Building the Puzzle Box - Thingiverse
Building the Puzzle Box David Kessner
Origins This puzzle box is based on one created by Hiroshi Iwahara. Google him to see his amazing work. His original box was made out of various woods, with intricate inlays. The craftsmanship was awe inspiring. This 3-D printed box is a challenging and rewarding print, but it doesn’t hold a candle to the original.
Introduction These instructions contain many spoilers. It is required in order to build the box. If you’re not going to build one, I suggest that you stop reading now. This is a challenging print. It requires that your printer be properly tuned for the parts to fit and move well. It also requires printing at a high resolution (thin layer height). Make sure you and your printer are up to the challenge before proceeding. All of the exterior faces of the box are printed against the build platform. For this reason, I highly recommend using a glass platform and hair spray. Using Blue Tape, Kapton Tape, or other methods will still work, but the results won’t be as nice. Use of rafts is highly discouraged.
All of the STL files are arranged for printing in a Makerbot Replicator 2. The parts have been rotated so dimensional errors in the printer are less problematic. Also, the more critical surfaces are on the left side, to make best use of the Filament Cooling Fan. If you are using a different printer, keep these things in mind as you arrange the parts on the build platform. No supports are needed, or wanted. Supports could cause rough surfaces that interfere with the moving parts. This print was designed to not require supports. This print requires 0.1 mm layers. Part of this is because of the surface finish that’s needed for parts to move smoothly, but also there are overhangs that will print well with no support at 0.1 mm layers. If you print this with 0.2 mm layers, those overhangs will not be smooth and the overall fit and finish of this print will greatly suffer.
Supplies In addition to the filament, you will need:
Super Glue (I used Loctite Gel Control). Three 15mm x 3mm stainless steel rods. Four 1/4” diameter x 1/16” thick Neodymium Magnets (http://amzn.com/B0012AUU84).
Tools
A straight needle file (http://amzn.com/B000NPUKYS). Needle Nose Pliers A Dremel tool or equivalent, with cut-off disks. Calipers or Micrometer
Bar
Print the bar at 0.1 mm layers, 100% infill, and 1 total shell.
This part needs to be strong and dense. Strong but not dense, or dense but not strong, will result in a box that doesn’t operate as smoothly as it should. Ideally this part would be milled out of aluminum, but since we’re compromising by using plastic go ahead and splurge for the 100% infill.
Drawer
Print the drawer at 0.105 mm layers, 2 or 3 total shells, 20% infill, and 6-8 total solid top/bottom layers. It doesn’t have to be exactly 0.105 mm layers, but it can’t be 0.100 mm. The reason for this is simple: This part will rub against other parts printed with 0.100 mm layers. If this part is also printed with 0.100 mm layers then the layers of this part will perfectly line up with the layers of other parts—causing more friction than what we want. But if this part is printed with a layer thickness that is close, but not exactly, 0.100 mm then the ridges formed by the layers won’t perfectly line up and the parts will move more smoothly together. I printed this part at 0.105 mm layers and it worked well. Depending on the filament, you will want 2 or 3 total shells. The choice is purely aesthetic. With more opaque filament I found that 3 shells gave a better surface finish/color, while more translucent filaments were better with 2 shells.
The Other Printed Parts
All of the other parts (Ends, Sides, Main Body, Lid) should be printed with 0.1 mm layers, 2 or 3 total shells, 6-8 solid top/bottom layers, and 20% infill. You may choose to not print the sides. If you omit the sides, the box will be fully functional but the internal mechanism will be exposed for people to look at. Of course this is a huge spoiler, but it is a source of amusement.
Stainless Steel Rods This box needs three stainless steel rods, 15 mm long and 3 mm in diameter. 3mm diameter rods are commonly available. A search for “3mm stainless steel rod” on Amazon.com will bring up thousands of options. I recommend buying longer rods and cutting them to size with a Dremel tool. The actual length can be 14.5 mm to 15.5 mm. It is important to measure their length after cutting and trim them down more if required. Bevel one end of the rod with the Dremel tool, to make inserting them easier.
