How to Make a Planetary Gear Menorah

First off, I'll acknowledge that this is technically a "hanukkiah", however, I figured that due to the common misconception of associating a menorah with Hanukkah, more people would understand what the project was about so I decided to go with that name instead. With that out of the way, this is one of my favorite creations and I'm very excited to share it. I have not seen any hanukkiah that has any moving parts like this one, so I believe that is the first of its kind.

I won't go too in depth in to Jewish tradition (after all, this is an engineering tutorial) so here's the wikipedia page on Hanukkah if you wish to learn more: https://en.wikipedia.org/wiki/Hanukkah Instead of a traditional hanukkiah, where you light each of the candles with a shamash (often the center candle), my hanukkiah uses gears to rotate the individual candles around the shamash. The shamash can than tilt down to light each of the candles. Admittedly, I am not the most involved with Jewish customs, so please let me know if there is some cool spiritual significance that this hanukkiah adds where others don't or if it is somehow offensive (hopefully not!)

As for the usability, despite being made out of plastic and basically being a fire holder, I have not run into trouble with the plastic melting. The candles are held by 3/8" T-nuts with a bolt beneath them, and those seem to contain the molten wax well enough that the plastic remains unharmed. The only problem I've had is occasionally the shamash will drip over the plastic when its tilted, but the wax has never had any issues when coming off. Also if you can't get the wax out of the T-Nuts, you can always just unscrew them and clean them out from the other side.

Tools:

• Phillips screw driver
• Wrenches or a pliers
  • 14 mm (for M8) (I recommend 2, or 1 and a pair of pliers)
  • 10 mm (for M6)
• Screw Tap
  • M3
  • 6-32
• 3D Printer

Materials:

• 3D printed parts
  
  • 8x - Planets (one for each candle)
  • 1x - Everything else
  • Note: The carrier is the largest file to be printed and is approximately 204mm across.
• Screws
  • 4x - M3 x 16mm Counter-sunk screw
  • 3x - M3 x 8mm Screw
  • 1x - M3 x 16mm Screw
  • 24x - 6-32 x 3/8" Screw
  • 3x - 6-32 x 1/4" Screw
• Bolts
  • 8x - M8 x 30mm
  • 1x - M6 x 50mm
  • 1x - M6 x 40mm
  • 1x - M6 x 30mm
  • 1x - M6 x 22.5mm or M6 x 20mm
    • Note: a 22.5mm bolt is ideal, however I don't think they are commonly made, so I used a 20mm which works fine too.
• Nuts
  • 1x - M6 Nut
  • 4x - M6 Lock nut
  • 8x - M8 Nut
  • 8x - M8 Lock nut
• Washers
  • 2x - M3
  • 2x - M6
  • 8x - M8
• 8x - 3/8" T-Nuts
  • Note: The reason for the 5/32" screws; the 3/8 fit my candles the best. Also, make sure they are the ones WITHOUT the spikes.
• Bearings
  • 8x - 608 - ID:8, OD:22, H:7 - Buy on Amazon (Pack of 8)
  • 5x - 686 - ID:6, OD:13, H:3.5 - (I can't seem to find the bearings I used, so you may rather want to use the attached stl files to print spacers.)
  • Note: I was going through a "bearing phase" when I made this. If you would rather not use the bearings I have also attached stl files for the bearings so you can 3D print spacers of equal size. It probably will not run as well without real bearings, but it will still run decently.
• 5/32" x ~6" All-Thread
  • Note: The all-thread is for the handle; length does not need to be exact and an M3 all-thread should work fine.

Assemble each of the 8 candle holding gears (planets) as shown in the picture. or with the following instructions:

• Place all of the 608 bearings into the carrier.
• Tap the 3 holes in each of the planets with a 6-32 tap.
• Place the M8 x 30mm bolt through the gear so that the cap is embedded in the gear and the shaft sticks out the other end.
• Screw and tighten a M8 nut onto the end of the M8 bolt.
• Put an M8 washer on the bolt.
• Place the assembly on the carrier.
• Fasten assembly with a M8 Nylon lock nut. Tighten it, but not too tight that there is resistance. I found a good tension to be when the planet cannot move significantly move up and down, but still has room to wobble back and forth a little bit.
• Attach the 3/8 T-Nut onto the top with 3 6-32 x 3/8" screws.
• Repeat for the remaining planets.

Follow the pictures to assemble the crank assembly.

For the gear with the two slots on either side of it (the left one in the first picture), follow the first two pictures and/or these instructions:

• Place an M6 x 20mm bolt through the bottom of the crank base and put an M6 lock nut followed by a 686 bearing on the other end.
• Put the gear bracket over the spur gear as shown in the second picture and then place both of them on top of the M6 bolt.
• Make sure the holes from the gear bracket line up with the holes on the crank base and tap both sides with an M3 tap.
• Screw an M3 x 8mm screw into both sides of the bracket to keep it in place.
• The purpose of having the bracket here instead of just a nut is because the carrier is so close that it could be unable to turn if a nut was sticking up right there, so I designed a bracket to hold the gear on.

