A fixture for mitred through dovetails (with a story).

[Derek Cohen (Perth Oz)]

When my son Jamie was 10 years old, I build him a chest of drawers, somewhat Shaker-esque. This was an all-hand tools build, made easier as the wood used was Pine, with just Jarrah trim.

Jamie is now 29, married, and lives on the other side of Oz. He still has the chest of drawers, which is gratifying since he clearly treasures it (having said this, he asks me to build for him all the time - which I do - so perhaps he is just short of furniture).

In his last move, from Sydney to Canberra, the chest was dropped and the Jarrah base broke. It is not repairable, at least not by him. My wife and I are due to visit in February, and I said I would bring along a new base for the chest.

Now the issue is, how does one get it to him? It would be too expensive to ship. And the last time I carried (packaged) furniture on the plane to him (as hand luggage!), I was strip searched and treated like a possible terrorist. See: http://www.inthewoodshop.com/Furniture/CoffeeTableForJamie.html


I decided that the best way to do this would be to construct the base in knock-down format, and assemble it in Canberra. I also decided that the best joinery would be mitred through dovetails at the front corners, since these are mechanical joints, and would just require a little glue once there. The parts could either be rolled up and carried as hand luggage, or perhaps it might fit inside a suitcase. The base is 30" wide.


A while back I decided that I needed a better way to pare the mitre in mitred dovetails. Up until now, I used a mitred guide on top of the mitre to guide a chisel ...

I have made a number of cases this way, and have not been happy with the method, the results of which can be unpredictable. The danger is that the chisel causes breakout at the edge of the mitre. Watching Japanese woodworkers, who use this joint quite frequently, more often as part of a blind dovetail (or secret mitred dovetail), they will pare the mitre from the side.


This is the fixture I built ...

It is made with more of the Merbau panels (used for the MFT bench) as it is cheaper than plywood. The clamps used are by Veritas: Wonder Dog clamp and Surface clamp. The fixture rests against two small bench dogs at the rear.

The method is to pare the mitre from the side ...

The fence/guide is only on one side as this makes it possible to use it on boards wider than the fixture itself.

The fixture is also reversible, for mitres on the other end of a board ..

Pushing the joint together for the first time ..

And a dry fit (prior to chamfers and internals being added) ..

Regards from Perth

Derek

 

[deema]

Beautiful job as ever.
I like your version of the Japanese work bench, it’s one of the things on my extremely long list of things to do. With it, making hidden mitred dovetails is relatively easy. I have never fully understood why the mitred hidden dovetail isn’t used more often. I’ve meant to do a thread on how to do them, but haven’t so far for a long time made any furniture. In the UK brown furniture is (polite version) not valued or wanted at the moment. I wonder, with your skills, which are far superior to mine, is it a challenge you might consider doing a thread for and incorporating it into a piece of your wonderful creations?

 

[Hornbeam]

Impeccable joinery as usual Derek, but I wouldnt call those mitred dovetails, more through dovetails with mitred ends
A full mitred dovetail is effectively a double lap joint where the 2 lap parts meet as a long mitre. The critical bit is the fit of the mitre a you never see any of the joinery but now very seldom done as there are very strong ways (dominos etc) to strengthen a standard long mitre

 

[Jacob]

Impeccable joinery as usual Derek, but I wouldnt call those mitred dovetails, more through dovetails with mitred ends
A full mitred dovetail is effectively a double lap joint where the 2 lap parts meet as a long mitre. The critical bit is the fit of the mitre a you never see any of the joinery but now very seldom done as there are very strong ways (dominos etc) to strengthen a standard long mitre

Well yes impeccable joinery but a very modern idea of the mitred DT, where the convention is to display DTs and other workings. A traditional mitred DT would be nearly invisible. You wouldn't know it was there until pulled apart.

 

[doctor Bob]

Fabulous, Jacob's comment may be factual (albeit totally unnecessary) but I prefer DT's on show. Great skill.

 

[Sgian Dubh]

Fabulous, Jacob's comment may be factual but I prefer DT's on show. Great skill.

Jacob's comment isn't factual. It's close, but the name he was probably seeking was secret mitred dovetail(s) - the missed key word is secret. Slainte.

 

[Jacob]

Jacob's comment isn't factual. It's close, but the name he was probably seeking was secret mitred dovetail(s) - the missed key word is secret. Slainte.

OK but it's the dovetails which are secret - not the mitre, which you'd detect on the board edges corner.
I doubt you'd see a mitred through DT in any older work.

