Miter chopper attachment for measuring picture frame molding

A measuring attachment for a standard miter chopper used in mitering rabbeted picture frame molding employs two arm members one of which can be adjusted in reference to a fixed scale on the front rail for measuring off a desired length of rabbeted molding and the other of which can be located so as to bring the leading inside edge of a previously mitered molding rabbet to an appropriate temporarily fixed position corresponding to the desired length to be chopped.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to apparatus for chopping picture frame molding and 
more specifically to a measuring attachment for a standard miter chopper. 
2. Description of the Prior Art 
Miter choppers employed for chopping picture frame molding have essentially 
become standardized in their construction. The standard miter chopper 
employs two blades mounted at some predetermined included angle, e.g., 
90.degree.. In use, it is necessary to measure off the length of molding 
to be cut and then a foot operated pedal linkage is used to bring both of 
the blades through the molding at the desired location to effect trailing 
and leading cuts. So far as is known, there are only two types of 
apparatus utilized for measuring off the length of molding to be cut. In 
one form of prior art measuring apparatus used on a standard miter 
chopper, a scale is scribed on the bed of the chopper at a 45.degree. 
angle to the front of the bed. The molding length is determined by 
aligning the point at which the inside of the rabbet and the mitered end 
of the molding intersect with the appropriate mark on the chopper bed 
scale, then sliding a movable stop along the front rail of the chopper 
until it abuts the end of the molding. While this is the most common 
method of determining molding length, difficulties of accurate measurement 
are frequently encountered in attempting to read a scale at a 45.degree. 
angle to the operator, graduated in one-eighth inch increments, and 
covering the full width, normally five and one-half inches, of the chopper 
bed. 
In another type of measuring apparatus used on the standard miter chopper, 
a vernier arrangement composed of three scales is employed. The first of 
these scales is a molding width scale located near the chopper head and 
perpendicular to the front rail of the chopper bed. The first scale is 
used for determining molding width as measured from the back of the 
molding to the inside of the rabbet. The second scale is a standard inch 
scale affixed to the front rail of the chopper. The third scale is a 
vernier scale mounted on the movable stop. Thus, molding length is 
determined by first determining the molding width with the first scale, 
then lining up the corresponding mark on the third vernier scale with the 
desired molding length on the second inch scale mounted on the front rail. 
While this second form of prior art apparatus is more easily read than the 
first mentioned prior art measuring apparatus, users frequently encounter 
misreadings by virtue of the three scales involved. 
Thus, it becomes the general object of the present invention to improve 
upon those prior art miter chopper measuring devices described above and 
particularly to simplify and make more accurate the measuring operation. 
SUMMARY OF THE INVENTION 
The measuring attachment of the invention is designed to be slidably 
mounted on the front rail of a standard miter chopper on which a reference 
measuring scale is mounted. The measuring attachment of the invention 
involves one arm, referred to as the mounting arm and which is slidably 
mounted on the front rail in reference to the measuring scale. The 
mounting arm provides an outwardly extending cantilever arm on which a 
second arm, referred to as the positioning arm, is slidably mounted with a 
spring-loading arrangement. 
In use, the mounting arm is appropriately positioned and fixed in reference 
to the scale at a position corresponding to the desired length of molding 
to be cut. Then, the engaging arm is brought into engagement with the 
leading inside edge of the previously mitered molding rabbet and is 
temporarily fixed in that position with the molding otherwise supported by 
the conventional supports. The conventional foot pedal linkage is then 
used to draw both of the blades through the molding to effect the cuts, 
one being a leading and the other a trailing cut.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The measuring attachment of the invention is adapted for mounting on a 
standard miter chopper such as manufactured and sold under the Morso and 
Jyden brands. Since the construction employed in the standard miter 
chopper is generally well known and understood by those who practice the 
art of making picture frames, only a limited description of the standard 
miter chopper 10 will be given. 
As best seen in FIG. 1, the chopper knives 15, 16 attach to a knife support 
member 17 and move up and down against the chopping bed 20 to effect 
cutting by means of the foot pedal arrangement 25. A pair of adjustable 
supports 30, 31 operate in guideways 33, 34 and are secured against the 
molding 40, indicated in dashed lines in FIG. 1, by means of tightening 
knobs 42, 43. While not pertinent to the present description, it will also 
be observed that provision is made for swinging the fence structure by 
means of the additional adjusting knobs 50, 51. 
