New to dado blades, couple of questions...

[Nick Decker]

Just got my first dado set, 8" Forrest Dado King. Set it up this morning, according to instructions, and have a couple of questions.

1) Based on the photo, does the bottom of the cut look flat enough to you. Seems to me the two outside blades are a hair deeper than the chippers. Maybe I'm being too anal.

2) I'm using two 1/8" outside blades and four 1/8" chippers. Should add up to 3/4"' but the cut is about 1/64th shy of that. I know I can add shims, but should I be concerned?

Thanks in advance for your voices of experience.

[Jim Becker]

The Forrest Dado King is designed to work that way so that cross cuts are extremely clean. The outside blades have a high angle on the edge that's slightly proud of the chippers. This slices through the cross-grain like a razor and reduces or eliminates chip-out.

[Cary Falk]

Looks typical of the dado sets I have seen but I would have expected that the fangs on the Forrest King set would have been smaller. Better 1/64 too small than 1/64th too big. That is what the shims are for. If you want a truly flat data then use a router.

[Nick Decker]

OK, thanks guys. Makes sense, so I'll call it good. FWIW, the cuts on plywood are, as advertised, very clean.

[Dan Cameron]

It is common to have the outside blade widths less than 1/8" so that you can set up for slightly less than 1/4". They havn't figured out how to make negative shims just yet.

[Nick Decker]

Actually, the teeth on the outer 1/8" blades measure a hair over 1/8". Same for the chippers. I assume it's done purposely because the cutting paths of all of them need to overlap a bit.

Negative shims? Now that's some weird science.

[Chuck Nickerson]

Negative shims? Now that's some weird science.

If anyone can make weird science work in the shop it's Dan. The man is a magician.

[Peter Christensen]

A good saw sharpening service can sharpen all blades so the cut is flat bottomed if you are using it for joinery where the bottoms will show, half laps for example.

[Steve Jenkins]

If you need shims you can make some from Manila folders. They are .010 thick

[Nick Decker]

Thanks, Steve. It came with magnetic shims, two .010 and two .015. If I need more I'll remember your tip.

[Johnny Barr]

Apart from the blades not exactly being the stated width, there can also be slight blade deflection/expansion/vibration/wobble/arbor error etc etc etc. So here's a tip I use. I lay all the appropriate blades on top of each other using a simple jig ( https://www.youtube.com/watch?v=M1UQj8iudxk ), bolt them down, measure the exact width and nearly always the actual cut is roughly 1/64" bigger. So I allow for that when deciding what blades and shims to use. Most times that works. So don't go by the stated width, measure it yourself.
Your cut and the "batman ears" look perfectly normal.

[Matt Day]

I thought everyone’s first dado set was supposed to be a piece of junk Craftsman?

[Jim Becker]

I thought everyone’s first dado set was supposed to be a piece of junk Craftsman?
That brand hasn't kept up I guess... :) :D

[Nick Decker]

I thought everyone’s first dado set was supposed to be a piece of junk Craftsman?

Probably would've been, if I didn't have things like the Creek and the internet. :)

In fact, my first major tool purchase was a piece of junk Craftsman slider. Found this place shortly after that.

[Ben Rivel]

That looks like one clean and crisp cut dado! Enjoy the new dado stack!