Question about using a dado set

[Steve Tanski]

Hi,
I am new to fine woodworking and recently purchased a dado blade set. It seems to be working okay but the blades are leaving ridges in the surface that they cut through. Is this common? I expected a perfectly smooth surface. Could I be doing something wrong as far as how I have the blades and chippers positioned?
Any advice would be greatly appreciated
Steve

[Mike Henderson]

You should get a pretty smooth surface on the base of the dado. What brand (including model number) and size is your dado set?

Mike

[matt dumney]

I have a cheap dado blade set and mine leave some ridges in the bottom of the dado. Again, mine are a cheap set of blades but work for what I do.

[Steve Tanski]

It is a Sears Craftsman 6" set. I don't know the model # off hand. I paid about $35 for it. Is that my problem?

[glenn bradley]

the blades are leaving ridges in the surface that they cut through. Is this common?

If you check some dado stack reviews in some of the mags, a smooth flat bottom is one of the elusive and highly regarded performance features of better dado sets. In some reviews the Freud SD200 series (about $100) came pretty close. The SD500 series (about $200) generally takes the prize along with some other $250 and up contenders that routinely do an excellent job.

I have the SD508 and the dados almost look like they were done with a router. There is just a touch of "ears" at the outside edge if you look real close before assembly.

If you go to Google or Yahoo and search on 'dado stack review' or 'dado blade review' you'll find lots of stuff. The individual reviews are OK but the bake-offs are more telling.

[Steve Tanski]

Sears Craftsman 6" set. Model # 32175.

[Steve Tanski]

thank you for helping out a beginner

[Lee Koepke]

if its a really critical dado cut, you could always use a router.

[Jude Tuliszewski]

Welcome to the Creek :D. Tons of great info here. A good DADO set is a bit spendy but well worth the money in the long run (like alot of woodworking tools). It will do a much nicer cut and will stay sharp alot longer than the inexpensive sets.

P.S. if you like what you see and plan on staying around, please make a donation.

[Mike Henderson]

I went and looked at that model on the web. It appears to be one that does not have carbide teeth. The lack of carbide does not cause the grooves on the bottom of the dado but the set is probably not the best set available.

The major problem with the non-carbide sets is that the blades get dull faster than the carbide sets, and sharpening them requires that all the elements of the set (outside blades and chippers) be sharpened so that they're all the same size (this is true of carbide sets, also).

If you're going to do a lot of dado work, I'd look into maybe buying a better set. If you don't do much dado work, use what you have until it gets dull and then buy up. You'll have a better idea of what you need by then, also.

Mike

[Jim Becker]

And what model is your saw? Craftsman? I ask because there have been a few saw arbors that have a "dip" that causes this issue with a stacked dado set no matter how good it is.

[Jesse Cloud]

Flat bottomed dadoes are hard to achieve, if nothing else, you may be varying the downward pressure a bit from cut to cut. On the other hand, if you are just cutting a slot to hold a shelf, and not gluing, it probably doesn't matter anyhow. Being a little anal-retentive, I use a hand plane to clean up machined dadoes, both tablesawn and routed:

http://www.leevalley.com/wood/page.aspx?c=2&p=52609&cat=1,41182,41192

[Corey Bellis]

Hi,
I am also relatively new to woodworking and even newer to the creek. And I also just purchased my first dado blade (Freud SD 508) and was questioning the grooves left on the inside and outside of the cut. If I make a single pass it is very smooth, obviously the edges of the cut are not noticeable. However if I take multiple passes i get the groove at the edges of the blade. I believe some one called these "ears". Is this normal? I guess i was hoping for smooth cuts even if i were to make multiple passes.

Is this an error on my part, or simple a limitation to the blade design?
-Corey

[Rod Sheridan]

I think part of the problem is that people refer to two different types of cuts as dados.

A dado goes across the grain, while a groove goes with the grain.

To cut a dado in solids, you need a cutter that can shear wood fibres, so a bevelled tooth is best.

To cut a groove in solids, you need a rip style tooth, which can be square across the top.

(Shaper cutters differentiate grooving with the grain, or grooving across the grain, and have optimised geometry for each operation)

Most dado cutter sets therefore have a shearing type, beveled outer cutter, and a square ripping type chipper to hog out the waste. This is a compromise to allow us to use it in both circumstances, however it isn't as good as having the correct geometry to start with.

If your arbour is OK, and not one of the saws with a problem as indicated by Jim, you can have your set reground as a set, and let the sharpening service know you want them ground to an identical diameter, I had my set reground and am very happy with it.

Incidentally, most european machines will take a dado cutter that looks like an insert shaper cutter. They have scoring and hogging cutters and produce a perfectly square, flat bottom profile, just like a shaper.

For rebating and grooving, I use the shaper as much as possible, that's what it's built for, and it has the best cutter sytems for that sort of work.

Regards, Rod.