Another Coffee Table: Mitred Through Dovetails
The
immediate challenge is to create the curved ends. The plan is to make
dovetailed corners, round them on the outside and add a filler/filet
to the inside corner, which will be hollowed to compliment the outer
radius.
Complicating this is the need to mitre the insides of
the dovetailed ends, since this will permit the shape to flow better
than butt ends. Interesting ... as I have never made mitred dovetails
to date. This is going to be a steep but quick learning curve!
I
spent some time researching mitred dovetails. There is not much
around. The only book I could find with directions was Ian Kirby's
"The Complete Dovetail". I like Ian's work, but the writing
here were not his best. There is a short video by Chris Schwarz
(Google for it), which was helpful. There was also an article on the
UKWorkshop forum (by Custard), which is a Pins-first method (I tend
to saw Tails-first). There were one or two other articles to be
found, of less assistance to someone like yours truly, who becomes
easily spatially challenged. In the end I worked it out but,
reflecting on the method that evolved, it does not look like those
who came before. Perhaps it is a different way of doing it? I really
do not know. Let me have your thoughts here. Anyway, I plan to show
it for the education of those who want to learn a method.
Beginning
with a tail board that has been marked and sawn (to speed up the
description). Note that there is no shoulder here (which is common on
butt ended dovetails). The wood is Merbau, which is hard, hard, hard.
20mm thick, as per the panels on the table ...
The
aim is to saw all the tails. Forget about the mitre for now (... this
is a departure from the methods I observed).
To make the
removal of waste easiest, undercut the baselines (shallow cuts to
avoid losing vertical) ...
Now
fretsaw away the waste. Get as close to the baseline as you dare! My
cuts are about 1mm ...
This
enables the minimum of waste removal. You can place the chisel
immediately against the chisel wall and pare/chop down halfway
...
With
the waste removed, mark the mitre cuts at the sides - but do not cut
them yet (this is another departure) ...
Time
now to transfer the marks to the pin board.
First, here is an
alternative to the "#140 trick" (the #140 trick involves
creating a shallow rebate to securely connect the tail board to the
pin board when transferring marks. This was popularised by Rob Cosman
and Chris Schwarz, amongst others). My alternative is three layers of
blue tape, which is peeled away afterwards.
Lay three layers
of blue tape over the baseline. No need to be careful ...
Now
use the cutting gauge (which marked the tails) to slice away the
tape, leaving an edge butting against the baseline ...
This
is the fence. Here it is seen with the pin board, which has a layer
of blue tape on the end ...
The
"fence" makes it easy to align the boards, while the blue
tape on the pin board also acts as a non-slip ..
When
you trace the sockets (with a knife), the outlines look like this
(great for old eyes!) ...
Drop
all the vertical lines, with the exception of the line on the outside
at each side ...
Remove the waste in the same way as done on
the tail board (undercut the baseline, fretsaw and chisel)
...
Mark
out the mitre lines ...
...
and drop the verticals on the reverse side...
Now
saw the mitre cuts and remove the waste ...
Do
this on the tail board as well - the reason it was left until now was
that it would be difficult to transfer the outside tail if the mitre
was sawn.
Stay about 1mm from the mitre line. Do not saw to
the line. This will be more accurately shaped with a chisel.
For
chiseling, use a mitre guide. This is just a 45 degree saw cut. I
made a double-ended guide - to use on opposing sides ..
Take
it slowly, a smidgeon at a time.
Finally
... the moment of truth arrives ... will she .. won't she
??
Looking
promising as the top is pressed together with finger pressure. Then I
wack it - the wood is uncompromising. The clamp is to prevent any
cracking in such circumstances.
Not
too shabby.
Mitres are tight ...
Now
about the rounded edge ... here is the secret weapon:
After
marking out, the waste is removed with a block plane, and then sanded
smooth. Just lacking the inner filet ...
Enough
practice. Now for the real thing. A bit more of a challenge as the
panels are 500mm wide.
Regards from Perth
Derek
December 2018