Splines...

> As background, I have a thin-kerf blade with a 1/8" kerf. No dado set.

Usually, 1/8" is considered full kerf, thin is more like 3/32". I'd check
that.

>
> Firstly, is a 1/8" spline thick enough to be useful? (The pieces will
> usually be some flavor of 4/4 stock glued edge to edge.) I'm especially
> wondering if this is enough to hold cantankerous pieces at bay during a
> wide glue-up.

It can be. It depends in the size (not just thickness) of the joined pieces,
and the stresses that they are likely to encounter. Also the species
matters. Why not try a test joint; let the glue dry completely (24Hrs) and
try to pull (push, twist, smash) apart the joint?

Two splines is also an option for added strength.

> Secondly, I have a bunch of three-layer junk mystery plywood that I found
> inside a furniture box. It's a little less than 1/32" shy of being 1/8",
> and isn't quite a tight fit in the slot, but it has three distinct layers
> so should be better grain-wise than using some kind of solid stock. Is
> ~1/32" undersized too loose for a good fit, or should that be OK? Seems
> like I'm probably pushing what a glue layer can do here, but maybe you can
> make me feel better about using the rest of the plywood for this.
>

Although it may be adequate for your application, it is not ideal. Plywood
has alternating grain in its plys. Optimally, a spline will have it's grain
aligned in the direction of the force that it is designed to protect
against. If the spline is at 90 degrees to the force, it will be relatively
week, and likely split.


-Steve

> --
> Michael McIntyre ---- Silvan <[email protected]>
> Linux fanatic, and certified Geek; registered Linux user #243621
> http://www.geocities.com/Paris/Rue/5407/
>

Stephen M wrote:

>> As background, I have a thin-kerf blade with a 1/8" kerf. No dado set.
>
> Usually, 1/8" is considered full kerf, thin is more like 3/32". I'd check
> that.

Never thought of that. It's a really sloppy saw. I'll bet it wallows out
to 1/8". It's a "thin kerf" blade, but my typical kerf measures out to
right around 1/8", or maybe sometimes a hair more. I'll check this.

> It can be. It depends in the size (not just thickness) of the joined
> pieces, and the stresses that they are likely to encounter. Also the

4/4 hand planed until it's just smooth. Pieces are about 18", with 15"
splines. One big piece (15" wide) and one small piece (.75" wide).

> species matters. Why not try a test joint; let the glue dry completely
> (24Hrs) and try to pull (push, twist, smash) apart the joint?

Good thought.

> Although it may be adequate for your application, it is not ideal. Plywood
> has alternating grain in its plys. Optimally, a spline will have it's
> grain aligned in the direction of the force that it is designed to protect
> against. If the spline is at 90 degrees to the force, it will be
> relatively week, and likely split.

Fair enough. So it's effectively even thinner. I do have them so that the
longest grain is running the right way for strength, but that leaves the
1/64" outer layers running the wrong way, so I have a 1/32" spline
basically.

Not much of a compromise though, and I'll bet if I use two of them it will
be adequate. Until I use up the plywood anyway.

Thanks for the thoughts.

--
Michael McIntyre ---- Silvan <[email protected]>
Linux fanatic, and certified Geek; registered Linux user #243621
http://www.geocities.com/Paris/Rue/5407/

Michael,

Think about that 3 ply. After you cut the strips to use as splines you will
have a strip with 2 ply's of long-grain and the middle ply being short
grain, or, 2 ply's of short-grain and 1 ply of long grain depending on how
you cut it. At 1/8" thick, you will want all the long grain you can get if
the spline is needed for support. As for how thick a spline needs to be is
a matter of how it's being used. If its just for alignment, then the ply
will work fine.

If you are applying a wide edge board around a tabletop and want the spline
to help support the glue joint, then I would be looking for a bit thicker,
solid spline material of around 1/4" for a 1" thick board with a 1/2" deep
slot in each board to get a better glue surface area.

As for your 1/8" thin-kerf blade... a 1/8" wide blade is a regular blade -
not a thin-kerf. If you had a thin-kerf blade, that ply would probably fit
a lot better. Last I looked, there really is not "standard" for thin-kerf
blades since I found about 6 different listings. Only thing common was that
they were less than .125" thick.

Bob S.

"Silvan" <[email protected]> wrote in message
news:[email protected]...
> I wanted to attach a frame to a chess board with nothing visible on the
> outside this time. Considering that doing blind dowels meant drilling
> before assembly, it would have removed the fiddle factor. Instead, I
> decided to do splines, in order to be able to slide the pieces around a
bit
> to settle them into perfect alignment.
>
> Now that the clamps are off and it looks fine, I'm second-guessing my
> splines. That worked so incredibly well, that I expect to use this
> technique often. Hence the questions...
>
> As background, I have a thin-kerf blade with a 1/8" kerf. No dado set.
>
> Firstly, is a 1/8" spline thick enough to be useful? (The pieces will
> usually be some flavor of 4/4 stock glued edge to edge.) I'm especially
> wondering if this is enough to hold cantankerous pieces at bay during a
> wide glue-up.
>
> Secondly, I have a bunch of three-layer junk mystery plywood that I found
> inside a furniture box. It's a little less than 1/32" shy of being 1/8",
> and isn't quite a tight fit in the slot, but it has three distinct layers
> so should be better grain-wise than using some kind of solid stock. Is
> ~1/32" undersized too loose for a good fit, or should that be OK? Seems
> like I'm probably pushing what a glue layer can do here, but maybe you can
> make me feel better about using the rest of the plywood for this.
>
> --
> Michael McIntyre ---- Silvan <[email protected]>
> Linux fanatic, and certified Geek; registered Linux user #243621
> http://www.geocities.com/Paris/Rue/5407/
>