That's what I've done for years, and still do it. Quick, simple, and accurate.
Two pieces of straight edge decrease the chance of slipping outside of your lines.
I used to have a permanent wooden jig that was screwed and glued for making shelves.
Most of my plates are round. A flat side is a bonus. If you plan to do it often, a square plate would be to your advantage.

 

ok yea pretty much what I plan on doing. Just wanted to confirm if there was an accuracy difference between the different contact points (Flat + Curve versus only curved touching the fences).

 

I have a tool called a DadoWiz, which gives you a perfect fit dado, and that runs on a rail. Not sure it's still made, but you fit a piece of what goes into the dado, a shelf for example, then in two passes, you cut exactly that width dado. The straight rail allows you to make any length dado.

For shop made jigs, I think this design is the way to go. Make it 24 inches wide, use a top mounted bearing on your bit. Be very exacting on getting the long top fixed rail exactly 90 degrees to the side rails. You insert a piece of what goes into the dado. Add a playing card or two to allow for glue.

The problem with using a single rail and butting the router base against it is that the bit must be centered in the base. If it's off, and you rotate the router at all, the dado will wander. Using the bearing to guide the bit against the jig's rails, eliminated this issue.

 

Yes this is different than what I plan on doing. I plan making a onetime use jig that traps the router base between two fences.

 

I agree with Tom.

 

You've been quite agreeable lately. Sure wish we lived near each other, I think we'd be chums.

 

Tom, we did a road trip across USA in May/June 2012.
Had lunch one day, on the way to LA, at Victorville.
You must have joined just after.
We did meet a few forum members during that trip.

 

Yup, we live in Apple Valley, which is just East of Victorville. Those are some of the best months to visit the high desert. I joined about then. I bought my first table and band saw around 2004. My oldest brother moved up here and had been doing woodworking. I'd been dong DIY projects all my life with minimal tools and had my shop up and running. We're heading into hell month, August and early September, but the summer so far has barely hit 100. It's quite beautiful up here and the best air quality in California.

 

Welcome to the forum, @straightShot

 

Welcome to the forum @straightShot

 

@straightShot
I just realized you're asking about the DadoWiz, not the shop made jig in previous posts.

The DadoWiz in the picture shows how you place the piece that goes into the dado to get an exact fit dado or groove. The tool is attached to the rail that comes with it. When cutting really small pioces, you would probably put a couple of same thicknes pieces (or even slightly thicker than your workpiece), on each side of the piece you're dadoing. Bridge the straight rail between them. Tape down the workpiece. Just don't pull the router off the DadoWiz until the router stops. Mine has a bite mark in it. Doesn't affect results, but not so pretty anymore. I think someone is still making this, but lost track of which company carries it. I always clamped the bar down on the ends to keep it from slipping. If you can find one, it's my favorite way to cut dados or grooves. I use a half inch downcut spiral bit to cut up to a 7/8ths dado in 2 passes.