Stumbled on a better way to handle dados last week while fixing an old bookshelf job I did back in 2018

I was fixing a shelving unit I built maybe 6 years ago for a client in Eugene. The dado joints were opening up a bit on the ends, and I figured it was just wood movement or maybe I didn’t glue them right. But as I was cutting a new piece to replace one of the shelves, I tried using a router with a spiral bit instead of my usual stacked dado set on the table saw. The fit was way cleaner, less tearout on the plywood edges. Now I’m thinking I should have done that from the start. Has anyone else switched methods like that and found it works better for certain materials?

2 comments

2 Comments

emmaclark14d ago

Blown out the top edge instead of the bottom? That's a new one on me, @grantp14, and I've been doing this long enough to think I'd seen it all with plywood. I always figured a spiral bit would just cut smoother in general, not change where the tearout shows up. I'll have to keep that compression bit tip in mind for the next time I'm stuck with a tough plywood job.

grantp1414d ago

Yeah so spiral bits are great for dados but you gotta be careful with the direction. Actually a spiral upcut bit will lift the workpiece a bit if youre not using a good featherboard or something to hold it down. I learned that the hard way on a birch plywood project and it blew out the top edge instead of the bottom like a regular bit would do. The key is using a compression spiral bit if youre doing plywood since it cuts both directions and keeps both faces clean. Your stacked dado set still has its place for sure though like when youre doing MDF or softwoods where tearout isnt as big a deal.