"Marblevator Air" is the latest in my "Marblevator Series" of marble machines.
Many fans of the Marblevators Series have sent me links to videos of marble machines that are truly quite amazing. A couple of the videos included designs incorporating "drums", where the marble bounces off a drum surface and into a catch bin. Some of the Marblevator fans went even further and challenged me to design a 3D printed Marblevator that included drums and, well, I was hesitant. However, when my wife and I recently visited the "Paul Boyer Museum of Animated Carvings" (http://www.kansastravel.org/boyergallery.htm), I finally became convinced that I should except the challenge.
Mr. Boyer has created some absolutely stunning automata, one of which is an almost unbelievable marble machine incorporating 6 drum heads! We thoroughly enjoyed our visit to the museum, and highly recommend taking the slight detour north of I-70 in Kansas to visit this small yet wonderful museum displaying his extraordinary craftsmanship.
If you wish to experiment with different drum head diameters (the included drum head is 50mm) and drum surface thicknesses (the included drum head is .4mm), I have included the file "Marblevator Air Drumhead v0.f3d" which is an Autodesk Fusion 360 export of the drum head design.
A few notes about my experience designing, assembling and testing Marblevator Air. A marble machine incorporating drums is challenging to align, operate and maintain; one this small, printed in PLA, is even more challenging. This marble machine works best on a smooth, solid, level surface, such as granite or marble. I found that granite and marble suppliers were happy to give me scrap pieces at no cost (especially after I showed them the prototype Marblevator Air video), and small squares of either are available for purchase online. Completing a Marblevator Air requires a few non-3D printed items as described in the next step, and the 3D printed parts can be a challenge to print (the drum head surface is only .4mm thick and requires a .1mm first layer thickness). Assembly is fairly easy (installing the motor into the tower can be tricky), but alignment requires time and a lot of patience.
As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make mistakes in plenty.
Designed using Autodesk Fusion 360, sliced using Cura 2.6.2, and printed in PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.
Step 1: Purchase, Print and Prepare the Parts.
Marblevator Air requires a small gear motor ("DC 6V 30RPM 3mm Shaft Mini Metal Gearwheel Gear Motor GA12-N20"), a variable power supply (1.5 to 6VDC), at least 10 8mm ball bearings (see "Alignment and Test") and wire.
I printed all parts on an Ultimaker 2+ Extended and an Ultimaker 3 Extended at .1mm vertical resolution. I've attached a PDF containing the name, count, infill, brim, raft and support settings for each of the parts. Note that the drum heads are printed with an initial thickness of .1mm (as opposed to the default setting of .26mm). Prior to assembly, test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely sure that all build plate "ooze" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.
This model uses M8 by1 threaded assembly and may require a M8 by 1 tap to clean the threaded holes.
Step 2: Assemble the Tower.
Start the tower assembly by soldering a 6" length of red wire to the positive ("+") motor terminal, and a 6" length of black wire to the negative ("-") motor terminal.
Press "Auger.stl" onto the motor shaft. This is the auger assembly.
Slide the auger assembly into "Tower.stl", wires first. "Fish" the wires out the side slot in "Tower.stl", then carefully position the motor and press it into the motor slot in "Tower.stl". Attach the power supply to the wires, and check to make sure the auger rotates easily in the tower.
Carefully align the slot in "Entry.stl" with tower upper "key", then slide "Entry.stl" all the way down the tower to the lower key and fully seat it on the ledge.
Carefully align the slot in "Exit.stl" with the tower upper key, then press it fully into position.
This is the tower assembly.
Step 3: Assemble the Drums.
Carefully position one "Drum Base.stl" into one "Drum Head.stl", then secure it in place using two "Knob.stl".
Repeat this process for the remaining two drums.
Step 4: Final Assembly.
Place each of three drum assemblies into each of the three drum positions on "Base.stl" and secure each in place with one "Knob.stl".
Place the tower assembly into the center hole of "Base.stl", align the funnel in "Entry.stl" exactly between two of the drum assembles, then secure the tower assembly in place with the final "Knob.stl".
Step 5: Alignment and Test.
To align and operate Marblevator Air, place it on a solid, level surface in a location that it will reside.
Begin the alignment procedure by placing a ball bearing at the start of the exit track, let it roll down the track and drop to the first drum surface below. If it strikes the center of the drum surface, great! But more than likely it will land off center which requires careful rotation of the tower assembly to align the exit track so the ball bearing does strike the center of the drum surface. Once correctly aligned, tighten the tower assembly knob to securely hold the tower assembly in position.
Next, using the rotate and pitch adjustments of the first drum, continue rolling a ball bearing down the exit track allowing it to strike the surface of the first drum, then aim the first drum until the ball bearing strikes the center of the second drum surface. Once aligned, securely tighten the three knobs to maintain orientation.
Next, using the rotate and pitch adjustments of the second drum, continue rolling the ball bearing down the exit track allowing it to strike the surface of the first drum, then the surface of the second drum. Aim the second drum until the ball bearing strikes the center of the third drum surface. Once aligned, securely tighten the three knobs to maintain orientation.
Finally, using the rotate and pitch adjustments of the third drum, continue rolling the ball bearing down the exit track allowing it to strike the first drum, the second drum, and the third drum. Aim the third drum until the ball bearing strikes the center entrance funnel in "Entry.stl". Once aligned, securely tighten the three knobs to maintain orientation.
Apply power to the motor then one by one, add the 10 ball bearings to the entry funnel (the mass of the ball bearings provides the energy required to push a marble into the auger). Watch the ball bearings as they round the circuit and make any final minute adjustments as necessary. While my Marblevator Airs have operated for hours without dropping a ball bearing, it does happen. To increase reliability, if you have or have access to an accurate electronic scale, purchase 20 or more ball bearings and weigh them in order find 10 with the closest matching weights.
Congratulations, you're finished!
Hope you enjoy it!