I MADE a DADO JIG

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About: 1945 was a very good year. No, not for wine ... for me. I was born. Yes, I'm old, Father William, but brillig, and my slithy toves still gyre and gimble in the wabe. So let me welcome you to the Little Sho...

You don't need an expensive dado blade set for your table saw to make accurate dadoes. As I've mentioned before in other Instructables, I have a small one (not something a DIYer brags about), and my small table saw will not take dado blades.

Step 1: WHAT IS a DADO?

A dado (pronounced DAY DOE) is a grove cut across the grain to receive the butt end of another piece. These pictures really explain it best.

That's Smoochy who insisted on assisting with research for this Instructable.

Everybody sing: Dado, day day day doe, dado come and we wan' go home.....

Step 2: PARTS OF MY JIG

I made this jig for my small router. It was all made from scraps from my lumber cart. I bought the wing nuts and bolts.

Hmmmm..small table saw, small router.... 'scuse me while I check my hands -- nope, they're OK. Whew!

Step 3: DADO PARTS

These pictures show all the parts to create this jig. I made this for the Shadow Box Bookcase I built. This jig was made for a specific router and for routing into boards up to 12" wide and determine the final dimensions shown in the last picture. Yours will probably be different if you make one.

Step 4: MAKE TWO

The first step is to secure the hardboard to the 1 x 4. Do this twice. Place the router against the 1 x 4 and rout the hardboard. This cut in now EXACTLY where the blade cuts. Make two of these. Use a dado router bit the exact width or NARROWER than the thickness of the boards you will be using to go into the dado.

Step 5: ADD RIGHT ANGLE GUIDES

I cannot stress the importance of this step. These two guides which are further apart than the width of the board you are dadoing must be secured at right angles. If not, every dado you make will be off. Secure two bolts and epoxy them in place.

Step 6: ADD ADJUSTMENT SLOTS

Line up the two bolts you epoxied and mark them on sliding part of the jig. These slots are made by drilling two holes and connecting the holes using a jig saw. Make them as far apart as you'd like to adjust the gap. Mine went from zero to 1 1/2+.

Step 7: THE GAP

Slide the adjustment guides apart and put in a piece of wood you'll be making a dado for and close the adjustment slide tight to the wood. Secure the wing nuts and this gap now matches the exact thickness of the wood you are using.

NOTE: Obviously, the round over bit shown in the router is not the one used to make dados. See step four for the bits to use. I was just too lazy to change bits.

Step 8: TEST THE FIT

The fit should be snug. A Goldilocks type of fit. Not too tight, not too lose--just right.

CLAMP THE JIG TO THE WORK PIECE. Because the slightest slip of the jig and your project is ruined.

NOTE: Route up the left side of the jig then down the right to get the full width of the dado.

Step 9: DEPTH OF CUT

The only other thing you must take into consideration is the depth of the dado. You should add this depth times two (one for each side) to the length of the shelf you are installing. If you look at the intricacies of this shadow box bookcase I built you can see how an error can magnify itself by the time you're done.

Hope this Instructable helps you. Let me know if you have any questions.

Enjoy,

KJ

2 People Made This Project!

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32 Discussions

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MoparDude

2 months ago on Step 8

Great Video. Simple & easy to understand. I am going to make one. And it also useful to hold wood for sanding etc. I voted.

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Kink Jarfoldclickclackclunk

Reply 3 months ago

I'm gald you found my level of detail informative, CCC.

For me, this jig worked wonders. Thanks for the comment.

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Kink Jarfoldtytower

Reply 4 months ago

Hi, Tytower, your vote is truly appreciated.

KJ

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STAN D

Question 4 months ago on Step 9

CAN YOU TELL US THE DIMENSIONS OF YOUR JIG PARTS? LENGTH, WIDTH OF THE PARTS. THANK YOU

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Kink JarfoldSTAN D

Answer 4 months ago

Hi, Stan, below is a picture with the dimensions for this jig. Please understand it was made for my router and the router you use might be different. I also made this specifically for 1 x 12 dimensional lumber since that is what I was routing the dadoes in. And the big thing is it was made from scraps I found in my lumber cart like the laminate flooring and the 3/4" x 3" wide boards used in all the rest of the jig; so whatever you have lying around would probably work just fine.

