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Steampunk Puzzle Box – part 3

The Steampunk Puzzle Box

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The Concept

Completed Steampunk Puzzle Box

In part 1 and part 2 of this project we saw the completion of the box up to the point where the Steampunk Puzzle Box was functioning, but nothing at that point locked the left side panel in place. Now we will look at how the puzzle/locking mechanism for this side was designed and created. The final puzzle for the Steampunk Puzzle Box is a set of gears on the front and back of the box that require rotations to specific positions in order to slide off the left side of the box which is the first step in opening . When all gears are turned to the right location, locking bolts will retract from the left side panel allowing it to be slid off, which is the first step for opening the box. This image shows the completed gear puzzle from the front of the box.

On the front side there are two gears interlocked, a small and a large. Each gear has five spikes and each spoke will be marked with a number. The small gear spokes will be marked with one number each: 16, 17, 18, 19 and 20, and the large gear spokes with 95, 96, 97, 98 and 99. Turning the gears so that the number reads 1898 across the front gears, as in the lower picture, will pull the front locking bolts completely from the side panel. The 1898 is hinted at by the date stamp on the bottom of the Steampunk Puzzle Box.

Letter Puzzle

The rear gears will be stamped with letters. The large gear will be stamped with F, G, H, I and J, one on each spoke and the small with A, B, C, D and E. Turning these gears so that the letters read FB across the rear gears will pull the rear locking bolts completely from the side panel. There is a clue to “FB” hinted at by the name on the side of the Steampunk Puzzle Box , Feder Bros, and the initials on top (FB). When both sets of gears are set to these positions the side panel can be slid off, and any other gear rotation will keep the panel from being removed.

These images are of the locking bolt positions in the locked and unlocked states. So let’s start with the process of designing this locking mechanism puzzle for the Steampunk Puzzle Box.

A Prototyping Corner

As usual, I have an idea as to how I want to construct this mechanism but not an intricate design. To avoid doing damage to the pieces already completed I decided to make a corner piece with similar dimensions to that of the inside of the the Steampunk Puzzle Box which allows me to do some trial and error testing without cutting holes in the completed (so far) puzzle box.

Side Piece

To make the test piece I am just recreating one corner rather than a complete mock up. The “bottom” is a 3/4 inch piece of oak, the “front” is a scrap piece the same thickness as the Steampunk Puzzle Box sides and the “side” is a piece of the 1/4 inch poplar I used for the inner box on the real puzzle box.

I drilled two 5/16 inch holes in the front at the right, spacing for two of the gears I’ll be using for this part of the puzzle. The back and front are identical in design so I will be making two of everything I design here. The gears are manufactured by Boston Gear. The small ones on each side are part number G149 with 120 teeth and the large are part number G150 with 144 teeth. When meshed together, the large gear needs to go through 5 complete rotations to bring both the large and small gears back to the same orientation.


Boston Gears

The front and back of the Steampunk Puzzle Box will have two each of the meshed gears attached to a locking bolt that extends into the left side of the box. When extended, the left side of the box will be locked into place. All four gears will need to be in a specific rotation in order to pull all four bolts that lock the side as seen in the picture above.

Gears and Shafts

The gears have 5/16th inch ID holes in their hubs for mounting onto shafts. To hold the gears to the shafts each gear hub is drilled and tapped to accept a 6-32 set screw.

The shaft for each gear extends through the front and back of the Steampunk Puzzle Box and these are cut from 5/16th inch brass rod. Here I have rough cut the shafts then faced one end of each in the lathe. The other ends are cut to approximate length using a cut off tool on the lathe, which makes them all the same length with square ends. The exact length they need to be will be determined during the design process.

Two of the gear/shaft combos are slid into the test corner for a trial fit.

Retaining Rings

I used a piece of 5/8th inch brass rod to fashion the retaining rings for the inside part of each gear shaft. These rings go around the shafts on the inside of the box not only to hold the shafts in, but also to act as supports for the cranks that will be added shortly. Two different lengths of ring are required: the ones farther away from the locking side are longer and those that are closer are shorter. By doing this, the cranks that move the locking bolts that are attached to the rings will be offset from one another.

