7 Attachment(s)
Blade Grind Profiles of three Golden Era Disston No. 77's
Here are the saws. Two are 12" and one is 8".
Attachment 457618
The etches are a little hard to see on the 12" saws but here are some better shots.
Attachment 457619Attachment 457617
Here are some graphics depicting the profiles.
First the 12" saws.Attachment 457623
This is what the 8" saw looks like.
Attachment 457622
Now comparing the three saws over the first four centimeters up from the toothline.
Attachment 457624
Finally the average deviations for each saw.
Attachment 457620
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Did the No. 7 backsaw become the No. 77?
Here are three earlier taper ground backsaws.
Attachment 458012
The upper and lower saws are 1860-1865 production, the middle is an 1865-1871 bearing an '& son' medallion. The saw at the bottom of the frame has an etch or stamp, but it's perpendicular to the toothline and it's clearly a No. 7.
Attachment 458011Attachment 458013
The other two saws have no visible markings on the plates.
Attachment 458015Attachment 458014
The early saws weren't ground much, but they were ground.
4 Attachment(s)
Pre-1860 Disston No. 7/77?
Here's the oldest saw I have of this type.
Attachment 458017
No stars adjacent to the wingtips of the eagle.
Attachment 458016
As you can see the toothline has drifted up over the years because of sharpening bias toward the toe which complicates my measurements somewhat as the thickest part of the blade is at the toothline at the extreme heel. Nonetheless the measurements still show a taper.
Attachment 458019Attachment 458018
Thus it seems that Disston was taper grinding saws prior to 1860, but only backsaws. The hand and panel saws were not taper ground until after 1860. Maybe Disston hadn't developed the techniques or machinery to do bigger saws prior to his first saw grinding patent (The history of taper grinding of saw blades, post #3) in June of 1860.