dado tearing out

That is the way of dado sets it doesn’t matter how much you paid for it. You need a backer board.
All saw blades will tear out when cutting like that to some degree dado sets just do it worse. When cutting box joints on table saw or router table I always use a backer.

-- Bruce, Boise, ID

Not sure just how you are making the cuts. Most any blade or dado stack can, and will, tear out the back side of the cut if the workpiece is not supported. For cutting finger joints most would use a jig that does several things at once. It sets the space for the first cut, and then sets the spacing for all of the subsequent cuts, and it provides a perfect backing to prevent tear out in the stock.

You could use a backerboard. Myself I use blue tape before I cut to eliminate this problem. I have access to 2” tape free so it is never an issue how much I use, have no idea how much it costs normally.

-- Live to tell the stories, they sound better that way.

ok damn .. i should have done that