Dado set advice

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Forum topic by Vrtigo1 posted 02-14-2011 06:47 AM 1887 views 1 time favorited 22 replies Add to Favorites Watch
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434 posts in 2411 days

02-14-2011 06:47 AM

I bought my first dado set, a Freud SD208, about 6 months ago and am mostly happy with it. The one serious drawback is that the shims get torn up and deformed around the arbor to the point where they’re unusable. Instead of buying more shims, I’m looking at dado sets that come with a 3/32” chipper so I don’t have to shim so much when working with plywood.

I’m looking at the DW7670 which knotscot gave a positive review on. My question is, if I use the two outside blades, three 1/8” chippers and the 3/32” chipper, does that really yield a dado sized perfectly for 3/4” plywood with no shimming or is that too good to be true? I guess the second question has to be, is all 3/4” plywood really 23/32” or is there some variation? I seem to recall that the combination of shims I found worked one time didn’t work the next, but that could be due to the aforementioned deformation of my shims.

Right now, I dread having to work with plywood because it takes me 5-10 minutes to find the right combination of shims to get a good fit. I’m trying to determine if a new dado set will change that.

22 replies so far

View deucefour's profile


285 posts in 2673 days

#1 posted 02-14-2011 07:32 AM

my limited experiance is that the plywood sizes vays slightly, but it is easy to build a jig that sets itself up for the exact width of the stock. and then you use a router and pattern bit to make the cut. I think I saw the woodwhisperer make one

hope that helps


View Don's profile


514 posts in 2492 days

#2 posted 02-14-2011 07:37 AM

Most 3/4” plywood is imported and is actually 18mm in my experience. That’s a little less than 3/4”. I much prefer using a router and jig like Robert describes when cutting dadoes.

-- Don - I wood work if I could. Redmond WA.

View knotscott's profile


7145 posts in 2795 days

#3 posted 02-14-2011 09:36 AM

Plywood isn’t overly consistent from sheet to sheet, or within a sheet, so I can’t say for sure whether or not you’ll get a perfect size dado for 3/4” plywood everytime without shims, but can say from experience that the shims on my DW7670 set didn’t get deformed as much as the ones on my SD208 did.

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

View Sawkerf's profile


1730 posts in 2488 days

#4 posted 02-14-2011 03:35 PM

I would bet that your shims are slipping into the arbor threads during your setup and that they’re getting crushed when you tighten the arbor nut.

About three years ago, I replaced my metal shims with magnetic shims. They’re similar to refridgerator magnets and come in .010”, .012”, and .015” thicknesses. Thet stick to the chippers and blades and stay put during the setup.

-- Adversity doesn't build reveals it.

View ScottN's profile


261 posts in 2099 days

#5 posted 02-14-2011 04:10 PM

Many years ago I gave up on the dado blades and went to router bits. I would recommend buying a good set of plywood router bits. You can start and stop your dadoes where ever you like. I get perfect dadoes every time.

-- New Auburn,WI

View Pop's profile


427 posts in 3366 days

#6 posted 02-14-2011 04:33 PM

Have you looked at the Freud “Dial-A-Width” dado set? It’s pricey but a super nice set and no shims. It’s not a wobble blade but adjust straight in & out. You also don’t have to disassemble the set on the saw to make small adjustments. You just loosen the arbor nut and adjust.


-- One who works with his hands is a laborer, his hands & head A craftsman, his hands, head & heart a artist

View SnowyRiver's profile


51452 posts in 2900 days

#7 posted 02-14-2011 05:04 PM

I have magnetic shims on my Forrest dado set and they sometimes get pulled into the arbor threads also. I have even had to clean the arbor off in order to get the nut back on when changing blades. I have watched them carefully when installing but every now and then they get into the arbor threads so I am not sure what is going on either.

-- Wayne - Plymouth MN

View JJohnston's profile


1614 posts in 2711 days

#8 posted 02-14-2011 05:34 PM

I have a set that has 1/8, 1/16 and 3/32 chippers (an 8” “Avenger” brand from Woodworker’s Supply), and I still have to shim every time, so I don’t think having the narrower chippers will help in that regard. One thing that having the narrower chippers does help with is cutting dados for hardboard drawer bottoms: I’m currently on a sheet of hardboard that’s about 0.175” thick, and the only combination that works is 1/16 + 3/32 + about 0.020” of shim. The set warns not to use the chippers by themselves, but as long as I feed slow, there doesn’t seem to be any problem.

Anyway, I have the same troubles with my shims, so one of these days, I’m going to dispense with them and get a Freud dial-a-width.

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

View Jeff in Huntersville's profile

Jeff in Huntersville

404 posts in 2614 days

#9 posted 02-14-2011 06:02 PM

Because plywood varies so much as knotscott says both between and within sheets, I set my dado to slightly under the size I need. Then I move the fence for a second cut to get the exact size needed. I know it takes extra work and extra tests of the cut but I can get the exact size dado I need without messing with the shims.

View Vrtigo1's profile


434 posts in 2411 days

#10 posted 02-14-2011 08:00 PM

Thanks for the info. I’m sure that the shims are getting torn up because they’re falling down into the arbor threads. I didn’t know about magnetic shims, but now that I do I’ll probably pick up a set.

View Blue Mountain Woods's profile

Blue Mountain Woods

110 posts in 2354 days

#11 posted 02-14-2011 11:13 PM

My $.02:
For absolute ease of adjustment, ridiculous accuracy, durability and profound spiritual enlightenment, I concur with those suggesting Freud's Dial-A-Width dado set. I’ve had mine for about a year and a half, and won’t use anything else.

-- Pete -----

View pintodeluxe's profile


4825 posts in 2233 days

#12 posted 02-14-2011 11:43 PM

I tend to put my shims toward the outside of the stack for ease of installation / removal.
I agree that plywood sizes vary a little bit. Even if they were consistently sized, I like the ability to add the .004” shim to allow a little room for glue. Other joints I want really tight, so I just use the .020” and the .012” shims.
I just make a 12”x12” sample board with all the common dado widths cut into it. Label each dado, and then it’s a simple matter of checking the fit with your project parts.
Best of luck whatever you decide.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Vrtigo1's profile


434 posts in 2411 days

#13 posted 02-14-2011 11:53 PM

I noticed that a few people have complained about their arbors not being long enough to utilize the full width of the dial-a-width dado set. I assumed those people are probably using benchtop saws, but this dado set doesn’t strike me as something someone with a benchtop saw would buy. I assume the standard arbor on a unisaw is long enough?

View Blue Mountain Woods's profile

Blue Mountain Woods

110 posts in 2354 days

#14 posted 02-15-2011 12:07 AM

It is… my saw is a 5-year-old Unisaw, and while a bit close, I can get the whole set on (though I usually don’t need it…..leaving out one chipper can still put me over 3/4”).

-- Pete -----

View mcase's profile


446 posts in 2549 days

#15 posted 02-15-2011 12:21 AM

Freud makes a dial in dado set that does away with shims altogether. Its design is not like the old spiral sets at all. Its is outstanding. You can make adjustments without removing the blades from the arbor. The only drawback is its around $250.00

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