Filing After all of the parts have been printed, some will inevitably not fit smoothly and require filing. Test fit everything before inserting the rods or gluing anything. Everyone’s printers are different, and have different issues. In my experience, the biggest issue was with the ends fitting into the main body. Below is how I fit things together, but keep in mind that your experience will likely be different. When the end is inserted into the main body, the end should slide freely. It should, using only the force of gravity, slide all the way down in the groove. If it binds at any point then you will need to file things down to make it smooth. Test fit the end piece by placing it in the main body backwards, according to the picture below:
Slide the end up and down, making sure it moves smoothly. If it binds, file the appropriate faces with the needle file. Next, insert the end piece correctly, using the tongue and groove. If it does not move smoothly then there are several areas that will require filing. Start by filing the two highlighted faces in the picture below:
Next, file the end of the tongue, highlighted in this picture:
Hopefully, at this point everything will be moving nicely. If not, carefully file. Having a tight fit, but still smooth motion is ideal for this box. If you have any remaining hairy parts on your print, now is a good time to remove them. Pay particular attention to make sure that the bar moves freely in the main body.
Installing The Magnets Installing the magnets is not hard. Installing them correctly, with the poles facing the right way, is tricky. Start by installing one magnet into the lid. Put a small amount of super glue into the indentation, and press the magnet into place. Let the glue dry. Take a second magnet, and place it on the first magnet in the lid. Using a marker, place a dot on the face of the magnet. Remove the magnet, and do this again for a third magnet. Install these two magnets into the end pieces, with the dots pressed against the super glue. Let it dry. Place the fourth magnet on one of the magnets in the end pieces. Draw a dot. Install this magnet in the remaining position in the lid, dot side against the glue. If you are printing more than one puzzle box, use the installed magnets from a previous box as your reference for building later boxes. This will assure that your lids are interchangeable, and will also make installation faster since you won’t have to wait for glue to dry.
Installing The Rods
Insert the drawer into the main body so that the hole for the rod is visible through the side window. Insert one of the ends into the main body. Insert the bar. And then insert the other end. Look through the windows and make sure that everything looks good. Remove the drawer. Carefully place a small drop of super glue into the hole for the rod. This is more difficult than it sounds. Use a very small drop. You don’t want glue oozing out once the rod is installed. You also want all the glue to be inside the hole, and not on the rim. When you re-install the drawer into the body you don’t want any glue to touch the walls of the main body. I found that using the Loctite Gel Control Super Glue was ideal for this, since it was easy to place a small amount and it didn’t run everywhere. Re-install the drawer. Slide the bar back and forth until you have a good view of the hole. Using a needle nose pliers, insert the rod into the hole, bevel end first. You might need a reasonable amount of force to do this, since the hole is intentionally tight. The rod should not stick up so much that it rubs against the side panel, once that piece is glued in place. Carefully inspect your work, making sure that super glue didn’t ooze out of the hole when the rod was pressed in. If it did, carefully clean it up using toothpicks or something similar. Don’t get excess glue on the rods or bar, since those surfaces need to slide smoothly together. Repeat this procedure with the two end pieces.
Opening The Box
Before installing the sides, it is important to know how to open the box. These instructions for opening assume that you can’t just look through the windows and see the mechanism at work. But if you are building the box, take advantage of that while going through these instructions. The original box by Iwahara had some laser engraving on the lid. There was an apple tree, with a falling apple, and the same formula that is on this box. The formula on the lid is 𝐹 = 𝐺
𝑀𝑚 , 𝑑2
which means Force
equals the Gravitational Constant times Mass1 times Mass2 divided by distance-squared. The only part of the formula that is important is G, or gravity. It is important to have the correct side of the box facing up, otherwise it won’t open. The correct orientation is with and end piece facing the ceiling, and the formula right-side up. Keep it in this orientation until the box is opened. Opening the box does not require much force. If you are forcing something then you are probably doing it wrong. Carefully slide one of the ends about 5 mm. Hold it in position and carefully move the other end about 5 mm. With both ends in that position, you should hear something if you gently shake the box up and down. Shaking isn’t important for opening the box, but it does tell you if you are in the correct position. Once in position, simultaneously slide both ends all the way. If successful, the lid should easily slide open, pulling the drawer with it. Then slide the lid to the side to remove the lid.
Installing The Sides Dry-fit one of the side pieces into position. While it is in position, tape one of the long sides down. Using the tape as a hinge, flip the side “open”. Lay down some super glue. Flip the side back into position and tape the other long side. Apply pressure or place a weight on it until the glue dries. Repeat this for the other side. As you do this, it is important that you use only the minimum amount of glue. You don’t want glue oozing out where it could compromise the exterior finish, or oozing in where it can glue the internal mechanism together.
Why Is This Puzzle Hard? I have had many people try to open this box. Super smart engineer types take about 1 to 2 hours to open it. Mere mortals have taken several days of off and on tinkering before they are successful. The combination of the coordinated moving of the ends and proper orientation is something that most people just don’t think of when working a puzzle. The magnets add another level of difficulty. More than just keeping the box closed, they make the coordinated movement of the ends difficult.
