Thread: Handsaw hang angles.

Hi Ian. If h represent the depth of saw plate then its still retains an influential value. For example; if I have 2 backsaws at the same hang angle and saw plate length, but the saw plates vary in depth, the line of directional force on the deeper saw plate will be nearer the toe of the saw plate as it crosses the tooth line.

Stewie;

http://www.telegraph.co.uk/news/heal...100-years.html

Height not length.

Originally Posted by rob streeper

Derek,

Isaac's analysis is interesting but I haven't come across an analysis that includes h, the height of the saw plate. Have I missed it?

Rob

I'm supposed to be getting ready for a tool show tomorrow mornign, so I have to keep this short for now. Consider yourselves fortunate on that front...

The effects of changing h are shown in this analysis. I don't explicitly discuss it, but if you look at equation 3 on page 2, it's evident that the moment required to balance/use the saw changes with h.

In plainer English: when you cut with a saw, you are not simply pushing straight ahead, but also have to apply a moment (also called a couple or torque). As the height of the plate changes, so will the torque required to use it. The magnitude of this effect varies along the length of the stroke.

Changing h also has an effect in the third dimension that is not considered in this analysis. This would show up in real life as how tippy (I think that's the technical term) the saw feels.

Stewie

I am putting on my charlatan's hat here, but my take is that the weight of a saw has a huge bearing (oops, sorry about that, it just flowed out) on the positioning of the handle and in saying that I am not attempting to suggest geometrical angles.

If you compare the two extremes in back saws being the humungus mitre saws and the diminutive dovetail saw you can see that there is really no need for downward pressure on a mitre saw while there is on the dovetail saw. The weight of the mitre saw is quite sufficient to cut, assuming it is sharp, and all the effort can go into the horizontal push.

So all other saws with a spine are going to fall in between and this fits in with Derek's quote from Blackburn tools. I think the range was 23 deg to 50 deg. The only modification to this might be the height at which you work. IanW has had input to this in the past. For example dovetail cutting might be performed at a greater height than work on a bench hook.

Just out of interest I measured the only vintage back saws I own (the charlatan mantle is revealing itself now) and these were the results:

Simonds No.95 Mitre saw - 22 deg
Simonds No.96/97 back saws 10",12" & 14" - 24 deg
Thos. Turner open handle 12" - 47 deg

All the saw are in the 11/12 ppi range.

The results surprised me a little and they were crudely measured using protractor, ruler and set square so in the rough ball park but not perfect.

Possibly this indicates that the hang angle is more dependent on end use than weight or any other factor. I also should point out that my sample is very small and not truly representative. I feel sure there are others among you who could give a far more comprehensive set of data.

Regards
Paul

Originally Posted by ian

The "ideal" hang angle will then be related to the relative height of the sawyer, the height at which the work is held or clamped and the depth of the cut.
Relationships to the saw plate depth will be then be related back to these fundamentals

I heartily agree with that.

Originally Posted by rob streeper

The rake angle, and all of the factors you mention, are connected to h as well.

I don't think that changing h should have any effect on the rake you want to use. Rake is dependent on/related to the hang angle of the saw.

Originally Posted by planemaker

If you take dovetail saws as an example, I personally dislike the higher hang angle Isaac prefers. That doesn't mean I devalue Isaac's opinion.

I make two basic dovetail saw designs. I still prefer using the larger one with the lower hang angle, but the other is growing on me as I become more familiar with it. It's reinforcing my belief that you can get used to a wide range of saws (within reason) given enough time and practice.

I should also say that the example saws in the illustrations were chosen for their extreme designs, so as to make the contrast and differences clearer. They shouldn't be viewed as an endorsement, dislike, or repudiation of any particular design.

Interesting. The hang angle thus seems to be heavily influenced by preference or opinion as well as mechanics. As I wrote on the prior thread before transfer I find the finger method to work pretty well. On my handsaws I've found that a hang angle that points the finger above the horizontal works well, in fact I just received a No. 7 from the 1877-1888 era that has that feature.

A worth while read. Of interest to Isaac. Note the different methodology to measure the hang angle . http://www.wkfinetools.com/hUS-saws/...-WMB-No3-1.asp

Stewie;

Personal preference is a very big factor.
Of importance is that the hang angle of our knuckles to our forearm all differ.
Type "hand fist" into Google and check out the images.
Some knuckles are perpendicular to the forearm others are at almost 30 degrees.
The saws that the two extremes would find comfortable will be very different!

I agree. Within certain bounds the various combinations of dimensions and methods of use work for some people and not for others. My experience has been that most people prefer a saw with a relatively relaxed rake angle, but preferences vary over a broad range of hang angles. Some people prefer heavy backs, some want lighter. Blade length preference varies quite a bit too.

Originally Posted by planemaker

A worth while read. Of interest to Isaac. Note the different methodology to measure the hang angle . http://www.wkfinetools.com/hUS-saws/...-WMB-No3-1.asp

Stewie;

Hi Stewie,

Coincidentally, I bought a Monhagen saw recently. It has a nearly positive rake and the hang angle is about 10^o above the toothline.

Rob

Monhagen rip saw.jpg

Thanks for posting. To avoid a rather lengthy reply I would only add the height of the grip area of a hand saw ( measured center of the hump vertically to the tooth line ) is absolutely related to the height if the plate. By lowering the grip area you compensate for the "tipsy" effect, Issac mentioned, along the Z axis, for more balance control. This also helps to maintain the wrist in a more neutral position in line with the forearm. Hence a more comfortable and efficient stroke. The Wheeler Madden-Clemsen hand saw is a good example of a lowered grip area to maintain control and balance functionality while maintaining an aesthetically pleasing design. Best wishes.

Hi Rob. Very nice looking hand saw. Those truncated cone bolts and cover plate give the saw a unique appearance.

Stewie;