Monday, January 30, 2012

Jig, Crutch, Contraption, Heresy

I'm going to show some interesting (I think) jigs and jig alterations that we used in Melbourne, and before I get any berating emails and comments about going over to "the dark side", please remember, a traditional Japanese woodworker might walk into your shop and look at your workbench, vise and adjustable planes in bewilderment of the overkill of it all.

My goals in making and teaching chairmaking have more to do with making a great chair, having fun, and opening doors to accuracy and understanding. As I do this, I often try to isolate the variables at play and even if I abandon the idea, the thought process that I engage almost always deepens my understanding.

The first class in Melbourne was a continuous arm rocking chair, and once I realized what a different experience the troublesome timbers were giving the students, I set out to make a way to tame the rocker slot beast. In past classes, I've used the router to cut all four rocker slots in about 6 minutes and by the end of a class like this, students are bleary eyed and exhausted.

So I gave instructions on how to lay out the rockers and cut them by hand, and then we proceeded to use this set up to get 12 chairs to rock exactly the same, with nearly no balancing or fitting and no layout.

Here's the deal. Legs don't matter on a rocker. Yep, that's right, they are not the reference that counts. What counts is the relationship between the rockers and the seat. If the rockers are in line with each other, and have the correct position in relation to the seat, then the chair will rock beautifully. Of course, if the rockers are poorly positioned, the chair with tip to far one way or the other, so when setting rockers, the art of balancing them to each other and also to the seat at the same time is a challenge.

So, given my success in routing rockers in the past, I set out to make a jig that responded to the variables that count. By placing the chair upside down in the jig, I've already nailed one vital reference, the seat plane.


The next variable is the splay of the legs (and therefore rocker). The idea here is to split the difference between the front and rear leg splay and then to split it again from one side to the other. By coming to a single angle that the slots are cut and the rockers get beveled on the bottom, you can be assured that the curve remains consistent and balancing them will be possible. Imagine if the two rockers sit at different angles to the floor, they will actually be acting as different curves and become a nightmare to balance.

To knock out this variable, the jig that we used has a tilting board that is set to one angle for all of the legs. The only concern then, is that the legs register in the jig so that the slots are cut in the center of the leg at the full depth of the router cut, so there is no weaker side.

To achieve this, I cut a beveled edge on the bluish piece of ply that is attached below the  surface where the router runs. When the chair is pushed up against the bevel edge of the plywood, the leg is in position to ensure that the deepest part of the cut is centered, regardless of the splay of the leg. It's all about relating the path of the router to the platform and then the leg to the path of the router.

The final variable is the height of the rocker slots as they relate to the seat. This is really where this process earns it's keep. By setting the heights of the two platforms in relation to the seat, the position of each rocker will be identical to all the others (the fact that they will perfectly align back to front is not even an issue with this thing!) The depth that each leg is cut might be different, but once again, it aint the legs that matter, it's the rockers relationship to the seat.

One clamp pulls the legs against the beveled board and the piece is ready to be routed. 

Once we routed one rocker, we simply made an exact pattern of the two slots in space (knowing that they would all be the same) and made our rocker pattern to coincide.

This was a first go at this, and the results were amazing. All 12 chairs rocked the same and except for a couple of warped seats that threw it out a hair, there was no fussing or trimming. I don't know about you, but I've never found joy in shaving the end grain in rocker slots.

There is an even simpler way to rig this, and I will be constructing and showing it when I can, but I wanted to introduce this concept, if for no other reason than to get the point across that by isolating the variables that count, we can arrive at a new understanding of rocking chair construction that even a "purist" would find useful.

It's enough to make a Tasmanian smile!!

Wednesday, January 25, 2012

A Southern Perspective

Australia is a lovely landscape with marvels from desert to rainforest and I got to see plenty while I was there. This was one of the most surprising views that I came across early in my trip.

This wood seems almost more animal than plant!

It's a timber called "Black Box" and it highlights the incredible difference between the woods there and the ones back home.

This was a burl that another Pete (I had one class with 3 Peters in it!) cut out in the bush. He is one of a rare breed there that hunts spectacular wood for the musical instrument makers. I went out on an excursion with one of them, but more about that later. Isn't it wild that it looks so fleshy!

Here is the truck that Pete uses to go a'gathering.

I don't know about you, but to me, this is a real truck!! From the winch to the water and gas cans, you can tell that this is no vanity SUV. The snorkel looking thing is an air intake for when he crosses rivers.

Below is a class photo of the last class that I taught (I had 3 classes and a lecture). You can actually see chairs from the other two classes in the image, one is the continuous arm rocker and the other is the green birdcage in the back.

The Aussies don't have a tradition of painted furniture like we do, so I spent a lot of time brow beating them about the positive impact that paint has on the chairs. The solid silhouette, the taming of various wood, the richness of the paint...and so on. My intrepid host Glen Rundell took the bait and painted his birdcage with one of the most lovely finishes I've seen. You'll see more of it here (with recipes and process) or you can see it and more about his view of my trip on his blog.

I have lots to share, some new techniques, a jig or two and plenty of pictures of me relaxing in Tasmania ( from which I'll spare you). Even leaving a balmy summer for the New England slush, it's good to be home.