Cutting "Double Blind" Dado for Small Box

[TomInNC]

I made a sliding top pencil box based on Doug Stowe's book (first picture below) for my kids. Someone recently saw the box and asked if I could use a similar design to make a larger box that would sit upright and hold 2 small wine glasses with a small shelf in between. The closest example I can find online is the second picture below, but lid would slide up and down instead of side to side, and there would be no spot for the wine bottle as seen on the left. I'm trying to figure out the best way to add the shelf. If I run a dado completely through the side pieces to house the shelf, the dado would be visible from both the front and the back of the box, which I think would be unsightly. I was thinking that the easiest approach would be to have a dado that is stopped on both ends before the grooves (I this a "double blind" dado?), what in essence would be a very small mortise. Then I would house the shelf in the stopped dado. 

The pieces are only about 4 inches wide, so cutting this with my large plunge router could get a little dicey. Would the best approach be to cut the dado using a plunge cut and stop blocks on a router table?

 

[wtnhighlander]

 

This is how I would roll with it.

[TomInNC]

On 7/8/2022 at 12:18 PM, wtnhighlander said:

 

This is how I would roll with it.

While I do have a router plane, I have only used it to clean up dados, never to make one. In this case, because the shelf would need to be in the middle of the box, the dado would be about 6 inches from where the router plane fence would register. At least for my router plane, that is waaaay to far in to use the fence I have. Is there a trick for using router planes to put dados beyond the reach of the fence?

[Coop]

You could cut the groove with a series of holes on the drill press and clean up the sides and ends with a chisel. Then cut a tongue on the ends of your divider and the shoulders would hide any irregularities in the groove.

[TomInNC]

On 7/8/2022 at 4:28 PM, Coop said:

You could cut the groove with a series of holes on the drill press and clean up the sides and ends with a chisel. Then cut a tongue on the ends of your divider and the shoulders would hide any irregularities in the groove.

Thanks, but unfortunately I still do not have a drill press. 

[Ronn W]

4" wide pieces should be no problem with a plunge router provided that you lay the piece to be routed flat on the bench and put board of the same thickeness on each side of it to help support the router.  Clamp them so they can't move.      I would then make a jig to guide the router either with a flush trim bit or a router bushing.  Then finish up as Coop suggests.

[G Ragatz]

For cuts that short and not terribly deep, I think I'd just lay them out with a marking knife and use a chisel.

[wtnhighlander]

Router planes have fences???  

I would saw cut the edges, using a square as a guide, hog out most of the waste with a chisel, and clean up with the router plane.

[Just Bob]

1 hour ago, wtnhighlander said:

Router planes have fences???  

I would saw cut the edges, using a square as a guide, hog out most of the waste with a chisel, and clean up with the router plane.

Yes. Fence

[Wimayo]

On 7/8/2022 at 10:50 AM, TomInNC said:

 

 Would the best approach be to cut the dado using a plunge cut and stop blocks on a router table?

 

 

 

That's what I would do. I might consider cutting the dado before I cut the piece down to overall size so that I would have a larger piece to work with.

I might also take Ragatz's advice.

[Tpt life]

If I needed a fence for a router plane, I’d clamp one to the work piece. 

[TomInNC]

On 7/8/2022 at 8:57 PM, wtnhighlander said:

Router planes have fences???  

I would saw cut the edges, using a square as a guide, hog out most of the waste with a chisel, and clean up with the router plane.

So something like what is in the video below, but just stopped on both sides?

 

 

 

[G Ragatz]

Hi Tom,

I was re-reading your original post, and I was wondering why the dado needs to be stopped on both ends. I'm assuming there will be a back of the box - likely seated in a rabbet. If the rabbet is as wide as the dado is deep, wouldn't that hide the dado from the back? Given the weight of a wine glass, that dado doesn't need to be very deep to provide sufficient support.

Gary

[TomInNC]

On 7/12/2022 at 11:58 AM, G Ragatz said:

Hi Tom,

I was re-reading your original post, and I was wondering why the dado needs to be stopped on both ends. I'm assuming there will be a back of the box - likely seated in a rabbet. If the rabbet is as wide as the dado is deep, wouldn't that hide the dado from the back? Given the weight of a wine glass, that dado doesn't need to be very deep to provide sufficient support.

Gary

So at least with the pencil box, the back (well, bottom in that case) was solid wood floating in a groove. If I used the same approach to make the back here, the dado would show on the back side of the box. If I am still using solid wood, wouldn't gluing the back panel into a rabbet cause issues because of expansion and contraction? I'm open to suggestions on alternatives to the back. I'm still really new at this, and I was just trying to build off of something that I knew worked already.

[wtnhighlander]

The stopped dado idea is fine, and if you plan to add the "back" floating in a groove, I would cut the grooves first, to serve as the stop and depth guide for that end of the dado. 

Since you don't want to come through on either end, I would knife cut the layout lines pretty deep, then excavate it like a shallow mortise, whether by chisel or electric router. Sawing the sides will be pretty tedious with both ends stopped.

[G Ragatz]

On 7/12/2022 at 1:24 PM, TomInNC said:

So at least with the pencil box, the back (well, bottom in that case) was solid wood floating in a groove. If I used the same approach to make the back here, the dado would show on the back side of the box. If I am still using solid wood, wouldn't gluing the back panel into a rabbet cause issues because of expansion and contraction? I'm open to suggestions on alternatives to the back. I'm still really new at this, and I was just trying to build off of something that I knew worked already.

I see your point. You could consider veneered plywood for the back - then wood movement wouldn't be an issue. If you want to stick with solid wood, then I think your design is the way to go. And I'd go back to my earlier suggestion of a marking knife and chisel for the stopped dados. I also like @wtnhighlander's suggestion of cutting the grooves first.

What's the plan for joinery where the top/bottom and sides come together?

[TomInNC]

For the joinery on the sides, I was just going to use box joints that would be virtually identical to what was on the pencil box. 

[G Ragatz]

On 7/19/2022 at 11:00 AM, TomInNC said:

For the joinery on the sides, I was just going to use box joints that would be virtually identical to what was on the pencil box. 

That should look nice. You'll still need a couple more double-stopped dadoes - either in the sides or the top & bottom - but close to the edge of the piece, they should be pretty easy to manage at the router table.