So I've had people ask, watch and wonder how to cut a round profile with a standard circular saw (outer profile only). It is no more dangerous than cutting anything with a circular saw. This is less dangerous really because you're cutting small triangular pieces off the outside with straight cuts.
1) Lay the top or whatever it is on a table, clamp it.
2) Make sure whatever you're cutting is marked well enough to see.
3) Make a straight cut as close as you can get to your marking line. After the 1st 2 or 3 cuts you'll see the idea unfold a bit easier. Work your way around the outside. Just keep in mind that the thinner edge of the circular saw "base or table" is flat to the wood you're cutting. A quick minute or 2 around the edge with a belt sander to make that pencil line disappear around the edge, makes it perfect.
Ive made multiple 42" table tops with my Band saw and its not very forgiving if you go off the marking for whatever reason even the slightest bit, you can't add that back to the table, and it will show a deviation in the formed circle. At least with a circular saw you can see it more accurately and slower.
Good luck and you'll never know unless you try. Use a thin kerf Freud blade or Dewalt. Their non stick coatings are some of the best...
Step 1: Compass
Here you see the rough square shape of the table top. Find the center and set the compass to your desired circumference. This is an antique "Beam Compass" used for post and beam construction. This one will make a 67" round table.
Step 2: First Time for Everything.
I use a thin kerf Freud blade to do these. It allows for more of a curve action when cutting. All you do here is shave off the outside. What you end up with are long triangular shaped cutoffs. Essentially you're cutting the contour, on pass at a time, the blade will help give you more of a slight curve (bend of the blade) so you can cut a bit more than just straight passes with the saw. Keep the outside cut an 1/8th" from your circular control line.
The clear advantage of doing it this way: A jigsaw blade will wander vertically when you're cutting. You end up with a pain in the A** wavy edge in the end, that takes forever to round out to a perfect outer vertical edge.
A 54" round tabletop cannot be done on a bandsaw, even with 2 people. Its impossible not to mess up the cut.
The most important part and tool for completing this is a belt sander. Orbital sanders and detail sanders do not work with this application of making a perfectly round edge. Passes with a belt sander around the outer edge, while sanding away your round pencil line, will give it the edge you want it to have. It doesn't matter if the base of your circular saw makes minute scratches, the whole table has to be sanded anyway.
You have to use a brand new blade. And the reason why is because it will get to a point where the used blade will burn the edge of the table top. That takes forever to sand without making a flat spot on the curve.
Like always, test on a 36" x36" or whatever measurement piece of plywood, and ruin that first while you're figuring it out, before you try it on your new table top. This whole method works very easily, no worries needed.