Scarf Joints in Plywood

[Kyle Boatright]

One of these days, I'm gonna dust off the Hatz project, and when I do, I'll
need to make some scarf joints in 1/16" ply.

Suggestions?

KB

[Bob Kuykendall]

Earlier, Kyle Boatright wrote:
> One of these days, I'm gonna dust off the Hatz project, and when I do, I'll
> need to make some scarf joints in 1/16" ply.

Whenever I need info about ways to make wood aircraft parts, the first
thing I think of is Sequoia:

http://www.seqair.com/skunkworks/WoodWkgMethods/Methods.html

Bob K.

[JKimmel]

Bob Kuykendall wrote:
> Earlier, Kyle Boatright wrote:
>
>>One of these days, I'm gonna dust off the Hatz project, and when I do, I'll
>>need to make some scarf joints in 1/16" ply.
>
>
> Whenever I need info about ways to make wood aircraft parts, the first
> thing I think of is Sequoia:
>
> http://www.seqair.com/skunkworks/WoodWkgMethods/Methods.html
>
> Bob K.
>

Another scarfing fixture:

http://www.oneoceankayaks.com/stitchglue/plyshophtm/scarfjig2.htm
--
J Kimmel

www.metalinnovations.com

"Cuius testiculos habes, habeas cardia et cerebellum." - When you have
their full attention in your grip, their hearts and minds will follow.

[Rich S.[_1_]]

"Kyle Boatright" > wrote in message
. ..
> One of these days, I'm gonna dust off the Hatz project, and when I do,
> I'll need to make some scarf joints in 1/16" ply.
>
> Suggestions?
>
> KB

Kyle........

It's not a big deal and you do not need a fixture. A scarf for 1/6" ply is
1" wide. Make a pencil line on each area to be scarfed 1" back from the
edge. Draw a bunch of lines from that mark to the edge to give you a visual
when you are removing wood.

Using a quick-clamp, clamp the ply to the workbench in front of you so the
right edge of the ply is at or just a BCH over the right edge of the work
surface. Using a razor sharp 5" or 6" plane, taper the edge of the ply
evenly from the mark to the edge. The plies will become visible as you
remove the material and give you and excellent guide to keep it even.

It takes only a few seconds to make a perfect scarf this way and you'll
enjoy the process.

Rich S.

[Lou]

I used my radial arm saw (craftsman). I was able to turn and tilt to
the desired angle.
Then set up a fence to just run my plywood through. The down side is, I
haven't used my saw for sawing in over a year because I don't want to
have to set it up again. I've even considered buying another smaller,
saw just for the scarfing set up.

[Dan Horton]

Kyle,
You didn't mention what parts you were scarfing, but if it is just
the leading edge ply wraps you might wish to visit Darin Bishop's
excellent Model 12 site.

http://www.2wings.com/

Click FAQ, select Wings, and find the leading edge topic. No jigs
or special tools, just an sanding block. Works fine, did a set last
year.

Dan

[flybabybuilder]

The classic Bingelis library has info on setting up a motor and a
sanding drum, but that's probably overkill for 1/16 unless you're doing
a lot of it.

If your plane isn't razor sharp, a long sanding block with medium grit
will work fine. Just be sure to blow the dust off (do not use a tack
cloth). Rich is right - the plies will give you a good visual
indication. They should be evenly spaced.

You might plan on having some extra at the other end (if possible) in
case you mess up and have to cut a strip off the end. Practice on a
piece or two.


