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Circle Drilling Jig

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Blog entry by Karson posted 07-04-2007 12:20 AM 2289 reads 1 time favorited 4 comments Add to Favorites Watch

Circle Drilling Jig

I did not design this jig. I didn’t make this jig. But I’ve been using it for the last couple of weeks, and I thought that I’d post it as an ingenious drilling jig.

It was designed and made by John Nole of our Mason Dixon Woodworkers Club. He passed away about a month ago, so in memoriam I wanted to post this jig that he designed.

John was a machinist by trade and owned his own machine shop. So he was always looking for ways to make repetitive tasks easier and faster. We will miss him and his skills.

This jig is used to make a circle part where you need a bunch of holes that go around the center. Like a clock face where you put buttons where each of the numbers go. (We’ve used it for that. But for this process we are making wheels for what we call our “Lawnmower”

You start out with a square piece of wood say 10” x 12”

A hole is drilled in the center for a ¾” dowel section and a V is cut on the right for attaching the stop block. The stop block is a 3/8” dowel section about a 1” long and sanded with a flat side on one side.
The dowel is glued and screwed to a flat spring board about 6” long. Its purpose will be shown later.

You then need another board about 9 ½” wide. What you will now need to know is how many holes you want to drill. If it was a clock it would be 12. For the lawnmower we are making we need 14 holes.

So what John did was get a saw blade that had 28 teeth or some multiple of the number of holes you need. A 60 tooth blade could be used for the clock. He then made a mark on the board at the appropriate teeth. On the 28 tooth blade he skipped every other tooth. That way he didn’t have to figure out the formula for marking segments. He just let the MFG of the saw blade figure that out for him. So he marked the 14 points. He then drew across the points to get the center of the jig. He used a compass at 4 ¾” and marked the edge of the circle from the center.

He then drilled 3/8” holes around the jig where the lines intersected the circle just drawn. He drilled 14 holes. He then cut on the line, and went through the middle of the just drilled holes. A small pilot hole was drilled at the center point for a #10 machine screw and he drilled all of the way through the jig. He then drilled a ¾” hole , not all of the way through to insert a piece of dowel. Glued the dowel section in. Turned it over and drilled back through the just drilled hole to drill through the newly inserted dowel. And then used a larger drill to allow the head of the machine screw to be below the surface. The appropriate length machine screw was inserted and epoxy in place to keep it from turning.

Now you have a surface plate with the appropriate spaced holes around the edge and the spring stop engaged into the holes with the dowel section.
You put your part on the surface plate.

Put the appropriate spacer in your part to center it on the jig. In the case of the clock our hole is the same size as the machine screw so no filler plug is required.

Put a small piece of wood to span across the hole and use a wing nut to fasten it to the board.

You’ve already set the depth of your drill bit and you now drill your first hole.

You lift the stopper and spin the jig to the next hole.

You continue all the way around to the last hole.

You are then finished.

A stack of finished parts.

This is what we will make after all of the parts are finished and assembled.

Thanks John.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †



4 comments so far

View Don's profile

Don

2603 posts in 2923 days


#1 posted 07-04-2007 01:10 AM

And thank you, Karson. Your pictures made this easy to follow.

-- CanuckDon "I just love small wooden boxes!" http://www.dpb-photos.com/

View woodspar's profile

woodspar

710 posts in 2846 days


#2 posted 07-04-2007 02:40 AM

Thank you Karson, that looks like a great jig.

-- John

View Bob Babcock's profile

Bob Babcock

1804 posts in 2832 days


#3 posted 07-04-2007 03:08 AM

What a great jig…ingenoius! Thanks for sharing Karson.

-- Bob, Carver Massachusetts, Sawdust Maker http://www.capecodbaychallenge.org

View David's profile

David

1970 posts in 2885 days


#4 posted 07-04-2007 07:22 AM

Thanks Karson – very interesting jig.

-- http://foldingrule.blogspot.com

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