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My Introduction To Dovetailing

A woodworking project for:
  • reclaiming wood from a pallet
  • working with dovetails
  • building storage boxes for vinyl singles

Prelude

Since I've decided to learn a bit about woodworking it seems important to have a bash at making all of the different kinds of joints that are possible – but without the expense of buying every conceivable tool on the market. After all, DIY joinery really ought to end up cheaper than buying pre-made, shouldn't it?

Actually, that's hard to achieve for all kinds of reasons – but if we don't have to buy an expensive tool, or blade or bit to achieve a joint we can at least make the things we want to make whatever the inevitable crushing limits on our budgets. And at least we know this is possible as most joinery methods pre-date the advent of power saws, and routers, and dado blades, and jointers, and Dominoes, and Kreg jigs, and pocket holes and all the rest of the many and varied options.

So I set about learning how to dovetail with just my back-saw, chisels and mallet (more or less, as you'll see).

We also happened to need three wooden storage trays for our 7" vinyl collection, to sit on The Bookcase that I'd recently finished. So now all I needed was some wood...

First of all, I didn't want to chew-up good quality (expensive) wood while I was starting out. I'd managed to get a hold of a few planks of really nice hard woods (oaks and maple) which are currently cluttering up the cottage. I've mangled them a little bit practising my hand planing – so I've put them aside for when I feel I could do them proper justice; that is until I've made 100 effective, and at the end of the day, sweet-looking dovetails.

You're joining the story here some 72 dovetails in to that journey.

Reclaiming wood from a pallet

We had recently taken delivery of a tonne of eco-friendly high efficiency wood fuel (from www.woodfuel.coop whom I heartily recommend) which had been delivered kerb-side. 50 trips up and down the garden path by Christine and I later left me with an empty standard (1 x 1.2m) wooden pallet. Each board of the pallet was the perfect width to construct the trays I wanted to make for the 7” singles (I also had a whole bunch of 6mm plywood sheets kicking about from which I would cut the bases for the trays).

I've seen an awful lot of 'pallet re-use' woodworking projects on-line which maybe gave me the idea of reclaiming the wood from this one; mostly though such projects are pretty 'rustic' (i.e. shonky as hell) because the wood in pallets ain't necessarily of the finest of finishes... I'd watched this pallet being unloaded from the delivery truck as it almost toppled over on to a sweet family and their dog who were meandering down the way at the time. It didn't in fact topple (and to be fair the driver was sure it never would have) but it did certainly rip a long split into one of the bottom lead boards of the pallet; so there was at least one piece of really poorly finished wood that I wouldn't be reclaiming.

A few other pieces ended up in our stove too as they split badly whilst I was working out the worst way to dismantle a pallet! I could have reclaimed 2 or 3 additional boards if I'd understood pallet construction better in the first place. For a good look at the components of a pallet checkout this blog-post at palletconsultants.com.

The deck boards remove easily, but of course the temptation is to start with removing an upper lead board. Don't do this, you will only end up ripping those boards to pieces. It is best to start from underneath, removing the lower lead and stringer boards first, then whacking the blocks off before separating the upper lead, deck and stringer boards (or whatever combination your pallet has). Fortunately I only needed 4 deck boards (without splits) to make the 3 trays required for our singles collection (each tray comfortably holds 125 singles).

Having reclaimed four 1m long boards without major splits in them, the wood now needed cleaning up. I suppose the right thing to do would be to plane them, but I just don't have the tools (or perhaps skills) for that – so I simply sanded them down instead (using my random orbit power sander). At this point I'm concentrating on reclaiming the wood, not on 'finishing'. I'm sanding to attain a reasonably smooth splinter-free board, and to finely inspect the piece for previously unnoticed defects and splits – so I can decide which parts of the board I will make use of; I want the boxes I'm making to look more decent than 'rustic'. I used a 40 grit paper and the sanding took quite sometime, maybe 20 minutes or more per plank. Given how long the sanding took it would have made way more sense to just buy some PSE (planed straight edge) for the project, but I reminded myself of the importance of saving the planet, and what a good man I am to be re-using the material... and ultimately I was rewarded – not only through the satisfaction of not having another tree chopped down but by the look and feel of the boards once I'd finished. The wood does, come up beautifully.

image showing a reclaimed board versus a finished piece

Working with dovetails

I had no idea how confusing dovetails can be until I started making them. Fortunately I was working in my small studio, so none of the household cats were around to 'help'; nevertheless I managed to cut one set of pins back-to-front somewhere along the way... The difficulties arise from the sheer number of options available, and from the need to maintain really good spatial awareness.

