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Gluing together tops and back of musical instruments is known as plate joining.
There are many ways to join plates, some of them more difficult than others.
In this video I am going to show you an easy way using a plate joining jig.
This commercially made jig actually makes joining plates enjoyable
and completely removes any possibility of error while joining.
Here is what some of my students said when I told them I could join a top or back
flawlessly in under a minute.
Hahahaha…
Here is their response when they saw me do it.
Oooohooo…
So, just how does this jig work?
First you must make sure that you have a good joint.
I do this by using a shooting board and a handplane.
Watch my video on shooting boards to learn more about this useful jig.
Once you have a tight joint it is ready to be joined using the plate joining jig.
Start by holding the two pieces together and apply glue to the edges to be joined.
Then place them on the plate joining jig.
On this commercially made jig there is no need to place anything between the plate and the jig
because this area is made from a glue resistant material
keeping the plate from sticking to it and allowing for easy clean up later.
Now place the top part of the jig over the two plates you are joining.
This will apply even downward pressure on the two halves
so that they are perfectly aligned while gluing.
Take one of the three ropes attached to the jig and wrap it around the jig as shown.
It doesn’t need to be very tight.
Tuck the end of the rope into one of the plastic pieces to secure it.
Do the same thing with the other two pieces of rope.
Wrap them in a figure eight pattern
and secure the ends by placing them in the plastic pieces.
Next insert the wedge pieces of wood supplied with the jig
into and under the rope that you just wrapped around the ends of the jig.
This applies even downward pressure keeping the plates aligned.
It also applies the lateral pressure needed to join the two pieces of the plate together.
A few light taps with a hammer or other sophisticated banging device and you are done.
It doesn’t get much easier than this.
After appropriate dry time you can remove the pieces of wood and unwrap the rope from the jig.
You now have a perfectly joined back or top plate
and are ready to continue building.
This jig even works well for plates with irregular edges.
However, if you want to join smaller shapes you will need to make some modifications.
Fellow luthier and friend Edward Dick has made a jig that allows him to join plates for an instrument
he developed called the banjola.
The plates are pear shape and he is able to get two banjola backs from one guitar back.
However, this creates a problem when joining them.
Using the same principles employed by the jig I just showed you,
Edward made a version that suits his needs.
Instead of using a shooting board, he uses a jig he developed
that has a piece of plate glass with sandpaper glued to it.
A fence is set at a 90 degree angle and the edges of the plate to be joined
are then run across the sandpaper to true them up.
Let’s watch as Edward demonstrates his version of the plate joining jig.
Not only does Edward make beautiful instruments but he plays them beautifully as well.
You have just seen two different versions of a plate joining jig.
I hope this is useful when it comes time for you to join your tops and backs.