Thread: Dovetail joints - angle of pitch

At this level(1:2, 1:4,) Kevin, sideways forces tend to be transferred to the short grain and rip it out.

at 1:6 pitch and shallower, the sideways forces tend to compress the grain.

1:6 = strength dovetail
1:8 = show dovetail (Slightly more likely to rip out, but unlikely nonetheless.)

Cheers,

eddie

If you want them to stand out, try using something other than regular spacing. If they're fine dovetails do something like three blocks of three, with large spaces between each block. Or graduate the spacing from each side towards the middle.

One dovetail technique I've tried, but constantly failed, is to make the tails on an arc. I saw it in an old Fine Woodworking and it looked really elegant, but I suffer from hand/eye co-ordination like a three year old, and I just can't get the arc right. (cue jokes about stammering and cash registers).

Ron.

Originally Posted by eddie the eagle

At this level(1:2, 1:4,) Kevin, sideways forces tend to be transferred to the short grain and rip it out.

at 1:6 pitch and shallower, the sideways forces tend to compress the grain.

1:6 = strength dovetail
1:8 = show dovetail (Slightly more likely to rip out, but unlikely nonetheless.)

Cheers,

eddie

Have you got that right Eddie? 1 in 8 is a shallower pitch than 1 in 6, but there's not that big a difference, so the stress-resistance really depends on the wood.

I was taught the same rules at school, but have settled on 1:7 for just about everything. Cutting steep pitches on softer woods is an exercise in frustration - you end up with corners chipping off when you do a test fit (I like my DTs tight!

Kevin - it's not just the pitch angle of dovetails that make them stand out - using two contrasting woods is a good trick, or at least a wood that has a very obvious end-grain cf. its side-grain. Also varying width & spacing across the joint makes a good statement (it says "these are unlikely to have been made by a machine")

Cheers,

We do dovetails these days mainly for show. The angle is not really relevant (as long as you follow basic rules - I'd say that 1:4 is about as wide as one should go).

Try different ratios (as well as different patterns). I find that I want to go wider as the boards get thinner - 1:8 will look like a box joint on thin boards.

Like Ian I prefer 1:7 for most things around 3/8" thick.

Regards from Perth

Derek

We do dovetails these days mainly for show. The angle is not really relevant.

Could you expand on this interesting remark, Derek? Why is dovetailing any different today than it was a hundred or more years ago? Why is the angle any less relevant?

Hi Silent

Because we make a fuss about joinery these days, as if it is something extraordinary. In the "old" days it not typically done for show, except at the higher end. Yes, you will find quality dovetails, but also many that just did not fit as perfectly as we strive for these days. Its as if a dovetail is a badge now of quality handmade furniture. Frankly, most modern glues will do well enough if all you want is 10 years from an item. What lasts longer than that?

Regards from Perth

Derek

I don't have a dovetail gauge (I set my dovetails out by eye using an adjustable bevel), but if I were to settle on a set ratio, I'd use a ratio of about 1:7 for everything too as it looks 'right'.

Originally Posted by derekcohen

.......Frankly, most modern glues will do well enough if all you want is 10 years from an item. What lasts longer than that?

Well, if you've only got crappy stuff like Jarrah to work with, what do you expect??
,

Seriously, though, you make a good point - in the 'old days' a lot of the joinery was deliberately hidden, & dovetails were not only done with generous-sized pins, they were rough! I've noticed the saw cuts often go well over the scribe lines, & scribe lines themselves seem to be laid out with careless abandon (s'pose you had to move fast to make a quid then, just as now). The most common places I've found knife-thin dovetails are on small, fancy drawers that were going to be very visible when pulled out. I also have a Victorian chest of drawers (in a Georgian style) that has really thin oak drawer sides with wincy little pins. I've had to fix at least two of the drawers in it because all of the pins were sheared off.

Cheers,

Because we make a fuss about joinery these days, as if it is something extraordinary. In the "old" days it not typically done for show, except at the higher end. Yes, you will find quality dovetails, but also many that just did not fit as perfectly as we strive for these days. Its as if a dovetail is a badge now of quality handmade furniture.

OK, so if I can rephrase that, what you're saying is that people only make dovetails these day for show, and so the angle is not playing a role in the stability of the joint, so therefore you can go by what you think looks good and not be concerned about the physics of the joint because the glue will hold it together

Personally, I can't see the point in going to the trouble of making dovetails if they're not going to perform the function they were intended to. I'd hope that would go for the majority of people here too. Generally I think that people like to make things 'authentic' by doing our joinery the tried and true way. People are interested in the technicalities of why things are done a certain way and want to imitate them.

