Monday, July 23, 2007

More Seat Carving

Here is Doug Roper working on his high back sack back (It's actually done now but this is the first chance I've had to write!)
We had a great week working on the finer points of chairmaking and designing a chair together, I look forward to seeing the chair painted!

I've had a number of questions lately about travishers and inshaves. Elia Bizzarri is making travishers based on the one that I made and use. The most frequent concern about these tools seems to be the curvature. When we look at a windsor seat, we see curves. The seat is scooped, the sides are curved and the underside is rounded. This gives us the impression that the seat is extremely shapely and dished. This turns out to be an illusion. Most windsor seats are merely a number of gently curved planes intersecting. The flatter seat allows more movement and therefore is more comfortable. Most important to the shape of the seat is that the deepest part is correctly located in relation to the back and that the front is properly relieved to prevent cutting off the circulation of the legs. I have found that a 5" or 6" radius on a travisher is fine for achieving both the tightest radius and the flattest areas of a seat.

The key to working the flats and curves with a single tool is the angle at which you hold it. Above is a photo showing the curve at the bottom of my travisher. I use it to carve the flatter areas by making a series of strokes in one direction and then going over the same area in a different direction, much as you would while using a scrub plane. As I approach the desired shape and depth of curvature, I lighten and overlap the strokes to get a finer surface. This is a fine time to mention that nearly every stroke that I take with the travisher is across grain and with the tool at least slightly skewed. While cutting cross grain, I make sure to skew the tool in the direction that will cut cleanest (normally towards the deepest part of the seat).

Below is the same travisher pictured while skewed. You can observe that the curvature of the bottom is tighter. It is in this position that I am able to cut the curved at the back of the seat. When cutting this area, I simply stop when the tool won't cut anymore. The problem that I most often see with students is that they are trying to cut the deepest part of the curve without cutting the areas around it. It is a good rule of thumb that if the tool won't cut the desire area, try cutting the surrounding material. Think of the way that a handplane cuts, always riding the high spots. A travisher works the same way, if all the surrounding areas are high, it stops cutting. This is when folks start reaching for tools with a tighter radius. I think that this is a mistake. The idea behind the shape of the travisher is similar to the handplane. With either, the idea is to "map" the shape of the tool onto the workpiece. With a handplane, the desired shape is flat, and when flattening a board, we reach for the largest practical tool because it will take in more information (high spots) and more easily do the job. The same goes for the travisher. The information taken in by the increased contact of the flatter curved tools will yield a more consistent result.
Working the tighter curved shaves is the equivalent of using a small block plane to flatten a plank. Yes is always cuts but it will be difficult to get the surface uniform.

There are other advantages of using the travisher in the skewed position. Below is an image of a chisel blade showing the direction that the shavings travel across the cutting edge when used straight and skewed. As you can see, the path of the straight cut shavings will go directly up and have to deflect the full angle of the bevel. This makes cutting more difficult and yields a coarser cut when cutting crossgrain. The path followed by the shaving when skewed is less extreme. The benefits are many. Less force is required to cut, the tool cuts cleanly cross grain (while pointing with the grain), the bevel angle is reduced (actually acting as a thinner, sharper blade) and the ease of slicing while cutting is increased. With the travisher, you also add being able to adjust the curvature of the bottom. Most of what I've touched on here also applies to the inshave, which is why I also advocate for the flatter ones. I would like to note that I have no financial involvement with Elia. I just want to see a good tool made by a good craftsman.

Tuesday, July 17, 2007

Testing Grounds

Here are the results of a couple of the experiments that we did in the iron shop at Penland. Above is a piece of hickory that I shaved green and bent around a pipe that we heated in the forge (obviously a bit too hot). It was thrilling to see the hickory wrap around the pipe and relax as the heat permeated the wood. After it cooled just a bit, the bend was set. This experiment really drove home the idea that the effects of heat are common to forming both wood and iron.

I have always been interested in the way that basket makers pound ash to separate the growth rings for weaving material. And when I saw the power hammer in the iron shop, I couldn't help myself. Probably a bit of overkill, but it was great to see the weak layer between the rings give way and the wood come apart like a bent lamination. One of the students combined these experiments to bend the separated ash around a pipe to make some beautiful circular forms. She let the interior of the bends char. The power of the forge heated iron to burn the wood seemed to strike a chord with some students, as well as myself, as one of the more interesting interactions between the processes. I suppose it's a nod to the caveman in all of us that there is satisfaction in seeing wood ignite.

This week I am happy to have Doug Roper in the shop. Doug is a chairmaker from California and is in the east on a chairmaking odyssey of sorts. He just finished a couple of weeks studying with Curtis Buchanan in Tennessee where he made a substantial writing arm chair, now he is making a high sack back rocker with me, and then he is heading up to Vermont to make a chair with Dave Sawyer. I'll post pictures of his progress.

Saturday, July 14, 2007

Home Again

Everytime that I return from Penland, I find coming home a mixed experience. I am thrilled to be home again, though the lawn has grown into a jungle. I am happy to be in my own shop again, but I am too tired to work. I enjoy sleeping in my own bed, but having to prepare my own meals seems downright daunting! Now that almost a week has passed, I'm ready to get back in the swing.

The class that I taught ,in collaboration with blacksmith Marc Maiorana, focused on conveying the basic skills in the wood and iron shop while exploring the connections between the two. We often used tools and toolmaking to blur the line between what are often seen as separate disiplines. The image above is of a class project. Each student, having been versed in the iron shop skills of blade making and the woodshop requirements for a proper tool, created a handmade tool. These tools were then gathered into a collection which featured a variety of gouges, an adze, a froe, a mallet, a scribe, a slick, and chisels. I made a box for them and we sold it at the scholarship auction for over $500!

This project was the culmination of much experimenting and learning (by Marc and I as well) about the interplay of the two materials and shops. I have long believed that to be a woodworker, especially one that works with handtools, requires one to be almost half iron worker. Being able to manipulate the iron begins with sharpening, sadly a process often mystified and neglected, and ends with the ability to form a tool to meet the woodworking requirements at hand. Now that I am able to create tools to better suit my needs, there is one less obstacle to my creating with wood. My ideas take me from my forge, to my woods and into my woodshop.

One of the points that I tried to stress during the whirlwind introduction to green woodworking, was that handtools are not a Luddite response to modern production methods. Just like walking across country may seem extreme, so might driving to the mailbox. I've found that being versed in wood technology and handtools offers me a flexibility and speed that suits my level of production.

Penland has a fully outfitted and impressive machine room that proved to be too much to resist for some students. I have no problem with using those tools appropriately, but I did try to point out that they bring their own restrictions, along with the whizzing blades. Once engaged, these tools require one to work in the world of square and flat, which is not necessarily bad, but can seep unrecognized into the choices we make not only about how a piece is made, but how it looks and feels. Every step into the world of the curve can cost time and effort, and often isn't attempted.

At the end of the class, I was impressed with the creativity of the students efforts, some of which I'll be sharing in the next posts. As a chairmaker, I have only needed to push the limits of the wood so far, and seeing the successes and failures as the class pushed further has deepened my understanding and respect for wood. Thanks to all of you who worked so hard to make the class a success.