Entry hall table for a niece: Part 3
I've
been away from the workshop for a month, travelling around a few
cities in Austria and Germany, as well as Prague. It was a good trip,
but it's great to be home.
The current build was on hold.
This is the entry hall table my niece asked me to build ...
...
and this is where we left off last time - ready to fit the first
corner ...
Today
we shall put the complete case together. What I wish to focus on is
the dovetailing. Not just any dovetailing, but mitred through
dovetailing in unforgiving hardwood (here, Fiddleback Jarrah).
Of
all the commonly used dovetails, I consider the through dovetail more
difficult than the half-blind dovetail. Why ... because two sides are
exposed against the single face of the half-blind.
In my
opinion, by mitering the ends, the level of complexity is tripled ..
at least. Not only are there three faces now, but each needs to be
dimensioned perfectly, otherwise each is affected in turn.
This
is more difficult than a secret mitred dovetail, where mistakes may
be hidden.
I have posted before on building the mitred
though dovetail, and it is not my intention to do this again.
Instead, what I wish to show are the tuning tricks to get it
right.
This is the model of the tail- and pin boards
…
In
a wide case, such as this, it is critical that the parts go together
ideally off the saw or, at least, require minimal adjustment. The
more adjustments one makes, the more the dovetails will look
ragged.
Tail boards are straightforward. Let’s consider this
done. Once the transfer of tails to pins is completed, the vital area
is sawing the vertical lines … well, perfectly vertical.
I
use blue tape in transferring the marks. The first saw cut is flat
against the tape. Note that the harder the wood, the less compression
there will be, and so the tail-pin fit needs to be spot on. Where you
saw offers an opportunity for ensuring a good fit: if you hug the
line (edge of the tape), you get a tight fit. If you encroach a
smidgeon over the line, you loosen the fit slightly.
Saw
diagionally, using the vertical line as your target …
Only
then level the saw and complete the cut …
I
do not plan to discuss removing the waste. That was demonstrated in
Part 2.
So, the next important area is the mitre. These are
scribed, and then I use a crosscut saw to remove the waste about 1mm
above the line on both the tail- and pin boards …
Now
we are ready to test-fit the boards …
Mmmm
…. not a great fit …
… even though the mitres at the
sides are tight/coplanar …
The
problem is that the mitres are fat, and the extra thickness is
holding the boards apart …
Even
sawing to the lines here is likely to leave some fat, which is why it
is a waste of energy to try and saw to the line in this instance. It
needs to be pared away with a chisel, using a 45-degree
fixture.
As
tempting and logical as it seems to pare straight down the guide
…
…
what I experience is that the chisel will skip over the surface of
the hard wood rather than digging in and cutting it away. What is
more successful is to pare at an angle, and let the corner of the
bevel catch the wood …
This
is what you are aiming for …
Okay,
we do this. And this is the result …
Not
bad. But not good enough. There is a slight gap at each side, quite
fine, but evident close up.
The source is traced to the mitre
not being clean enough. It is like sharpening a blade – look for
the light on the edge. If it is there, the blade is not sharp. If
there is a slight amount of waste on the mitre, the case will not
close up.
To
clear this, instead of a chisel – which is tricky to use for such a
small amount – I choose to use a file. This file has the teeth on
the sides ground off to create “safe” sides.
Try
again. The fit is now very good. I will stop there.
So,
this is the stage of the project: the case is completed. This is a
dry fit …
One
end …
The
other …
The
waterfall can be seen, even without being smoothed and finished
…
Regards
from Perth
Derek
January 2020