# F***ed up a dado... how to fix it?



## Thadius856 (Nov 21, 2011)

First, a little back story... or skip to the bold part...

So, two mornings ago I set about cutting dadoes. I stacked my bookcase sides up into two piles, aligned the bottom ends, marked off my measurements on both piles from the bottom edge, and then used a square to mark all the dado edges. Lesson one... stack in one giant pile and mark, use stop jigs, or go home.

To double check my measurements, I had the carpenter measure my lines and read them aloud. Everything matches within 1/32", great. I made my cuts and was done. Right?

Wrong. Dead $%(*ing wrong.

See, even though the carpenter and I have synced down to even using the same brand of tape, we apparently think and speak in different units... his from a career of framing and concrete forms and mine from a mechanical drafting perspective. While he was calling "two three and five" and meaning 2'3-5/16", I was understanding 2'3-5/32", though if I was calling that measurement I'd call "two seven and five thirty-seconds" from my military training. I'm sure you see the problem already, and thus lesson two.

My dadoes just don't line up. The shelf dadoes are within 1/8" over a 23" shelf span, so probably not visible and thus acceptable, even with a 3" face frame. Except for one dado... and it's a solid quarter inch low. My choices were to split the difference on all of the shelves, shortening half of the side pieces at the bottom and the other half of the side pieces at the top (they'd still be off about half as much), but that would require crosscutting all the sides and backs again, so I'd have to retool the radial twice and the table saw once. No thanks. So, I widened the dado up 1/4" and accepted the imperfection in alignment. However, that opened up the bottom of the dado.

*So now I have four bookcases with a dado which is 11" long, 1/4" too wide, and the open end is going to fall on the bottom (no support on the underside of the shelf). I've already resigned myself to the fact that I'll probably have to cover the underside of the shelves with a decorative moulding. What can I do to give structural support to the shelf that could be hidden under quart round, shoe molding, etc?*

For reference, this is in 7-ply undersize 3/4" red oak ply with the dado against the veneer grain. The backside of the side pieces and backs will never be seen once installed.


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## Upstate (Nov 28, 2011)

Not sure if I understand completely, but can you widen all the dados and use thicker shelves? So instead of 1/2" shelves, you'd use 3/4" material? I think I read you were about 1/4 off, right?


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## Thadius856 (Nov 21, 2011)

Already using undersized 3/4". Shelves were glued up last night.


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## cabinetman (Jul 5, 2007)

Thadius856 said:


> Already using undersized 3/4". Shelves were glued up last night.


I would just use a small 1/4 round or cove moulding and glue in place. Use mechanical fasteners if you can...pin nails for the moulding and shelves. Small holes can always be dressed up.

Since the gap is at the underside of the dado, slip in a shim the depth of the dado just to maintain support. Gluing on the add on will also help with support. I would use the mouldings on all the shelves so it looks purposeful.












 







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## BWSmith (Aug 24, 2010)

Thicker shelves as has been mentioned.....but,as resaw add-ons that are only on ends.Kinda hard to describe,we've done a few highend libray's like this from the get-go.

The resaw pcs of solid/matching species are the same width as shelf,glued to shelf bttm.Usually 3 or so inches from end of shelf.....and reluctant to even suggest a thickness but in the 1/2" range.The "trick" part is their profile.Its a flat...then they're cut on a Cyma(the hard way).

Can be done with contrasting woods,but it draws attention to a detail better left un-noticed,IMO.These are the tiny details that seperate the chaf from the wheat so to speak.......You really have to pay attention to finished pce to even see them.Its so easy to "add" elements(Martha) that jump out at you......Its the stuff that you don't see or really have to study that keeps me going back to antiques,and in general looking to the past for answers.Best,BW


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## mikeswoods (May 18, 2009)

Change the way that you two take measurements----use inches only---no more math conversions in your head--


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## GeorgeC (Jul 30, 2008)

cabinetman said:


> I would just use a small 1/4 round or cove moulding and glue in place. Use mechanical fasteners if you can...pin nails for the moulding and shelves. Small holes can always be dressed up.
> 
> Since the gap is at the underside of the dado, slip in a shim the depth of the dado just to maintain support. Gluing on the add on will also help with support. I would use the mouldings on all the shelves so it looks purposeful.
> 
> ...


This seems very simple to do and it will solve your problem.

