Jig for Cutting circles on a bandsaw

I am looking for a photo / web site / written description of the making
of a jig for use on a band saw for cutting circles.
The idea is that you use an auxiliary table with a "Pin" in it, set the
pin at distance D/2 from the blade edge, mount the center point of the
material you want to cut the circle from on the "pin at one radius or 1/2
Diameter of the circle you want, and slowly "spin" the material on the pin
as a center point. The material goes into the blade, and you get your
circle.
My geometry is fine, but I'm having trouble rigging up the mechanical
mounting for the auxiliary table.
Pointers appreciated.
Thank you.
--
Jim McLaughlin
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Reply to
Jim McLaughlin
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I've already Googled. Found about 10 commercial products ranging from a little over ten bucks to almost fifty bucks. Couldn't find any reviews of any of the products.
This is to be used on a plain jane type Ryobi 901 bench top saw.
Again, thanks for any pointers.
-- Jim McLaughlin
Please don't just hit the reply key. Remove the obvious from the address to reply.
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Reply to
Jim McLaughlin
Greetings,
Almost, but not quite there. You build this jig as a sled with a runner to go in the miter gauge slot of the table and a block of wood on bottom on the operator edge to stop it at the same place everytime. The stopping point should occur where a straight line from the pin to the blade forms a right angle with the cut in the sled.
You mount your blank on the pin, slide the jig so it cuts a tangent to the circle when it hits the stop. Then you just spin the blank to get your circle.
The solution changes for very large circles. What size of radius do you want to cut?
Sincerely, Bill Thomas Jim McLaughl> I am looking for a photo / web site / written description of the making
Reply to
Bill Thomas
A couple of thoughts. First of all, the pivot pin must be at exactly 90 degrees to the blade, and in line with the cutting edge (teeth).I have used a carpenter's square for set-up, using the slot in the table for a guide to align one edge of the square.
For small diameter circles (about 15" or less) try an auxiliary table top made from scrap 1/2" plywood and clamped on top of the regular table. Just cut your way into the new top with the blade, stop the saw, and clamp it down.
For larger circles (any size up to the width of your material), a camera or camcorder tripod will work if you are careful. You will probably need a helper to hold the tripod steady while you make the cut. The down side of the tripod idea is that it leaves you with a 1/4" hold at the center of your piece.
walt
Reply to
OLDFARHT
Go to
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This is the site for the shopnotes magazine. On that page is a bunch of jigs. The band saw circular cutting jig is about half way down. It works ok, but use aluminum instead of plastic to make the 'I' slide.
Eddie
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Reply to
Diane
There's a circle cutting jig plan (along with plans for other shop jigs) available from the New Yankee Workshop. See
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Reply to
Mike Iglesias
The big thing here is to make sure that the pin is rigid to the blade and is at 90deg. to the blade. Normally I put a piece of scrap plywood on top of the table and clamp it to the table - a few bolts in appropiate holes or a clamp to the bottom of the table with aligning pads is a nice way. Large radii tend to be a bit harder and require that you put legs on the far end of the plywood to support the pin end of the plywood. The pin can be anything from a real pin of some diameter to a nail or other pointed thing to locate the center point. With the nail method, you have to be a bit careful that the center doesn't move about as you do your cutting. The process of cutting curved surfaces is an established process in woodworking.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
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Bob May

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