Chris Schwarz's Blog

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

25 thoughts on “It's a Balancing Fact

  1. Free Shed Plans

    It’s my first time visiting your blog… Looks like there’s a lot of good info to learn from here.

    I’m still some what new to wood working but it looked like it was balanced pretty good.

  2. Goddard Finley

    You can use two small high strengh magnets placed on the spline (if steel)or upper portion of the blade to vary the center of gravity (COG). This significantly changes the "feel" of the saw by balancing the blade above the tooth area being used. If the depth of cut is not too great this works fine and changes the handling noticably. There is no need for complex measurements; just find what is comfortable.

  3. me.yahoo.com/a/iW1ZUdFypdN6QP5sQc6EBs75k3Qi7Q--

    I think the feel of particular saws, like other tools is an aquired process (like food). I have tried many hammers in my day and the one I always revert to is an old 20 oz Plumb, a hammer I first used when learning the trade some 35 years ago. My dovetail, tenon, and carcass saws are a set of Lie Nielson I purchased about 5 years ago and they have "grown comfortable" to me in my work. Fine tools are great, however the beauty of the end result lies in the hands of the artist.

  4. Dave Brown

    A couple thoughts:

    In your closing comments you mentioned that the Eccentric’s blade is smaller at the toe than the heel. I think you meant to say that its brass back is also smaller at the toe. The brass back weighs more than the blade and has a commensurate impact on its balance.

    It seems like the reviewers prefer a blade/handle ratio of 60/40. Ideally the mass of the blade and spine should get heavier towards the handle. You didn’t mention the Veritas dovetail saws but they appear to exhibit these weight and balance characteristics.

    60/40 weight distribution is also preferred by many driving enthusiasts. Even though 50/50 is touted by engineers, under acceleration weight is transferred to the rear which improves acceleration and handling is improved because with less weight in the rear the 60/40 car rotates less easily. A porsche 911 is about 40/60 which explains their tail-happiness.

    What does all this mean? The weight of the components and how they’re balanced with regards to each other matters. 😉

    Dave

  5. Luke Townsley

    Chris,

    Interesting research. Kudos for making this conversation happen.

    As you know, vertical and horizontal centers of gravity, teeth set and geometry, handle hang, shape and angle, vertical and horizontal weight distribution, finish of the blade and handle, plate thickness and flexibility, overall size, type of saw, and how they relate to the wood, the job and the operator should all be taken into account in designing the "perfect" saw.

    I suspect that a great deal of this would indeed be quanitifiable, but it would sort of be like quantifying what makes a fast runner. Some things are obvious, others, not so much, and just when we get it all worked out, someone comes along and breaks all of the rules. That doesn’t mean it isn’t worth crunching the numbers though.

    My feeling is that the numbers you came up with are interesting, but not informative enough to be very useful by themselves.

  6. Mike Siemsen

    It looks to me like all of those saws are hung differently and would act differently in your hand. To really understand what is going on you need to change only one variable on one saw. Try putting a weight at different points along the back and see how it affects the feel and action of the saw. Try the weight on different saws and see if you come up with the same conclusions. Where does the weighted saw cut best and what is the placement of the weight in relation to the saws center of gravity with and without the weight.
    Mike

  7. Dan S.

    Chris,

    It would be interesting if you looked at the center of gravity, I bet if you measured it, it would be right in the center of the Eccentric blade. It would feel more balanced this way, because the center does twice as much cutting as the ends.

    -Dan S.

  8. tms

    Hey Chris,

    While I found your study interesting, I agree with Bob that you haven’t found the parameter that your looking for.

    I suspect that "moment" is going to come into the equation eventually. If you put all the weight in the center, you will have a maneuverable tool. Separate the weigh to the ends and you will have a stable tool.

    Tom

  9. Mark Coleman

    Chris,

    I’m an absolute novice when it comes to dovetail saw’s, or any ‘quality’ saw’s really. I read the article and all of the comments with great interest.

    One of the key things I’ve learnt about working wood is that the tool you are using is an extension of your body (absolutely no pun intented). I would have thought that what ever the dimensions of the saw, within reason, it would be something you get used to over time and that your body would adapt to the nuances of the tool.

    I think after reading your blog I realise that I would benefit most by buying the best tool I can, stick with it and don’t chop and change, as I understand you have to in order to complete your review’s

    Mark

  10. John Cashman

    I was interested in the balance point as well. Is it close to the handle, or farther away?

    The angle of the handle to the blade, and the distance of the handle above the tooth line would also be worth knowing.

    The total weight would be most interesting if you were doing a lot of dovetailing in one session.

  11. Tom Bier

    Chris,

    What is the handle of Rob Cosman’s saw made from; or is it loaded with lead shot? It is easy enough to see the weight difference in blades – more metal in the blade or back – but not so easy with the handles.

    I think another set of numbers may be interesting (or possibly pointless). Locate the center of gravity for each saw and a reference point on the handle (say the radius where the web between your thumb & forefinger rests). What is the distance between your hand and the CG and what is the distance of the CG above the teeth? Back to the lab!
    I vaguely recall an old posting where you said a large tenon saw was easier to keep tracking straight than a small one – I think that has something with a higher CG.

  12. Jeremy

    I agree, you measured something not very useful. What might be more useful? center of gravity. Its easy to find, then mark and see if you can find a correlation between good and bad saws, perhaps related to where the index finger is pointing when holding the saw to incorporate the hang variable?

    You can easily find the cg thanks to high school physics. Hang the saw from a string on the handle and a plumb line from the connection point will go through the cg, hang it from another place (magnet on plate?) and then where those 2 lines intersect will be the cg.

  13. Rob Porcaro

    Hey Chris,

    I hope you were wearing a white lab coat while doing this.

    Sure, it comes down to "feel" when choosing a saw but still it is worth doing some investigation like this because then we can begin to understand what contributes to a certain feel, and so we can alter these factors in a directed manner to produce different effects.

    It might be interesting to check the front-to-back balance point of the saws for the same reason.

    Of course, as long as it is humans pushing these saws, there will be no single ideal. (Like tennis rackets, etc.)

    Very nerdy of you, but I like it.

    Rob

  14. Dave Rodgers

    Lie-Nielsen saw: This saw weighs .72 lbs. total. The handle is .2 lbs. and the blade assembly is .52 lbs Where is the missing weight? .52 + .2 + X = .72

    Eccentric saw: This saw weighs .68 lbs. The handle is .28 lbs. and the blade is .4 lbs.
    Where is the missing weight? .28 + .4 + X = .68

    I’m not understanding something here.
    (Another retired engineer).

  15. Lyle

    Chris:

    You have been the crap out the subject of handsaws! How about graduating us to other types of hand saws namely fret saw and coping saw. Those too have a place in the workshop. 🙂

    In fact, last night as I was struggling with my fret saw I was thinking of getting you to educate us on its nuances. I see fret saw and coping saw as the Fein Multimaster and Dremel of hand tools (okay so maybe I am exaggerating) however, I hope I have made the point.

    Cheers,

    Lyle

  16. Bjenk

    Roubo’s descriptions of saw blades is very revealing in this regard too. They were intricate pieces of blacksmithing with varying thicknesses on the same blade.

  17. Bob Lang

    At the risk of sounding like a retired engineer, I think you fell into the trap of a diligent search for meaningless numbers. It isn’t just the weight of the handle vs. the weight of the blade, it’s how the combination feels when it fits in your hand. There is a difference between the saws, but I don’t think it can be quantified.

    Bob Lang

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