IMPROVEMENTS IN FRAME SAWS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Edward Newton at the Office
of the Commissioners of Patents, with his Petition, on the 19th
November 1875.
I, EDWARD NEWTON, of 16, Southampton Buildings, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN FRAME SAWS," to be as follows (that is to say):-
This Invention relates to improvements in frame saws.
.
According to my Invention I use a light rigid frame, either angular
or curved, and strain or tighten up the saw blade by a direct screw
action, as herein-after explained, applied in the direct line of the length
of the saw blade, which is strained between two handles inserted in the
opposite extremities of the frame. The frame should be as light as
possible, and yet quite rigid or nearly so; this I construct in various
ways. One method is to have the two sides joined by a stretcher and
strut at the opposite ends to that of the saw, the stretcher being attached
outside and the saw strained over the strut, which is placed as near the
stretcher as possible, the one serving to lock in the other. The stretcher
may be of wire with a nut or burred head at each end, and the strut of

page_text: shaped wood; or the stretcher and strut may be formed in combination.
When a stretcher and strut or the two combined in one piece are thus
used, the sides may be formed of any suitable material, but I prefer to
turn them out of suitable wood, thus giving the shape to the sides
entirely in the lathe, except what may be afterwards shaped for bearing
surfaces.
If one piece of bent wood be used for the frame I prefer to let in or
add to the top part a thin plate or bar of steel or other metal, thus
adding greatly to the rigidity of the frame, with but a very slight
.addition to the weight.
I find in practice a tubular metal frame both light and strong, and
this may be formed either of ordinary sheet metal or metal tubing, or by
stamping out two half tubes longitudinally, without or with a flange on
one or both sides, and uniting them by riveting, soldering, or by
other suitable means, or very light T or L iron may be used to form the
frame.
The two extremities of the frame are adapted to receive each a handle,
between which handles the saw blade is stretched. The bearings for
the handles may be formed in various ways. If the sides of the frame
are of wood a circular hole may be bored through each in the direction
of the saw to receive the handle, which should be turned to a tight fit,
so as to well support the weight of the frame from turning when the
saw is in use; or a band formed of sheet metal may be attached to the
end of each side to receive and clasp the handle; or instead two blade
springs, may be attached, one on either side of each handle to clasp. and
hold the handles between them, the springs being formed to fit round
the handle. If the frame is made of stamped metal, as described, the
proper form. to receive and grasp the handles may be imparted to the
extremities in the process of stamping or otherwise forming.
The two handles between which the saw blade is stretched are made
different to one another, one being intended merely to hold the saw,
whilst the other is constructed to stretch or strain the saw blade for
work. The former is very simple; in form it is similar to handles
usually employed for bow saws, but the part to form the bearing in the
frame is turned of larger diameter than usual for the purpose of getting
a greater surface to be gripped in the bearing in the frame. A hole is
bored through lengthwise, and through this a piece of ordinary round

page_text: or square bar iron is driven from the back so as to project for a short
distance through at the front. If round iron is used an angular head
is burred on the back end to prevent it from turning round in the
handle. The part that projects through has a saw cut in it, and a pin is
also fixed through at right angles to the cut. This pin is to hold the
end of the saw blade, in which a notch is formed to drop over the pin;
and in order that the saw may not be slipped off when stretched the
notch is formed in a slanting or angular direction, or the end of the saw
is bevelled off, and takes under a corresponding bevel in the end of the
saw cut in the handle. The handle used to tighten up the saw is similar
in outward formation to the one described, and has likewise a piece of
iron rod passing through it, which however has a screw thread cut on it,
that when the saw blade is attached to its inner end it may be drawn
through the handle, and thus tighten or slacken the saw as desired, the
handle being in two pieces, and the back or outer part being provided
interiorly with a nut for that purpose. The metal bar is either round or
square, and is prevented from turning round in the handle by a cap on
the inner face of the handle, having a square opening in the centre
when the bar is square, and projection corresponding with a like recess
cut in the bar when it is round. The saw is attached at this end by a
notch dropping on to a pin through a saw cut, as with the other handle,
and in the process of stretching the saw is drawn within the handle, and
so prevented from being slipped off the pin.
To increase the hold of the handles in their bearings in the frame an
india-rubber ring may be fixed in a groove formed around the bearing
part of the handle, or other spring arrangement may be employed.
The handles are prevented from passing too far through the frame by
a shoulder made to bear against the side of the frame, and the required
flexibility of the saw is provided for by a washer of india-rubber or
other spring action between the said shoulder and frame side of one or
both handles.