Origins This puzzle box is based on one created by Hiroshi Iwahara. Google him to see his amazing work. His original box was made out of various woods, with intricate inlays. The craftsmanship was awe inspiring. This 3-D printed box is a challenging and rewarding print, but it doesn’t hold a candle to the original.
Introduction These instructions contain many spoilers. It is required in order to build the box. If you’re not going to build one, I suggest that you stop reading now. This is a challenging print. It requires that your printer be properly tuned for the parts to fit and move well. It also requires printing at a high resolution (thin layer height). Make sure you and your printer are up to the challenge before proceeding. All of the exterior faces of the box are printed against the build platform. For this reason, I highly recommend using a glass platform and hair spray. Using Blue Tape, Kapton Tape, or other methods will still work, but the results won’t be as nice. Use of rafts is highly discouraged.
All of the STL files are arranged for printing in a Makerbot Replicator 2. The parts have been rotated so dimensional errors in the printer are less problematic. Also, the more critical surfaces are on the left side, to make best use of the Filament Cooling Fan. If you are using a different printer, keep these things in mind as you arrange the parts on the build platform. No supports are needed, or wanted. Supports could cause rough surfaces that interfere with the moving parts. This print was designed to not require supports. This print requires 0.1 mm layers. Part of this is because of the surface finish that’s needed for parts to move smoothly, but also there are overhangs that will print well with no support at 0.1 mm layers. If you print this with 0.2 mm layers, those overhangs will not be smooth and the overall fit and finish of this print will greatly suffer.
Supplies In addition to the filament, you will need:
Super Glue (I used Loctite Gel Control). Three 15mm x 3mm stainless steel rods. Four 1/4” diameter x 1/16” thick Neodymium Magnets (http://amzn.com/B0012AUU84).
Tools
A straight needle file (http://amzn.com/B000NPUKYS). Needle Nose Pliers A Dremel tool or equivalent, with cut-off disks. Calipers or Micrometer
Bar
Print the bar at 0.1 mm layers, 100% infill, and 1 total shell.
This part needs to be strong and dense. Strong but not dense, or dense but not strong, will result in a box that doesn’t operate as smoothly as it should. Ideally this part would be milled out of aluminum, but since we’re compromising by using plastic go ahead and splurge for the 100% infill.
Drawer
Print the drawer at 0.105 mm layers, 2 or 3 total shells, 20% infill, and 6-8 total solid top/bottom layers. It doesn’t have to be exactly 0.105 mm layers, but it can’t be 0.100 mm. The reason for this is simple: This part will rub against other parts printed with 0.100 mm layers. If this part is also printed with 0.100 mm layers then the layers of this part will perfectly line up with the layers of other parts—causing more friction than what we want. But if this part is printed with a layer thickness that is close, but not exactly, 0.100 mm then the ridges formed by the layers won’t perfectly line up and the parts will move more smoothly together. I printed this part at 0.105 mm layers and it worked well. Depending on the filament, you will want 2 or 3 total shells. The choice is purely aesthetic. With more opaque filament I found that 3 shells gave a better surface finish/color, while more translucent filaments were better with 2 shells.
The Other Printed Parts
All of the other parts (Ends, Sides, Main Body, Lid) should be printed with 0.1 mm layers, 2 or 3 total shells, 6-8 solid top/bottom layers, and 20% infill. You may choose to not print the sides. If you omit the sides, the box will be fully functional but the internal mechanism will be exposed for people to look at. Of course this is a huge spoiler, but it is a source of amusement.
Stainless Steel Rods This box needs three stainless steel rods, 15 mm long and 3 mm in diameter. 3mm diameter rods are commonly available. A search for “3mm stainless steel rod” on Amazon.com will bring up thousands of options. I recommend buying longer rods and cutting them to size with a Dremel tool. The actual length can be 14.5 mm to 15.5 mm. It is important to measure their length after cutting and trim them down more if required. Bevel one end of the rod with the Dremel tool, to make inserting them easier.
Filing After all of the parts have been printed, some will inevitably not fit smoothly and require filing. Test fit everything before inserting the rods or gluing anything. Everyone’s printers are different, and have different issues. In my experience, the biggest issue was with the ends fitting into the main body. Below is how I fit things together, but keep in mind that your experience will likely be different. When the end is inserted into the main body, the end should slide freely. It should, using only the force of gravity, slide all the way down in the groove. If it binds at any point then you will need to file things down to make it smooth. Test fit the end piece by placing it in the main body backwards, according to the picture below:
Slide the end up and down, making sure it moves smoothly. If it binds, file the appropriate faces with the needle file. Next, insert the end piece correctly, using the tongue and groove. If it does not move smoothly then there are several areas that will require filing. Start by filing the two highlighted faces in the picture below:
Next, file the end of the tongue, highlighted in this picture:
Hopefully, at this point everything will be moving nicely. If not, carefully file. Having a tight fit, but still smooth motion is ideal for this box. If you have any remaining hairy parts on your print, now is a good time to remove them. Pay particular attention to make sure that the bar moves freely in the main body.
