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How To Make An Edge To Edge Glue Joint - WOOD magazine



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one of the most basic joints in

woodworking is simple edge to edge glue

joints it's the way you can make wide

panels like this one if you try to find

a single board of quarter sawn oak

that's as wide as this good luck this is

actually is three separate boards of

narrower widths that have been glued at

their edges to make this wider panel

now when woodworkers first get started

and they're hearing about joining two

boards edge to edge with nothing but

glue in between and they're a little bit

skeptical how can glue be strong enough

to hold boards together like that well

let me give you a little demonstration

that hopefully will illustrate how

strong modern glues actually are this is

three pieces of poplar I've glued

together you can see that I've I've left

the glue squeeze out there on the joint

so you can see I didn't cheat and use

too much glue or al too little glue this

is about a properly glued joint mostly

if I can break this and see if this

breaks the wood or if it breaks the glue

joint

now take a look at that so I think that

pretty clearly demonstrates the strength

of the glue joint compared to the actual

strength of the wood this split right

along the grain of the wood the glue

joint is fully intact right down here at

the very tip you can see that the wood

did peel away but it's still attached to

the mating piece the glue joint did not

fail the wood failed that's what you're

going to hear a lot is glue joints are

stronger than the wood they bond so have

no fear when your edge gluing boards

when you are edge gluing boards there's

a couple things that you need to know

about number one is unless there's glue

on the surface of the boards you don't

get any adhesion that may sound rather

simple but here's what I mean by that if

you look at these two boards you can see

between them I've got a pretty good gap

going right there

now you can put glue along there but the

glue doesn't touch both boards those two

boards don't touch there so the glue is

not going to create a strong bond what

you need is a true surface on each board

so it you get a nice tight joint line

like you saw on these other two panels

and there's a couple of ways you can

create that one way the simplest way

perhaps is simply to go to the table saw

and rip a clean edge on each board so

let's do that okay over here the table

saw let's say I want to join these two

boards just like that I'm gonna mark

these just so we can keep them straight

as the process goes through here I'm

gonna call this board number one and

this board number two

now this is the edge at which they'll

mate so I want to rip each of those

ideas I'm just gonna mark that again

just wing keep it straight you can see

clearly what I'm doing what I want to do

is to rip one with this good face up and

rip the other one with the good face

down the reason for that is if my blade

isn't perfectly ninety degrees those two

angles will offset each other so when

the board comes together the angles

offset and the pain

we'll stay flat so let's rip the first

one a good 40 tooth blade you need a

very sharp blade to get the best edge

possible so a good 40 tooth multipurpose

blade or a there are what they call glue

line rip blades perfect for this job

now when I bring those two boards

together you can see I've got a nice

clean joint line from one end to the

other and sitting here on my cast iron

surface of the table saw you can see

that those two boards lay flat okay I've

got the edges prepared the next thing is

to do the glue up now the first question

we have when you're ready to do a glue

up is if you've never done it before how

much glue do you use well enough it's

one of those things after you done it a

couple times you know start with a beat

about like that then just use a spreader

or a brush you like and I prefer using

fingers that's always there I know where

it is spread it so you get a thin even

coat along the full full face of that

edge I'm going to go from one face to

the other end and cover it with a even

coat of glue then simply lay it down on

your clamps lay the mating face down and

the next question is how much clamping

pressure do I need begin the answer just

like the glue just enough all you need

is a enough to bring those boards

together firmly and if you've applied

glue as I just showed you you'll see a

thin bead start to pop up along your

joint line that's another sign although

we can tell if you've got the proper

amount of glue we got just a thin little

bead of glue popping up along that joint

line then I can take my square or any

kind of straightedge check along there

make sure the boards aren't bowing up or

bowing down sometimes clamps will tend

to force those up that's staying nice

and flat

on both ends if by chance you're having

a little trouble getting that joint line

to a line just take a clamp such as this

and clamp all on that joint line to

bring those into alignment that'll keep

the panel a lot flusher and save you

planing and surfacing after the glue

dries so that's one method for making

edges for Ed's gluing panels using a

table saw and a nice sharp blade to get

your true edges there's also a special

machine called a jointer that you can

add to your shop very useful and its job

is to make jointed edges let's take a

the jointer is kind of a specialized

tool but it's perfect for making really

clean edges for joining things up it

consists of an in feed table here an

outfeed table here then under this red

guard we've got the cutter head that

rotates to use the jointer I'm gonna do

some one two what I did on the table saw

I want my pieces to line up like this so

number this one number one this one

number two then what I'll do is I'll

join one with the number facing out one

with the number facing in that'll again

will offset any variation for 90 degrees

in the fence

so let's joint

start by applying light pressure to keep

the edge of the board on the infeed

table after about six inches of the

board passes on to the outfeed table

shift pressure to that end of the board

you can hear the cutter head cutting it

each end of the board but not in the

middle with each pass the edge gets

flatter until the full length of the

board is being jointed to nice clean

edges when they come together joint line

practically disappears then you can go

ahead and glue this up just as we did

with the other panel it's been about 20

minutes since we first glued up this

panel so I want to come back to it and

give you another tip on your glue ups

glue is starting to set up by this time

you want to leave the glue up in the

clamps for at least an hour even longer

if you can however we talked about the

little bit of glue squeeze-out that

occurs along this joint line you want to

get rid of that before it cures too hard

back on this panel we broke I left that

bead in place and it glue dries it gets

very hard and not only does it get hard

but it can also if you try to take it

off at this stage it can peel up little

wood fibers because again the glue is

stronger than the wood so it's better to

come back to your glue up at this point

you can see those little beads they're

just getting to be kind of jelly like

you can press on them they feel a bit

like pudding

bring a chisel along and just gently

scrape those off get rid of them before

they turn into those hard beads later on

again about 20 minutes is what you want

to wait until you see those little beads

appear

there's that face when I turn it over

and work on the other face - I'll reek

lamp that let that sit for I'm gonna

give it another hour hour and a half

before I remove the clamps and that

panel will be ready to go

you