Sunday, 10 November 2013

The eagle heads of the sella curulis

It has been more than a year since I posted on my sella curulis project. During this time almost nothing happened to the medieval folding chair. I had to carve the four eagle's heads, and was very reluctant to start with the feathers, thinking this would take a long time to do and that perhaps there was a smarter and faster way to do it. Then, a couple of months ago I laid my hands on an interesting book 'Make a joint stool from a tree' by Jennie Alexander and Peter Follansbee (ISBN). This book is basically showing you the 17th century joinery techniques. One of the decoration techniques described produced a carving which did look a bit like a line of feathers. The technique looked very straightforward and easy to do. You only needed a scratch stock and some gouges.

Above: The decoration technique as shown in Peter Follansbee's book 'Make a joint stool from a chair'. Left: The adjustable scratch stock from the book.

The scratch stock feathers

I did have gouges, but no adjustable scratch stock. It needed to be adjustable in order to 'crease' mould parallel lines for the rows of feathers. The scratch stock looks very similar to a marking gauge, which I had made before. Thus I made an scratch stock myself of some spare pear wood from the sella curulis project. As scratch blade I used a cut-off piece of a scraper, which I filed in the form needed. The scratch blade was hold into position with a bolt-screw and nut.

My adjustable scratchstock made from pear.

Unfortunately, the moulding technique from Follansbee's book did not produce good eagle feathers. The scratch stock could not follow the curve of the head, and the lines of feathers did not look very natural. Luckily I only tried it out with some test eagle heads.

Two test pieces of the eagles head. The left one shows the first attempt at carving the feathers, the right one the lines of feathers using the technique from 'Making a stool from a tree'. 


You can see that the scratched lines are unable to follow the curve of the eagle's head.

Carving the eagle's head

Before being able to start carving feathers, I needed to shape the head of the eagle, and carve the beak and eyes. I used a  test eagle's head as a model for the four heads of the chair. A pencil line was drawn on the middle of the head as a guide for symmetry. The rough carving of the head was done with a draw knife, and the detailed sculpting and smoothing with gouges (sweep 2, 3, 5 and 7) and a carving knife. At first, the beak of my eagle looked more like a beak of a parrot. However, I could adjust this to a beak more suitable to a raptor by changing the form of the beak, as well as the mouth line. Together with the eyes it produces the grim look of a (bald) eagle...

The (bald) model head of the eagle. 

Carving the fourth 'bald' eagle head. You can see the pencil line in the middle of the head as a guide for symmetry. At the back the second (finished) and third (half-finished) eagle heads can be seen.

The first two 'bald' eagles.

Carving the eagles feathers

With the scratch stock feathers being unsuitable for the sella curulis, I was at loss. Luckily, someone commented on a blogpost of mine and mentioned he was a wood carver. He offered advice and hinted on some tools that could be of help: fishtail gouges and hooked skew carving knives. This last one is also called an Abegglen detail knife. It is sharpened on both sides with a hollow and round ground blade. I added another gouge to this set: a 7 mm wide, sweep 11 gouge that has the same rounding as the tip of the feathers. For those who want to know it, the carving knife is custom made, while the gouges and the Abegglen knife are from Pfeil.

The carving tools used most for the feathers starting from above: a fishtail gouge (sweep 5), an Abegglen detail knife, a sweep 11 - 7 mm gouge and a carving knife.

With the use of these tools, carving proved to be far more quicker and easier than I anticipated a year ago. At the moment already two eagles heads are finished, and the third is on it's way. In the photos below the process of carving is shown and the final result.

First, pencil lines for the feathers are drawn on the head.

 Then the tips of the feather are marked by pushing the sweep 11 gouge into the wood.

A carving knife is used to extend the markings of the feather tips, and connect the feathers to each other.

The fishtail gouge is used to deepen the cut at the feather tips. 

The Abegglen knife is used to cut deep into the connecting point of the feathers.

The deep cut triangle is removed by a flat cut of the Abegglen knife.

Finally, the Abegglen and carving knives, as well as the fishtail gouge are used 
to create an overlapping 'roof tile' feather structure.   

A finished eagles head

The back and side view of a finished and an unfinished eagles head.