Installing The Magnets Installing the magnets is not hard. Installing them correctly, with the poles facing the right way, is tricky. Start by installing one magnet into the lid. Put a small amount of super glue into the indentation, and press the magnet into place. Let the glue dry. Take a second magnet, and place it on the first magnet in the lid. Using a marker, place a dot on the face of the magnet. Remove the magnet, and do this again for a third magnet. Install these two magnets into the end pieces, with the dots pressed against the super glue. Let it dry. Place the fourth magnet on one of the magnets in the end pieces. Draw a dot. Install this magnet in the remaining position in the lid, dot side against the glue. If you are printing more than one puzzle box, use the installed magnets from a previous box as your reference for building later boxes. This will assure that your lids are interchangeable, and will also make installation faster since you won’t have to wait for glue to dry.
Installing The Rods
Insert the drawer into the main body so that the hole for the rod is visible through the side window. Insert one of the ends into the main body. Insert the bar. And then insert the other end. Look through the windows and make sure that everything looks good. Remove the drawer. Carefully place a small drop of super glue into the hole for the rod. This is more difficult than it sounds. Use a very small drop. You don’t want glue oozing out once the rod is installed. You also want all the glue to be inside the hole, and not on the rim. When you re-install the drawer into the body you don’t want any glue to touch the walls of the main body. I found that using the Loctite Gel Control Super Glue was ideal for this, since it was easy to place a small amount and it didn’t run everywhere. Re-install the drawer. Slide the bar back and forth until you have a good view of the hole. Using a needle nose pliers, insert the rod into the hole, bevel end first. You might need a reasonable amount of force to do this, since the hole is intentionally tight. The rod should not stick up so much that it rubs against the side panel, once that piece is glued in place. Carefully inspect your work, making sure that super glue didn’t ooze out of the hole when the rod was pressed in. If it did, carefully clean it up using toothpicks or something similar. Don’t get excess glue on the rods or bar, since those surfaces need to slide smoothly together. Repeat this procedure with the two end pieces.
Opening The Box
Before installing the sides, it is important to know how to open the box. These instructions for opening assume that you can’t just look through the windows and see the mechanism at work. But if you are building the box, take advantage of that while going through these instructions. The original box by Iwahara had some laser engraving on the lid. There was an apple tree, with a falling apple, and the same formula that is on this box. The formula on the lid is 𝐹 = 𝐺
𝑀𝑚 , 𝑑2
which means Force
equals the Gravitational Constant times Mass1 times Mass2 divided by distance-squared. The only part of the formula that is important is G, or gravity. It is important to have the correct side of the box facing up, otherwise it won’t open. The correct orientation is with and end piece facing the ceiling, and the formula right-side up. Keep it in this orientation until the box is opened. Opening the box does not require much force. If you are forcing something then you are probably doing it wrong. Carefully slide one of the ends about 5 mm. Hold it in position and carefully move the other end about 5 mm. With both ends in that position, you should hear something if you gently shake the box up and down. Shaking isn’t important for opening the box, but it does tell you if you are in the correct position. Once in position, simultaneously slide both ends all the way. If successful, the lid should easily slide open, pulling the drawer with it. Then slide the lid to the side to remove the lid.
Installing The Sides Dry-fit one of the side pieces into position. While it is in position, tape one of the long sides down. Using the tape as a hinge, flip the side “open”. Lay down some super glue. Flip the side back into position and tape the other long side. Apply pressure or place a weight on it until the glue dries. Repeat this for the other side. As you do this, it is important that you use only the minimum amount of glue. You don’t want glue oozing out where it could compromise the exterior finish, or oozing in where it can glue the internal mechanism together.
Why Is This Puzzle Hard? I have had many people try to open this box. Super smart engineer types take about 1 to 2 hours to open it. Mere mortals have taken several days of off and on tinkering before they are successful. The combination of the coordinated moving of the ends and proper orientation is something that most people just don’t think of when working a puzzle. The magnets add another level of difficulty. More than just keeping the box closed, they make the coordinated movement of the ends difficult.
