US2747628A

US2747628A - Guard for cutting tool of woodworking machine

Info

Publication number: US2747628A
Application number: US423922A
Authority: US
Inventors: Robert S Ford
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-07-19
Filing date: 1954-04-19
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29
Also published as: GB702856A

Description

May 29, 1956 5, FORD 2,747,628

GUARD FOR CUTTING TOOL OF WOODWORKING MACHINE Original Filed July 19, 1950 FIGJ United States Patent GUARD FOR CUTTING TQOL 0F WOODWORKING MACHINE Robert S. Ford, Pascagoula, Miss.

Original application July 19, 1950, Serial No. 174,763,

new Patent No. 2,679,871, dated June 1, 1954. Divided and this application April 19, .1954, Serial No. 423,922

1 Claim. (Cl. 144-249) This invention relates to guards for the cutting tool of woodworking machines such as jointer planers or the like.

This application is a division of my prior application Serial No. 174,763, filed July 19, 1950, now Patent No. 2,679,371, granted June 1, 1954, and entitled Work Holder for Jointer Planer and Other Wood Working Machines.

My invention is broadly directed to improvements in work holders for woodworking machines, and particularly to a guard for such machines wherein is incorporated a mechanical work holder which serves to hold the work piece against the fence of the machine as the workpiece is traversed over the rotating cutter head. It presently appears that the most valuable application of this invention is for jointer planer machines, and the embodiments herein described illustrate application to this type of machine; however, it must be understood that some of the inventive principles involved are useful on machines of other types.

When using a jointer planer not fitted with a cutter guard and work holder, the operator is required manually to hold down the workpiece and push it over the machine bed with his hands in hazardous proximity to the cutter head. Manual operation of a jointer planer without a cutter guard and work holder is extremely dangerous, often resulting in serious maiming accidents to the hands. The frequency of such accidents over a long period of time has given the jointer planer the reputation of being one of the most dangerous of all the standard woodworking power tools. Consequently the need for a satisfactory mechanical cutter guard and work holder on these machines has been known for many years, and various devices for the purpose have been developed in the prior art, though none have proven satisfactory enough to merit general acceptance due to various shortcomings and defects which have been avoided in the subject invention by mechanical principles and combinations of elements widely different from anything developed in the prior art.

The principal object of the invention is readily seen to be the safeguarding of the operator.

Another object is to improve the quality of the Wor A further object is to lessen the fatigue and nervous strain of the operator by eliminating the necessity for manually holding a workpiece against a fence.

A still further object is to provide for quick adjustment and removal of a guard for a jointer planer or the like.

In the drawings:

Fig. l is a plan view showing a combination guard and work holder incorporating the features of this invention;

Fig. 2 is a sectional view of the guard taken on line 2-2 in Fig. 1, showing the combination guard and Work holder; and

Fig. 3 is a portion of Fig. 2 modified to show an alter- A 2,747,628 Patented May 29, 1956 nate construction embodying a second wheel on the flap guard.

The flap guard depicted herein has counterparts in a general way in the prior art which are adapted to function purely as guards or covers for the cutter head. In the present invention the guard has been modified and fitted with new mechanical elements which form a combination useful also as a work holder as well as retaining and even improving its utility as a guard.

Sidewise Work holding pressure near the bottom edge of a workpiece, such as is required to keep it from tilting away from the fence at the bottom, is provided by the combination flap guard and work holder shown in Figs. 1, 2 and 3, wherein a wheel 24 is caused to press on a workpiece 28 and hold it against a fence 6 along the bottom edge of said workpiece. This action complements the function of overhead pressure wheels such as are shown schematically at 1, 2 and 3 in fully guiding the workpiece being jointed.

