Large Radius Circle Cutting with Jigsaw

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Forum topic by RHH posted 06-25-2014 03:30 PM 1347 views 0 times favorited 4 replies Add to Favorites Watch
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23 posts in 3944 days

06-25-2014 03:30 PM

I need to cut some plywood arcs to make a couple of conduit bending jigs. One of them requires a 25-1/4” radius. This cannot be done with the circle cutting jig that came with my Bosch barrel grip jigsaw. It has a limit of ~16”.

Yes, I could build a jig and cut circles with my router, but the jig building time is onerous. I have the jigsaw and it should be more than adequate but I’m scratching my head to figure out how to get an extended radius. I have to make 4 different arcs for this project.

Ideas? Suggestions? What did you do?

-- RHH - Temple, Texas, USA

4 replies so far

View Fred Hargis's profile

Fred Hargis

4949 posts in 2457 days

#1 posted 06-25-2014 03:44 PM

I would probably get a piece of steel stock that approximates the size of the arm on the circle cutting jig (but one long enough for your needs), clamp to the jig saw and go.

-- Our village hasn't lost it's idiot, he was elected to congress.

View nailbanger2's profile


1041 posts in 3107 days

#2 posted 06-25-2014 03:50 PM

Depending on how accurate this needs to be, you can A) take a thin ~ 2” wide strip of ply and square one end. Measure 25.25” down the center and put a nail or screw or pin there. Put the nail in the center of your circle, then scribe the arc at the squared end. Use your eye and jig saw to cut a pretty good, not perfect, arc. or B) take the same strip and cut perpencicularly about an inch in from the end. Measure 25.25” from the inside of this cut down the center. Put a nail there and pin it to your plywood center. You now have a trammel. Go slow or your jigsaw will drift on the bottom side of the cut.

Hope this helps. Oops, forgot to say, attach ply to the jigsaw with a screw or two.

-- Wish I were Norm's Nephew

View RHH's profile


23 posts in 3944 days

#3 posted 06-25-2014 06:31 PM

Good suggestions!

Thank you.

Will take a look at Lowe’s for some metal bar.

-- RHH - Temple, Texas, USA

View bondogaposis's profile


4682 posts in 2315 days

#4 posted 06-25-2014 07:26 PM

A strip of 1/4” MDF and double stick tape and a nail is all you need for jig.

-- Bondo Gaposis

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