japanese tansu - mystery groove in carcass?

[jamie shard]

Can someone identify the purpose of the groove that appears on the right hand side of the top carcass panel, in from the edge, further from the two squares?

250884

It seems like the little squares are to key in the front of the horizontal drawer dividers. The vertical groove isn't cut off by the drawer dividers, which makes me think it is for a locking mechanism of some sort:


250883

If this is the case, anybody know how the locking mechanism works?

-jamie

[jamie shard]

Here's the video... these screen captures are from the third video clip in the series.

https://www.youtube.com/watch?v=85GrCHbdaJ4&playnext=1&list=PL0EE69A1875DE0619&feature=results_main

[jamie shard]

Maybe something like a drawer stop?

250981

Little pegs are visible on the left hand side, but these wouldn't work with the way the drawers are designed in the video (no cutout on sides).

I'm stumped.

[David Wong]

If you look at 28 seconds into the 6th video, when he has the cabinet in his drying closet for the finish, you can see the pegs have been cut flush. Could the function of the pegs be to help hold the drawer shelves in place?

[jamie shard]

Good catch! That makes sense... but do you see them on the other side? I don't, but I'll look some more...

[jamie shard]

Interesting, too, that the bottom carcass panel doesn't appear to be mechanically jointed together in a way that would keep the bottom edges from moving outward.

[jamie shard]

Is it possible that the groove is a mistake? It doesn't seem necessary from a functional perspective. It's a lot of work for a redundant drawer shelf stop. Anybody else have an insight?

[Jonas Baker]

I agree that the groove is for a locking mechanism to keep the drawer deviders (or whatever you call the horizontal slats that go between the drawers) locked in place.

After partially assembling the carcass a strip of wood would be slid into the groove, assuring that the drawer dividers don't move around in their dados. I suppose its a similar concept of a stopped dado. You can see in 2nd pic of the first post, that there are little cut outs in the dividers that line up with the groove. Once a strip of wood was put into the groove, I would assume that he would have to chisel out the part that would impede the drawer from being put in place (I don't think they are drawer stops because it appears that this groove is on the front side of the cabinet, but I could be wrong, in fact I could be wrong about all of this!)

Jonas

[Harlan Barnhart]

Is it possible he has the drawers fit so tightly that he needs to vent the air out to allow the drawers to close quickly? In video five at the 3:00 min. mark you can see one drawer being closed creating enough air pressure to push out the drawer above.

[Correy Smith]

Harlan you win the golden egg. Yes the vert groove is to allow air flow as to not open all the drawers as any single drawer is slid in. The drawers typically made of sugi or paulonia are exceptionally light with side and back parts that are only about 12mm thick. The drawers are all finely fitted, and with out the grooves no way for the air to move from the cavity behind it.
Pax

[jamie shard]

Good to see this thread alive again! I checked with some other folks and they all thought it was an air vent. Oh well, I was hoping for a secret door mechanism, but until I hear a convincing counter argument, the "air vent" hypothesis seems to be the winner. Correy out of curiousity, is this your personal opinion or are you aware of some other authority/reference?

[jamie shard]

Reviving my old thread...

I no longer think it's an air vent. If it was, the vent would be in the back of the drawer, not near the front.

I no longer think it's for pinning the drawer blades in place. That's what the two square mortises at the front of the drawer blades are for.

Any other ideas?

-jamie

[Brian Holcombe]

It’s for a drawer stop you can see it at 2:23 in video 3/6.

Venting the air behind the drawer below/above would drive the user nuts.

[jamie shard]

Brian, could you explain how a drawer stop would work with these kinds of drawers?

[Brian Holcombe]

I’m not sure how to answer, can you further explain your question?

[jamie shard]

Sure! When I look at the drawers, they seem to be designed to completely fill the space of the drawer pocket. In other words, the bottom runs flat on the bottom, the sides run flat on the sides. So a english style drawer stop (that sits in the space underneath the drawer bottom and comes in contact with the back edge of the drawer front) wouldn't work here... and I can't figure out how any drawer stop would work with these drawers -- unless it was at the back of the drawer, but it looks like those "pegs" are at the front side of the carcass... And another oddity is that those groves and pegs don't appear on the left side of drawers. It really has me puzzled.