The standard miter chopper of the type to which the present invention 
attachment is adapted includes a base guide rail 55 against which the 
molding 40 is clamped during chopping and an additional rail member 
referred to as a front rail 56. For purposes of the present invention a 
suitable scale 57 is secured to front rail 56 on which the desired length 
of molding to be cut is measured as later described. 
The apparatus of the invention basically employs two interconnected arm 
members one of which is designated as the mounting arm 60 and the other of 
which is designated as the holding arm 61, the interconnected arm assembly 
being designated 11. As best illustrated by FIGS. 1 and FIGS 5-7, the 
mounting arm 60 provides a slot arrangement enabling mounting arm 60 to 
slidably engage the front rail 56 and to be temporarily secured thereto by 
means of a clamping knob 65. A lens member 66 has an index line 67 which 
can be brought in alignment with a desired scale indication. As best 
illustrated in FIG. 7 showing a setting of four and one-fourth inches, the 
position of index line 67 with reference to scale 57 indicates the length 
of molding to be cut. A leaf spring 70 assists in maintaining the 
appropriate alignment of index line 67 with reference to scale 57. The 
longitudinal axis of the outwardly extending arm portion 60' of mounting 
arm 60 resides at a 45.degree. angle with respect to the longitudinal axis 
of front rail 56 and at a 90.degree. angle with respect to the 
longitudinal axis of the holding arm 61 as depicted in FIGS. 1 and 2. 
Holding arm 61 resides and slides in a slotted portion 75 of mounting arm 
60 and moves back and forth against the tension of a coiled, constant 
force, ribbon spring 76 mounted on the slotted end portion 75 of mounting 
arm 60 and having a secured end held by screw 77. Holding arm 61 can be 
positioned against the tension of spring 76 and held in a selected 
position by means of a fastening knob 80. 
The lower end of holding arm 61 is formed with a flat serrated face portion 
angled at 45.degree. to coincide with the angle of cut and a curved face 
portion 86 adjacent thereto, i.e., adjacent face portion 85. 
In use, it will be noted that the holding arm 61 maintains a 45.degree. 
relation to the longitudinal axis of front rail 56. When a new piece of 
molding is to be cut, the mounting arm 60 is moved along the front rail 56 
of the chopper until the index mark 67 on mounting arm 60 aligns with the 
scale indication corresponding to the desired length of molding to be cut. 
Mounting arm 60 is then locked in position by means of the locking knob 
65. The molding, whose leading end 41 will have already been mitered is 
then moved along the chopper bed 20 in such a way as to cause the flat 
curved surface 86 and flat surface 85 to ride up the leading mitered end 
41 of the molding until the line of intersection of flat surface 85 and 
curved surface 86, indicated at 90 slides under the rabbet of the molding 
and assumes the position indicated in FIG. 8. At this point the mitered 
leading end 41 of the molding 40 is abutting the serrated surface 85 on 
the end of holding arm 61 thus restricting any further forward movement of 
the molding. Thus, the point at which the inside edge of the molding 
rabbet intersects the leading mitered end 41 of the molding has been 
effectively located allowing its use in conjunction with the appropriately 
located scale measure for determining the length L of the molding to be 
cut as measured inside the rabbet of the molding. At this stage, supports 
30, 31 will also be temporarily securely clamped against molding 40 by 
means of their respective clamping knobs 42, 43 as depicted in FIG. 1 
after which the trailing end cut will be taken by knife 16 as depicted in 
FIG. 1 by operating the pedal linkage 25. Simultaneously, when two knives 
are being employed, e.g. knives 15, 16, as shown in FIG. 1, the leading 
end for the next succeeding piece of molding may also be cut by blade 15. 
While illustrated as being adapted to measurement of a miter of 45.degree., 
it should be noted that simply by changing the angle of the holding arm 61 
with respect to the front rail 56 of the chopper either in a fixed 
relation or by making such angle adjustable, the measurement attachment of 
the invention might easily be adapted to measurement of miters other than 
45.degree. as illustrated. 
It may also be noted that the measuring attachment of the invention is 
generally applicable to other types of cutoff devices provided with a rail 
for mounting the measuring attachment of the invention and having other 
means, e.g., a saw, for cutting and means for supporting and holding the 
molding other than that shown. Also, the material of which the molding is 
formed may be other than natural wood, e.g., plastic, and of different 
cross-sectional shape from that illustrated. 
In summary, the measuring attachment of the invention thus provides a 
simple, extremely easy and quick method for measuring the length of 
molding to be cut, precisely and accurately positioning the molding prior 
to chopping or otherwise cutting the strip and for providing a means for 
securing the molding in position during cutting so as to result in precise 
and accurate cuts on each occasion of use of the attachment.