Each retaining ring is also drilled and tapped.

When completed, I do a quick test mount of the long and short rings to the shafts and corner. You can see in this second picture how one ring is shorter than the other and how they also hold the gears and shafts in place.

Crank it Up

I make cranks out of 14 gauge by one inch wide brass strips. I want the radius of crank rotation to be 1/2 inch and the width to be a bit over the 5/16th inch of the shaft diameter..

The cranks are trimmed to the correct widths and lengths then two holes are drilled 1/2 inch off center. One hole is 5/16th inch for the shaft, the other is 1/8 inch for a connector piece.

In these pics you can see how the cranks will attach to the shafts and how the cranks are offset from one another.

Tapers Look Better

Cutting tapers into the cranks is done on the mill with all of the cranks stacked together so they will match after trimming. Small brass rod pieces through the holes help keep them all lined up while they are milled.

After inserting the cranks over the shafts and into the test corner I then mark where they need to be cut for the proper length. There are two different rod lengths for each set of two.

The shafts are cut to their final lengths. The bottom image is what they will look like when complete.

Solder Crank Shafts

I don’t want these cranks slipping on the shaft as the gear locations are critical to the locking mechanism. If they move in relation to the shafts, the numbers on the gears will no longer match where they need to be to unlock the side panel. So I do over kill and both place pins in the crank and into the retaining rings and solder all of the crank shaft pieces together.

Solder Them Together

I pre-tin the crank and retaining rings and then solder these to the shaft along with the pin.

I then cleaned off the excess solder with sand paper, a wire wheel and a small file.

I did a bit more polishing and the crank shafts are complete.

Crank Shafts Complete (almost)

With the soldering and cleanup complete, the crank shafts are close to completion.

The crank shafts will connect to rods that will ultimately slide the locking bolts in and out of the side panel. For this reason I need some way of holding these connecting rods in place while allowing them to swivel. I am using 3/16 inch OD brass tube that will be soldered into the connector holes along with some #4-40 brass screws. This will allow for a crank shaft with a 3/16th inch hole to swivel while being held in place by a #4-40 nut. First I need to drill the connector holes a bit larger so the tubes will slide into the cranks snugly.

Connectors for Connecting Rods

After I drill out the crank connector holes to size I cut small tubing pieces to size to be inserted into them.

The ends of the tubes are cleaned up on the lathe by holding them in place on a smaller diameter brass rod.

More Solder

Finally the tubes and screws are soldered to the cranks. I hold each in place while soldering with a #4-40 nut made of steel which prevents the nuts from being soldered to the tubes.

Completed crank shafts with connectors. The image on the left shows a brass plate with a 3/16th inch hole to slide over these connectors demonstrating how the connecting rods will be attached.

Bolt Hole Header

The connecting rods will act on lock bolts that slide in and out of the left side of the box locking and releasing it. I am going to mount a brass header piece to the left side of the box for these bolts to slide in and out of. In the top right image you see that I have added an extra piece to my test corner filling out a full depth for the side. This will allow attachment of the header to the side in the same way it will be done in the final box.

Mounting the Header

The header itself has four bolt holes where the 1/8 inch brass bolts will slide into, it also has two #6-32 threaded holes for mounting to the test corner.

Header attached to test corner

In this picture I have screwed the bolt header to the test corner, you can also see the four 1/8th inch holes where the locking bolts will slide into. I have inserted a length of 1/8th inch brass rod into one of the bolt holes. This rod will be used to create the four bolts.

The Locking Bolts

Each locking bolt is made from two pieces of brass rod. The bolts themselves will be made from 1/8 inch brass rod, and then will be soldered into short base pieces made from 1/4 inch brass. In this gallery I am rough cutting the 1/4 inch base pieces for each of the four bolts.

Using a lathe I first face the ends of each base getting them all to the same length with nice flat end surfaces, and then each base is drilled with 1/8th inch holes.

The Bolts are Cut and Shaped

The bolts are made from 1/8th inch brass rod, cut to length and then one end is rounded with a file. Rounding the end keeps them from snagging as they slide in and out of the bolt holes that will be drilled into the side piece.

