Various Projects #9: Mom's Bookcase Part 6: Great. I Can't Cut a Stinking Dado Right

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Blog entry by Tomcat1066 posted 01-02-2009 12:09 AM 1776 reads 0 times favorited 15 comments Add to Favorites Watch
« Part 8: Mom's Bookcase Part 5: Getting Jiggy With It Part 9 of Various Projects series Part 10: Sometimes, you just need a sawmill »

It’s true. Apparently, I am unable to cut a sufficient dado to join the shelves of Mom’s bookcase. This isn’t good at all. But first, let me run down my day for you.

11:00 AM: I finally get out to the shop. It’s a little chilly this morning, so I wait for it to warm up a bit before heading out there. I plug in the new router (Porter Cable 690 for those keeping score at home) after putting in a 3/4” bit, set up a straight edge and cut a dado to test. Sure enough, I was told right. It’s not quite enough to allow the 3/4” wood to slip in. Even some “persuasion” with my mallet wasn’t quite enough. But that’s OK though. I was prepared for this (thanks for the heads up on that one Todd) and switched out the bits, replacing it with a 1/2” straight bit and prepared to cut two passes.

I decide to run another test, just to make sure I’m doing things right. I set up my jig, clamp everything down, and make a pass. So far, so good. I adjust the jig and go to make another pass. It’s at this point that I notice that something isn’t right. I started my pass right at the pencil line. Now, I’m finding it veering to the right. Just great. My fence doesn’t seem to be square. I check it again, and it’s not. Apparently, it’s just a hair (maybe 1/16th out of square?) It’s just enough to screw things up. I go to pull the screws, thinking that I can fix this. Nope…the screws are stripped. Go me.

I try using just a straight edge. I manage to make two half inch dados instead of one 3/4” dado (although I really needed something like 13/16”).

12:00 PM: I figured out what I was doing, but by this time I was good and frustrated and went inside to get some lunch.

2:00 PM: A trip to Lowe’s. I pick up some plywood to try and make a new jig that’s illustrated in one of my books. It’s not until I get home that I realize he made the jig with a router table. I have bushings and all, but I’m still sort of stuck. I try and try to get something that will work. No such luck.

4:30 PM: After bashing my head against the wall (figuratively) and still not getting a workable jig, I call it quits. Woodworking is supposed to be enjoyable, and I’m damn sure not enjoying myself right now. I’m just glad I did everything on scrap first!

So, I get to spend this evening and tomorrow trying to figure out how to get through this little dilemma. Here are my choices as I see it:

A. Say screw it and use some other method. I happen to have a Miller Dowel set en route from Lee Valley, the product of a Christmas gift card from my wife and son. I could just clamp and drill and use the Miller dowels and call it done. Mom’s not picky about the joinery, but I’d rather stick with my original plans.

B. I could figure out some way to widen the 3/4” dado slightly, just enough for the boards to fit. I have no idea how to do this.

C. Order a 13/16” bit from Lee Valley. Of course, I’m not 100% sure that’s the right size either.

D. Figure out a new jig. I don’t have any ideas on this one either though.

E. Dance naked under the full moon and perform sacrifices to the wood gods to appease them. I think this one rules itself out, don’t you?

Honestly, I could really use some help here. Any suggestions are welcome. I have to figure something out, and frankly I’m running out of ideas.

Who am I kidding? I ran out of ideas two hours ago. :(

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

15 comments so far

View Bob #2's profile

Bob #2

3809 posts in 3990 days

#1 posted 01-02-2009 12:22 AM

The trick is to use two guides for your router guide to travel in.
By making on guide adjustabe you can vary the width of your cut.
They should be longer than your dadoes .
You can now do a test joint and set the distance of the guides in or out to give you the right size groove ( dado).
I use a dadowiz but that is a bit costly if you only do a few.


-- A mind, like a home, is furnished by its owner

View Tomcat1066's profile


942 posts in 3765 days

#2 posted 01-02-2009 12:29 AM


I was trying to use two guides, but I couldn’t manage to get anything that would actually work worth a darn. Now I need to find the plans for that jig somewhere. That looks like it’ll do the job. Unfortunately, I suspect that jig would take longer than the bookcase I’m trying to build ;)

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

View Scott Bryan's profile

Scott Bryan

27250 posts in 3791 days

#3 posted 01-02-2009 12:32 AM

Hey we have all been there and done that. I was working on two drawers last night and somehow cut the sides 3/4” too short despite rechecking my figures many times. So now I have to replane some more lumber, cut them to size and recut the dados for the front and back pieces.

To tell you the truth E probably would make you feel better but unless you live out in the middle of nowhere the neighbors might object!! :)

With regard to your dado situation you can cut dadoes with straight cutting bits if you have a straight edge to follow. I would recommend just using the 1/2 straight bit and using two straight edges to define the width of the dado. Or you could make an adjustable dado jig similar to the one pictured here. I have build one similar to this and it worked pretty well. Like anything else it takes some practice to learn to use as I found myself putting too much pressure on the straight edge guides and opening up the dado enough to give a sloppy fit.

Another point is that I am not sure how deep you are making the dado but if you are going deeper than 1/4 inch I would make it in two passes setting the router to the final depth on the second pass.

