Is this typical for a dado set?

[Keith Carlson]

I'm just making my first box joints - using a dado blade, cross-cut sled and spacers (seems simpler, faster, and maybe more accurate than something like a lynn jig).

The diagram on my Freud 8" dado (stacked) set says the main two cutter blades together should be 1/4". I quickly found out it wasn't even close for the box joints. Went and got my vernier caliper, measured a cut, and it was only .230 wide.

Is this typical of the accuracy of a dado set? They get you close, and you need to shim it from there?

TIA

[Bob]

I don't know about all dado sets but the forrest set is designed that way on purpose - to be a bit undersized, so you can shim out to fit your exact requirement.

Bob

[Lawrence Wasserman]

I'd rather have it as you described than have the 2 outside cutters cut a .250" slot. If they add up to .230 as yours do, you can shim it out to a full 1/4" if need be, but if you're cutting a groove for undersized plywood, there is no way to reduce it from 1/4" to say

7/32"

[BruceR]

Yep.

Measure the blade teeth. Chances are they are right at 0.125 (1/8"). The problem is the blade steel is less than 1/8" (for cut clearance). You probably can see that the teeth overlap a bit when you have both cutters installed. Of course that is why they make shims. I found it is best to keep a record of what blades and what shims are required to obtain certain cut widths. Mark a unique identifier on each blade. Even though each chipper blade looks the same, there may be enough difference that mixing them up could turn a perfect fitting dado into one that is too loose. Another tip when using shims is to wrap your arbor with a single turn of scotch tape. Often the shims will partially slip into one of the arbor threads before you can get the nut on tight. This results in a different cut width than you'd expect plus it mangles your shims 8^)

-Bruce

[Tom Veatch]

Another "Now, WIH didn't _I_ think of that!" moment.

I haven't noticed variations in cut width so much as the nearly impossible task of getting the bloody things off the arbor when you go to take the dado stack off.

THANKS!!!

Tom Veatch Wichita, KS USA

[John]

Very normal and expected to be a tad shy of the full width listed for the blade combo, as you can always shim to make up the shortage, but nothing you can do if it is cutting oversize

John