KJ

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Kink Jarfoldbamcmurray

Reply 4 months ago

Hi, Bamcmurray, thanks for the question. This is strictly a dado jig. A lap joint jig is completely different. What I usually do when building a new jig is research all the DIYers' videos out there and pick and choose what works best for me and my little shop.

KJ

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BillH233

4 months ago

Nice jig, I agree all my jigs are made of scrape wood that I have left over from other jobs. The problem I have is storage! LMBO! So most of the time l just wait until I need the jig to build one. Unless I made a real good one then I keep it! LMAO!

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Kink JarfoldBillH233

Reply 4 months ago

Yes, storage of jigs and of scraps can become a problem for those of us with small shops. One thing I love is my lumber cart. All my savable scraps go into it.

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RenéB2

4 months ago

This is quite cool! But doesn‘t the width of the cut depend on the cutting bit you use?

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Kink JarfoldRenéB2

Reply 4 months ago

Not really, the width of the cut doesn't depend on the bit since I built this for 3/4" plywood boards which, if you're familiar with plywood, is not exactly 3/4".. I had a half inch bit. This jug cuts along both sides of the base (look at the image I posted where I'm clamping the shelf in the jig). So I go up one side and down the other, and voila! a perfectly sized dado. Had I needed a narrower dado this jig wouldn't've worked at all. Excellent question. Keep 'em coming.

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charlessenf-gm

Tip 4 months ago

With a 1/4" od 5/16" straight bit, you could use this jig to create the slots used to adjust a jig like this! Then, you wouldn't need Fender Washers!

Nice instructable. Using the click-lock flooring - brilliant! I knew there was a reason I saved that extra flooring.

By the way, I used the excess kitchen flooring to finish the toe-kicks in our last kitchen - worked very well.

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Kink Jarfoldcharlessenf-gm

Reply 4 months ago

Yes, Charles, I use leftover flooring plus anything hanging around to build things. My momma always said: waste not, want not.

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charlessenf-gmKink Jarfold

Reply 4 months ago

Mine said "Watch the pennies and the dollars will take care of themselves."

Had a thought. One of the rails that guide the router can move to allow adjusting the dado width. The support that lines the jig up with the board to be 'dadoed' is fixed and square on one end/side. The other/opposite support 'hangs out there' unless the board being cut is wide enough.

However, if you cut slots on the one side of the rails, you could slide the 'other/opposite' support flush to the board being 'dadoed.' IMHO, this would make the jig more stable.

BTW - the bit I see in your router appears to be a half-inch roundover. Ar you using a top-bearing bit to cut the dados? Since your router base has a 'flat' spot, guiding it using the base might prove problematic. With a tpo bearing bit, the edge of the bearing is 'at' the edge of the bit (same plane) so setting the guides to the width of the board meant to fit into the dado, gives you a dado the width of the board used to set teh jig.

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Kink Jarfoldcharlessenf-gm

Reply 4 months ago

Lots of great points, Charles. Yes, I've seen dual length and width adjustable dado jigs. I made this for the project I mentioned in the Instructble, not thinking ahead to other projects. The bit pictured is definitely not the bit used to make dadoes. I added a caveat to my instructable--good catch. I was too lazy to change the bit. Yes, that flat spot on my router caused that ding in the guide you can see. It slipped onto the flat spot. I use regular dado bits as pictured in the Instructable, no bearings. Your observations are greatly appreciated.

KJ

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Bill WW

4 months ago

Very nice jig. It is important that users clamp the jig into position before using it, as you show in the photos.

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Kink JarfoldBill WW

Reply 4 months ago

Yes, Bill, clamping the jig is a must. Those puppies just have to slip a tad to ruin a job.

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