Power tool drop arm with offset ribbing

• US 10,213,853 B2
• Filed: 03/04/2016
• Issued: 02/26/2019
• Est. Priority Date: 03/12/2015
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH, Robert Bosch Tool Corporation (Robert Bosch GmbH)
• Original Assignee: Robert Bosch GmbH, Robert Bosch Tool Corporation (Robert Bosch GmbH)
• Inventors: Doumani, Robert S., Szweda, Timothy, Talesky, Mark S., Taylor, Brian
• Primary Examiner(s): Peterson, Kenneth E.
• Assistant Examiner(s): Dong, Liang
• Application Number:
  US15/060,733
• Publication Number:
  US 20160263678A1
• Time in Patent Office: 1,089 Days
• CPC Class Codes: B23D 45/067 the saw blade being adjustable according to depth or angle of cut
• CPC Class Codes: B23D 47/08 of devices for bringing the circular saw blade to the workpiece or removing same therefrom
• CPC Class Codes: B23D 59/002 for the position of the saw blade B27B5/36 and B27B9/02 take precedence
• CPC Class Codes: B27G 19/02 for circular saws

Abstract

A power tool assembly includes a drop arm frame with an opening configured to rotatably support an arbor shaft, a lower surface spaced apart from the opening, and a plurality of ribs extending between the lower surface and the opening. The plurality of ribs define a respective one of a plurality of axes, the plurality of axes intersect at a locus, and the locus is adjacent to, but spaced apart from, a center of gravity of the drop arm assembly. The power tool assembly further includes an actuating device configured to transfer a force to the drop arm assembly when the drop arm assembly is at the first drop arm assembly position, and a control system configured to control the actuating device to transfer the force to the drop arm assembly when an unsafe condition is sensed.

Claims

1. A power tool assembly comprising:

a drop arm assembly movable along a drop path between a first drop arm assembly position whereat a portion of a shaping device supported by the drop arm assembly extends above a workpiece support surface and a second drop arm assembly position whereat the portion of the shaping device does not extend above the workpiece support surface, the drop arm assembly including a drop arm frame with

an opening configured to rotatably support an arbor shaft,

a lower surface spaced apart from the opening, and

a plurality of ribs extending between the lower surface and the opening,

wherein the plurality of ribs define a respective one of a plurality of axes, the plurality of axes intersect at a locus, and the locus is adjacent to, but spaced apart from, a center of gravity of the drop arm assembly, such that when the drop arm frame, the locus, and the center of gravity are projected onto a drop plane defined by the drop path, the projected locus and the projected center of gravity are spaced apart by less than a diameter of the opening;

an actuating device configured to transfer a force to the drop arm assembly when the drop arm assembly is at the first drop arm assembly position; and

a control system configured to control the actuating device to transfer the force to the drop arm assembly when an unsafe condition is sensed.

2. The power tool assembly of claim 1, wherein;

the drop arm assembly moves within the drop plane as it moves along the drop path;

the center of gravity is at least in proximity to the drop plane; and

the drop arm frame includes a semi-spherical strike pin located in the drop plane configured to receive the force transferred by the actuating device.

3. The power tool assembly of claim 2, further comprising:

a stop pad mounted to the lower surface and configured to cushion the drop arm frame.

4. The power tool assembly of claim 3, wherein the stop pad is positioned directly outwardly of at least two of the plurality of ribs.

5. The power tool assembly of claim 2, wherein

the drop arm frame is formed from aluminum, the drop arm assembly further comprising at least one hardened steel pin extending from the drop arm frame;

and

the power tool assembly includes an alignment housing configured to receive the at least one hardened steel pin thereby aligning the semi-spherical strike pin with the actuating device.

6. The power tool assembly of claim 5, wherein the plurality of ribs comprises at least four ribs.

7. The power tool assembly of claim 5, wherein:

the drop arm frame includes a pair of spaced apart brackets, each bracket including a respective inner bearing wall;

an orbit shaft fixedly mounted to a height adjust carriage;

a first bearing positioned about the orbit shaft and against a first of the respective inner bearing walls;

a second bearing positioned about the orbit shaft and against a second of the respective inner bearing walls;

an orbit bolt threadedly engaging the orbit shaft; and

the orbit shaft and the orbit bolt are configured to compress the first and second bearings against the respective inner bearing walls.

8. The power tool assembly of claim 7, further comprising:

a stop pad mounted to the lower surface and configured to cushion the drop arm frame.

9. The power tool assembly of claim 8, wherein the stop pad is positioned directly outwardly of at least two of the plurality of ribs.

10. The power tool assembly of claim 9, wherein the plurality of ribs comprises at least four ribs.