Background Of The Invention

This invention relates to plunge type router and, more particularly, to an arrangement for lockin the router at a desired depth of cut.

Plunge type routers are similar to convention al routers in that they include a drive motor secure within a motor housing, the motor having a shaft whic extends outwardly beyond the lower end of the moto housing, with the shaft adapted to have a cutting too secured thereto. The router also includes a base plat which is displaceable substantially vertically relativ to the motor housing. In conventional non-plunge typ routers, the motor is locked in position relative to the base plate such that the cutting tool projects axiall beyond the lower workpiece engaging surface of the base plate to the desired depth of cut at all times. Howev¬ er, plunge type routes provide biasing means whic operate to retract the cutting tool above the workpiece engaging surface of the base plate during periods of non-use. In order to enable a plunge type router to be "plunged" to the desired cutting depth, such routers are also commonly provided with adjustable depth stop systems and may also include arrangements for locking the motor housing relative the base plate at preselected positions, such as the cutting depth. It is therefore a primary object of this invention to provide a depth of cut locking arrangement for use with a plunge type router.

Plunge type routers typically include a pair of handles by means of which the operator may hold and

guide the router during use. These handles are al used when the operator "plunges" the router to i desired depth of cut. Once at the desired depth of cu the motor housing and base plate are preferably lock relative to each other so that the operator may conce trate on guiding the router without at the same ti maintaining sufficient downward pressure on the mot housing to maintain the desired depth of cut. Howeve if the operator must release his grip on the rout handle in order to effect the locking function, this ma result in an inadvertent change of the depth of cut. I is therefore another object of the present invention t provide such a depth of cut locking mechanism wherei the operator does not have to release the handle. It is a further object of this invention t provide a release mechanism for the locking arrangement Since the parts of a router are subject t wear, it is yet another object of the present inventio to include in the locking arrangement some means t provide adjustable compensation for such wear.

SummaryOfTheInvention

The foregoing, and additional, objects ar attained in accordance with the principles of thi arrangement by providing a plunge type router comprisin a motor housing with a drive motor secured therein, th motor having a shaft extending outwardly from the lowe end of the motor housing and adapted to have a cuttin tool secured thereto, a base plate displaceable substan tially vertically relative the motor housing, means fo guiding the displacement of the base plate including hollow guide sleeve secured to the motor housing and guide tube secured to the base plate, the guide tube

being arranged for sliding movement within the guid sleeve and the guide sleeve being formed with a latera opening exposing the guide tube, a plug member, a hollo member having exterior threads at one end so as to b threadedly secured to the motor housing, the interior o the hollow member having a major axis substantiall perpendicular to the major axes of the guide tube an the guide sleeve and co-linear with the axis of th exterior threads, the interior of the hollow membe communicating with the guide sleeve lateral opening, an said plug member being captured within the hollow membe interior so as to extend through the lateral opening and means for rotating the hollow member about th interior major axis.

Brief Description Of The Drawings

The foregoing will be more readily apparen upon reading the following description in conjunctio with the drawings in which like elements in differen figures thereof are identified by the same referenc numeral and wherein:

FIG. 1 is an elevational view of a plunge typ router in which the principles of this invention may b incorporated;

FIG. 2 is a cross sectional view illustratin the locking arrangement according to this inventio incorporated in the router of FIG. 1;

FIG. 3 is a cross sectional view taken alon the line 3-3 in FIG. 2; and

FIG. 4 is an exploded perspective view of th locking arrangement according to this invention.

Detailed Description

Referring now to the drawings, Fig. 1 illus trates a plunge type router, designated generally by th reference numeral 10, incorporating an arrangemen constructed according to this invention. The router 1 includes a motor housing 12 in which a drive motor 14 i secured, in a conventional manner. The motor 14 has shaft- 16 which extends outwardly from the lower end o the motor housing 12. At the distal end of the shaf 16, there is a collet, or chuck, 18 adapted to hold cutting tool.

The router 10 also includes a base plate 2 having a work engaging lower surface 22. The base plat 20 is displaceable substantially vertically relative t the motor housing 12. To effect and guide such dis placement, hollow guide sleeves 24 and 26 are secured t the motor housing 12 and guide tubes 28 and 30 ar secured to the base plate 20. The guide tubes 28 and 30 are arranged for sliding movement within the guide sleeves 24 and 26 _r respectively, so that a constant relative orientation between the base plate 20 and the motor housing 12 is maintained while at the same time allowing the base plate 20 to be displaced relative to the motor housing 12. As is conventional, the base plate 20 and the motor housing 12 are biased away from each other. Therefore, within each of the guide sleeves 24,26, there is a spring 32 (Fig. 2) for providing a separating force.

When using a plunge type router of the type illustrated herein, the operator places the lower surface 22 of the base plate 20 on an upper surface of a workpiece. The handles 34 and 36, which are part of the motor housing 12, are gripped by the operator and

the motor housing 12 is displaced downwardly against t force of the spring 32 until the cutting tool attache to the collet 18 is at the desired depth of cut in t workpiece beneath the lower surface 22. The depth o cut may be preset by an arrangement including the sto bar 38 supported on the motor housing 12 for relativ vertical displacement in a guide (not shown) and secur able in the guide by a clamp 40. A turret assembly 4 is rotatably mounted on the base plate 20 and include fixed abutments (not shown) and adjustable abutments 4 which cooperate with the lower end of the stop bar 38 t achieve the desired depth of cut. Once the desire relative displacement between the base plate 20 and th motor housing 12 is attained, it is desirable to secur that position in order that the operator may guide th router 10 without being concerned with maintaining th relative displacement against the return force of th spring 32.

