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