3/4" slot in plywood -- route or dado?

On Sun, 17 Jan 2010 19:53:53 -0700, Robert Bonomi wrote (in article ):

I've gone the router route ;^)

Problem with a dado set is you must make sure the wood is _firmly_ forced against the table or the resulting bump in the bottom of the groove will throw everything off. Also consider cutting more than a foot into the center of a board (side shelf supports). Either you need a really long miter gauge or a good panel sled setup.

-Bruce

Good guide rail, and do it in two full-depth plunges, one for each side.

If you've got a really good guide rail, you could do it in one pass (for 1/4" depth) or multi-depth passes, cutting both sides simultaneously. That's a hateful process though, as the forces are pushing you both ways simultaneously, so are far harder to control.

Same here, although it's actually just enough below 3/4" that it fits a 3/4" dado just nicely, merely needing the edge broken. Another reson to use the good stuff.

I don't use cheap ply much, certainly not for making cabinets out of. Repeatable results like this are just one reason. The only ply I've used lately has been some cheap Chinese stuff (sorry) for dy-lining the refurbed workshop, and the thickness of that wasn't even consistent from one end of the board to the other.

Don't try to get to the thickness of the plywood.

Cut a rabbet to a "known" thickness(1/2" is good) and then route a slot using a 1/2" bit.

Using this method, you can really get very close and not worry about weird sized plywood.

Actually, I would make my dado and sneak up with the rabbet.

You can do this with a table saw or a router table.

mkr5000 wrote:

I've used that method when I've pre-finished the components. The rabits and dados then expose unfinished wood for the glue to bond to.

-------------------------------------------- According to one of my ply suppliers, the Chinese are shipping pure crap or at least they were.

I'm reminded of the old saw about the seller usually knows the value of what they are selling.

Lew

Yes, they do make a

The response "b) cut a rabbet on the inset piece of a specific thickness and use the proper bit size for it instead. "

is they way I did it last time. It's forgiving and hides the joint nicely.