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Questions about 8" dado sets

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Forum topic by groland posted 06-15-2013 04:01 PM 619 views 0 times favorited 9 replies Add to Favorites Watch
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groland

129 posts in 2158 days


06-15-2013 04:01 PM

Topic tags/keywords: dodo sets

I have a Craftsman 8” dado set that I bought a long time ago. It has two outer blades and a set of “chippers” that assemble inside the outer blades to determine the thickness of the dado.

I have never been totally satisfied with it because the chippers are about 1/16-3/32 inch shorter than the outer blades resulting in a high center to the dado that then has to be chiseled, planed or routed out. This seems really inept to me, forcing one to do what the dado saw is supposed to take care of—making a flat-bottomed accurate dado. If this is the best one can do, one may as well use a router from the get-go.

Are all dado sets designed this way?

If there is a set which makes flat-bottomed, accurate dados, what is it?

Many thanks,

George


9 replies so far

View ajosephg's profile

ajosephg

1860 posts in 2307 days


#1 posted 06-15-2013 04:07 PM

My Oshlun set does not have that problem.

-- Joe

View kdc68's profile

kdc68

2071 posts in 1023 days


#2 posted 06-15-2013 04:14 PM

I own a Fulton 8” Dado set and achieve flat bottom dados. I bought from Peachtree Woodworking when they offered a 50% sale price

http://www.ptreeusa.com/fulton_dado_boxjoint.htm#2884

Here is a forum topic that will interest you…in it offers good advice on Freud and Oshlun dado sets

http://lumberjocks.com/topics/50649

-- Measure "at least" twice and cut once

View Fred Hargis's profile

Fred Hargis

2033 posts in 1239 days


#3 posted 06-15-2013 04:16 PM

The outer blades will have the outside tips a little higher than the teeth on most of the better dado sets, but nothing on the order of 1/16”-3/32”. This is for a more clean cut, particularly on veneers (like hardwood plywood). I have a Freud SD 508 set, and do not have that problem….same with a CMT set I have. That’s not to say the bottoms are always crystal clean, if you cut tenons with a dado set they will need a little clean up. The pic isn’t as clear as I would like, but here’s a pic of 3 dados, one cut by a 12-13 year old Freud 508 set that had just been sharpened, a new 508 set, and a new CMT set. The bottoms of these dados are perfectly flat, other than the voids in the plywood I used for the test cut.

-- Our village hasn't lost it's idiot, he was elected to congress.

View knotscott's profile

knotscott

5601 posts in 2122 days


#4 posted 06-15-2013 05:05 PM

For ~ $100 you can get really good dados.

The best set I know of in the ~$100 range is the Delta/DW7670. The Freud 208, CMT, Irwin Marples, and Oshlun are good performers too for a little less. For much less than that, you take your chances. For $200 you can get stellar cuts from the Infinity Dadonator, Forrest Dado King, Freud 508, Ridge Carbide, and Amana sets.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Fred Hargis's profile

Fred Hargis

2033 posts in 1239 days


#5 posted 06-15-2013 06:50 PM

Scott brought up a good point, the $100 sets are very good. In my pic above the CMT set is one of the ~$100 sets I bought when Lowes was clearing them out for a whole lot less (I paid $36 for that one).

-- Our village hasn't lost it's idiot, he was elected to congress.

View groland's profile

groland

129 posts in 2158 days


#6 posted 06-16-2013 04:17 PM

Many thanks to all who replied. I do a lot of work with plywood, so that chiseling/planing flat the bottoms of poorly cut dados is really a pain. It’d be worth it to me to have a decent set of dado blades if I’m going to bother with this technique at all.

The photos are much appreciated, and it is obvious to me now that I can do much better with a different set of blades.

Thank you again!

George

View mtenterprises's profile

mtenterprises

836 posts in 1439 days


#7 posted 06-16-2013 07:15 PM

A proper jointing and sharpening of your dado set will achieve the same results as buying a new set. Explain exactly what you are looking for to your sharpener. He should be able to joint (sharpen to the same size) the two outside cutters and then joint the center chippers a few thousands smaller. If he cannot properly do this find another sharpener.
MIKE

-- See pictures on Flickr - http://www.flickr.com/photos/44216106@N07/ And visit my Facebook page - facebook.com/MTEnterprises

View NiteWalker's profile

NiteWalker

2710 posts in 1323 days


#8 posted 06-16-2013 10:29 PM

What knotscott said. I’ve been using that delta/dewalt dado set for a while now and it leaves no bat ears. The cmt set I have does, but clean otherwise.

-- He who dies with the most tools... dies with the emptiest wallet.

View Sandra's profile

Sandra

4984 posts in 821 days


#9 posted 06-16-2013 10:41 PM

I’m very pleased with my Freud set. To be fair, I’ve never tried any others, but if my Freud dado set walked away tomorrow, I’d replace it with the same ones.

-- No, I don't want to buy the pink hammer.

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