 

[--Tom--]

Really neat work, and great seeing the jig making. Hadn’t thought of paring from the side but it does make sense now you show it

 

[Jacob]

Well yes impeccable joinery but a very modern idea of the mitred DT, where the convention is to display DTs and other workings. A traditional mitred DT would be nearly invisible. You wouldn't know it was there until pulled apart.

Just had a flip through the bible (Joyce "Technique of Furniture Making" 1970) and I was wrong - Derek's mitred but through DT features there on page 199 in a section of "Rebated or mitre box corner joints" as a decorative joint where the top of the box shows a mitre. So it's older than I thought. Can't say I've ever seen one in the flesh though.
Joyce's main emphasis is on the aforementioned and more familiar secret mitre DT, and a whole rake of other variations, mitred or otherwise.
He goes into details about how to do them - and there's plenty to argue about there!

 

[Derek Cohen (Perth Oz)]

This is not a secret mitred joint. It is not a full blind dovetailed joint. It is a through dovetailed joint with a mitred end (a single mitre in this case. I generally do these at both sides).

The joint is worth learning. I have used it, and will continue using it, for all cases. It not only looks good (balanced) at the front, but makes it so much easier to cut rebates for panels at the rear of the case - one is simply planing or routing into a mitre. No stop rebates needed …







I have a pictorial on all this on my website. Link: http://www.inthewoodshop.com/Furniture/AnotherCoffeeTable2.html

Regards from Perth

Derek

 

[Sgian Dubh]

Just had a flip through the bible (Joyce "Technique of Furniture Making" 1970) and I was wrong - Derek's mitred but through DT features there on page 199 in a section of "Rebated or mitre box corner joints" as a decorative joint where the top of the box shows a mitre. So it's older than I thought. Can't say I've ever seen one in the flesh though.

Not in "the flesh", but below is an example where the corner mitre accommodates the tongues/ovolo mould of a solid wood box lid to account for cross grain expansion and contraction. Also, note a mitre worked in the run of the through dovetails works as a way to create a neat appearance on the meeting edges of the box lid and the main body of the box - see the second image down for an example where the exposed edges of the lid and the box are mitred. You'll probably note also that the size and spacing of the dovetails and pins for the lid are different to the spacing used on the box's bottom part. As you can see, I'm more than happy to leave the cross grain cutting gauge lines showing after assembly. Slainte.

 

[Derek Cohen (Perth Oz)]

That middle photo of yours is beautiful, Richard. That cove is stunning. The mitred corners draw one's eye to it. It would be so different if the case corners were butt jointed.

The same applies to this cabinet, which was a wedding present for a niece (her choice of furniture and design). I simply made it my way, which included mitred through dovetails. In addition, the mitres were (also, as with yours) emphasised with a chamfered surround. Without this, the result would have been very boxy ...

Regards from Perth

Derek

 

[Jacob]

I still see at as a bit quirky - going to the trouble of hiding a joint with a mitre and then exposing it with through DTs.
Could be seen as rather over-cautious "structural expressionism"?
Very neatly done though!

 

[Sgian Dubh]

Nice of you to say that, Derek. I hadn't thought much about the point you made regarding the mitre drawing the viewer's eye to the cove. I guess it's obvious when it's pointed out. To me the mitre at that point was just the standard means of construction. Slainte.

 

[Sgian Dubh]

I still see at as a bit quirky - going to the trouble of hiding a joint with a mitre and then exposing it with through DTs.
Could be seen as rather over-cautious "structural expressionism"?
Very neatly done though!

As far as I was concerned there was no quirkiness or structural expressionism about it Jacob. The techniques illustrated in those images were, as I was taught, completely normal and standard. I guess our perspective differs on that sort of thing because my background and training was in craft furniture, and I think your background is perhaps more in joinery type work. I'm not sure I have your background right, but I get the impression from your rare (sic) pearls of wisdom posted here that joinery is your primary thing rather than furniture. Slainte.

PS. I trust you'll notice there's a bit of a tongue-in-cheek joke in my response above.

 

[Jacob]

As far as I was concerned there was no quirkiness or structural expressionism about it Jacob. The techniques illustrated in those images were, as I was taught, completely normal and standard. I guess our perspective differs on that sort of thing because my background and training was in craft furniture, and I think I'm right in saying your background is perhaps more towards joinery work. I'm not sure I have your background right, but I get the impression from your rare (sic) postings here that joinery is your primary thing, and not craft furniture. Slainte.

PS. I trust you'll notice there's a bit of a tongue-in-cheek joke in my response above.

Have had my hand in various areas over the years. Mainly "craft" architectural joinery. But craft furniture is just another branch of joinery; same/similar tools, joints, materials, but different products.
I have never seen (or noticed) a mitred though DT joint anywhere but there are surprises all the time such as these DTs here Mystery box