if you are focused on precision....


up the fence. do whatever is needed on your home made table so the fence can be put, and stay put (i.e. clamped) where you want it.


when I'm plowing a deep groove, I use the table saw to remove most of the material.
then the router to do the finish work.


if the router is only 'shaving' a bit off the side(s) and bottom, it turns out perfect.
trying to do a monster cut (depth/width...) with a router often fails.
for a single groove, raise the router bit a little at a time.

that does not work well when you need multiple pieces with "identical" depth grooves....


example, if you're doing a 3/4" groove, hog out the majority of the material on the table saw.
multiple passes or a dado set - doesn't matter. width less than (finished) 3/4" - depth less than finished depth.


use a 1/2" straight router bit to finish, first one side (& bottom) then the other side (& bottom)


for narrow grooves - there are "flat topped" tooth designs. situations where you can make 2-3 passes on a table saw with a FT blade on the table saw works like a charm. just be careful with the depth set up. use test pieces....

 

A quality dado set will cut much faster and just as clean, a router has less up-front cost but is a bit more of a PITA in use. Personally I'll go for the dado stack over the router for everything, unless I need to make a stopped dado

 

I've done it both ways .......

(A) I agree that for a single groove/dado the table saw is faster and easier IF you have your dado stack ready to go for the correct width.

You just set the fence and make the cut. There may be tearout on plywood veneer, but a strip of painter's tape will help with that. The real issue is setting the width if you are making it for a plywood insert.That's the PITA part of the dado stack. I have the dial a width dados as well, and they can be left to any desired width. However, shimming a stack is not one of my favorite things .... in and out of the throat with sharp cutters and sharp edges.



(B) The router may be easier and faster if you are not set up on the table saw. I make mine with a single edge guide on the router base. Now the question is whether to use a "correct width" bit or make it in two separate passes with a small bit.....? Even then, several shallow depth passes is better than a single full depth pass. You probably don't want to use an upcut spiral on veneer plywood since it will tearout.


(C) The best way is to use a PC guide bushing or bearing bit in a channel on both sides of a jig made especially for that diameter bit.

The jig needs to be long enough to span all the way across the panel like one of these:
https://www.youtube.com/results?search_query=router+jig+for+dados

An "improved" version:

 

(C) The best way is to use a PC guide bushing or bearing bit in a channel on both sides of a jig made especially for that diameter bit.

The jig needs to be long enough to span all the way across the panel

Those are interesting, and I might give that a try sometime, but in most cases I'm looking to put a groove in a long piece of wood, like 8'.

 

I've got a question about that third video about making a router jig. Part of the assembly is cutting a piece of plexiglass to fit on your router. What's the point of this? Why couldn't I just use the plate that came with the router? Is it important that the router keep the same alignment through the cutting process? Aside from that, it's pretty slick and I wouldn't mind making one of those. I wish I could buy a 1x8 sheet of MDF. A full 4x8 sheet is going to give me a hernia.

 

a clear plastic router base allows one to visually observe - to some degree - where the bit is going / what the bit is doing.
the "clear" bit - they do get scratched, they do get cloudy - but still better that blindly applying router bit to work piece.....

example - for dove tails, I have clear bases on both routers.

yes, makes me more confident I'm not monumentally screwing it up.....
and, keeps me from stupidly running the angle cutting bit into the guide and chipping off the carbide tips ..... clear plexi winning at 4:1 . . .

 

I'm not sure I saw it mentioned, but yes there are dado sets that will give you a nice flat top. Here's a pic from the Ridge dado set, for example

 

I rarely use the dados anymore. But I do spend a lot of time with routers and patterns. Depending on specifics will depend what is easiest.

 

It often depends on what you are cutting. I like using a stacked dado set, except on plywood. Plywood, especially import stuff, is not always dead flat and does not always remain dead flat on the saw table, not without a powerfeed at least. That can result in inconsistent depth of cut. I prefer to use a fence or router sled and move the router over the piece, vs a router table where you are moving the piece over the router. I can maintain farm more control that way. I also to it in multiple passes, depending on the width and depth of the cut.

 

It depends. Sometimes I am using table saw for notch cut, sometimes router.

I want using table saw for all notch cutting, but is not safe. One time crosscutting notches in long board on table saw, was spoiling two boards because too hard to keep board straight on table saw crosscutting notches near ends of the boards. And too much table saw danger. Third time using router after making router fence guide. I am clamping guide to board and getting perfect 90 degree notches on long board both ends and middle.

If using router, you can be using straight bit for through notches, but needing plunge bit or spiral bit for stopped notches.