Idealy, I think you want a spindle sander to do that...

Here is a link that might be useful:

YES!!!

I WANT!!!

W/table & all it looks kind of expensive. I wonder if there is a budget version of that? Could I get one for under a hundred? Maybe a way of mounting my belt sander sideways? ( sanding against the round front edge, not the flat part)

Delta makes a little cheapie version. I think it's called the "Boss."

You can get a sanding drum and mount it in your drill press, if you have one. The spindle shapers oscillate, which helps keep the sanding sleeve from clogging, but for occasional use, the drill press will work.

First draw the curve on a piece of MDF and cut as close as possible to the line. Then use a spoke shave to true the curve. Lay this on top of another piece of MDF and trace the curve then cut this as close to the line as possible. Screw the first piece to the second piece and trim with a flush trim bit mounted in a router table. Now you have a pattern for the rest of your brackets. Works for me.

Using a spindle sander would be fine for one bracket, but if you want them all to look alike, you should investigate Russ's note a little more. Make a pattern with mdf (or anything else), cut your brackets oversize with your jigsaw, use a pattern bit in a router, and temporarily attach each bracket to the pattern with double-sided tape or finish nails, and run the router along the rough edge with the bearing riding on the pattern.

A-ha!! That is brilliant! Is there any reason I couldn't use my handheld router? Don't have a router table. Thnx much.

If the curve is a simple radius, you can use the following method to either make a perfect curved pattern, or mill the actual pieces.
Make or buy an extended base for your router- I use a piece of 1/4" hardwood plywood, with a pattern of screw holes matching the router I'm using. A 36" long base is pretty useful, as you can always extend it with additional lengths. Using a 1/2" diameter two-flute straight bit, measure the desired radius from the outside cutting edge to a point of the plywood jig. Drill a small hole for a screw (this is the pivot point) After anchoring your workpiece to a surface (I use a sheet of plywood) draw a perpendicular line and locate your pivot point and screw the jig down. You now have the router mounted on an extension arm that is pivoting along the radius that you want to cut. With a small router, cut 1/4" deep passes until you're through.
I used this jig yesterday (for the unpteenth time) to make some curved casings on the jobsite. I've also used it to shape half-round window sash, cut arched beams, etc.
Casey

Sombreuil is correct. Use a circle cutting jig to make a pattern on MDF. You can make your own or order one from a woodworking catalogue like rockler or woodworkers supply. Then the pattern would be on the bottom for a handheld router.