Good Dado Fits

[Vince Shriver]

When measuring with calipers, ideally how much wider should a dado cut be to accommodate the piece that fits in to it?

[Bruce King]

.001 is plenty but if you are using plywood it will vary some. Also I have found that if you measure the dado blades from outer tooth to outer tooth it will actually cut wider than that. My saw has near zero runout and the dado stack is near perfect. It’s just the way it is. I always do test cuts. I bought the shim kit that is intended for a kerf splitter product but I just bought the shims for setting up the dado stack perfectly.

[Prashun Patel]

I aim to cut mine exactly the same width, leaning on the 'too tight' side, which IMHO is more easily fixed than too wide. Your limitation is not the calipers but the tool (cnc notwithstanding)

[Jim Matthews]

While I work mostly by hand, I do make plenty of dadoes. As Prashun suggests, I try to size the dado exactly off each piece to be fit.

It's rare that ends up too tight.

For adjustment:

https://www.leevalley.com/en-us/shop/tools/hand-tools/planes/joinery/60012-veritas-side-rabbet-plane?item=05P4401

[Ron Citerone]

When ever possible, I make the dado about 3/8' wide and then cut a rabbet to fit. I use a dado blade or a router table to sneak up on it until it fits. This also give you a shoulder to make glue up esier and a stronger joint.

Not sure about the .001" part.

[Robert Engel]

I set up a dado narrower than needed make one cut then bump fence till fit is right. Test piece imperative

Setting up a dado to an exact width often involves shins & isn’t worth the aggravation unless there’s a a lot of dados to make. But that’s me.

Plus plywood is never going to spec out within .001 that’s way to tight. Even box joints are like .003-.005

[Von Bickley]

I cut most of my dados with a router using a simple dado jig that will allow you to make a perfect size dado.
452513

[Tom Bain]

When ever possible, I make the dado about 3/8' wide and then cut a rabbet to fit. I use a dado blade or a router table to sneak up on it until it fits. This also give you a shoulder to make glue up esier and a stronger joint.

Not sure about the .001" part.

This is my favorite approach as well when using plywood. If you end up with a rabbet that is a little too tight, you can often rerun across the dado stack with a little extra downward pressure and it will fit.