Monday, November 30, 2009

Come to Life pt. 2

In bringing the series on drafting to a close, I thought that I'd show the process from conception to completion. Below is the thumbnail of the Balloon Back childs chair that I will be teaching next year at The Center for Furniture Craftsmanship in Maine. I designed it with the time limit of the one week class in mind. It hits all the chairmaking high points but is still comfortably achievable, plus, its a sweet little piece, great size for a kid, but also big enough for an adult to use as a stool.

Below is the actual measured drawing that I used to make the pattern and build the piece.

And here's the finished piece. It was so fun to make that I'm starting another right away.
It's a good size project for experimenting with finishes, the one below is a mix of blue and black with a shellac top coat. I've been playing with the shellac lately, but that's another post!

If you look at the image below and then back at the first drawing, you'll notice how close they are to each other. Usually, my quick sketches are meant to capture the intended "gesture" of the piece, then I try to measure it out and build it without killing the fresh quality of the sketch. It's tough to do. All to often, the piece gets muddled, compromised and downright embalmed and it takes some further study of the sketch to pull it off.

Friday, November 27, 2009

Full Frontal

Today, as I headed out to my photographer to have some shots taken of the child's balloon back that I designed to teach in Maine next year, I grabbed this recently finished rocker to document as well. When designing a chair, I've often dreaded the full front view. The symmetry can make it difficult to create a dynamic look and balance in the proportions is touchy to say the least.

I've changed the spindles to make them wider in the midback region. I credit this change with making the center of this chair more lively than it's predecessors. Also by twisting the spindles to orient them for alignment in their widest part, the back has a seamless feel to it, a fine improvement.
With respect to the finish, I painted certain areas a slightly darker black to help define the transitions from one shape to another. The effect on areas like the arms and spindle deck adds a crisp somewhat formal quality that I like.

The backs of the spindles are also a shade darker.

Last week I had a young couple in the shop making their first chairs. Here's Prentice splitting up a slew of spindles.

They lucked out on the first day, I think that the days of shaving away the day on the porch are just about gone.

The assembly took an interesting turn when we realized, much too late, that Kyle and Prentice had switched undercarraiges and put them in the wrong seats!! Actually, it was pretty impressive as both went together just fine. Being new to chairmaking, I don't think that they understood what a good job they must have done on all the preceding steps to have interchangeable undercarraiges. Of course, when they switched arm bows later on (honest, I'm not making this up!), it became apparent more quickly. I guess sharing can be taken too far.

As they packed up, I couldn't resist this photo. It captured so much about them.

Now that the holidays are upon us, I'm taking some time to work on some writing and preparing to head back to Boston to teach a weekend seminar to the students at North Bennet Street. Just thinking about the cannoli has me ready to hit the road.

Saturday, November 21, 2009

Guest Blogger Elia Bizzarri

Here is a description of using and maintaining the travishers that Elia Bizzarri makes. I recommend this tool as a great value, but more importantly, it's made by a chairmaker who understands how to make a tool that really performs. While I helped Elia design the tool but am not in any way financially invested.

These travishers, unlike most on the market, operate via a slightly curved sole which gives depth-of-cut control while the tool is in use. There is no fussing with the blade to get the depth set, leaving you with only one possible shaving thickness. Sharpening is also easier because the back of the blade is concave to make removing the burr faster, plus the blade has no tangs to get in the way when sharpening the bevel. The handles are designed for chairmkers and the curve of the blade closely matches the curves in a Windsor chair seat, leaving a smoother surface.
Use: In my shop, travishers are an intermediate tool in the seat carving process between initial shaping with an inshave and fine tuning the surface with a card scraper. Travishers remove the gross irregularities and they do it in a hurry; they are the jack plane of seat carving. That said, the body mechanics involved in using a travisher are somewhat counter-intuitive and can take some getting used to.

As with most edge tools, practicing NOT cutting is the best way to learn to use a travisher correctly. Hold the travisher in two hands, thumbs resting on the flat pads on either side of the throat, with the blade facing away from you (travishers are usually pushed). Put the travisher onto the work, then roll your wrists up and away from you until the blade is no longer in contact and the sole of the travisher is all that contacts the work (see photo). Now push the tool, trying to keep the blade from cutting.