For the gear next to the previous one (the right one in the first picture), follow the first picture and/or these instructions:

• Place an M6 x 30mm bolt through the bottom of the crank base and put an M6 lock nut followed by a 686 bearing on the other end.
• Put the 3d printed bevel-spur gear on top followed by another 686 bearing and M6 lock nut.
• Tighten the lock nut enough so that the gear cannot move across the bolt, but does not hinder its ability to spin freely.

For the crank shaft / bevel gear, see the 3rd picture and/or follow these instructions:

• Place a 686 bearing on either side of the vertical portion on the right side of the crank base.
• Align an M6 washer and the bevel gear in line with the bearings.
• Slide the M6 x 40mm bolt through the gear, washer and bushings. The reason for assembling it this way is because the bevel-spur gear bellow makes it challenging to place the bevel gear with the bolt through it.
• On the other side of the bolt, place an M6 washer and an M6 lock nut.
• Tighten the lock nut so the bevel gear cannot slide back and forth, but not so much that it hinders the ability to turn.

For the crank itself, see the 3rd picture and/or follow these instructions:

• Place an M6 x 50mm bolt through the side of the crank arm with the circular indentation.
• Place the crank handle on the bolt and cap it with an M6 lock nut.
• Tighten the lock nut enough so that the handle cannot move across the bolt, but does not hinder its ability to spin freely.
• Place an M6 nut in the other hexagonal hole of the arm.
• Place the crank arm on the M6 x 40mm bolt and tighten it tightly so that the arm is sandwiched between the M6 lock nut and M6 nut.

For the center candle / shamash holder see the 3rd picture and/or follow these instructions:

• Tap the holes on the top of the center candle holder with a 6-32 tap and the holes on the side of the center candle holder and tilt bracket with an M3 tap.
• Attach the 3/8 T-nut to the top of the center candle holder with the three 6-32 x 1/4" screws
• Attach top side hole of the center candle holder to the far hole on the left side of the crank base with an M3 x 16mm screw and an M3 washer in between the two printed parts. Make sure the triangle on the center candle holder faces the rest of the crank as shown in picture 3.
• Place an M3 washer onto the M3 x 8mm screw and push it through the thin track of the tilt bracket and tighten it into the lower hole of the center candle holder. Make sure the tilt bracket faces outwards. The screw needs to be a little bit loose so the tilt bracket can slide on it so be warned that you will probably have to re-tighten this screw often.

Follow the pictures and/or these instructions to finish the hanukkiah:

• Place the carrier on the sun base and then place the sun top on top. The planets will probably need to be moved around slightly so that the sun top will go down all the way.
• Slide the crank assembly into the side of the sun base. You will probably have to place the sun base over the center candle holder before sliding it in the rest of the way.
  • Tap the 4 screw holes with an M3 tap and then put the M3 x 16mm counter sunk screws into holes.
• The all thread will act as a handle for the center candle, so cut your all thread to a length of about 15 cm / 6 in to span from the tilt bracket to outside the hanukkiah.
• Tap the tilt handle and tighten it onto the end of the all thread.
• Put the all thread through the hole in the sun base and tighten it in the tilt bracket.

You may also want to add some rubber feet to the bottom so you can spin it without the whole thing sliding, however I did not.

That's all there is! Now you should have your very own planetary gear hanukkiah!

Using it is relatively simple:

Setup: First screw the candles into the T-Nuts. The wick of the candle in front of the shamash should be facing to the right (from the perspective of the crank) so that the wicks meet when the shamash leans over. Each gear rotates 225° in place for every 45° they go around the hanukkiah. To compensate for this, offset the wick of each candle 225° per gear so that the shamash has an easier time lighting each candle.

Lighting the candles: The video shows me lighting the candles (admittedly, not all that well.) To light the candles, pull the lever to the right of the crank to tilt the shamash. Leave the shamash tilted until the other candle lights. To avoid dripping wax on the plastic, tilt the shamash back up. The only time wax seems to drip on the plastic is when the shamash is tilted, so watch for drips while it is tilted. If it does drip, the wax usually can scrape off easily with no marks afterwards. Turn the crank clockwise (hanukkiahs are traditionally lit from right to left, but this one is a circle, so clockwise is close enough) until the next candle is in aligned and repeat.

Clean up: Usually I blow the candles out once they are close to the bottom so they are easier to remove and don't get to close and melt the plastic. If the candles are to difficult to remove, or there is too much wax in the T-nuts to put another candle in, just unscrew the T-nut and push the wax out the other side.

Happy Hanukkah!