Cutting slot into base

Before soldering to the bolts each base has a 1/8th inch slot cut into it for attaching connecting rods to the crank shafts.

Bolts to Bases

Each bolt is soldered into a base piece. When this was completed I again used the lathe to clean up the surfaces.

In this image you can see two of the bolts with slotted bases slid into the header on the test corner. You can see the bolts extending out of the side of the test corner where on the Steampunk Puzzle box they would lock the side panel in place.

Two Design Concepts

In my first design concept a connecting rod was to be attached to the crank shaft and then extend into the slot in the bolt. A hole drilled through the slot in the bolt base would hold the connecting rod to the end. The other end of the connecting rod would attach to the crank shaft and a nut would hold it in place there. When a gear was turned the bolt would then slide in and out of the locked and unlocked positions.

New Test Box

Now that I was getting closer to a final design for the gear puzzle I needed a test box that was closer in shape to the Steampunk Puzzle Box. This was made from some oak and poplar scrap pieces, and as you can see in the picture it will provide a more complete test bed for finishing my design.

Now that I have my new test box I need to drill holes for the bolt header made previously. I first drill for the mounting screws and then use the header to drill for the locking bolts.

Remounting Gears

With the header mounted the next step is to drill holes in both the front and the back for the four gears. I marked the spot for the first small gear on each side and drilled that hole then used both gears and a center punch to mark the location of the second larger gear. Looking at the test box you can see that I am writing all of the distances and hole sizes onto it. This makes the test box into kind of a three dimensional blue print and will be very helpful when all of this hardware is transferred to the Steampunk Puzzle Box.

After getting all the holes drilled, the gears with their crank shafts are mounted to the test box.

Connecting Rods

With my initial locations for the gears the cranks wound up too close to the header. I moved the small gears back an inch and retested. A longer connecting rod was added and this seems to work better. I then drilled second holes for the larger gears, also moving them an inch.

In the image on the right you can see how the connecting rods are held to the bolts with 1/16th inch pins. This completed my initial design concept, but when testing I noticed as I turned the gears with the connecting rods attached I was getting multiple locations where the locking bolts would be retracted enough to slide open the side. I want the locking mechanism to be pretty specific to the “1898” and “FB” positions so it’s time for a bit of redesign. This is why I used the test box since it allows me to make changes without damaging my other work.

Spring Bolts Instead

In this design change I decided to use a spring to hold the bolt into the locked position then a chain is attached to the bolt on one end and a shorter connecting rod to the other. A small locking ring allows the spring to push against the bolt holding it in place. Now when the gear is turned, the crank again pulls the bolt out of the locked position with the advantage of the bolt staying extended or locked for a longer period of time for each rotation. With the old concept I was getting both bolts retracted at odd intervals during gear rotations. With this new concept both bolts are only fully retracted (unlocked) when both gears are in the correct position.

New Side Panel

The new spring bolt design will require a new bolt header to accommodate the springs and hold the bolts in place, and that means I will need different holes drilled into the side piece. Rather than wind up with a mess of confused holes in the side piece I just replaced it.

The new header is made from two 1/2 inch brass strips drilled for both mounting holes and holes for the locking bolts. There will be a space between the plates when mounted where the springs and small locking ring fit.

Mounting the Two Piece Header

I used one header plate as a template to drill bolt holes and mounting holes into the new side panel that we added above then the mounting holes are counter sunk using a tapered bit.

New Locking Bolt Header

Here I have mounted the new header pieces and one of the bolts. You can see how it all works with the two brass plates mounted with screws and the bolt extending through the both of them. A spring and retaining ring hold the bolt pushed against the outer header plate extending the point through the side of the box.

In the new design I needed to lengthen the bolts in order for them to extend and retract properly. These images showing the measuring and replacing of the locking bolt ends.

Spacers and Nuts

Because of the spacing in the new header, standard #6-32 hex nuts on the screws would be crowded to close to the bolts so I made some round nuts from 1/4 inch brass rod. I milled one side flat so I could apply some torque to the nut more easily than if it was perfectly round.