I'd hate to think that it ever comes down to doing things purely for appearances and relying on the glue to hold it together as you suggest. Otherwise you might as well just cut the dovetails from veneer with a sharp knife and stick them on.

Originally Posted by silentC

....I'd hate to think that it ever comes down to doing things purely for appearances and relying on the glue to hold it together as you suggest. Otherwise you might as well just cut the dovetails from veneer with a sharp knife and stick them on.

Well - it has been done before! Seen a few examples of what is near enough to that in W'working mags over the years............

Of couse we do things for 'appearance' - isn't the whole point to make it appear as good as we are able? As for 'authentic' - there were plenty of blokes doing substandard work before Pharonic times, so even a crappy job is, in its way, 'authentic'.

Can't resist a bit of a stir...

Well yes, but if we're going to the trouble of cutting dovetails just so that we can brag about them, then we need to take a long hard look at ourselves

Do we not use them because it is the best joint to use in that situation, or are we really just a pack of conceited fops?

Don't answer that

Originally Posted by IanW

Seriously, though, you make a good point - in the 'old days' a lot of the joinery was deliberately hidden, & dovetails were not only done with generous-sized pins, they were rough! I've noticed the saw cuts often go well over the scribe lines, & scribe lines themselves seem to be laid out with careless abandon (s'pose you had to move fast to make a quid then, just as now). The most common places I've found knife-thin dovetails are on small, fancy drawers that were going to be very visible when pulled out. I also have a Victorian chest of drawers (in a Georgian style) that has really thin oak drawer sides with wincy little pins. I've had to fix at least two of the drawers in it because all of the pins were sheared off.

Cheers,

In the 'old days', the overall appearance of the piece was what mattered. The dovetail (yes, a single dovetail, then later two and subsequently multiples) was devised as a means of more securely attaching the drawer front to the sides so it wouldn't pull off – it wasn't conceived for its aesthetics.

Early dovetails were extremely crude, often cut at ridiculously steep angles (with imaginable breakages), but as the centuries advanced, the dovetail became more refined, though it still wasn't the art form it is today.

As you say Ian, cut lines often careered over lay-out lines because it wasn't considered bad practise at the time. Dovetails became more refined in the eighteenth century (practise makes perfect) and the Huguenot craftsmen that arrived in Britain from France and more importantly, Holland, brought immense cabinetmaking skills with them.

The small drawers in bureaux and cabinets that were subject to close scrutiny were of much finer construction by this stage, though I suspect more because it's necessary to make clean accurate dovetails when working with the typically thin stuff of small drawers. Even so, the dovetail was still regarded as a technique rather than an art form. This can be evidenced by examining an English bureau of the early eighteenth century; in the interior of the bureau, the small drawers below the pigeon holes are normally beautifully made, yet the (usually) four long drawers beneath the writing compartment exhibit the previously described over-cuts and other discrepancies.

In any aspect of life, the more familiar one is with a process, the more accomplished one becomes and so it was with English cabinetmakers; by mid eighteenth century, it's difficult to spot a badly executed dovetail.

The appreciation of woodwork joints and techniques in their own right didn't really take off until what's known as the 'Arts and Crafts Movement' of the late nineteenth century. Thereafter, or at least while the fad lasted, woodworking joints were seriously scrutinised and made visible as a form of art. The Septics still haven't got over it – I think they call it 'Craftsman Furniture'.

Originally Posted by silentC

Do we not use them because it is the best joint to use in that situation, or are we really just a pack of conceited fops?

Don't answer that

Um.... Oh, OK!

Originally Posted by IanW

Have you got that right Eddie? 1 in 8 is a shallower pitch than 1 in 6, but there's not that big a difference, so the stress-resistance really depends on the wood.

Hi Ian,
I wouldn't cut less than 1:6 slope is what I was trying to say - the number's been settled on by years of empirical evidence. ie: 1:5 has proven marginal as far as ripping out end grain due to short grain.

I still lay out dovetails with a sliding bevel. There's a visible difference between both slopes.

I'll attach a little movie I stuck together for another forum below- 'correct' layout (note the inverted commas as there's more than one way to do things,) is as shown in the movie.

Cheers,

eddie

Originally Posted by IanW

I was taught the same rules at school, but have settled on 1:7 for just about everything. Cutting steep pitches on softer woods is an exercise in frustration - you end up with corners chipping off when you do a test fit (I like my DTs tight!
Cheers,