As uncomfortable as this may seem, this is where you should start each and every cut. Once you get the feel of not cutting, straighten your wrists slightly and the blade will come in contact with the work. Straighten them more for a heavy cut, less for a light cut. End the cut by rolling your wrists away from you to bring blade out of the cut; it's awkward, but rolling your wrists down will make the tool cut deeper before exiting the cut.
Blade Adjustment: As I already mentioned, these travishers are meant to be used in a way that gives you control over the depth of cut as you are using the tool. However, if you need to increase the blade exposure, inserting pieces of paper between the blade and the body will raise the blade; evenly scraping the sole will have a similar and more permanent effect. Carefully filing the shoulders which the blade seats on will lower the blade. It doesn't take much; one thickness of paper will have a noticeable effect.
Sharpening: Sharpening most tools is the same basic process: you sharpen the bevel with a coarse enough stone to be expedient, work up the grits to polish the surface and make a longer lasting edge, then remove any burr you've created by working it back and forth with your finest stone until it breaks off, leaving a crisp edge. There are many ways to do this, most of which work. Here are some thoughts:
The Bevel: A deburring wheel called a Beartex wheel (from MSC or Highland Hardware), followed by a hard felt or leather buffing wheel, is a quick way to sharpen the bevel. The Beartex is like a very aggressive buffing wheel and the tool can overheat or the edge be rounded over in a hurry, so it takes a little getting used to. Putting your wheel on a homemade threaded-rod mandrel, chucking it in a variable speed lathe and reducing the speed could solve this problem.

A safer method would be to screw the blade bevel-up to a wooden form and use some kind of slip (diamond, Japanese waterstone...) An old Japanese bench stone, the face rounded with a rasp, gives plenty of room for the hands if you plan on a lot of sharpening. The bevel can then be polished on a felt or leather wheel by skewing the blade on the wheel to give maximum surface contact. Start with the heel of the bevel contacting the wheel (to give you a frame of reference), then move the blade across the wheel towards the edge until you see a very slight feathering of the polishing compound curling up off the edge. This indicates that you are right on the edge. A heavy curl indicates you have tipped the blade too far, changing the shape of the bevel and blunting the edge.
The Back: The back of the blade must be kept flat. If the back is rounded over or made convex, however slightly, the tool will not cut, so only sharpening stones should come in contact with the back. No strops and definitely no buffing wheels. The back comes flattened and polished, so, unless you run the tool into a nail, your finest grit stone should be enough to remove the burr after sharpening from the bevel.
If the Beartex wheel gets away from you and grinding the bevel is the only option, a small grinding burr chucked into an electric drill should do the trick.

Elia Bizzarri - Hand Tool Woodworking
101 Nicks Bend West
Pittsboro, NC 27312

Tuesday, November 17, 2009

Plotting Curves

Now that I have a new scanner/printer (aaaarghh!!), I am able to continue the drafting series, although the images may vary a bit as I work out the bugs in my new tool.

Below is a three view sketch of a basic chair top design. It shows two posts as they emerge from the seat. To start, I thought that it would be best to have the posts be straight, to determine their basic limits.

As I covered in previous posts, information is taken from one drawing to the next to create the three views. When I design a chair, I work from some basic limits. For instance, I generally know where in space that I want the crest to sit, and you can imagine that the points on the end of the posts in each drawing would be in contact with the crest at that point.

Well, that being the case, it may not matter if the posts are straight or curved, as long as the top points are at the correct spot to support the crest at the chosen position. So for fun, let's throw in some curves. Initially, I like to focus on the front view, although it might change later based on the results in the other views. This curve is a bit extreme for an actual chair, but I thought that it would help to illustrate the point.

One very important factor to note about the chair that I am drawing, is that the curve that I am going to draft still sits in the sight line plane. In other words, just like the straight post, when viewed from above, the post will look like a straight line, so the overhead view won't change as I plot the points.
Below, you can see that I've plotted a point to start the side view.

I do this by selecting a point on the front view of the post and drawing a line horizontally to the side view. Then I project a line vertically from that same point and then "refract" it back down to the side view. Where they meet is my new point. It's fun to watch the curve emerge as I plot more points.