I remember when I'd made my first box, Christine asking me “But how do you join the fourth corner up?” - which is something I'd been pondering myself when I started out! We imagine dovetails to be some kind of magical interlocking which once created will never again be separated. But actually, they're much simpler than we imagine. Dovetail joints will never pull apart in one direction (from the 'front'), but actually slot together and pull apart relatively easily in the other direction (side-to-side). This is why dovetail joints are used for drawers – which are pulled from the front and never much troubled from the sides (or indeed for a tray, which will be pulled off a shelf from time to time by its front panel).

image showing how dovetail joints interlock

If you're making a box, with no real distinction between which is the 'front' and which is the 'side' then you may as well use box-joints instead of dovetails. Box-joints are very similar to dovetails, but the tails and pins are not flared like they are in a dovetail joint.

So let's examine the anatomy of a dovetail joint:

image showing the anatomy of a dovetail joint

The side panels (tail-boards) will have flared prongs (dovetails) at each end which slide into equally flared notches cut into each end of the front and back panels (pinboards). Of course, the notches in the pinboards also create prongs, which are called Pins. So the side panel dovetails slide between the front & back panels' pins. The very top and very bottom pin (or tail) will be a partial pin – since the top and bottom will be flat, not flared like the internal faces of the pins are.

There's lots of things you can think about, e.g.
  • How many dovetails should there be?
  • How tall should each tail be?
  • What's the separation between tails (or, how tall should the pins be)?
  • Do we start and end with pins or tails?
  • How much of a partial pin (or tail) should there be at the top and bottom?

See the confusion? The fact is, almost any answer to these questions is acceptable, within the limits of the height of the joint and the strength of the material (very skinny tails will snap off). These are more questions of aesthetics than engineering and it is best to draw the design out first (I use Autocad's 123D to model my woodworking before committing saw to wood).

My diagram shows what I consider to be 'classical' dovetailing. The (exterior) height of the dovetail is equal to the width of the boards that are being joined, and the spacing of the tails is equal to the height. Looking at the join from the pinboard face therefore renders equal, regular squares of pins and tails – to my eye this is most pleasing. It's equally possible to create the join with a single dovetail and very tall pins; or to create several tall pins with slender tails, or whatever arrangement satisfies.

I don't need to think about how many dovetails there should be, that falls out as a natural consequence of deciding they will be as tall as the board is thick with an equivalent spacing. In fact I can say that the number of dovetails will be given by:

height of joint / 2 x (width of joint)

This is exactly how I made my very first dovetail joint which had 5 tails, 4 whole pins and two (one at the top, one at the bottom) partial pins:

image showing my first complete dovetail joint

If the height of the joint is not an exact multiple of the thickness of the material, then you will find that the first and last partial pins are not exactly half a pin. Depending on the geometry of the wood you might find that the partial pins are very slender and liable to snap. In which case you might elect to do away with them and to have slightly larger first and/or last tails instead. If you draw your design out first though, that kind of thing becomes really clear.

There are other reasons you might want the first pin (or tail) to be larger or smaller than a half pin. In the vinyl storage boxes I had to cut a dado (a groove along the grain) to accept the plywood base. This dado needs to run across (at least some) of the bottom pin and depending on the precise arrangement could leave a very slender strip of wood which would be liable to splitting. In the vinyl storage boxes I adjusted my starting 'classical' design to account for these issues.

image showing the design of the vinyl storage box front piece

All of the above is my preference regarding what I think looks good when it comes to a dovetailed edge, and is a fair starting point if you've never designed a dovetailed joint.

The only remaining question is, by how much should the dovetail flare out? If the angle of the flare on the tails is very steep then a modestly sized tail will become very thin at the rear of the tail, which may make them overly delicate. If the angle of the flare is very modest then the gripping force of the pins against the tails may be too low, especially if the wood should contract. The 'received knowledge' is that softwood dovetails should be at a 1:6 gradient and hardwood dovetails at a 1:8 gradient. I really like the look of dovetails and so I emphasise the nature of the joint by using a gradient of 1:5 (11.3degrees). This means that a dovetail of 15mm front-facing height and 15mm depth will be 9mm tall at the rear of the tail.

In summary
  • Design your dovetail joints in accordance with aesthetics; draw them out first.
  • Place your pins on the front (and rear) panels, with the tails on the side panels.
  • Don't make your tails or pins so thin that they might snap.
  • Remember that the top and bottom pin (or tail) is a partial pin, since it must be flat on the outsides

Building storage boxes for vinyl singles


So by now I had the raw materials and design basis for the vinyl storage boxes all sorted out and all I had left to do was actually make the boxes! I completely made the first box before cutting any wood for the next two; just in case something I hadn't thought of turned up. Which of course it did!

