A serious challenge

[Beave2012]

Very interesting. I was thinking of a deep vertical rail (like a deadbolt) going between the drawers front to back (imagine a floating middle partition).

On each drawer at the back would have a tab coming out the side towards that vertical rail/partition. These tabs would essentially "glide" next to the main center rail/partition. However, on that rail/partition you could have angled slides protruding on each side (small right triangles), that when the the exact right drawer tab came into contact would lift that main rail the exact height of the tab. That would lift it into position for drawer #2, and so on until it lifted the rail/partition up far enough to unlock.

This way if you open the wrong drawer the drawer's tab would/could sit on top of one of the "lift slides" that protrude from that main rail/partition, preventing it from lifting until that drawer was sent back in. When the correct 1st drawer isn't used, they would slide along the main rail without issue, but if you line up those lift slides at the correct height along the rail/partition and where the "key" drawers are, they would slowly nudge the rail up and up and up.

The main rail could slide into a slot of the secret drawer, letting it just sit deep enough so that all 7 lifts would lift it out of the drawer slot.

Essentially creating a sliding vertical deadbolt that requires a specific order of drawers to be used in order to open it, and other opened drawers would (but not always) interrupt the unlocking mechanism.

The key to it all would be ensuring the lift resulting from each drawer pulled out was at least 1/7th the depth of how far the column enters the secret drawer on bottom, but not more than 1/6th.

As for making it so that it falls smoothly if someone pushes in all the drawers... well... maybe a counter weight would help, not to mention help the "friction" of the drawer slides as they rub against the lifts. This would help reduce someone figuring out the order by pressure.

I hope that all made sense.

[benush26]

Are the 7 drawers "specific" letters?
If the chest is 3 by 9, (guessing this because of the height) is she expecting them to be in alphabetical order with the ability to open 7 specifiic letters with each determined location by her?
A B C
D E F
G H I
J K L
M N O
P Q R
S T U
V W X
Y # Z

I would set up a pivot / scissor arm on the bottom of each "chosen" drawer (basically left right or middle of a drawer so it doesn't interfere with any other pivots in the same column) with the pivot point attached to the case while the leading arm is attached to the bottom front (hidden) of the drawer, which when the drawer is pulled open, would push the back arm against the beveled top of a rod in the back, effectively pushing that rod down a small distance. When all seven rods have been pushed down by the drawers being pulled open, a lip that was on the bottom of all the rods ( think French cleat) is then low enough that the bottom rear edge of the "special" drawer is no longer held in place and can be pulled out.

Anyway, I designed this as I sat here and thought about it as I watched the football game, so there could be "numerous" flaws!! Hope it gives you more ideas.

Be well,
Ben

[benush26]

Quick drawing
this would be looking at the drawer bottom up side down with the back facing you

The green cylinder is attached to the case as the pivot point (maybe by a screw ??), the front attached to the drawer bottom and the back has guides on both sides (though only one is showing) to keep the back arm going in the correct direction.

dbc.jpg (52.94 KiB) Viewed 3289 times

As the drawer is pulled open, the anchor point (pivot), because it is fastened to the case forces the other arm towards the back of the drawer.

Though it does not show well, the back arm has a bevel if you would prefer it on the arm rather than the post (rod)

Hope this makes some sense.

Be well,
Ben

[masonsailor2]

Consider this. The cabinet will be designed with the required blank space behind the drawers. Each drawer will have a 3/4 " dia dowel on the back of the drawer. At the back of the drawers are a series of 1/4 ply panels which have holes through which the pegs will extend through. All the panels will notch into the bottom ( 27th) drawer. It would require that all the panels be lifted to open the drawer. That's as far as I have gone for today.
Paul

[Ed in Tampa]

Even simpler
Make each drawer have an open close latch. Perhaps a strict of wood with keyholes. Min the open position the big opening would be on the bar in locked position the narrow part would hold the bar from moving.

Then set up the combination
llllllllollllllllllolllllllolllloolllool.
I means open drawer locks slide holding the 27 th drawer closed. O means the slide is released.

Basic amounts to mounting key hole strip to drawer where for l drawers the slot in on the big hole Iif the drawer is pulled out it locks the slide. On the 7 magic drawers the keyhole strip would be turned so
that the closed drawer puts the narrow locking the slide. Pulling the drawer out moves the strip to the large hole releasing the slid.

Spring load the rod to relapse the 27 th drawer when the others are in right position.

The 'binary' stuff is the simple part.

The trick is to translate that into wooden parts.

Consider a vertical rail.

Notches on both the front and rear edges corresponding each of the 26 drawer locations(the 27th will be a different scene).

The notches on the rear are entered when a 'non 7' drawer is opened.

The notches on the front are vacated when each '7 drawer' is opened.

Thus the front notches perform the +and function of the '7 drawer', and the
rear notches perform the -or function of the other 19('non 7 drawer').

Any 'non 7' drawer open prevents the rail from moving vertically

Any missing '7 drawer' open also prevents the vertical bar from vertical movement.

