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One Inch Dado Cut

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Forum topic by PPD417 posted 07-15-2020 08:50 PM 613 views 0 times favorited 21 replies Add to Favorites Watch
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PPD417

6 posts in 870 days


07-15-2020 08:50 PM

All,,

Surprisingly, in all my years of woodworking, I have never had a dado set.
Now an upcoming project requires me to get one, which I did.
I got the Oshlun 6”set for my Ridgid R4513 portable table saw.

My question is I need to make a 1” wide dado (1.5” deep). This set only
goes to a width of 9/32”. Would I make a 0.75” cut then and additional
0.25” cut? My only concern with doing it this way is I could run the risk of
making the dado too wide if my cut is not right on.

Does anyone have a better way to do this?


21 replies so far

View SMP's profile

SMP

2233 posts in 705 days


#1 posted 07-15-2020 09:10 PM

I usually accomplish this by going more than half, and flipping it so there is overlap in the center. For example set the dado to .6 make one cut, flip to cut other edge and there is .1 overlap in the center. At least thats how I do it.

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shampeon

2148 posts in 2983 days


#2 posted 07-15-2020 09:46 PM

I’d do something similar to SMP, but with two spacers and a stopblock. Set the stopblock and put a 1” spacer (an offcut of the piece you’re putting in the dado works best) against it. Put your piece against the 1” spacer and stopblock. Make an initial cut, which will be .6” wide. Take away the 1” spacer, and add another spacer the same width as your dado set (.6”) against the stop block and make the second cut. Now you’ve cut a 1” wide dado.

This works best with a crosscut sled.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

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maxyedor

40 posts in 1124 days


#3 posted 07-15-2020 10:20 PM

No real way around making two passes, but you can do some things to make sure you don’t go over.

Are there a lot of dados in the same spot in relation to the end? If so a stop-block on the fence, to establish one side, and then a spacer to establish the other side is an easy way to do it.

You can do roughly the same thing with a spacer on your miter-jig or sled, same set-up as a a finger joint jig, if that makes sense. You’d just have to make all the first cuts, then all the second passes, so it may screw up your workflow.

If that’s too much set-up, you can take a 3/4” pass, and then another that gets you just shy of the finished dimension, then use a router jig to complete the cut to the exact width required.

Lastly, just be really careful, and shoot for a butt-hair undersize, then massage the part to be fit into the miter with sandpaper or a handplane.

Which method to use kinda depends on what exactly the project is.

View PPD417's profile

PPD417

6 posts in 870 days


#4 posted 07-15-2020 11:43 PM

Don’t know why I did think to flip the piece around, makes sense!
And I do appreciate the suggestions, will give them all a try.

I should have mentioned that I am making an iPhone stand and the portion
that requires the 1” dado is the foot portion that slides over a 1” wide tenon that at the bottom
of the stand. It’s hard to describe without a photo, think of it as an angled “L” with the horizontal portion of the “L”
facing backwards and there are two 0.75” parts that protrude in the front to hold the phone and it rests against the vertical portion. Make sense??

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pottz

10243 posts in 1784 days


#5 posted 07-16-2020 12:49 AM

it’s simple do test cuts until you get it perfect then make your cuts,dont over think it.

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

View SMP's profile

SMP

2233 posts in 705 days


#6 posted 07-16-2020 12:59 AM

Another tip, if you are new to this, cut the dado erring on the small side. If its close, but just a hair too small its much easier to sand the “tenon” part down to fit, than if the dado was too big.

View Lazyman's profile (online now)

Lazyman

5626 posts in 2187 days


#7 posted 07-16-2020 01:30 AM

I am a little confused. Your dado set only goes to 9/32” wide? Most are closer to about 7/8”. Yours sounds more like a finger joint blade, though those are usually exactly 1/4” unless it is a metric one and is actually 7mm? It is going to take at least 3 passes to get to 1” with such a narrow dado blade. Also, when you say a depth of 1.5” do you mean 1.5” long ? If you truly mean 1.5” deep, that is way too deep to make in a single pass so you will need to make at least 3 cuts for each pass going 1/2” deeper in each cut to prevent bogging down almost any table saw.

