Archive for May, 2009

Chopping Mortise and Tenon Joints By Hand

Sunday, May 31st, 2009

This project has had more than its fair share of challenges. First the dovetails that needed to be cut by hand and then the tails that were cut standing on a stool with the six foot board clamped to the top of pallet rack. Now the through mortises that add strength to the carcass and keep the bottom of the case from sagging also need to be cut by hand because the board is too wide to use our mortiser.

chopping-mortises

Chopping Moritises

To make the layout and chopping of the mortises easier, I ran a stop dado in the top and the bottom of the case referencing off the fence to ensure that they are in the same orientation on both boards. I laid out the tenons on the two vertical boards, scribing them with a marking gauge slightly more than the thickness of the horizontal boards, so that the tenons stand proud of the top and bottom and can be planed flush. Then I cut them on the table saw standing them vertically and using the miter gauge to run them across a 3/4″ dado blade. I was not too concerned about the size of the tenons because I was going to scribe the mortises directly from the tenons.

After scribing the mortises, I used a forstner bit to start the mortise and finished it with a mortising chisel and mallet.

chopping-tenons-2

After the mortises were chopped, I fit the tenons taking care that the mortises bottomed out the same time that the front shoulders closed up.

fitting-tenons

Everything went together without a hitch, but if I were to build a case piece with similiar construction I would shoulder tenons so that I would be less concerned with gaps opening up. Also, I would have used Tage Frid’s technique of cutting the tenon diagonally and wedging it to add strength and close up any gaps.

Still learning…

-CB-

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Oh No, The Leigh Jig Is Broken!

Monday, May 25th, 2009

While we were moving, the locating arms of the Leigh jig were damaged. (Why do manufacturers insist on cutting corners on the most integral and delicate parts? They are needed to remain square to the jig yet they stick out 6″ from the main body of the jig, and it is made out of pot metal.) With deadlines looming and all the North Bennet Street School moxie I could muster, I decide for a mix of hand and machine work on the dovetails that hold the case of the low Shaker side board that will ultimately be used as a TV stand.

First I cut the pins of the half-blind dovetails by hand.

cutting-pins-by-hand

Hand-cut pins

In this picture you an also see how I laminated up the sides of the case. The outside is a resawn panel from the flitch that I bought from Berkshire Products for this client that is book-matched and the inside is shop-made quarter-sawn cherry. (More on that at a later date.)

And then switched to the router to hog out most of the material.

routing-set_up

Router Set-Up

I clamped the two sides together with a board on top so that board and other side would act like a stop while routing so I would not rout too deep into the pin board. This made the process go quickly. All I had to adjust between passes was the depth of cut of the router bit.

dovetail-bit

Router Bit

Because the router bit does not cut a flat face, I decided to do multiple passes to make the clean-up of the bottom of the tail socket dovetail joint easier. This is avoided when using the jig because the tails are sloped to match the bottom of the pin board, but when hand cutting and chopping the pins you need a flat bottom of the tail socket. Also, by cutting in lighter passes, it was easier to come close to my initial saw cuts without the fear of the router bit pulling into the keeper side of the pin.

Stepped Bottom of the Tail Socket from Router Bit

Stepped Bottom of the Tail Socket from Router Bit

Below is the sequence of cuts that I made.

first-pass

First Pass with the Router

Second Pass with the Router

Second Pass with the Router

Last Pass with the Router

Last Pass with the Router

I left about 1/32″ to pair along the face and checks of the pin board. It was quick work to clean up these cuts with a chisel.

Paring the Cheek of the Pins.

Paring the Cheek of the Pins.

Pins Are Paired

Pins Are Paired

Whenever dovetails are visible I take the time to cut them by hand, as there is a certain quality to dovetails that are cut well by hand. Since these dovetails are not visible once the top is on or unless someone is on the ground looking up at the piece, this was an expedient way to cut these dovetails.

A secondary challenge in the cutting of this joint was cutting and paring the tail boards that are about 6′ long. I ended up clamping them to the pallet racks that we use for storing our sheet goods and standing on a step stool.

One of the things I love about furniture making is while there are some standard practices, there is not “one way” to build a piece. Each piece has unique challenges and solutions, and each time you build a piece of furniture you are learning new techniques and strategies for common problems and adding to your knowledge base.

“When you stop learning, stop listening, stop looking and asking questions, always new questions, then it is time to die.” Lillian Smith

Still learning something new everyday,

-CB-

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