This was when I managed to cut one set of pins back to front! Pins are flared (in order to accept the dovetails) such that they are shorter at the front face of the pinboard than they are at the rear face. Because I hadn't yet cut the dado it wasn't clear when handling the piece which was the front and which was the back face – and of course at one point I carelessly confused the two. This meant remaking an entirely new piece... so I gave up for the day and went downstairs to burn some of the unreclaimable wood from the pallet in serene (and toasty warm) revenge.

The next day I realised that it would also be important to remember which set of tails had been fine tuned to mate with which set of pins – i.e. I had to ensure not only that I remembered which face of a piece was the front and back but also which side panel mated with which each edge of the front and back panels. So I took to labelling each corner on the front face; I nominated the corners as A, B, C and D; writing the appropriate letter on the front face of the top pin and top tail as I created each joint.

image showing how pieces in progress are marked-up

To make the joints I started with the side panels, cutting the dovetails rather than starting with the front and back panels cutting the pins. When it comes to finessing the joint so that the tails fit snugly between the pins it is way easier to shave the pins than it is to shave the tails; this is because of the direction of the slope with respect to the wood grain. Once cut the tails are what they are, the pins get shaped to match them.

I started by marking the edges of the tails, since they are perpendicular. After making the first box (joint by joint) I was able to 'gang-mark' the edges for all four side panels of the next two boxes, which helped to speed the job up a little.

image showing gang-marking dovetail ends

After clamping all four side panels of the second two boxes in a stack I mark out the ends of the dovetails with pencil and set-square. I then go over the marks with a marking knife, which later leads to a cleaner cut. In fact I use the marking knife on all cut lines throughout the process, it really makes a difference.

image showing fully marked dovetails

Next, using one of the end pieces as a template, mark the depth of the tails on each face. Then using a dovetail marker draw in the angled sides of the tails. I'd been planning on making dovetails for yonks, so when I last had some money I treated myself to quite a fancy dovetail marker. It was a bit of an extravagance to be honest, but I really do like it... you can make your own template out of stiff card, you really just need a trapezoid of appropriate dimensions. I'm cutting dovetails at a 1:5 gradient, so here's a suitable template for those:

image showing 1 in 5 gradient dovetail template

Notice I use a clutch pencil for mark-up, this gives me consistent lines. Also notice that I keep a big mug of tea on hand, that's probably even more important than marking out the waste material (as shown in the previous photo). I haven't yet accidentally cut a dovetail off...

Now remove the waste material from between the tails. Start by sawing down to the backline on ech side of the waste. Then pare a very small sliver of the waste with a chisel up to the back line. You will have marked this line with a marking knife so that sliver should come away cleanly. This gives a tiny, but significant step against which you can place your chisel to make a chop stroke. Do not attempt to chop the whole waste material out at once; you need to make sturdy smacks more than almighty thwacks. Again, pair material away at the rear of the waste up to the chop line you just created. Turn the board over and repeat the process. Keep doing this, making chops and paring away material at the back line until suddenly one chop releases all of the remaining material. With my reclaimed wood and freshly sharpened chisels I had to repeat the process around 3 times on each side to remove each chunk.

Now transfer the dovetail pattern to the end edge of the pinboard by abutting the end edge of the pin board up against the dovetails and then drawing around the tails. Make sure the pencil point sits right in at the edge of the tail, do not allow the barrel of the pencil to displace the pencil point from the edge. This will give some pretty wonky lines, so thereafter reinforce the transferred pattern by going back over each line using the dovetail template.

image showing how to transfer dovetail pattern to pinboard

Having marked the edge of the pinboard you can now mark the faces. Add the back line as was done for the tails and then use a set-square to extend the pins from the edge to the back line. The pins are perpendicular on the faces, and you will see how they are thinner on the front face than on the back face (which is why the joint is resistant to pulling forces applied to the pinboard).

Remove the waste in a similar manner to how the waste between the tails was removed. Don't forget that this time there is more waste at the back than at the front, so you will be angling your chisel for many of the chop cuts.

Now it's just a matter of finessing the pins until the joint mates well. The pieces should slot together with a modicum of force applied by body weight or else light mallet taps – anything more risks snapping tails off.

I then cut the dado slots at 5mm deep and the plywood for the base, finally glueing, sanding and oiling to complete the boxes. I guess if you're interested in dovetailing you'll be fairly happy with this part of the work.

I made my boxes 22cm wide (internally 19cm) to accommodate 7” singles, although singles with extravagant sleeves are a slight tight fit, so may want to choose something a little wider. These boxes are 39cm long (in order to fit well on the bookcase I had made) and they comfortably hold 125 singles. The plywood for the base was therefore 20cm x 37cm.

And that's it done. Now all we need is for Christine to alphabetise the collection, which I'm sure she will... thank you for reading.

image showing the three boxes in use

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