Here is the method I came up with to cut a dado to fit an exact width, even if the dado blade is smaller than the dado or groove you need to cut:
  1. Get a spacer that matches the width you want the dado to be—a cutoff from the piece that will be in the dado is ideal.
  2. Get or make another thinner spacer that is over half the width of the dado you want to cut and setup your dado blade to match that thickness exactly. I usually use a piece of 1/2” plywood and shim the dado blade to match.
  3. Place the thick piece between the fence and the piece of wood you are cutting and set the fence so that the side of the dado stack nearest to the fence (generally right side of the stack) will cut the edge of the dado you have marked out on the board that is nearest to the fence. Cut the dado by sliding the board with wide strip along the fence
  4. Remove the wide strip strip and replace it with the thinner strip that matches the thickness of the dado stack. Repeat the cut sliding the board and narrower strip along the fence to cut the edge of the dado away from the fence.

As long as the dado stack is exactly the same width as the thinner strip, the result is a dado or groove that exactly matches the thickness of the wider strip. Now if your dado stack is really only 9/32” wide, you will need to make 2 passes with the thin strips. First one using only one strip to cut the far side of the dado and the second with 2 strips to remove the center.

EDIT: I misstated the setup in step 3. It is now corrected.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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WhyMe

1290 posts in 2360 days


#8 posted 07-16-2020 02:12 AM

Oshlun 6” goes to 29/32, not 9/32. The OP made a typo.

View bandit571's profile

bandit571

26092 posts in 3483 days


#9 posted 07-16-2020 02:38 AM

Vermont American 6”...went out to 13/16” without using the shims…Craftsman 113…had to remove the washer so just the nut was holding them all in place.

-- A Planer? I'M the planer, this is what I use

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Lazyman

5626 posts in 2187 days


#10 posted 07-16-2020 02:50 AM

That makes more sense.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View HokieKen's profile

HokieKen

14466 posts in 1938 days


#11 posted 07-16-2020 01:04 PM

I’d go the spacer block route if the dado isn’t in the center of your board. If it’s centered, flip the board like SMP suggested. Another option is to use a dial indicator or micro-adjuster to make sure you move the fence the precise amount for the second pass.

-- Kenny, SW VA, Go Hokies!!!

View John Smith's profile

John Smith

2501 posts in 962 days


#12 posted 07-16-2020 01:04 PM

from his post on another forum, this is the project the O/P wants to make.
maybe it will shed some light on the tools and methods needed to make it.

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

View LeeRoyMan's profile

LeeRoyMan

1248 posts in 526 days


#13 posted 07-16-2020 01:40 PM

If that’s the case, I would just make 2 cuts on the table saw and cut the rest out with the band saw.
Does your 6” dado blade even go up to 1 1/2”?
If it does, and your going to use the dado blade, I would just mark the lines and use my miter gauge.
(You may need to add a fence to your miter gauge)
You should be able to eyeball and cut on your lines. Set the width of your blade to 9/16 and make 2 cuts.

If your making more than 1 then maybe I would set up some stops.
I doubt you will be able to use a sled with the added height.

Also, if you are going to stand these up to run them through, make sure you have a good fence to clamp the piece to, and keep your hands clear when your cutting. Dado blades can be mean to you.

-- I only know what I know, nothing less, nothing more -- That doesn't count what I used to know..

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Lazyman

5626 posts in 2187 days


#14 posted 07-16-2020 02:18 PM

With that design, LRM’s, approach is the way to go assuming your dado can be raised 1-1/2”. If not, cut the sides on the table saw and clean out the waste with band saw, coping saw or jig saw followed by a chisel. If you use the dado blade, definitely add a fence to the miter gauge to make it easy and safe. It will also help prevent chip out. You could use a sled if the fence is tall enough.

Note that many dado blades have beveled teeth on the outside blades that leave batman ears which may detract from the final appearance. If don’t want that, cut a little shy of the line and finish with a chisel.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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PPD417

6 posts in 870 days


#15 posted 07-16-2020 03:05 PM

Thanks all for the suggestions, very much appreciated and sorry for the typo, the Oshlun goes to 29/32 NOT 9/32.

I’ve got some experimenting to do to see if I can get this process down. I’ll give these a go tomorrow and let you guys know the results. Another option I was thinking of is, would it possible to lay the piece flat and cut the 1.5” notch or would that be a no no with a dado?

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