All the Pieces Complete

Header plate with new round nuts holding it in place

At the top of this picture you can see the two round nuts threaded onto the first header plate holding it to the box wit the #6-32 screws. The center screw has a standard hex nut that I later replaced with another round nut. In the foreground are retaining rings with set screws that hold the springs in place on the bolts.

I made some brass bushings to act as spacers in order to get the distance between the two header plates correct. You can also see how the springs are held in place on the ends of the bolts with small retaining rings and set screws. The springs push against these rings which in turn hold the bolts in the extended position through the side of the box.

Shorter Connecting Rods

The new design still needs connecting rods just shorter ones. These are cut from 1/4 flat brass stock. The larger hole end goes over the crank shaft and the smaller hole is for attaching the chain.

While the longer connecting rods that work with the larger gears seem to work fine, the shorter ones for the small gears are too close to the locking bolts to work properly. They jam against the bottom of the box when turning the small gear sooo… I have to move the holes for the crank shaft – again.

Move Those Gears – Again

I was having some difficulty getting the holes drilled just right into the wood for the crank shafts so before I drilled the new set of holes I made a steel jig that allows me to drill the holes just right every time. This will be very important when I transfer all this to the Steampunk Puzzle Box as I will really only get one shot to do it cleanly.

Ready to Move

After drilling the new holes and reassembling, everything seems to be working pretty well. Now it is time to transfer all this hardware to the Steampunk Puzzle Box.

Hardware Transfer

The first hole for the shafts on each side is drilled without the jig. To get it right I first drill an 1/8 inch pilot hole and then drill the 5/16th inch hole for the first shaft.

Drilling with the Jig

Using the jig went pretty well and the holes lined up very well, but one down side was that the tape pulled the varnish off the surface of the wood. I guess this is good as it cleans the surface better for applying a fresh coat of varnish. The second side was drilled the same way as the first.

Gears Remounted

All the gears and crank shafts transferred over pretty well. Next up – the bolts and header need to be moved.

Moving the Header

The header pieces were removed from the test box then the mounting holes were measured and drilled into the Steampunk Puzzle Box. The header pieces were then attached outside of the box to serve as a guide when drilling the bolt holes. This helps keep these holes perpendicular to the surface.

When completed there are four bolt holes, one for each gear, and three header mounting holes. Each of the latter are counter sunk so the screw heads will be flush with the surface.

Odds and Ends

In the spring locking bolt concept, a chain connects the connecting rod to the end of the locking bolt. The chain I used is from an antique clock that normally used to hang the weights that drive the clock. In order to connect the ends of the chain to their proper locations I made tiny rings cut from a coil spring which act like small key chain rings and slip through the chain links connecting the rod holes and the bolt pins.

Bolt Finishing

At this point I solder the 1/16th inch pins through the ends of the locking bolt slot area. These are soldered with a chain ring in place for each pin which is easier than trying to thread them through later.

Bolts with chain attachment rings

The locking bolts are now ready for the complete assembly of the Steampunk Puzzle Box.

Locking the Side Panel

The locking bolts extend into the side panel to hold it in place or locked. The holes for the bolts need to be drilled into the side panel to allow this. To get the holes in the side to line up with those in the header I slide the side panel into place on the box then I use a center punch through the bolt holes in the header to mark the proper hole locations. I then slide the side off and use a larger punch to mark the hole locations more deeply.

I don’t want the bolt holes to be visible from the outside after drilling so I remove the outer cover before drilling the holes in the inner side plate.

Locking Mechanism Complete

The whole locking mechanism is now reassembled and the fit into the bolt holes of the side panel are tested.

I do a bit of finish work here before moving on. The wood surfaces are all re-varnished after I strip of the old varnish with tape. The copper strips are also cleaned up and a coat of car wax is applied to them.

Shaft Set Screw Lock

Each gear needs to fit onto the crank shaft in a specific location and stay there, otherwise the gear could slip on the shaft and mess up the proper settings for opening the Steampunk Puzzle box. To prevent slippage each crank shaft is marked and drilled with a hole in the side that the gear set screw will rest in.

