I need to build two registers like the below ones. The second one (not shown in the diagram) is smaller but it will still be large, see the below image.

The design is not final, I could probably add one 3/4" horizontal edge each at each end instead of finishing with a 5/16" piece, that would be for aesthetic reasons.

I can see two ways to put these together:
-cut the parts to build the left side and use glue and nails (brad nails?) from the side to join the horizontal sort pieces with the vertical edges
-the other option would be to use glue and tongue and groove, I already bought the 1/4" tongue and grove bits shown below

Which option is the best ?
Are there better options ?
Is there a better design for this ? (I do not want to use a router to cut the openings as I will not have the material of that size). This will be white oak but for now I am playing around with left overs to build a mock up to see what it would look and feel like.

enter image description here enter image description here

Custom Register 3/4"x31 5/8” x8 1/16”
Custom Register 3/4"x18 ¼”x 8 3/16”

Update: apparently there are other ways to do that -the tongue and groove method requires a jig in order to cut the tongue in the short pieces otherwise it the going to splinter... learned that the hard way (mocked this using some leftover wood I had)

The method I am proposing below uses a straight bit and it seems simpler The long edges will serve more like a masking role , the short transversals will have more "meat"/wood at the end and they will rest on the subfloor This will have to be glued, not sure if side nails would work here. The advantage of this method is that the traversals will have around 3/4 of wood at each end sitting on the subfloor so more solid I would say enter image description here


Here is my first attempt (POC) to build this register using tongue and groove. Unfortunately I used pine (cheap) and it does not seem to be very sturdy, the traversals will collapse. I need to find some oak to try this one more time before giving up on tongue and groove.

enter image description here

  • 2
    Any question with "what's the best" in it is not ideal, because opinions. I'm sure you've gone back and forth over the two options presented and looked for pros and cons, it's much better to ask for input of that kind as even if it just repeats what you've already thought of it might help cement which you think is preferable.
    – Graphus
    Commented Dec 18, 2022 at 10:48
  • What is the size of the lip in the floor that these rest on? Commented Dec 18, 2022 at 20:31
  • 2
    As a suggestion, note that there is increased risk of tear out if you cut the slats to width and then make the tongues. It will be better to route the tongues on wider boards and then cut them to width.
    – Ashlar
    Commented Dec 19, 2022 at 2:19
  • One more question: do you have a tablesaw to do a custom rip that could be used to fill the gap between the slats on the long side pieces? Commented Dec 19, 2022 at 4:51
  • I have all the tools I need for this, Incra miter gauge 1000SE and Ridgid TS3650 + a router table + router Mastercraft Maximum 2HP Fixed/plunge
    – MiniMe
    Commented Dec 20, 2022 at 22:43

2 Answers 2


I don't own a crystal ball but I can almost guarantee that either of your two proposed methods will have been used by someone in the past, and successfully. The first could quite easily be strong enough for your needs, but of the two the second method is almost certain to be stronger, and it offers advantages in terms of ease of construction. Lots more milling of course, but you definitely gain something for the effort.

Are there better options ?

I can think of some other options but nothing I'd say is definitively better. And anyway it sounds like you already made your mind up about which method you'd prefer to use....

I already bought the 1/4" tongue and grove bits shown below

So I don't see any reason not to go with T&G construction.

(I do not want to use a router to cut the openings as I will not have the material of that size).

You wouldn't want to make something like this from a single board! Building up from pieces is 100% the right call (it would be different if this was plywood). In solid wood the routed grooves would substantially weaken the wood, to the point where breaks in service are virtually guaranteed.

  • Good answer. I hope the OP recognizes that the slats need to be well supported for foot traffic. I’d suggest a minimum of 1”, so the total width of the ledge should be 1-3/4” on the long sides. Hopefully, this won’t impede airflow too much. Commented Dec 20, 2022 at 14:02
  • 1
    @AloysiusDefenestrate, I'd hope so too!
    – Graphus
    Commented Dec 21, 2022 at 7:08
  • Just tested the first method using pine. I was interested in the process which is now clear as you can see I can get quite close to what the pros did (the small one in the picture from the update of the question) but it is not sturdy enough. What is interesting is that the small register has a much smaller tongue and groove (~3/16") for a little bit more half the length of the transversal pieces I used. It is also worth checking if they cut the transversals along the grain or not
    – MiniMe
    Commented Jan 9, 2023 at 1:27
  • Thanks for the update!
    – Graphus
    Commented Jan 9, 2023 at 8:04

the other option would be to use glue and tongue and groove, I already bought the 1/4" tongue and grove bits shown below

That's how I'd do it. If you don't want the groove to show between the slats, make up some filler pieces that you can glue in the grooves between the slats. The mechanical connection between slats and rails will be much stronger than just glue and nails, especially considering that these covers will be constantly in the flow of hot or cold air.

Mill the tongues on larger pieces of wood, and then slice those pieces into slats -- it'll be much faster than cutting tongues on each piece individually.

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