Rich S. wrote:
> "Kyle Boatright" > wrote in message
> . ..
> > One of these days, I'm gonna dust off the Hatz project, and when I do,
> > I'll need to make some scarf joints in 1/16" ply.
> >
> > Suggestions?
> >
> > KB
>
> Kyle........
>
> It's not a big deal and you do not need a fixture. A scarf for 1/6" ply is
> 1" wide. Make a pencil line on each area to be scarfed 1" back from the
> edge. Draw a bunch of lines from that mark to the edge to give you a visual
> when you are removing wood.
>
> Using a quick-clamp, clamp the ply to the workbench in front of you so the
> right edge of the ply is at or just a BCH over the right edge of the work
> surface. Using a razor sharp 5" or 6" plane, taper the edge of the ply
> evenly from the mark to the edge. The plies will become visible as you
> remove the material and give you and excellent guide to keep it even.
>
> It takes only a few seconds to make a perfect scarf this way and you'll
> enjoy the process.
>
> Rich S.

[Morgans[_3_]]

"flybabybuilder" > wrote

> The classic Bingelis library has info on setting up a motor and a
> sanding drum, but that's probably overkill for 1/16 unless you're doing
> a lot of it.
>
> If your plane isn't razor sharp, a long sanding block with medium grit
> will work fine. Just be sure to blow the dust off (do not use a tack
> cloth). Rich is right - the plies will give you a good visual
> indication. They should be evenly spaced.
>
> You might plan on having some extra at the other end (if possible) in
> case you mess up and have to cut a strip off the end. Practice on a
> piece or two.

The only down side here, is that sanding is considered to be a poor surface
preparation method, for glue joints. I think I recall that fact from the
Forrest products publication.

The surface should be scraped to prep for glue, at a minimum.
--
Jim in NC

[Lou]

I've always wondered about that. When gluing wood together it's always
been a good idea to rough up the area's to be glued so that the glue
goes in the roughend area and has a better grab. If the area is too
smooth it will hold less glue and more possiblity to squeeze out.

[Stealth Pilot]

On 16 Aug 2006 03:56:04 -0700, "Lou" > wrote:

>I've always wondered about that. When gluing wood together it's always
>been a good idea to rough up the area's to be glued so that the glue
>goes in the roughend area and has a better grab. If the area is too
>smooth it will hold less glue and more possiblity to squeeze out.

glue beam laminators have noticed that you can get beams about 20%
stronger if the wood surface is freshly prepared just before gluing.
they are not certain why but oxidation or some other chemical process
occurring on older wood surfaces may be a culprit.

on plywoods of course the reason is different. it removes surface
contamination from the presses.

Stealth Pilot

[Morgans[_3_]]

"Lou" > wrote in message
ups.com...
> I've always wondered about that. When gluing wood together it's always
> been a good idea to rough up the area's to be glued so that the glue
> goes in the roughend area and has a better grab. If the area is too
> smooth it will hold less glue and more possiblity to squeeze out.

Even then, it is the method of preparing the surface that counts.

While you sand, particles of sanding dust are forced "into" the pores of the
wood, thus preventing the glue from being able to wick into the wood, and
increase the surface area being "grabbed" by the glue.

The best prep is either scraping with a sharp blade, or sawing, or
machining, leaving the pores open.
--
Jim in NC

[Joe]

"Morgans" > wrote in
:

>
> "Lou" > wrote in message
> ups.com...
>> I've always wondered about that. When gluing wood together it's
>> always been a good idea to rough up the area's to be glued so that
>> the glue goes in the roughend area and has a better grab. If the
area
>> is too smooth it will hold less glue and more possiblity to squeeze
>> out.
>
> Even then, it is the method of preparing the surface that counts.
>
> While you sand, particles of sanding dust are forced "into" the
pores
> of the wood, thus preventing the glue from being able to wick into
the
> wood, and increase the surface area being "grabbed" by the glue.
>
> The best prep is either scraping with a sharp blade, or sawing, or
> machining, leaving the pores open.

I would try using a router table and jig for a job like that. Sanding
leaves to small of a surface area and is too smooth for good gluing
and is difficult to get a perfect square cut. Also you want to avoid
gluing a layer that has exposed glue. Make sure you use the
appropriate glue because some glues may breakdown or weaken the
plywoods existing glue.