The 1" boring bar consists of a 1" round bar, a slip-on connector and
a standard holesaw fitted with a 1/2" x 18" extension bar.
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The drive end of the tool is fitted with a 1/2" drive impact socket.
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A 1" ID pipe sleeve is used to connect the 1" bar and the impact socket.
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The coupler consists of a 1/2" drive 7/16" impact socket welded to a 1" ID pipe sleeve.
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The pipe sleeve is drilled for a 1/4" x 2" through bolt.
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To get the shaft hole started, a guide block was cut from a piece
of 4"W x 4"H x 9"L stock. A 1-1/2" holesaw was used to drill a hole
along the stock's length.
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The piece was then cut on the bandsaw at a 12 degree angle to suit
the propeller strut. To locate the point at which the holesaw will start
cutting the plywood bottom, insert the holesaw into the big end of the block
and push it in until the teeth are flush with the underside of the block.
Transfer the mark to both sides of the block.
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Insert an 8' long 1" bar through the strut. A scrap piece
of 1/2" plywood is slipped under the strut to simulate the
hull planking thickness. A piece of 1/8" masonite simulates
the fiberglass thickness.
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Push the bar through the guide block. Push until it contacts the keel
and mark the point. Using shims, center the guide block on the shaft
and mark the holesaw entry point. Clamp the guide block.
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Remove the shaft and insert the boring bar, coupler and holesaw into the guide block.
Use an inclinometer (angle finder) to verify the shaft angle is correct before drilling.
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The finished shaft hole.
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