Note: Descriptions are shown in the official language in which they were submitted.
8~37~3
BACKG~(~U~D OF Tl IE I~VI~NTION
The invention relates to a device for controlling the filing of a depth gauge
of a cutter link of a chain saw chain.
The cutter links or cutter teeth, as they are also known, of a standard chain
saw chain include a depth gauge and a cutter edge separated by a space.
The depth gauge preceeds the cutter edge in the direction of travel of the
chain. The depth gauge should project outwardly slightly less than the
10 cutter edge and thus determines the amount of material removed in each
pass of each cutter edge. The amount of material removed is
approxirnately the difference between the height of the depth gauge and the
height of the cutter edge.
15 The cutter edge i8 normally sharpened by use of a round file. Devices have
been developed for holding round files for sharpening saw chains as found in
the United States Patent Number 3,327,567 to Penberthy, United States
Patent Number 3,518,900 to Ehlen and United States Patent Number
4lû12,969 to Granberg. The latter shows an adjustable saw chain guide and
20 holder.
A problem arises however when the cutter edge is sharpened. This reduces
the height of the cutter edge 90 that the outws~rd projection oF the cutter
edge is reduced relative to the depth gauge. This reduces cutting
25 efficiency of the cutter link The efficiency can be restored by filing the
depth gauge until the proper relationship is restored. However, the depth
gauge must not be fil0d too much or the cutting edge will take too deep a
bite which increases the likelihood of kick back and potential serious injury
to the user.
Devices have been developed for adjusting the relationship between the
depth gauge and the cutter edge. An example is found in United States
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Patent Number },796,113 to Granberg which shows a depth gauge
attachment using a rotary grinder. The device rests on the tips of two
adjacer)t cutting teeth. Unfortunately, this leads to inaccuracies because
the heights of adjacent teeth are not necessarily the same. A device of this
5 type gauges the height of one depth gauge partly in relation to the height of
the cutting edge of an adjacent cutter link. The height of each depth gauge
should be determined solely in relation to the cutter edge on the same cutter
link.
10 Other devices have been developed for filing depth gauges. One example is
found in the United States Patent Number 4,412,463 to Beerens which
discloses a guide for resting on the tip of a cutting edge and having apertures
through which the depth guage projects. A file is then placed on a plate and
operated to file away the depth gauge until is it flush with the plate.
15 United States Patent Number 2,594,821 to Stone shows another gauge for
filing saw chains. Such devices have the disadvantage that the guide or
gauge must be held by one hand, while the file i5 operated by the other.
This is awkward in practice. In addition, the devices are typically adapted
only for use on specified types of chains.
United State Patent Number 2,297,01n to Milano shows a saw filing device
including a bar having clamps for securing the file.
The prior art does not oFfer a solution which permits simple filing in the
25 cnnventional manner where both hands are used on the file and without the
need for holding a depth gauge of some kind and which can be used on
essentially all chains having a common pitch.
SUMMERY 0~ THE INYEhiTION
The invention provides a device for controlling filing of a depth gauge of a
chain saw chain having a plurality of cutter links spaced-apart by non-cutter
links. Each cutter link has a depth guage, a top cutter edge and a back.
3 --
The device comprises an elongated file holder with a center portion having
means for holding a file. The file holcler has a flat surface along a first sideof the center portion and a longitudinally straight edge along a second side
of the center portion. The flat surface and the straight edge face
5 outwardly in a common direction with a filing surface of a file held in the
centre portion. The flat surface and the straight edge are positioned
relative to the center portion, such that after a depth guage of a first cutter
link has been filed to a desired level, the flat surface rests against the cutter
edge of the first cutter link while the straight edge engages a non-cutter
10 link and the back of a second cutter link which is adjacent the first cutter
link.
DE5CRIPTION OF THE ORAWlhlGS
15 Figure 1 is a perspective view of a device for regulatlng filing of a
depth gauge of a chain saw chain according to
embodiment a-F the invention, showing a file mounted
thereon;
20 Figure 2 is a fragmentary perspective view showing a portion oF
the device mounted on a chain saw chain;
Figure 3 i9 a fragmentary view of a variation having a 510t for
gauging a prùper file;
Figure 4 is an in view of the device shown in position on the chain
saw chain.
DESCRIPTION OF TIHE PREFERRFD 5~:MBODIMENTS
Referring to the drawings, Figure 1 illustrates a device 1 for regulating
filing of a depth gauge 2 of a chain saw chain 4 shown in Figures 2 and 4.
The device includes an elongated file holder 6 which is substantially
_ 4 3iL2~7~
r0ctangular in shape having a center portinn 8 in the shape of a channel
having a flat surface 10 for receiving a flat file 12 having a filing surface 14facing outwardly in a direction which is perpendicular to surface 11).
