Stacked Dado Blade Set

I have a Craftsman carbide-tipped 7" stacked dado set that I have had for several years. I had never noticed it before but recently discovered that when I cut a 1/4" dado, the dado is actually 1/4" + another 1/64-1/128" (a 1/4" drill bit is loose with side-to-side play, a 17/64" bit is a tight press-fit). I have cleaned the blades with no improvement. I examined the body of the plates where they mate together and find no nicks or dings.

Yeah, I know - I should buy a better set but am retired and money is very tight and I'd rather spend what I have on wood. I have given some thought to lightly honing the mating sections with sandpaper on a marble slab (this sounds like a tedious process: sand, assemble the blade on the saw, cut a dado, check the width, etc.) but it is about the only way I can think of to correct the problem.

Anyone out there have a better idea or any suggestions as to what grit sandpaper I should start with - 400 wet/dry?

JimC

JimC

Hi Jim...cutting 1/4 dados you are not using any chippers just the inside and outside blades. Are the teeth of the 2 blades overlapping? In other words the teeth of the outside and inside blades on top of one another? Unusual for your problem to come up as usually they give you shimes to build up the blade as it wears. I would send the set away and get it sharpened and tell the sharpener your problem. Save you a lot of work!

Jim - you might want to check for blade run out. As little as .005" will cause what you're describing. If you don't have a dial indicator to check it with a cheap set of feeler gauges will often do the trick.

Jim,

I really don't think you should attempt to modify the set. It's likely to get worse instead of better. Start with the fence alignment. For ripping, most of us toe our fences out slightly at the back. For dado cuts you want the fence dead parallel with the blade. Otherwise it will cut a wider swath and can affect the cut quality. Same is true with miter gauges and dado sleds.