Roubo Joinery Bowsaw Prototype 2

Aside from the fact that my first effort in producing a joinery bowsaw based on the Bad Axe saw plate didn’t look like Roubo’s, only one of several features rendering this prototype useless to Mark in designing a production run, it was way too heavy at over six pounds.  That extra weight was fine for when the saw was engaged but sure was a nuisance when trying to maneuver it in between cuts.

So, I went back to the starting point and recut all of the wooden elements to both be slimmer and look like the saw Roubo illustrated in Plate 12, Figure 3.  In the end the only dimension that remained unchanged as the length of the saw plate.  Everything else was thinned, widened, thickened, or narrowed as I felt necessary.

The resulting weight reduction of almost 25% was noticeable immediately.

I literally enlarged this image to almost life size when creating the template.  Again I used some of my stash of clear white oak left over from the fabrication of the Studley bench top for that exhibit five (!) years ago.

The cutting and configuration was straightforward in the gross sense, but I spent a lot of time getting the template for the end pieces just so, reflecting the illustration Roubo created for the tool.  This is a tricky proposition, as the proportions and details of tools are not always perfect (see Plate !! for confirmation) but it had to be closer than the Art Nouveau-ish version I created for the first one.  Once I was happy with the shape and proportions of the arms I made a solid template from which I could make as many tracings as I wanted.

Of particular interest to me was the juxtaposition of the stretcher to the end arms; the only way the saw made sense in the flesh was to have the stretcher be notably thicker than the arms.  So that is how I made those three pieces.  In the end I made the stretcher about 1-1/16″ and the arms 3/4″.  I fussed over this detail for a couple weeks.

Notching the arms to receive the stretcher was also an issue as I had to make sure the strength of the arms was not compromised by too large a mortise.  I accomplished this by making sure the loose mortise-and-tenon assembly was quite thin, just a bit over a quarter inch and shallow at a half inch.  Since the joint’s only purpose was to keep the pieces in alignment that worked out just fine.  All the stress was in compression so the tighter the windlass was turned the more solid the bow structure became.  Unless, of course, it broke.  Hence my fussing.

But that was not the worst of it as noodling and fabricating the stirrups for the end of the saw plate was way more problematic.

Stay tuned.