George


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## cabinetman (Jul 5, 2007)

Since you've glued and installed the shelves already, there's another method you could do. Cut 1/4" (or thicker) plywood the depth of the shelves, and the length to fit in between the ends. The front edge can be nosed with a moulding for the extra thickness. There wouldn't be any add on moulding showing.












 







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## Thadius856 (Nov 21, 2011)

Shelves are cut to dimension, less a 1-7/16 wide piece of quartersawn oak on the front. They are not glued in place yet (ran out of 220 grit).


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## Midlandbob (Sep 5, 2011)

Have you considered filling in any offending dado preserving the grain direction. Then recut the dado.
If the "patch" is above high shelves and below low shelves, it might be acceptable enough not to need the trim.
Or put the trim on all the shelves?


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## Thadius856 (Nov 21, 2011)

Looks like I'll be trimming all the shelves. If it wasn't $150 in plywood, I'd consider redoing them.


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## andrewscevich (Dec 17, 2011)

forgive me if i misunderstand... but... couldn't you just rip a strip of oak on a table saw on a bevel... then tap it under the offending shelves as a long long shim. glue it in place, then trim off excess flush with inside walls - i like to use a hand-plane iron by itself for flush trimming....if you fit the strip/shim in tight enough, you wouldn't even need to cover with a moulding - it would take stain just as the sides do. - does this make sense or do i sound like a fool?


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## jschaben (Apr 1, 2010)

Hi Thad - You're not likely to make that mistake again. But, as a suggestion for future reference. Initially cut the stock for the sides slightly wider than twice the final width. Then route your dados and then rip to final size. Dados will always match up. :smile:


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## woodnthings (Jan 24, 2009)

Thadius856 said:


> Already using undersized 3/4". Shelves were glued up last night.





Thadius856 said:


> Shelves are cut to dimension, less a 1-7/16 wide piece of quartersawn oak on the front. They are not glued in place yet (ran out of 220 grit).





Thadius856 said:


> *Looks like I'll be trimming all the shelves.* If it wasn't $150 in plywood, I'd consider redoing them.


Which is it, "glued up" the shelves or "not glued" in place? :blink:

Why would you trim the shelves unless the dados are *undersized*?

Quote:
*So, two mornings ago I set about cutting dadoes. I stacked my bookcase sides up into two piles, aligned the bottom ends, marked off my measurements on both piles from the bottom edge, and then used a square to mark all the dado edges.
*
NOthin' wrong with this procedure. If you mark up one as a "master" then transfer all the marks down with a square, one pile or two plies it won't matter. One pile is best since the transfer is once rather than twice, but a good master will make them the same. Stops will work equally well, right or wrong they will all be the same from one end.

Quote:
*So now I have four bookcases (sides) with a dado which is 11" long, 1/4" too wide, and the open end is going to fall on the bottom (no support on the underside of the shelf). I've already resigned myself to the fact that I'll probably have to cover the underside of the shelves with a decorative moulding. What can I do to give structural support to the shelf that could be hidden under quart round, shoe molding, etc?*

As suggested make a filler piece to close the difference and locate it in the least visible place, under the lower shelves and on top of the higher shelves. 

Aside from remaking the sides with new stock, there ain't no good way to make a wide dado more narrow than fill it. Unfortunately, the grain "should" run the same lengthwise, across the dado, but that probably won't happen. 

You "could" fill all the dados with length grain pieces and resaw them all, but that probably won't happen either.

Sometimes a "f" up is just that and you either live with and repair it as best as possible, or if you are like me you will just bite the bullet and make new sides.


Remember, measure 2x, cut 1X or in my case measure 1X cut 1X cut 1X again for good measure.  bill
BTW I would never trust anyone else's measurement to be the same as mine, unless we are makin' studs for a frame wall.... 7' - 11 1/8" and a fuzz....


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## Thadius856 (Nov 21, 2011)

woodnthings said:


> Which is it, "glued up" the shelves or "not glued" in place? :blink:
> 
> Why would you trim the shelves unless the dados are *undersized*?


"Glued up" the shelves as I'm glued the solid face onto the plywood shelves to hide the plies. Thats the only assembly that's been done... the carcasses have not been glued together. (yet).

And "trim the shelves" as in trim them out... or in other words add trim underneath each shelf where it meets the carcass wall to hide the screwup.

Clearer now?


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