According to this invention, there is provide an arrangement for locking the relative positions of th motor housing 12 and the base plate 20 for the desire depth of cut. Thus, the guide sleeve 24 is formed wit a lateral opening 46 (Fig. 2) at an appropriate locatio so that it always exposes the guide tube 24. Th opening 46 is in line with the handle 34 and a boss 4 formed as part of the housing 12. The boss 48 has a opening 50 aligned with the opening 46. The opening 5 is formed with internal screw threads and the opening 4 is larger than the opening 50. For effecting the locking function, a clam bolt 52 is provided. The clamp bolt 52 is externall threaded at one end and is threadedly secured in th screw threads of the opening 50. The interior of th clamp bolt 52 is hollow with a major axis substantiall

perpendicular to the major axes of the guide sleeve 2 and the guide tube 28 when it is secured as describe above. This hollow interior of the clamp bolt 52 i formed with internal screw threads over substantiall its entire length, but is smooth and free from interna screw threads in the region where the clamp bolt 52 i secured in the boss 48. A stop plug 54 is held partial ly within the interior of the clamp bolt 52 and is size so that it can slide freely within the smooth region o the clamp bolt 52 interior. An end 55 of the stop plu 54 extends outwardly from the interior of the clamp bol 52. An exteriorally threaded set screw 56 is threadedl secured to the interior threads of the clamp bolt 52 t limit the movement of the stop plug 54 inwardly of th interior of the clamp bolt 52, as will be described i full detail hereinafter.

The clamp bolt 52 is formed with a flatte region 58 and there is provided an actuator arm 6 formed with openings 62 through which the clamp bolt 5 extends. To secure the clamp bolt 52 to the actuato arm 60 in a relative non-rotative manner, a stop washe 64 is provided having a flatted opening 66 which i complemental to the flatted region 58 of the clamp bol 52. The stop washer 64 has exterior flats 68 and fits in a complemental recess 70 of the actuator arm 60 which surrounds the openings 62. The aforedescribed assembly is secured by the washer 72 and the lock nut 74. torsion spring 76 surrounds the clamp bolt 52 between the retaining ring 78 and the actuator arm 60. The torsion spring 76 has a first end tang 80 which is inserted in one of a plurality of anchor holes 82 formed in the motor housing 12 and a second end tang 84 which engages the actuator arm 60 so that the actuator arm 60 is biased counterclockwise, as viewed in Fig. 3, to

unscrew the clamp bolt 52 from the opening 50. Th purpose of having a plurality of anchor holes 82 is t provide adjustability of the return force of the torsio spring 76. In operation, after the operator has moved th motor housing 12 downwardly to the desired depth of cut, the actuator arm 60 is sgueezed relative the handle 3 so that it is pivoted clockwise, as viewed in Fig. 3. This operation is effected without requiring the opera tor to release the handle 34. This pivoting of th actuator arm 60 causes the clamp bolt 52 to be mor tightly threaded into the openings 46 and 50 and t press the stop plug 54, which extends outwardly from th open end of clamp bolt 52, against the guide tube 28. Typically, the guide tube 28 is formed of a relativel hard material, such as steel, and therefore, preferably, the stop plug 54 is formed of a relatively soft materi¬ al, such as brass. When the actuator arm 60 is pivoted to a locking position where the stop plug 54 is pressed in locking engagement against the guide tube 28, the friction induced by this locking engagement is suffi¬ cient to maintain the actuator arm 60 in its locking position, even against the opposing force exerted by the torsion spring 76. To release the actuator from this locking position, a release button 86 is provided. The release button 86 is slidingly received in the upper portion of the handle 34 and is biased outwardly by the spring 88. The operator forces the release button 86 inwardly of the handle 34 to cause it to pivot the actuator arm 60 counterclockwise, as viewed in Fig. 3, sufficiently to reduce the locking engagement friction so that the torsion spring 76 can pivot the actuator arm 60 until the projection 90 of the actuator arm 60

engages the interfering abutment 92 of the motor housin 12.

The purpose of the set screw 56 is twofold For one, the set screw 56 abuts against the stop plug 5 to prevent the stop plug 54 from moving toward th right, as viewed in Fig. 2, when the actuator arm 60 i pivoted. The second purpose of the set screw 56 is t provide an adjustment function to compensate for wea and insure that the small amount of rotation of whic the actuator arm 60 may partake is sufficient to mov the stop plug 54 into locking engagement against th guide tube 28.

Accordingly, there has been disclosed a improved plunge type router depth of cut locking mecha nism. While a preferred embodiment of the presen invention has been disclosed herein, it is understoo that various modifications and adaptations to th disclosed arrangement will be apparent to those o ordinary skill in the art and it is only intended tha this invention be limited by the scope of the appended claims.