Question: I have seen videos related to cutting circles on a table saw. I would love to try this but I am hesitant to make a jig that, to me, seems to be extremely dangerous. [Here is a video](https://youtu.be/z-xhYnWDCd0?t=33) of Matthias Wandel using his jig to cut a rabbet into the circle, which seems like it'd be even scarier.

How does one make this jig and do so safely? Are there any gotchas that should be considered when executing this jig?

Answer: 
Take a sled and add a pivot as far away from the blade as you want your radius. (riving knife and guards can remain in place)

As preparation rough cut your piece on the band-saw. 

![http://woodgears.ca/bandsaw/cut_outline.jpg](https://i.stack.imgur.com/jskvv.jpg)  

[source](http://woodgears.ca/bandsaw/wheels.html)

Then put your piece on the sled and attach it to the pivot. Clamp it down to avoid the piece rotating while you are cutting and make a cut. Unclamp, rotate, clamp and cut again; rinse and repeat until it is round.

To get it perfectly round while not rotating the wood against the blade is nearly impossible. The last passes would require very accurate turns.

Instead if you have a motor and some shaft and bearings handy you can attach you can attach a pully to the wheel and work on it like a lathe.

![enter image description here](https://i.stack.imgur.com/qcWBv.jpg)  

[source](http://woodgears.ca/bandmill/wheels.html)

The main advantage of this last step is that you are turning the wheel on its own axle so even if you make a mistake when mounting the bearings/putting it on the shaft you can true out the wobble.
What I think makes most of such jigs dangerous is that they allow rotation of the work piece **while cutting**. That is not a safety issue per se, but at the begging of the process, the work piece is not a circle at all which makes it awkward to work with.

Here's what I suggest

1. use a sacrificial board like a table saw sled, this will become the "jig", but it really is just a sacrificial board
2. Put the circle-to-be board on top of it, mark the center (depending
on the desired radius) and place is accordingly (there should be the
a distance between the blade and the center as big as the desired
radius)
3. Screw the upper board to the sled. Position the screw at the center
of the radius
4. Add a second screw. This one locks the upper board from spinning
around.
5. Feed that into the saw. This is not different from any other two
board being securely connected. It's just "one thicker board".
6. Pull back, unscrew the second screw, rotate the top board a bit,
srew the second screw back in. Go to 5. until you have a
sufficiently round work piece.

These are just my thoughts. I do not have a table saw.

I agree with TX Turner that other tools might be better suited for this task or will be much safer to use.