Split ring clamping arrangement

• US 5,188,492 A
• Filed: 11/05/1991
• Issued: 02/23/1993
• Est. Priority Date: 02/28/1991
• Status: Expired due to Fees

• Current Assignee: Ryobi Motor Products Incorporated (Techtronic Industries Company Limited)
• Original Assignee: Ryobi Motor Products Incorporated (Techtronic Industries Company Limited)
• Inventors: McCracken, Robert E.
• Primary Examiner(s): Howell, Daniel W.
• Application Number:
  US07/788,189
• Time in Patent Office: 476 Days
• Field of Search: 24/278, 24/279, 24/285, 144/134 D, 144/136 C, 144/136 R, 409/175, 409/181, 409/182, 409/204, 409/209, 411/6, 411/7, 411/409, 411/435, 411/911
• US Class Current: 409/182
• CPC Class Codes: B27C 5/10 Portable hand-operated wood-milling machines; Routers
• CPC Class Codes: Y10S 411/911 One-way drive
• CPC Class Codes: Y10T 409/306608 End mill [e.g., router, etc.]

Abstract

A router having a depth of cut adjustment mechanism including an adjustment ring which engages a screw thread on the motor housing and rotationally engages the router base. There is further provided an arrangement for preventing relative rotation between the motor housing and the base. The adjustment ring is formed as a split ring with projections adjacent opposite sides of the split, each with a frusto-conical camming surface. A circular clamp knob having a plurality of tabs extending axially outward from a top surface and radially outward from a central axis is mounted for threaded rotation on a bolt passing through the projections radially with respect to the router motor housing which bears against the camming surfaces so as to squeeze the ring in order to effect a clamping action as the knob is moved inwardly.

Claims

1. A router comprising:

a motor housing having an external cylindrical portion;

a base having a cylindrical bore for slidably receiving therein said motor housing cylindrical portion;

an adjustment ring including means for releasably engaging said motor housing and said base to secure them together at various axial positions, said adjustment ring being split forming an opening between two opposed ends; and

clamp means for releasably securing said adjustment ring to said motor housing so as to maintain the position of said base relative said motor housing, including;

a threaded member cooperating with the opposed ends of the adjustment ring;

a clamp knob threadingly cooperating with the threaded member and rotatable relative thereto in a first direction causing the adjustment ring to tighten and a second direction causing the adjustment ring to loosen, said clamp knob including tab means for limiting the torque which can be applied to the knob by a user in the first direction thereby preventing overtightening and enabling a relatively higher torque to be applied in the second direction to ensure the user can always release the adjustment ring.

2. The router of claim 1 wherein said clamp knob is provided with a frusto-conical surface;

and said adjustment ring opposed ends are each provided with complementary ramped semi-circular projection surfaces for cooperation with said clamp knob frusto-conical surfaces.

3. The router of claim 1 wherein said clamp knob tab means comprises two diametrically opposed tabs.

4. The router of claim 1 wherein said clamp knob further includes a peripheral surface having a plurality of serrations to provide a finger grip separate from said tab means.

5. An arrangement for clamping a split ring to an interiorly disposed surface, said split ring having first and second opposed ends adjacent an opening therebetween, comprising:

a first projection formed on said split ring adjacent said first opposed end;

a second projection formed on said split ring adjacent said second opposed end;

said first and second projections each being formed as respective mirror-image halves of a frusto-conical structure;

a clamp knob having an inner surface adapted to slidably engage the frusto-conical surfaces of said first and second projections; and

screw means for rotatably supporting said clamp knob with said inner surface engaging the frusto conical surfaces of both said first and second projections so that rotation of said clamp knob in a first direction causes movement of said clamp knob toward said split ring drawing said first and second projections toward each other and rotation of the clamp knob in a second direction causes movement of said clamp knob away from said split ring allowing said first and second projections to separate;

wherein said clamp knob includes tab means for limiting the torque which can be applied to the knob by a user in the first direction thereby preventing overtightening and enabling a relatively higher torque to be applied in the second direction to ensure the user can always release the adjustment ring.

6. The arrangement according to claim 5 wherein said clamp knob has a central internally threaded boss and said screw means includes a threaded member fixed against rotation with respect to said split ring and threadedly engaged with said boss.

7. The arrangement according to claim 5 wherein said clamp knob inner surface is frusto-conical to provide substantial surface engagement with said first and second projection surfaces.

8. A clamp knob for a router or the like comprising:

a body having a central axis and a peripheral surface extending circumferentially about said central axis between axially spaced body surfaces;

a tab extending axially outwardly from one of said body surfaces and radially outwardly from said central axis, said tab having a first side in perpendicular relation to said one of said body surfaces for receiving a finger grip to positively rotate said knob in a first direction, said tab having a second side opposite said first side, and helically ramped in relation to said first side limiting force capable of being applied when rotating said knob in a second direction opposite said first direction; and

screw means formed on the body aligned with the central axis for cooperation with a corresponding threaded member to cause the clamp knob to axially advance relative to the threaded member when the clamp knob is rotated in the first direction and to axially retract the clamp knob when rotated in a second direction.

9. The clamp knob of claim 8 wherein said peripheral surface comprises a plurality of serrations to provide a second finger grip separate from said tab.

10. The clamp knob of claim 8 wherein said tab comprises two diametrically opposed tabs.

11. The clamp knob of claim 8 wherein the second side is circumferentially ramped in a helical transition from a tangent with said one of said body surfaces.

12. A router comprising:

a base having an annular groove circumferentially located about said base, said base having a cylindrical bore therein, a lower support surface attached thereto, and a pair of handles for manipulating said router;

a motor housing having a motor, a cutter shaft connected to and rotatably driven by said motor, said cutter shaft having a collet for receiving a cutting tool, said motor housing having an external screw thread circumferentially located about said motor housing and said motor housing being axially movable relative said base through said cylindrical bore for movement of said cutting tool to a selected depth relative said base;

an adjustment ring cooperating with said motor housing and said base, said adjusting ring having an internal screw thread cooperating with said external screw thread for movement of said motor housing relative said base in response to rotational movement of said adjustment ring along said external screw thread, said adjustment ring having an inwardly directed projection cooperating with said annular groove allowing rotatable movement of said adjustment ring about said base while preventing longitudinal movement of said adjustment ring relative said base; and

a clamp knob extending radially from said adjustment ring and cooperating therewith for clamping and unclamping said adjustment ring, said adjustment ring rotatably cooperating with said external screw thread and said annular groove for movement of said motor housing relative said base for setting said cutting tool at a predetermined depth relative said base, said clamp knob having a body including a peripheral surface extending circumferentially about a central axis between spaced apart body surfaces and tab means having a first surface for positively rotating said clamp knob away from said adjustment ring allowing a first projection formed on said adjustment ring on a first opposed end and a second projection formed on said adjustment ring on a second opposed end to separate enabling movement of said adjustment ring, and said tab means having a second surface opposite said first surface for limiting force applied to said clamp knob when moving said clamp knob toward said adjustment ring drawing said first and second projections together preventing movement of said adjustment ring once the predetermined depth of said cutting tool has been set.