Thus, a wheel 24 is rotatably mounted on the guard 22 with the wheel rim projecting beyond the guard and adapted to run on the workpiece. The resilient force required to hold the wheel 24 against the workpiece 28 is provided by spring 23, one end of which is permanently anchored to the machine frame 32 and the other end is connected by means of the handle 29 and hook 3%) to any one of the several anchor holes provided in the extended crank arm 27, which crank arm is an integral part of the flap guard 22. The flap guard is rotatably mounted on the machine frame by vertical pivot 58. It is evident that the action of the spring 23 on the crank arm 27 produces a continuous rotative torque in a clockwise direction about the pivot 58 on the entire flap guard assembly, and further that the magnitude of this torque is quickly adjustable by changing the engagement position of the hook 30 from one anchor hole to another. By this means, the effective spring action can be varied from a light force only suflicient to return the guard to closed position after being deflected, to a heavy force suitable to hold large workpieces firmly against the fence. The set screw 26 is threaded into a lug 31 on the underside of the flap guard 22, and adapted to strike the machine frame for the purpose of limiting the inward swing of the guard 22. The lateral width of the guard 22 has been reduced so that the Wheel rim 24 does not reach all the way across the machine bed. This is done to minimize interference with

wheels

1 and 2 and, more important, to permil easy introduction of the workpieces when using it at high tension as a work holder. in this latter case the fence 6 is set at a distance from the wheel 24 only slightly less than the thickness of the workpiece 28, so that the actual deflection of the wheel 24 as the workpiece 23 is introduced is only a fraction of an inch. if desired a thumbscrew may be substituted for setscrew 26, and used to pre-set the guard assembly position as desired.

In certain operations it is desirable to have the flap guard out of the way. This is quickly accomplished by releasing hook 30 and swinging the flap guard 22 aside.

It may be found desirable in various jointer planer applications to utilize certain alternate constructions, which are described in the following paragraphs:

Fig. 3 shows the use of an additional wheel 25 on the top side of flap guard 22. In this construction, wheel 25 is mounted on a vertically adjustable support as in Fig. 3, wherein the wheel 25 turns on a stationary flanged bushing 35, which can he slid up and down on shaft 36 and locked in the desired position by thumbscrew 37. By such means wheel 25 may be centered on a board being jointed. The upper wheel 25 should be slightly larger than the lower wheel 24 so that wheel 24 will not touch the workpiece if wheel 25 is riding it.

Throughout the description of this embodiment, the means for contacting and pressing on the workpiece has been described as wheels. Other means may be utilized, such as spring blade sliders, sliding shoes, etc., though with generally decreased eificiency.

Though the embodiments described vherein show the invention as applied to jointer planer machines, the actual scope of invention is considerably broader and some of the principles disclosed have other utility. I therefore do not limit my claim to jointer planer utility, but I claim:

In a woodworking tool the combination of a guard for the operator of the machine and a holder for the workpiece to be operated upon by the tool, said combination comprising a guard body adapted to overlie the workpiece, a wheel rotatably mounted on the guard body and extending therebelow into contact with the workpiece, a fixed abutment on the tool, a pivotal connection between the guard body and the abutment and disposed eccentricallyof the rotatable mounting for the wheel whereby to make possible the raising or lowering of the wheel relative to the workpiece, an arm on the body extending radially of the pivotal connection between the body and abutment and provided with a flange extending parallel 4 with the axis of said pivotal connection between the body and abutment, said flange having a series of openings therein, each opening being disposed progressively farther from said last mentioned pivotal connection, a tension spring, means securing one end of the spring to the abutment at a point removed 'fror'n'lthe said last-mentioned pivotal connection, ahook secured to the othenend of the spring and engaging a selected one of the series of open 1 ings in the flange, and a handle on the hook adapted to be grasped by the operator for shifting the hook from one to another of the series of openings, whereby .to change the torque exerted by the spring on :the guard body and the force exerted by the guard body upon the wheel and workpiece.

References Cited in the file of this patent UNITED STATES PATENTS 103,677 Stilwell; May 31, 1870 998,873 Couture July 25, 1911 1,018,739 Beugler Feb. 27, 1912 1,758,834 Heston et a1 May 13, 1930 FOREIGN PATENTS 248,850 Germany July 3, 1912 rum-ad