Simple Center Finder

by Phil B in Workshop > Tools

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Simple Center Finder

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Superthunder bolt did a good Instructable titled Carpenter's Center Finder. He relied on careful measuring and drilling for critical dimensions. What follows automates the process of locating the necessary holes and makes accuracy inevitable.

Materials
1 x 2 hardwood
Dowel rod
Pencil
Glue
Masking tape

Tools
Drill press and drills
Clamp
Wooden base piece for drilling

Mark Center

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I made an "X" to mark the center of a piece of 1 x 2 inch oak. I marked the intersection of lines from opposite corners.

Drill a Pivot Hole

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I drilled a hole through the 1 x 2 at its center and let the drill go almost through a base piece of plywood. I hoped this hole would grip the pencil firmly, but the bit I had was a tiny amount large. So, the pencil was loose in the holes. I wrapped a layer of masking tape around the pencil to remove the slack. Make a line down the middle of the 1 x 2 that goes through the center of the hole just drilled.

I used the pencil as an axis for the 1 x 2 and set the pencil off an inch and a half or so. I clamped the base piece to the drill press table. Use the drill press to drill a hole to match the dowel you will be using on the line that runs the length of the 1 x 2. I had a 5/16 inch dowel.

A Second Hole Near the End of the 1 X 2

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Swing the 1 x 2 half of a turn and drill a second hole. The pencil used as an axis will guarantee that the distance of both holes from the center hole for the pencil is identical.

Add Dowels

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I cut two pieces of dowel identical in length and glued them in the holes.

Marks on the oak are from dirt on the workbench and are marks I made for another project before I changed my mind.

Mark the Center of the Work Piece

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Place the centering guide over a piece of wood or something else with parallel sides. The tip of the pencil lead needs to come though the oak piece just a little. Press the dowels firmly against the sides of the workpiece and slide so a mark is left as in the photo in the Introduction.

This is a no weld version. Originally, I see 1/8 inch strap iron and 1/4 inch rod. The center hold was drilled for the size of a finish nail, and then made conical with a countersink bit. The hole for the finish nail is about right for a pencil lead. I welded the 1/4 inch steel rod into holes drilled in the strap iron.