With the yard sale and flea market season now in full swing, old rusty tools shake off their dusty winter coats and wander out into the warm sunlight once more in hopes of finding a new home. Each Saturday morning in New England dawns with the promise of finding one of these long-lost treasures.
Last week, on one such morning, I stumbled across this apparently common table saw blade from a nest of saws in the bottom of an old tool chest…
I was first struck by it as the etch was very bold and it looked little used. As I picked it up to get a closer look at the etch, I then noticed what I first thought was a terrible sharpening job, but soon revealed itself to be a strange hybrid tooth geometry.
As soon as I got a chance to look more closely, I realized that this was no hack-sharpening job…this was a very deliberate filing…
It seems that the teeth are filed in groups of 2 + 5, meaning that there are two stout teeth followed by 5 finer teeth. The only difference I can see from the 2 teeth to the 5 is the degree of rake…the 2 teeth are more aggressively raked than the 5 teeth. This pattern repeats itself for the whole length of the saw…2 stout, 5 fine, 2 stout, 5 fine, etc, etc. You can see this very clearly in the picture above.
So what the heck is this all about?
The filing does appear to be factory original…meaning that this was the way the saw was filed by the Disston factory. The teeth are perfectly jointed and the fleam is very consistent on all of the teeth. Further, the saw has seen very little use…I know this because the blade is arrow straight (table, keyhole, compass and all narrow bladed saws are invariably found bent and kinked) and the etch is as bold as the day it was made.
If in fact the filing is not original and was filed by the owner, it was executed with such fine precision that it must have been done by a master filer, so that further suggests it was most deliberate. Either way, factory or custom, this tells us that someone very learned in the art of saw filing intended this tooth pattern….so there must be an advantage to it.
As I further inspected the saw, I tried to understand how this filing would benefit a table saw…
Table saws are intended to cut gentle curves in table tops and similar patterns, hence the narrow blade to follow a curved line. This means that in the wood, the teeth encounter grain parallel to the line and across it and thus make ripping and cross cuts. So does this strange tooth pattern help make both types of cut? Perhaps the aggressively raked teeth are intended to rip more effectively? But then why not file them straight across like true rip teeth?
I’ve never seen teeth like this before on a hand saw, and I’ve never read about them either. Disston and other saw makers patented many hybrid tooth patterns to improve the function of their saws…perhaps this is one more?
As I wonder about these odd teeth, it makes me think of what other knowledge of saw filing we’ve lost to history, perhaps never to find again.
In a way, we are starting over in this hand tool renaisance…we are reading Moxon and Roubo and Nicholson….all long dead. What secrets of working wood by hand died with them? Will we ever discover these secrets again?
What else have we lost to time and technology?