THE DISSTON D-8 THUMB HOLE RIP SAW

By Bob Garay

            The other day I purchased a Disston D-8 thumbhole rip saw. I have had some of these before and knew them to be very good saws. When I started to clean this one I noticed it had five patent dates stamped on the handle. I had not seen this before and thought it must be an early D-8. My suspicions were confirmed when I took the handle off. The saw nuts were an early type used just after the split nut variety. I decided to investigate the history of this saw further and found some interesting information.

            For a time in the late 1870's and early 1880's, Henry Disston and Sons exhibited their fierce protection of patents related to their saws, which were copied by other manufacturers. Patent dates were stamped into the wood of early D-8 saws.

The five dates shown are as follows:     
5/12/74 - is for patent #150,678 to Christopher Eisenhardt for the space in the hand hole to receive the user's left thumb for rip sawing;
1/19/75 - is for patent #158,921 to Henry Disston for the cut-out in the saw blade to receive a close-up handle;    
9/21/75 - is for patent #167,996 to Henry Disston for the cover-top handle design that wedged the blade in a round recess in the handle;       
8/29/76 - is for patent #181,648 to Henry Disston for the cast saw nut design;
11/18/79 (it's not clear which patent is applicable to the D-8 saw. It has been speculated that on this date a reissue patent #8,966 to R. Gates for a Saw Handle, may be the patent noted).

            The shape of the skew back blade was a historical breakthrough in hand saw design. The Disston No. 80 "Choice" handsaw was introduced in 1874 featuring this trend setting skewback blade design that broke American sawmaking away from traditions established in England. This saw was sold only briefly. Around 1880 the handle was improved and the saw's name was changed to D-8. The D-8 legend goes: Henry Disston sketched his design on the factory floor to show his engineers what he had in mind. The theory put forth by the company in 1874 advertising was that the "peculiar formation of the blade actually stiffen[s] and strengthen[s] it in a remarkable degree."

            Another interesting fact is that the D-8 was the first Disston saw to use the letter "D" in its designation. This was in 1880 and most saws in the Disston line-up did not get a “D” designation until 1928.

            The most obvious feature of some D-8's is the extra hole in the handle. Offered on 26" and longer ripsaws from about 1880 until about 1950, the Dual-Grip or thumbhole-handled saw was designed for those laborious rip cuts. The handle is gripped normally with the lead hand and the thumb of the second hand is put through the thumbhole. The fingers of the hand are then wrapped across the top of the saw handle. These early D-8 saws have a much deeper and more comfortable groove cut into the handle than later years. Although there is no patent that shows this exact shape a patent by W.J.Reagan, #157,634 on December 8, 1874 is for a recess in the saw handle for the thumb.

            Disston took this patent idea and one by Christopher Eisenhardt, patent #150,678 on May 12, 1874 and combined them. Eisenhardt’s patent was for an elongated opening in the handle to allow the thumb of the second hand to be comfortably introduced to allow more force when ripping with a handsaw.

            Another important feature and patent of this early D-8 saw was the saw nuts. They featured a Disston patent #181648 given on August 29, 1876. This patent is for cast saw nuts that use a regular screwdriver and is not a split nut. It also has a beveled domed head that is tighter and requires no filing at the factory to fit.

            Lastly, another unique feature of this early D-8 saw is the form fitting saw blade in a handle that has a covered top to more securely hold the blade. The blade itself is cut in a curve to fit farther back in the handle, a departure from earlier English saws. The handle was "let-in" by cutting away part of the blade and having a curved slot in the handle instead of the typical straight slot for the blade. Thus the handle places the user's hand closer to the work and at a more comfortable angle for the wrist. This design was a combination of the January 19, 1875 patent #158,921 and the September 21, 1875 patent #167,996, both by Disston.

            With all these advancements in saw design it is no wonder Disston wanted to protect his interests. This saw has a total of seven patent dates  marked. He knew a good thing when he saw it as the D-8 saw is one of their finest saws and one of their best sellers. Thus, it just goes to show you - when you think you have a simple tool look twice at all the incredible ingenuity that goes into what may at first look like a simple design.