US1461985A - Guide for grinding devices - Google Patents

Description

- 3 M. P. SCHMIYTT GUIDE FOR GRINDING DEVICES --Filed N0 v. 3, 1921.

. INVENTOR M Pficimz if.

Patented duly 1?, 1923.

mrsn STATES PATENT QFFMZE.

MICHAEL P. SCHMITT, or NORTH CHICAGO, rnmivois,

GUIDE FOR GRINDING DEVICES.

Application filed November 3, 1921. serial No. 512,449.

dent of North Chicago, in the county of Lake and State of Illinois, have invented;

- My invention relates to guides for grinding devices, and more particularly to that type of grinding device used for the sharpening of lawn mower blades and the like.

An object of my invention is to provide a guide for grinding device in which the depth of the out about to made may be accurately determined.

A further object of my invention is to provide a guide for grinding device in which variation in the grinding of a straight blade due to the elastic properties of the grinding wheel support is reduced to aminimum- Other objects and advantages will appear in the following specification, and the novel features of the invention will beparticularly pointed out in the appended claim.

My invention is illustrated in the accompanying drawings, forming part ofthis ap plication, in which Fig. 1 is a perspective view of an embodiment of my invention, 1 i

Fig. 2 is a sectional view along the line 22 of Fig. 1, and

Figure 3 is a partial sectional view of a part of the mechanism illustrated in Figure 1.

In carrying out my invention, 1 make use of the ordinary type of lawn mower grinding device, such as is illustrated in Fig. 1, the sub-base of which is shown broken away. This grinding device consists in a central shaft 1 rotatably supported upon the frame 2. Means for connecting the shaft to a driving mechanism is provided in a pulley wheel 3 mounted at one end of the shaft. A. grinding wheel 1 is rotatably supported upon a lever member 5 having for its fulcrum the shaft 1. The grinding wheel 4 is operatively connected by means of a chain 6 to a sprocket wheel 7. The sprocket wheel 7 is feathered upon the shaft 1 so that it may be driven thereby and thus in turn drive the grinding wheel 4. The lever member 5 is free to travel, carrying with it the sprocket 7 upon the shaft 1. j

Automatic means for feeding the lever carrying the grinding wheel 4 from one end in parallel relation with the shaft 1.

ofthe shaftl to theother end is provided in a threaded feed shaft 8 which is placed 1 Since the shaftl revolves at a considerable speed, it is necessary to provide a reduction gear mechanism intermediate theshaft 1 and the feed shaft 8. In this case, the reduction mechanism comprises a large sprocket wheel 9 which is operatively connected by means of a chain 10to a relatively small sprocket wheel 11 carried by the. shaft 1. The sprocket wheel 9 is operatively connected to drive the feed shaft 8. Asupporting shaft 12 is disposed parallel and closely adjacent the feed shaft 8 substantially as shown in Fig. 2. r i

A downwardly extending bracket member 13 is slidably disposed upon the supporting shaft 12. The bracket 13 is provided with a rearward extending threaded sleeve portion 14, the threads of which are in mesh with the threads upon the feed shaft 8. The lever member 5 is movably engaged with the bracket 13 so that movement 'or the bracket 13 along the supporting bar12 will carry the lever member 5 and the grinding wheel with it. The bracket 13 is also provided with adjustable means for limiting the downward movement of that portion of the lever 5 carrying the grinding wheel 1, the purpose of which will hereinafter be described.

A finger member 15 is supported upon the lever 5 at the outer end thereof and carries an adjustable hook 16 which may be extended or drawn into the casing of the finger 15. The finger 15 may also be'turned at various angles with respect to the lever 5 upon its fulcrum 17. A straight edge 18 consisting of a steel angle iron, one surface 19 of whichhas been ground to a true straight edge is movably supported upon a cross frame 20 of the frame 2 by means of adjustable clamping members 21.

From the foregoing description of the various parts of the device, the operation thereof may be readily understood. The

practice in the past of grinding a straight ing shaft 12 andthe feed shattS both are apt to give slightly from the weight of the grinding wheel/l as it approaches the-central points of these shafts. Also, chattering ot the grinding wheel 4 upon the blade'2 is likely to throw thelever 5 up slightlyand in coming down'it strikes the flanged clamp in such. a way as to cause a slightchange in position of the clamp. Because of the 'leverage present in the relation of the wei ht of the grinding wheel '4 and the position of the bracket 13 almost any undue pressure or vibration of the wheel willbe likely to cause a strain on the shafts 8 and 12 to bring about a variation in the blade when ground. r i

This means of guidingthegrinding wheel 4: relative to the blade22 and'its disadvantages are done away within the present invention. The straight edge 18 is supported in substantially parallel relation with the blade 22. The hook 16 of the finger is then adjusted so as to'rest upon the surface 19 of the straight edge 18 in a manner to menses limitthe downward movement of the grinding wheel 4. If the hook 16 is now elevated until the grinding Wheel at strikes the blade 22, the distance between the hook 16 and the surface 19 will be exactly the depth of the cut to be made upon the blade.

It will be seen by employing the straight edge 18 there isabsolutely no variation in the relation between the grinding wheel 18 and the blade from the beginning of the out until the'fin'ish.

This guide for grinding wheel may be applied ,to any of the grinding machines now in use without in anyway eitecting'the operation of the means forgrinding the 'rota'ry blades of the lawn mower.

I claim: I The combination with a grinding machine having a power driven grinding wheel, a

clamp for holding a straight blade transverse to said grinding wheel, and means 'for movingsaid grinding wheel from one end or said blade to the other, of a rigid angle 7 bar having an accurately fashioned flat stir-' Face thereon, a pair of clampingine'mbers it'or adjustably securing said bar {to said machine adjacent and parallel to said blade, and an adjustable finger associated with the support for said grinding wheel, said-finger being adapted to rest (in-said flat sur face'to cause said grinding wheel to be limited in itsengagementwith said blade uniformly throughout the grinding operation.

MICHAEL P. SCHMITT,

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