For the first time I need to join some planks of mahogany to make them
wider. They are relatively short - up to 650mm and they need to be about
I have a 12" planer/thicknesser. So I guess I must make the edges flat
and square and then apply glue and pressure.
But is that it or should I make a tongue and groove or use one of those
router bits that make an interlocking joint. The wood is to be used for a
bedside table and thus does not need to be too strong.
I am not sure how you are going to get the edges straight with a planer.
You really need a jointer or hand plane.
Once you get the edges straight, just glue will be fine. Spread a thin amt
of glue on each edge, and spread out with a small brush. Align and clamp
(with just a small amout of squeeze out).
I typically use a biscuit joiner, but that is mainly to make the aligning
easier. It is my understanding that today's glues are plenty strong.
Though, in this instance, there is no need for the additional strength, I
still apply the fundemental law of all joint making, which is to first have
a good mechanical strength. The other reason is that it makes alignment
much easier, though you will probably only be joining two comparatively
short boards, in the future you may be doing longer and wider.
Depending on the job, I use either an edge interlocking bit or cut blind
dados with the table saw and use ply tongues for long/thick boards. Believe
me if you ever glue up a table top you need all the help you can get with
alignment besides the difficulty of trying to apply corrective
upward/downward pressure to a gluey top.
Be aware that if you use an interlocking joint router bit that you need a
router table and a means of micro adjusting the cut height.
On Mon, 19 Apr 2004 11:24:07 -0500, "Bernard Randall"
Ok, I'm curious. This is a sincere question:
How do bicuits make a joint stronger? If worried about a break *at*
the joint, the material of the biscuit should make it stronger *only*
if the biscuit material itself is better than the wood and/or the
glue. I'm thinking of a shear at the joint. Either the biscuit
material is shearing, or the glue/original wood is shearing. So,
which really is stronger?
I do use biscuits, but have in mind only some really great assistance
in alignment. Other than that, the majority of the material is still
original wood and glue. I don't think it matters for strength unless
the biscuits are significantly stronger than the original material
(metal would work), but usually they are weaker.
Is there a physics/engineering expert here?
What's funny is that I know pros who admire some serious amateurs.
<G> One guy points out that pros often don't have the time to do the
really special stuff, due to financial pressures.
A serious amateur or semi-pro wooddorker can work at it simply for the
art. Unless one is one of those lucky folks who doesn't need luxuries
like food, shelter, or a dependable vehicle.
Very easy to do. In the past four years I've done WW, I did borrow a truck
once to bring home my contractor's saw. The dust collector, 14" bandsaw,
planer, router table all came home in my car. As have 2 x 8's and plywood
cut into three or four pieces.
I have use of a truck anytime I want it but I don't bother. Just not
needed and I'd rather drive a sedan than a truck.
On 20 Apr 2004 09:13:00 -0700, email@example.com (Bill McNutt) wrote:
The same way I do. With a trailer and a station wagon. <G>
I ditched my last truck a few years back. The upside to the trailer
is a low, easily loaded deck, MANY places to lash down an awkward
load, low taxes, insurance & registration costs, the trailer can be
left on site to be loaded or unloaded, you can tow it with multiple
vehicles, and you don't have the truck when you don't want the truck.
I tow my trailer with either a Jeep Wrangler Sport or a Subaru
The Outback is THE BEST snow and foul weather vehicle I've ever
touched. I've had 4WD trucks, SUV's you name it. AWD (which
operates differently than 4WD), ABS, traction control, a 5 speed stick
(NOT an automatic!), and most importantly, a low center of gravity
make it all work.. Too bad it's kind of ugly!
The downside is that you're towing a trailer, which does occasionally
require some forethought while driving and parking. <G> And, of
course, you need to store it.
Anything that increases glued area does increase the strength of the joint.
In the case of a panel glue up, long grain to long grain, the increase is
immaterial. However the increased glue area for something like a butt joint
makes a far stronger joint since you have essentially changed the weak butt
joint to a M & T joint.
It's all in how you look at it. If your only point of concern is panels,
biscuits are nothing more then alignment aids and increased strength, and
there is some, never becomes tested since, as you observed, the wood breaks
first anyway. It's only when you start applying the added strength to
otherwise weaker joints does the issue make sense. Think face frames,
shelving, that sort of thing.
Hope it helps
The biscuit is actually quite a bit stronger than your wood. The grain of the
biscuit is across the biscuit, or at least at a pretty good angle. So you're
looking at shear across the grain for the biscuit versus shear with the grain
for the joint itself.
In the end, though, they are more useful for aligning the joint than
strengthening it - assuming that you have a good fitting joint to start with.
If the boards are jointed properly, they will be plenty strong for
any purpose with no more than glue, since glue is stronger than the wood
For example, my workbench top is made of 18 3" thick strips of SYP.
They are joined by nothing more than glue, yet have withstood all the
stresses that a neander bench is subjected to with no signs of
separation at all.
Again, get the joint right and you'll have no worries. Get it wrong
and all the biscuits, etc. in the world won't help you.
Other then having the edges not only straight BUT ALSO at 90 degrees to at
least one of the faces of each piece (those would end up being the top of
the top) nothing further, for strength purposes, is required.
Biscuits, tongue and groove, splines, glue joints, etc are nice but add no
meaningful strength to a long grain jointed panel.
Note to those wetting their pants about the "no meaningful strength" part.
Don't bother, I'm not going to debate with some anal twit's nit picking. If
a properly made, glued, and clamped long grain joint is stronger then the
wood it follows that any additional strength, regardless of how added, is,
meaningless, redundant, overkill, unnecessary, pointless, purposeless,
You do not need tongue and groove, or the interlocking router bit
profile, or biscuits, etc. for strength, and they are not normally
used to glue up boards into panels. There is lots of info in the
archives here re this. Just remember that you will need to translate
your search into American-ese tool terminology for good results. The
thing you call a planer, we call a "jointer," and your thicknesser is
I was more worried that the "650mm width" would stump all the metrically
challenged out there!!
Thank you all for your advice - no prizes for guessing what I will be
doing this weekend. Should keep the SWMBO happy since she has had the
headboard for a while but no pedestals.
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