This puzzle box is designed by Erhan Çubukcuoglu 2012Istanbul /TURKEY

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Lobster Box

This puzzle box is my another design. I can say this is third generation of “Twin Lock Box” This time there aren't any visible keys or holes. For opening the box you must use gravity and magnetism. And lobster is a mile stone for the solution

I made the box from ovenghaul. It's a nice hard wood with a rich texture. First I was planing a red lobster. For this reason I selected a clear wood for box. After some try, I decided to this color for lobster. On this box, I also rounded all edges. I think the box looks better.

Overall dimensions of this box is 92x92x150 mm.

I carved the lobster from a hard wood. For my box ornaments I read a book about traditional Japanese small scale wood carvings called “Netsuke”. The name of this book is “Carving Netsuke”. A nice book for learning method and tools. And this lobster is one of my first attempts. I like use that type of carvings in my future projects.

The lobster on this box is only for hiding a small magnet. If you don't have enough carving experience or ıf you don't like carve a lobster, you can make a different ornament for hiding the magnet.

How it works

For making your own box first you must understand how this box works.

For opening the box first you must remove the center piece of the lobster. The center piece of the lobster is hold on the box with two small magnets (D:5 mm x 5mm) . One of this magnets fixed on the box and the other one into the lobster piece. And there is a small brass rod fixed on the box cover for preventing the rotation of lobster piece.

After removing the lobster you will find a small and thin magnet at the bottom of the lobster piece.On the photo also you can see fixed magnet of the lobster piece.

You must remove this thin magnet. (D:10 mm x 2mm) You will use this magnet for opening this box

This box has three hidden wooden keys on each side One of that three keys has a magnet. That means you have two key with magnet and four key without a magnet.

The box has,Two key left hand without a magnetTwo key right hand without a magnet.One key left hand with magnet (South pole of the magnet outside)One key right hand with magnet (North pole of the magnet outside)

This point is a little confusing,Left hand keys mounted to left side open when the box is tilted to front.Right hand keys mounted to right side also open when the box is tilted to front.You will mount right hand key with magnet to left side and left hand key with magnet to right side. In this case magnetic keys will be closed when the box is tilted to front.

For opening the box you will turn the box to it's front side. In this case 4 wooden key that works

with gravity will be open and two key with magnets will be closed.

In this step turn the box to its normal position slowly. Now you will open magnetic keys with the hidden magnet that you found. Use the magnet. You know the position of the keys. You must feel a pushing action and hear a “click” voice. If this not happens, change the side(polarity) of the magnet and try again. For opening the other side magnetic key you must change the polarity of the magnet and after push it with magnet from outside of the box.

Now the box is open. Slide the box cover up and open.

Lobster Box Material List

Pcs Name Dimensions (mm) Quantity (pcs)Wooden keys

Wooden keys 10x10x67 6 (3+3)Box

Slider support columns 25x10x80 4Frame base 10x10x80 2Frame top 20x10x80 2Fixed key guides 10x10x80 4Left and right panel 6x80x80 2Front and back panel 6x92x150 2Bottom panel 6x80x150 1

Box cover Slider body 30x10x80 2Cover plate 6x80x150 1Wooden pins D3x10 6Wedges for corners 20x20x30 2

How to make your lobster box

This puzzle box has three main section1. Wooden keys2. Box3. Box cover

I started to make this puzzle by making wooden keys. After box and box cover.

For material I advise to use hard woods like beech or mahogany etc. for keys and frames.

Making wooden keys

There are 6 keys. Three of them are left hand and other three keys are right hand. Left hand keys are in open position when they are pushed to the left and right hand keys are in open position when they are pushed to the right

This picture show only left and right keys. NOT IN SCALE. See drawing for key dimensions.Total dimension of each key 10 x 10 x 67 mm

On the photo below you can see two method for making the keys. The keys at the bottom of the photo is made with my firs method. ( with clear color made of beech) For making them after cutting the slot with a jewelery hand saw, I drilled two holes and connected them with a knife. This method is difficult for making the keys

I developed an alternative method. The keys on the top of the photo (made from mahogany and with dark color) are easy to make. You can cut the slots easily with any method that you like. I cut them by using a hand mitre saw and a jewelery saw.

After making the keys you must mount the magnets, Now you must have,

Two key left hand without a magnetTwo key right hand without a magnet.One key left hand with magnet (South pole of the magnet outside)One key right hand with magnet (North pole of the magnet outside)

I used for keys two small rare earth magnet D:5 mm x 5 mmYou must drill a hole D:5 mm and depth between 4,8-5 mm on one side of the magnetic keys and mount magnets. You will mount two magnet with different polarity.

Keys of the left side. All keys are shifted to the front side of the box. As seen on the photo if you push center key with a magnet to back side all three keys will be in open position

Six keys of the box. On the photo you can see magnets. You must place both magnet with diiferent polarities.

Making the box

This box has two frame. Frames support wooden keys and works as a guide for keys. Left frame and right frame. Both of theme are exactly same. You need to make two frame.

First I start by cutting left and right side panels of the box. (80x80x6 mm)I fix on the side panels two key guide (10x10x80 mm), frame base piece (10x10x80 mm) and frame top piece (20x10x80 mm). At the center of two key guide there are small slots (5x10x10 mm) and at the center of the bottom piece also there is a small slot (5x5x20 mm). For assembly you can use key pieces and small thin cardboard pieces for obtaining correct distance between key guides. Dont try to make keys or guides best fit. With a small clearence about 0,2 -0.4 mm your box will work better.

After you can mount two slider support columns( 25x25x80 mm) You can use your slider pieces and small papers for obtaining correct distance between columns.

Now you can prepare your box base for assembly (80x150x6 mm).In this step you will mount your left and right side frames on the base piece. For assembly you can use a gluing jig or machinist square for checking perpendicularity of the frames. This is important.

The picture show the box construction before mounting front and back panels.

For front and back panels there are a planned dimension. ( 150x92x6 mm) But that change related to material thickness. For a best fit, I prefer cut them after mounting left and right panels by measuring real dimension.

ImportantBefore fixing back and front panels don't forget putting keys in correct positions.

Making the box cover

Normally lobsters are symmetric. But as you can see from the photo the left and right arm of this lobster is slightly different. I made this asymmetric for finding the front side easily. Additionally I think looks better than a symmetric lobster.

The box cover is a flat wood pieces as seen on the photo at left. Two cover sliders are glued on this wood pieces. For fortify the construction two triangular wood pieces glued to the bottom of that sliders as seen on the photo.

On the box cover I mounted a small magnet that hold the lobster piece and a brass pin for preventing the rotation of the lobster piece. I advise first making your lobster after mounting that pieces on box cover according to your lobster. Al other lobster pieces are fixed on box cover with carpenter glue.

Making two cover sliders

Wooden pins are cut to 10 mm length. Drill holes 3 mm diameter and 6 mm depth. After fixing wooden pins, you will have 4 mm length wooden pins. Distance between pin centers is 20 mm and very precise. For easy marking pin locations you can use a compass.

Fixing cover sliders to correct position

Gluing sliders to correct position on cover precisely is tricky. I put small cardboard pieces under both slider. They became higher than the box height. And it's became easy to fix them in correct position

Lobster pattern

This is my handmade sketch of lobster from a lobster photo for carving. If you like yo can use this by scaling or you can make your own carvings. The highest point of my lobster is 20 mm (Top point of arms and the body)