And here's the finished curve, truly a bit extreme!

Now with the side view apparent, it would be a good time, if making an actual chair design, to adjust the side view and then plot the points back to the front to see how to possibly temper this intense curve. In this instance, the side view is extreme because of the limit that I set in the beginning that the overhead view remain straight. Getting into curves that lie in a tilted sight plane is a bit heady for this example, and frankly, it makes my head spin.

Now, this is all fine and dandy, but if I was actually making a form to bend this curve, the information to shape it isn't apparent in this drawing, after all, the actual curve isn't seen fully in the front or side view. What we need is a profile of the curve, or in other words, the view from the side of the sight line.

I figured out this method years ago and then promptly forgot how I'd done it! With my recent renewed interest in drafting my curvaceous chair, I rediscovered the method.

Basically, we want the view that the creepy eyeball in the image has. So by extending lines at 90 degrees to the post in the overhead view and refracting them at 1/2 the angle of the sight line of the post, we can begin the same process that we followed before to get the side view of the curve.

Below is the resulting curve. Hopefully you can imagine that if you rotated the curve that I plotted on the right, it would be the same as what you see in the other images.

Sitting down, working this out and thinking this way has help me understand more of the geometry involved in the chairs that I am making and the factors that I can control to make them more beautiful and comfortable. While it may seem like too much of a throwback to a time passed, to me, it's just like the time spent making chairs by hand, time well spent.

Monday, November 9, 2009

New Happenings

Recently I got a counterbore from Morris Tools in Tennessee for my arm to stile joints. Boy does it make a difference.

I used to first drill a "shoulder" with a large forstner type bit and then finish it with a smaller bit for the actual mortise. It wasn't impossible to line them up, but it took some doing. Once I reground and sharpened the cutting spurs on the counterbore, it drilled a gorgeous joint and the alignment was a non issue. Below is the finished mortise.

Also on the tool front, I've been meaning to mention that while in Atlanta, I noticed that Highland Woodworking carries the diamond profile parting tools in the 1/8th inch size. Folks have contacted me looking for this elusive creature after I posted that it was my preferred size for turning but especially for the way it works with my caliper. The smaller cutting edge means less vibration and resistance but still cuts a wide enough kerf to easily measure.

I'm not sure what it says about me, but one of the most exciting and fun things to enter life here is our new ice cream maker. It's of the old wooden bucket variety (but with a motor, sorry galoots) and we've been putting it through its paces. It fits perfectly with our plan to have our goat milking in the spring. After vanilla, we decided to try mint chip, but no extract and green food coloring for us, I found a recipe and headed to the garden to pick the mint. Yes, Sue is still mad that I put mint in the garden, we'll never be rid of it!
Below is the mint steeping in the milk.

Here is the finished custard.

And into the freezer.

And the finished ice cream (actually, I probably stopped a bit short, but it froze in the freezer fine)

By the way, half of the sweetener in the mix is maple syrup from last spring, just one more reason to look forward to next years sugaring season.

Monday, November 2, 2009

Come to Life

It's always fun to see a project from drawing to completion, and this week with Alan Gensamer, we did just that. The drawing above is scaled so that 3/16" equals 1". Below is the finished piece.

Other than a mishap with drilling the arm (I foolishly veered from the drawing and paid the price of bending another arm!), the piece went very smoothly. Here's Alan getting it all together.

I haven't forgotten the curved stretchers, their drying in their forms. Below is a new (to me) bending method. I was getting some trouble with separation where the turnings narrow and expose endgrain, so I thought that I'd finally found a place to use a strap.

Not only did the strap work nicely controlling the separation (just a little in the center), but it pulled the piece to the form very evenly. My handy Irwin clamp (spreader) put so much force on the piece that the texture of the strap is embedded in the surface of the stretcher!

I've been asked about a million times about using straps in bending, and honestly, I've never found the need. I know that some very tight radii or thick bends could call for a strap, but the "normal" bends in my chairs have always bent just fine. I attribute this mostly to using straight grain white oak and hickory and shaving carefully along the fibers. I'll be knocking this piece together this week (hopefully), but today will be slow, Alan and I put in 7 days and I'm whipped!