# circular saw circle



## Dreadpoet (May 8, 2012)

Next season I am going to build the ubiquitous turntable revolve for our stage. The revolve will be an 8 ft radius so the curvature wont be altogether substantial. Usually when I cut circles I reach for a saber saw or a router. However, because of the sheer size of the revolve (2 layers of plywood for 16ft diameter), I am hoping to reduce time (lazy way) buy cutting the curve with a circular saw. I know that a large arc can be cut with a circular saw and have seen plenty of video. I also know that products are made for this (arcus circular saw blade) particular application. After seeing the fore mentioned product I have questions that you may be able to answer. First, have any of you used your circ saw in this way. Second, have any of you made a jig (how) for this application as I would like to make a smooth circle. 3rd do I need a specific blade to cut this arc out of 3/4 ply. 4th any advice?


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## Van (May 8, 2012)

I've always built Arc guages out of plywood but you can build them out of steel or aluminum as well. If you use an agressively toothed saw bladeand you set the depth of cut to just barely make it through the material, you can usually cut 3/4" material on an 8' radius. I have used, and like, the the triangular "circle cutting blades" < don't know the brand names>. 
The major secret is going slow and having a very sharp/new blade. Be sure to keep an eye on everything as you're cutting the saw will obviously, want to cut straight out, away from, the circle. and the better job you do concentrating on maintaining the arc of travel the easier the process will be. 
I'm Assuming you are familiar with how to use an attachable saw-guide on your skillsaw. I'll see if I an get a picture of one of my circle jigs. is not I can draw you a sketchup pretty easily.


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## Dreadpoet (May 8, 2012)

cool. i think i"ll dread this project less if i dont have to reach for a jig saw.


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## scenerymaker (May 9, 2012)

You might try using a circular saw to knock off the big chunks, but a router on a stick will make wonderful circles, like this:



These arcs had to be concentric, so I made a pivot at the center with one bolt and clamped a router at the right radius for each arc. I used this same technique on my 25 foot dia. powered revolve and it worked well.


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## FatherMurphy (May 9, 2012)

I once had a carpenter in my shop make a trammel stick for a jigsaw to use when cutting plywood circles, it bolted onto the foot plate of the saw. The tops of the circles were spot-on, but the thin jigsaw blade followed the path of lesser resistance, and would bend in towards the centers of the circles, so by the end of the cut, the edge would have a nearly 30/60 degree bevel on it. Made framing and facing a lot less fun. I'd never had that problem when cutting freehand, the minor wanderings left and right seem to help keep the blade cutting square.


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## scenerymaker (May 10, 2012)

That's why a router works better.


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## 65535 (May 10, 2012)

I haven't had to cut any big circles lately but the router on a stick technique is by far my favorite. Cut it rough with a jig or circ then finish with the router. I prefer to cut it with a 1/2" shank 1/2" straight bit and the biggest router around.


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## Benjod82 (May 17, 2012)

We built a similar sized turntable a few years ago and made an arm out of MDF that worked really well. We had good luck with a 1/2" diameter up cut bit, we did a bunch of small passes and followed with a shop vac and the mess wasn't that bad.


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## Molinero (May 17, 2012)

I just had to build two 12' revolves for our school's big musical. Borrowed plans for a 16-footer and modified them; the result is a three-sectioned unit that is easily broken down for storage.

My advice: lay out your plywood, use a strip of lauan to make a compass, draw your arcs showing where to cut and where to mount casters, and rough cut using the jig saw. Once the revolve is built, use the router. The clean, smooth arc is worth the trouble, especially if you plan on skinning the outside of the revolve.

BTW, I'm happy to forward you my plans for the revolves we built. Just let me know.

M

EDIT: Forgot to mention: Use a spiral bit on the router. Yum.


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