It's a Balancing Fact
Don’t let anyone tell you that saws are just a hunk of wood plus a sheet of steel. The more that I work with different saws, the less I know about the tools.
Saws are a remarkable combination of materials and geometry. On the materials side of the equation, you can vary the weight, the balance and the amount of effort required to push the tool. On the geometry side of things, you can change the “hang” of the saw (which is basically the thrust pattern), and the aggressiveness of the teeth.
And you can vary all these characteristics almost infinitely.
This week I’ve been testing the dovetail saw from Rob Cosman for the April 2010 issue. It is, by far, the heaviest and longest dovetail saw I’ve ever handled. It tips the scales at 1.16 lbs. By way of comparison, my Gramercy dovetail saw weighs .42 lbs.
However, the saw from Cosman feels balanced, both to me and other members of the staff. But what do we mean by balance?
Some saws are “toe heavy,” which means they have a lot of weight at the tip. These saws tend to make me overcut on the far side of my work , something I try to avoid. Other saws have heavy handles, which just feels wrong to me.
This morning I tried to put some numbers to my gut feelings about balance. So I took apart four of the dovetail saws in our shop right now: The Cosman, Lie-Nielsen, Gramercy and Eccentric saws.
Then I weighed the handles separately from the back and blade assembly. I was surprised by how different they were. Here’s how the numbers came out.
Rob Cosman saw: This saw has a handle that weighs .5 lbs. and a blade assembly that weighs .66 lbs. That is a 43/57 handle-to-blade weight-distribution ratio. This is a 14-point spread.
Lie-Nielsen saw: This saw weighs .72 lbs. total. The handle is .2 lbs. and the blade assembly is .52 lbs. That’s a 28/72 weight-distribution ratio. This is a 44-point spread.
Eccentric saw: This saw weighs .68 lbs. The handle is .28 lbs. and the blade is .4 lbs. That’s a 41/59 weight-distribution ratio. This is an 18-point spread.
Gramercy saw: This saw weighs .42 lbs. The handle is .16 lbs. and the blade is .26 lbs. That’s a 38/62 weight-distribution ratio. This is a 24-point spread.
What does this mean? What is the ideal weight-distribution ratio? Is there one? Or is it just one factor that’s combined with the materials and geometry to produce a saw that cuts well?
None of these saws feels awkward in your hand. However, there are differences when you pick them up one after the other. I asked the staff to try each saw and tell me which one felt the most balanced. The universal answer: Everyone liked the Eccentric.
As one editor put it: “This saw feels so right that it’s like my hand grew teeth.”
The other major difference with the Eccentric is that the blade is smaller at the toe than at the heel. So its blade weight isn’t evenly distributed along the blade and back.
After a morning of fooling around, I now know even less about saws.
– Christopher Schwarz