[Stewie Simpson]

Where does 1 find a seller for those two toed sloth socks. I need a pair for my mother in law.

[Brian Holcombe]

Sure! When I look at the drawers, they seem to be designed to completely fill the space of the drawer pocket. In other words, the bottom runs flat on the bottom, the sides run flat on the sides. So a english style drawer stop (that sits in the space underneath the drawer bottom and comes in contact with the back edge of the drawer front) wouldn't work here... and I can't figure out how any drawer stop would work with these drawers -- unless it was at the back of the drawer, but it looks like those "pegs" are at the front side of the carcass... And another oddity is that those groves and pegs don't appear on the left side of drawers. It really has me puzzled.

Looks like the back of the case to me, and also that it simply hits the back of the drawer to stop it.

[jamie shard]

Without a doubt, it is the front of the case. In video #3 he slides the back panels in place and "pegs" are in the front.

[Brian Holcombe]

Taking a closer look, you are correct they’re at the front. I’m not sure if the purpose, the mystery continues.

[Christopher Charles]

Hi all,

OK, i'm sucked in :) Here's my guess... it looks to me like the dado and trimmed pegs near the front keep the drawer dividers locked in place and aligned with the front of the case (without glue?). The dividers do not quite reach the back of the case and by being fixed by the pegs near the front, most of the seasonal expansion would be toward the back. (See ~1:10 in the 3rd video).

Thoughts?

[jamie shard]

Christopher, I agree that makes sense, but then the next question is: why does he also make an interrupted little mortise at the front edge of the shelf which would also lock the drawer dividers in place? You see what I mean? The carcass has a little square hole that appears at the front of each drawer blade slot, which also holds the front edge of the drawer blade in place.

So strange...

[Christopher Charles]

Ah, yes, I do now. Starting to feel like a Zen koan...

[Brian Holcombe]

I'm still not quite understanding why he does that, seems like it would be a cause for future problems as well, given that wood does not necessarily stay tight forever I would expect it to drop onto the drawer below and degrade the top surface of the drawer side.

Given the long history of sashimono, I'm sure there is a purpose that we're simply unaware of.

[William Fretwell]

Yes the front square mortice locks the drawer shelves in place because they are not all the way to the back. Given that the dadoes and joints are just knock together, no glue on them, there is no dimensional stability for the case width. This is mostly needed to fit the drawer fronts accurately. Hence the groove near the front.
So the purpose of the groove is to allow the pegs to be driven in to straighten the side of the case and adding dimensional stability so the drawers can be fitted properly. They are then cut off. They may be glued in.

[Brian Holcombe]

Interesting theory William, that makes good sense.

[William Fretwell]

It is just a matter of taking up the slack between the divider edge and the carcass. This stops the side of the carcass from being pushed in. The peg might not seem like much but when there is a series of them the effect is substantial. It stiffens up the whole assembly.

The whole assembly has a lot of very soft woods, easily cut and assembled with a lovely wood skin. It makes sense when they have to knock these things out quickly to make a living. You get a sense watching the video that the construction is ‘adequate’. Precisely fitting the dividers would be a serious pain, the peg tensioners are a quick ‘adequate’ shortcut that matches the rest of the build. The fact they are set in from the front a bit but not half way is because it’s much easier to set the pegs and again is ‘adequate’.

The setting of the pegs is not a feature of the video because this quick fix shortcut to fitting the dividers, is a bit of a dirty secret.

[jamie shard]

Finally!!! That makes total sense. So it provides a kind of anti-racking structure and fits the drawer blades more tightly. That explanation also explains why it isn't also used on the other side, because then there would be a kind of unbalanced compression in the box, because the other side just has drawers on the bottom.

Excellent, thanks William!