A spring can move the rail vertically when all the notches are 'unoccupied'.

That vertical motion unlocks the 27th drawer.

The '7 drawer' have a pin that vacates the corresponding notch in the front rail.

The 'non 7 drawers' move a lever out of the corresponding rear notch when closed.

Missing is the details of how closing a '7 drawer' moves the rail back to the lock position as well as closing the 27th drawer. Some 'inclined' planes needed there.

notches, levers and pins lock and a slot unlocks.

That is what I was trying to say, you did it much better!

[masonsailor2]

JPG I like your solution and Beave I think a variation of hours might work. Thanks to all of you. Please keep the ideas coming. One the design criteria is that will have to be that the mechanism will need to be made of very dense hardwood, in fact as hard as possible to allow not only for wear but also humidity changes. The dead bolts for instance will probably need to be laminated in several layers for stability.
Paul

[rjent]

JPG I like your solution and Beave I think a variation of hours might work. Thanks to all of you. Please keep the ideas coming. One the design criteria is that will have to be that the mechanism will need to be made of very dense hardwood, in fact as hard as possible to allow not only for wear but also humidity changes. The dead bolts for instance will probably need to be laminated in several layers for stability.
Paul

Since you are asking for more, and there are some great ideas here. Here is my 2 cents:

Each "code" drawer when closed pushes downward (or upward depending on the logic) on a wedge at the back. That wedge/pivot is connected to a vertical rod attached to a horizontal rod that is pivoted in the exact center which make the opposite end move the same amount. The horizontal rod then is connected at the opposite end to another vertical rod that pushes down (or up) on a common pivot at the level of the magic drawer. The common pivot is the same design rod pivoted at the center which only moves (releases) when all the correct drawers are pulled which then releases the "magic" drawer.

The "rods" could be anything from hardwood to cold roll steel. the wedges are just short pivots that "get in the way" when the drawer is pulled and get pushed "out of the way" when closed. They would only need to move a half inch or so.

If you need a drawing, I will hand sketch one for you. Like I said a multi AND gate ....

[Beave2012]

JPG I like your solution and Beave I think a variation of hours might work. Thanks to all of you. Please keep the ideas coming. One the design criteria is that will have to be that the mechanism will need to be made of very dense hardwood, in fact as hard as possible to allow not only for wear but also humidity changes. The dead bolts for instance will probably need to be laminated in several layers for stability.
Paul

I think my way would be the simplest way to incorporate a sequenced code to open the lock. To make a lock that requires a specific order would be rather difficult without electronics, but with craftsmanship the drawer sequence in order could lift the deadbolt. If you do make it, post pictures.

Heck, I'm tempted to try it at this point... Sounds like a good challenge. Maybe after the fretwork piece.

[algale]

I'll play. I think this is the simplest solution.

I'll posit a 3x9 drawer arrangement with the "special drawer" located in middle of the bottom row but it can really go anywhere in the cabinet and the drawer arrangement need not be 3 x9. The seven "unlocking" drawers that must be simultaneously opened to unlock the "special drawer" can be scattered anywhere in the cabinet at random.

The trick is that each of the seven "unlocking" drawers has a simple 3/4 dowel extending 3/4 of an inch glued to the back. These dowels are invisible unless one of the seven "unlocking" drawer is completely removed from the chest and, if provision is made to prevent drawer removal (e.g. by a stop block or pin), will never be seen.

When the seven "unlocking" drawers are closed, their dowels fit into corresponding holes drilled into a "panel" inset behind the cabinet's real back, holding the panel in the "up" position. This "panel" could travel in a well waxed vertical groove in the cabinet sides, but to give rigidity to this "panel" and to ensure smooth travel/operation of the "panel" without wracking, the "panel" can be the "bottom" of a very shallow, vertically traveling "drawer" that rides on vertically mounted ball bearing drawer glides that open/slide downward with gravity.

The vertically traveling "panel" has a hook mounted to it (oriented like a picture hook) that grabs the lip between the back and bottom of the "special drawer." When the panel is in the "up" position, being held in place by the dowels of any of the seven "unlocking" drawers, the hook grabs the "special drawer" and prevents it from being opened. Only when all seven of the "unlocking" drawers with dowels have been opened can the "panel" drop to the "down" position, disengaging the hook holding the "special drawer" and allowing the "special drawer" to be opened.

The "panel" need only drop a small amount, perhaps a quarter of an inch. To reset the "panel" from the "down" to the "up" position, drill a finger hole in the bottom of the cabinet. First, close the "special drawer" then reach in through the finger hole and push the "panel" back up a 1/4 inch to engage the hook and lock the "special drawer." Finally, while holding the "panel" in the "up" position through the finger hole, close any one of the seven "unlocking" drawers, securing the panel in the "up" position and locking the "special drawer" in place via the hook.

Al

[BuckeyeDennis]

Al, I think I followed what you were proposing. But what is to prevent someone from simply opening all of the drawers, and thereby unlocking the "special" drawer?