But sometime it is best just to walk away and “recharge your battery”. It sounds like you are at this stage. Tomorrow is another day.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View Tomcat1066's profile


942 posts in 3765 days

#4 posted 01-02-2009 12:49 AM

Thanks Scott.

I planned on making the over all dado deeper than 1/4”, but since I couldn’t get it right with only 1/4” deep, I never bothered to go deeper.

I’ll probably give it another shot tomorrow and see what happens. Hopefully, everything will work out soon enough.

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

View clieb91's profile


3520 posts in 3904 days

#5 posted 01-02-2009 05:08 AM

I am going out on a limb using some knowledge I have only seen and not tried. But have you thought about maybe putting a small tongue on the shelf itself. Make the Dado with the 3/4” bit then take just a bit off of each shelf. They should lock in nicely.
Can some one else confirm this idea?

Or I just happen to find these plans for a jig.

Hope one of the m can help.


-- Chris L. "Don't Dream it, Be it."- (Purveyors of Portable Fun and Fidgets)

View Woodchuck1957's profile


944 posts in 3733 days

#6 posted 01-02-2009 05:24 AM

Surface plane the shelves down to fit.

View ajosephg's profile


1880 posts in 3530 days

#7 posted 01-02-2009 05:52 AM

The jig Ctl references is the way to go. Takes just a few minutes and is a no brainer for any board thickness.

-- Joe

View Tomcat1066's profile


942 posts in 3765 days

#8 posted 01-02-2009 12:11 PM

Thanks folks! You’ve given me plenty to think about. I’m sure I can come up with something based on these suggestions :D

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

View RichClark's profile


157 posts in 3399 days

#9 posted 01-04-2009 01:47 AM

They make the goofy bits for the new improved inacurate ply. Ive got them and still need to set up a block the thickness of the actual wood and sand the sides of the dado for a good fit… just use a glued up stack of 3/4 MDF to make a guide/straightedge (I make them 4’ long and 1.5 thick.. rip them in ya TS to square it) and use a adjustable T-square to set them to the line you need to cut and go for it.. get it close and then lightly sand the dado and the shelves and it will fit fine.

Take care rich

-- Duct Tape is the Force! It has a light side and a dark side and it Binds the Universe together!

View EEngineer's profile


1102 posts in 3582 days

#10 posted 01-04-2009 03:00 AM

The last time I did this without using the router table (it was a solid core door section 84” long for a lathe bench – much easier to move the router!), I just clamped a straight board for a guide and made the first cut with a 1/2” straight cutter. I then moved to the other side of the router with the guide and made another cut in the opposite direction. The reason I changed directions was to get the rotation of the cutter right

I had trialed and erred it in some scrap plywood to find out just how big it had to be to fit the plywood I was using (just about exactly 3/4” thick) and it all came out right. Chiseled the corners square and glued it up.

-- "Find out what you cannot do and then go do it!"

View Tomcat1066's profile


942 posts in 3765 days

#11 posted 01-04-2009 08:32 AM

Rich: The problem is that this isn’t plywood. I’m beginning to think that I’d have been better off if it had been, and I had gotten the plywood bits, but nope…I got actual wood. It’s cool though…I’ll manage.

EEngineer: That’s what I was trying all day Thursday, with no luck getting it right. However, with the help of the suggestions here, I’m confident that I’ll manage just fine when I’m able to get back onto it :)

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

View Ekim's profile


17 posts in 3423 days

#12 posted 01-07-2009 05:38 PM

Since you have solid wood shelves use your 3/4” bit and then take a handplane to the ends to get them to fit. I was sorry to read about the storm damage in you other post.

-- mike,

View Moron's profile


5032 posts in 3862 days

#13 posted 01-07-2009 06:04 PM

I know its not supposed to be funny but I cant help but chuckle.

I do mine on the TS.

Cut the dadoes, then slowly creep the dado blades up and out on the shelves until its a crisp fit.

-- "Good artists borrow, great artists steal”…..Picasso

View AaronK's profile


1506 posts in 3433 days

#14 posted 01-07-2009 06:58 PM

I had this happen to me recently – the dado was the right thickness, but the shelf boards were slightly cupped, so they wouldnt fit right. I started to hate everything when I couldnt make a friggin dado right!

to “trim” the dado with to the right size without making them any deeper, I:

used 1/2” thick board
fixed coarse sandpaper to the face
rode it along the inside of the dado pressed along the side that needs fixing.

probably best to keep a straightedge or mark a reference line, but any deviation from perfectly straight will probably be imperceptibly anyway.

actually, taking a look at this project history, if it’s poplar from lowes it could be slightly warped/cupped as well, and you could have the same difficulty I had (if not now, then soon!). Mine wasn’t from lowes, but after sitting in my shop for a couple weeks it really may as well have been. I had 12” wide boards like you do and they got nice an funny.

anyway, good luck.

View Tomcat1066's profile


942 posts in 3765 days

#15 posted 01-08-2009 12:30 AM

mike: Thanks. I had considered that, and just might do it that way. I’m not sure just yet.

roman: I’d do it that way, except I don’t have a table saw. Nowhere to store one for the time being.

Aaron: That’s definitely a neat idea. The test piece didn’t appear cupped, but it’s a possibility. I’ll have to try that!

-- "Give me your poor tools, your tired steel, your huddled masses of rust." Yep, I ripped off the Statue of Liberty. That's how I roll!

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