'barely held' on others. That's
why I'm careful.

Brian D



"Brian Nystrom" wrote in message
news:%D2bf.233$SV1.39@trndny01...
wrote:
On Thu, 03 Nov 2005 14:32:49 GMT, Brian Nystrom
wrote:


I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for making
scarfs.


Brian, you can't blow out the sanded area with a high pressure air
gun? I can't imagine ANY sand or grit being left in a sanded area
after a thorough blasting with an air gun using 100+ psi.

Actually, you're as likely to blow grit INTO the pores in the wood as out
of them.

Cutting scarfs
 

Well, actually, I've demonstrated that one can get non-level quite as well
with the electric block plane and the RO sander. The plane got better after
I put a 36" steel dowel thru the hole where the edge guide would normally
mount. The eye ball detects tilt and parallel better with a long reference
line; e.g. roughing a stack of plywood edges down to an angle for scarfing.

The RO sanders tear up the edge of the disk and use up/dull the sandpaper
much faster than the belt sander in my limited experience.

The belt sander is best for curved surfaces, particularly free-form types
such as cleats, but it also does well on bevels (to epoxy glue tolerances).
As I mentioned, mine is quite happy lying on its back on the work bench with
a rubber pad to prevent too much walking around. Setting the speed low
enough for control and picking the proper grit also helps. The flat
pressure plate helps and the drum on the end is also useful for hollows.
One does have to remember that it cuts fastest where the sandpaper first
meets the wood. The trailing edge is cushioned by sawdust.

I guess I haven't used it where "level" was a goal.

Roger (Yes, I do scarfs with the plane.)

http://home.earthlink.net/~derbyrm

"Brian D" wrote in message
. ..
People always say that having a belt sander is a good idea, but I have a
good Bosch one that's been sitting on the shelf for years and years, just
collecting dust. I find that with my Bosch power hand plane, low-angle
block plane, 5" random orbital sander, and 7" random orbital angle sander,
that I just don't need anything else. It's very difficult to do a nice
job of anything with a belt sander ...very easy to get non-level in one
direction or the other and you can't see it happening. Maybe I haven't
found the right wood working project to match up with the belt sander?

Brian D



"Brian Nystrom" wrote in message
news:lcpaf.3490$5F3.808@trndny03...
Roger Derby wrote:
My reaction to belt sanders was the same as yours. I'd borrowed a
neighbor's contractor grade unit made it the 1960s and it was vicious.
Then, a few years ago, I bought a Ryobi BE-321 and it's one of my
favorite tools. Variable speed and a case that lets it be set down on
the bench upside down for use as a fixed sander.
http://www.ryobitools.com/index.php/.../tool/be321vs/

I prefer the electric block plane for making scarfs in plywood,
primarily because I think it leaves the pores open, but the belt sander
is a must have. Yes, by definition it is an abrasive stock removal
tool, but the flat sole and the variable speed allow quite small amounts
to be removed.

I don't think anyone is disputing the utility of a belt sander and I
wouldn't be without one, but it's definitely not the best tool for making
scarfs.

Cutting scarfs
 

Brian D wrote:
Maybe I haven't
found the right wood working project to match up with the belt sander?


snip

I agree, a belt sander, especially around a boat, has limited usefulness.

It is basically an abrasive device to hog material.

Now if you are in a cabinet shop, that's a different story.

BTW, if you are going to have a belt sander, then the Porter-Cable 5*4
is the only way to go.

Compared to it, every other belt sander is simply a toy.

That comment based on having destroyed at least 6-8 belt sanders in my time.

Lew

Cutting scarfs
 

Brian D wrote:
Here's a free opinion (and I've made a lot of scarfs ...never a failure
either);

- I prefer cut pores, not pores sanded and smooshed flat. Use of a circular
saw attachment (followed by a low-angle block plane finish) or a power hand
plane is what I do in my shop. I want the epoxy to suck as deeply in the
wood as possible, and judging by how many coats it takes to keep the cut
edges looking wet (3 coats, sometimes a 4th), I'd say that the epoxy is
going SOMEWHERE where it's doing some good for the strength of the joint.
Right into the pores.

- I vacuum scarf joints with a ShopVac prior to gluing. Then I wipe down
with a damp hand towel and let it dry for 20 minutes. Then I pre-wet with 3
or 4 coats of clear epoxy, then glue it up with a mix appropriate to the
task ...straight silica thickener, or silica plus milled glass fiber.

Just my 2-bits. When it comes to scarfing, there are a lot of ways to skin
the cat. I've heard of others having scarfs pop open when bending wood
around a boat, and wonder how many scarfs 'barely held' on others. That's
why I'm careful.

Brian D

That sounds like a very sensible approach to scarfing.

Cutting scarfs
 

Brian D wrote:
People always say that having a belt sander is a good idea, but I have a
good Bosch one that's been sitting on the shelf for years and years, just
collecting dust.

I have to admit that I find that my belt sander is far more useful when
it's upside-down, clamped in a bench vise, than when it's handheld. ;-)