Marking the Gears and Shafts

Each gear/crankshaft combination is unique so the front gears and shafts are each marked with an “F” and the rear ones with an “R”.

Gear Stamping Jig

It is now time to stamp numbers into the front set of gears and letters into the rear set. I use 1/8 inch letter and number metal stamps for imprinting the gear spokes. In order to make all these number and letter stamps line up cleanly I am making a stamping jig from the 2×2 oak piece above. They are first drilled so that the hubs of the gears can rest flush with the wood surface when inserted into the holes.

Striker Plates

The stamping jig is set up so that the hubs of the gears rest inside the wood block but the spokes that will be stamped need more than just wood for support so I made some steel plugs that will be used as striker plates beneath the gear spokes. This is why there are two gear hub holes in the block because the large and small gears wind up having different locations for this striker plate. In this set of photos the striker plate for the large gear is installed in the jig.

In a similar fashion the second striker plate for the small gears is installed. In the image on the right I am holding one of the number stamps over the small gear where the numbers or letters will be stamped into the bronze gear.

Stamping Numbers

I used some pine to make guide blocks for stamping. They not only keep the stamps lined up over the correct spot but also keep them vertical during the stamping process. I used this large aluminum block to support the jig and a 5/16ths inch bolt holds the guide block in position.

I then insert the stamp and strike it with a hammer. For the numbers the two holes in the guide block are offset so that the two digits of the numbers line up next to each other. The letters are only one digit and are easier to stamp. All in all there are six stamp locations, two for each number digit on the large gear, two for each number on the small, one for the large gear letters and finally one for the small gear letters.

I first stamp the numbers 16, 17,18, 19 and 20 on the spokes of the smaller gear.

Red for Contrast

Red paint is applied to each number and then the excess is wiped off giving the numbers a red hue for better contrast.

First number gear complete

After completing the stamping and painting of the first small gear, the other gears are completed in the same way.

Completed numbers

The large front gear is stamped with the numbers 95, 96, 97, 98 and 99. Once the numbers are done I reinstall the gears onto the Steampunk Puzzle Box.

Letters on the Back Side

Back gears lined up for opening

The letters are completed in the same way with F, G, H, I and J on the large gear and A, B, C, D and E on the small. The gears on the back are then reinstalled.

Soldering brass nuts to crank shafts

The brass nuts that hold the connecting rods to the crank shaft have until now just been threaded tight onto the screws, but I don’t want these falling off inside the box. If that were to happen it would be impossible to open the Steampunk Puzzle Box without some disassembly . To prevent the nuts from falling off, the brass nuts are soldered to the brass screws holding them in place permanently.

I sign and date the Steampunk Puzzle Box as I do with all of my art pieces.

I had to remove the faux hardware when I re-varnished the pieces, I almost forgot to put them back in place so I do that now and the Steampunk Puzzle Box is complete.

Solving the Puzzles

The first part of solving the puzzle is to line up the gears to “1898” on the front and “FB” on the back.

Then the left side of the box is slid off and the top slid back.

Opening the Right Side

As seen in part 2 of the Steampunk Puzzle Box, the next step is to remove the knurled screw with the red dot hint tag from inside the box and match it to the threaded hole found on the inner left side. After threading the screw into the hole, the release for the right side can now be pulled back.

Pulling back on the knurled screw reacts the drawer knob from inside the right side panel allowing the right side to be slid upwards revealing the hidden drawer. In order to slide the drawer open the knurled nut is removed from the left side.

And We’re Open

The drawer can now be slid out and the Steampunk Puzzle Box is opened and solved. To close the box the previous steps are reversed.

Closed Steampunk Puzzle Box
The Steampunk Puzzle box.

I had a lot of fun creating this puzzle box and I hope you enjoyed seeing how it was made or better yet I hope it inspires you to create something similar of your own. As with all of my pieces let me know if you are interested in purchasing this piece. Keep in mind that it is a unique hand crafted design made over many months with a couple hundred hours of work involved.

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