5 The channel-shaped center portion is delineated on one side by a first
longitudinal flange 16 which has two portions. A first portion 18 extends
perpendicularly from the flat surface 1û o-F the center portion. A second
portion 20 is connected to the first portion and is perpendicular thereto.
Its flat surface 22, facing in the same direction as the cutting surface of the
10 file, is parallel to flat surface 10 of the center portion I. As may be
observed, slat surface 22 extends longitudinally along one side of the center
portion 8 and is spaced perpendicularly outwards therefrom by the first
portion l
15 The device has a second flange 24 along a wide of the center portion 8
opposite the first flange 16. This flange is flat and extends perpendicularly
from surface 10, having a Plat outer surface 26 and a longitudinally straight
edge 28 which faces outwardly in the same direction as the filing surface of
the file and flat surface 22 of tlle first flange 16.
The device also includes identical clamps 30 and 32 for holding the file 12
against flat surface ln. Pus shown in Figure 4 for clamp 30, each of the
clamps i9 substantially U-shaped, each having two threaded shanks 34 and
36. These project through larger apertures 3a and 4û in the file holder.
Wing-nuts 42 and 44 threadedly engage threaded ends 46 and 48 of the
25 shanks. Thus, when the wing-nuts 42 and 44 are tightened, the file is
tightly held between the clips and the flat surface 10.
The device as illustrated i9 intended to hold the flat file 14. The file must
be the correct thickness in order for the device to operate properly. For
30 this reason, the device may have a slot 52, illustrated in the embodiment
Figure 3, which extends inwardly at one end of the file holder. The slot is
the proper width for a file which accordingly may be gauged by placing it in
~2~
the slot. As observed best in Figure 4, flat surface 22 and straight edge 28
are spaced perpendicularly outwards from flat surface 1n a distance such
that they are beyond filing surface 14 of the file.
5 Ope~atl~n
Referring to Figures 2 and 4, the device is used for filing the depth gauge 2
on a cutter link 54 of the chain saw chain 4 and is used successively on other
cutter links, such as cutter link 56, each of which has a depth gauge 2. The
10 straight edge 28 is positioned so it rests on a non-cutter link 58, commonly
known a a "side link" while outer surface 26 contacts back 60 oF the next
adjacent cutter link 56 to the cutter link 54 being filed. Flat surface 22 is
adapted to slidably engage tip 62 of cutter edge 64 on cutter link 54. For
this reason, the file holder is preferably of metal and surface 22 at least is
15 hardened so it is harcler than cutter edge 64. This allows surface 22 to glide
easily over the cutter edge without causing damage to either surface 22 or
the cutter edge of the saw chain. The depth gauges are generally chromed
on the outer slde and filing is correctly done against the unchromed side.
The file i3 reversed in the holder to file depth gauges on the opposite side.
Surface 22 and the 3traight edge 28 are located distances outwardly from
surface 1û such that when a file 12 having a proper thickness is held in the
file holder, the depth gauge 2 i8 Filed the proper amount, For exarnple 0.025"
below the height of the tip of the cutter edge, by drawing the file back and
25 forth in the conventional manner along its longitudinal axis. It rnay be
noted that, initially, straight edge 28 rests against link sa and outer surface
2~ contacts back 60 of link 5~. At the same time, the filing surface 14 of
the file rests on depth gauge 2. Flat surface 22 initially does not contact
tip 62 because the depth gauge 2 is typically projecting too far outwardly in
30 relation to cutter edge 64. The device could be rocked so that surface 22
does contact tip 62, but, in this case, straight edge 28 would not contact link
5~ and so proper filing would not occur. The file is drawn back and forth
until depth gauge 2 is filed an amount efficient 30 that straight edge 28
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simultaneously contacts link 58, while surface 22 contacts tip 62 of cutter
edge 64. Further filing produces no more effect because the device is
supported by the straight edge 28 contacting link 58 and surface 22
contacting cutter edge 64. As may be observed best in Figures 2 and 4, the
5 filing action has the effect of angling the tip of depth gauge 2 downwardly
towards the corner formed by link 58 and back 60 of link 56. This is the
desirable configuration. Typically the device is configured so that, when
the proper thickness file is used, the tip 62 of the cutter edge 64 projects
approximately .025" beyond the tip of depth gauge 2.
Devices of different sizes and configurations are required for saw chains
having chains with different pitches. For example, typical pitches are
0.325", 0.365", 0.375", 0.41)4", 0.5", and 0.775". However, a device
adapted for any given pitch fits practically any chain saw chain and i5 not
15 restricted to the chain of one manufacturer.
It should be noted that each depth gauge is filed independently of the heights
of adjacent depth gauges which may vary consiclerably.
