31 July 2013

Bisaigue

After seeing on the web the making of a number of Roubo inspired benches,  I was curious to know how they were made in Roubo's days.  So I took a look in a book about charpentiers, those who deliver the heavy timber work.  The next two pictures are from an old french book Le théatre de l'art de charpenterie by Mathurin Jousse.  The text is from the 1607 edition,  the picture from a later revised 1702 edition.


Listed are the mortising tools
  • 7. La bezague: to cut and straighten tenons and mortises
  • 8. La jauge: gauge to draw the mortise
  • 9. La tariere: to drill the mortises, 13 or 14 lines wide.  The line is 1/12 of a pouce, close to 1/11 of a 1959-inch.  
  • 10. Les lacerets: smaller 8 lines drills for smaller mortises or to fix by drawboring standard tenons.
  • 11. Ciseaux:  Chisels to start the mortises.
The bezague is called bisaiguë nowadays and has probably a Latin root bisacutus - although the idea of a two sided spear would have been Greek for them.  It was apparently the main tool to cut mortises as chisels are only used to start and once a reference surface is created the rest of the mortice is parred-hacked away. The one on the picture is a long over the shoulder model, weights 4.5kg (10#) with a paring chisel of 50mm (2") on one side and a mortise chisel of 15mm on the other.

The picture of Juliette Caron shows that shorter models were used over the elbow.

The halved version is a demi-bisaiguë; stossaxt, stichaxt ... in German and more common and cheaper than his bigger brother.  I see it as a slick with a twist,  as the handle is not only useful for pushing but also to twist when hacking away wood.

So a carpenters bisaiguë for Roubo's bench?  Maybe,  the workshop of plate 11 with it's high ceiling is clearly made by carpenters,  did they stop there?  The workbench is described as traditional, and shows not much variation over the trades. Roubo's improvement is to put a shoulder to the back of the leg to avoid that the legs pass over time too easily through the bench top.  Talking about resawing he proposes to avoid it, as resawers are three times faster than other woodworker trades in sawing, it's possible he thinks the same about carpenters and that they are also able to make a bench three times faster than most woodworkers do.

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