I’m a retired engineer and I built a wave motion machine as a Christmas present for my wife. What started out as a pretty cheap project (under$100 for materials) now has turned into a mission and I’m currently well over $200… So much for cheap! Eventually I’m going to get this accomplished!
Hopefully someone is familiar with a wave motion machine. Here’s a brief description. I made an acrylic box 24"L x 4"H x 2"W. Filled with 2/3 clear oil, 1/3 dyed blue water. By moving one end of the box up and down about an inch and a half slowly the water moves slowly like a wave. There’s a pivot point on the bottom middle. Towards one end underneath I put a 5 rpm, 12 VDC gear motor with a cam that slowly lifts and lowers the wave box.
My problem is the noise being generated by the motor. The three gear motors I’ve bought off Amazon so far generate noise about as much as a VERY loud electric razor or hair trimmer. And even worse, when the cam is lifting the wave box, the noise frequency goes lower, higher with reduced load going down. Also, when it gets over the crest, because of gear slop, there is noticable additional noise (and looks bad visually) when the gear tooth shifts from one face to the other (hopefully I described this adequately). I packed the gear box with grease which helped a little with the slop / shift. I also made an insulated enclosure over the motor that only reduces noise a little.
I also bought a DC servo motor with a speed controller but it has no torque and stalls at 5 rpm.
A stepper motor with micro stepping might work mechanically but certainly not practical for this project.
So anyhow, this thing is supposed to be relaxing. All this variable noise is really just irritating.
I know this topic isn’t really robotics but I came across this forum while searching for another motor. I figured one of you techno geeks like me might have some suggestions. Looking forward to some feedback. Thanks, Dan
Hello, I tried to upload a video and some pics but since I’m new to the forum I’m not allowed to post attachments. I’m hoping someone has experience with very low noise high torque motors. Maybe they just don’t exist and that’s why they stopped making these machines many years ago. This whole thing started with my wife seeing one on an HBO show called In Treatment. Of course they didn’t show how much noise it makes! LOL! She said “I love those things”! And I thought “I can make one of those”… Ughhhh! I did see one called Smithsonian wave motion machine on line but it looks like a cheesy toy.
Hello, My only plan is to try to reduce noise level so that this thing becomes what it’s supposed to be. An enjoyable relaxing thing to look at. The noise level kills that notion. I don’t know the db level. It sounds like a loud hair trimmer. Very whiny sounding which varies as the load changes every cycle. Maybe a larger more expensive gear motor is the answer? I’ve yet to find one that I’m confident will work. I even talked to a motor manufacturer and they were no help. There’s gotta be a way!!!
I originally used 10 rpm motor and decided I decided I’d prefer slower so I went to 6 rpm then 5 rpm. 6 rpm gave the best visual result. All three motors exhibited the same amount of unacceptable noise to run in a quiet environment (which is the whole purpose for this thing - relaxation). Notice that video has music playing all through it! Trust me, you gotta play the music pretty loud to drown out the noise. That’s what I’ve been doing. Maybe 15 rpm is quieter? I’m not convinced it’s that much quieter if at all. In any case, I appreciate your feedback. Now let’s solve the problem. It’s gotta be doable!
Yeah, there’s tons of these out there being sold by various companies probably all made on the same production line in the same factory in China. Bringsmart just happens to be what I bought on Amazon. Guarantee it’s the same motor as Robotshop
If you want complete silence, use NITINOL wire springs, attached at each end of the unit.
Positive voltages expand the spring,
Negative or 0 voltages contract the spring.
One side is expanding its spring, the other side is contracting its spring.
Then they flip their duty cycle.
Like your legs do when sitting on a teeter-totter in a playground. One persons legs are contracting the other persons legs are expanded. You already have the center pivot point.
To expand and contract them slowly, use a voltage signal that ramps up and down slowly. The more power they receive, the faster they respond. So to control that you could have a pot dials regulating the voltage, and one that control something along the lines of a 555 IC timer circuit that issues pulses to the springs to expand them then a longer delay for retractions. This way you can very the speed of the entire up and down motion of the box.
Something flexible like a silicone sleeve or a rubber CV joint sleeve over the Nitinol assemblies to protect them and for visual appeal.
But the main point would be this ---- There would be no sounds what so ever except that of the fluids within the case striking the sides. Which is in a sense waves reaching the shoreline.
BTW, very familiar with the commercial versions of these, and yes, even those will hum and vibrate because they are copying the original design and it was motor based back then. Now days, we have Nitinol. Goggle searches will give you places and prices where to get the springs. It is better to buy them pre configured as springs, then to attempts to form the spring from a straight piece of Nitinol. Its a memory alloy so you form the spring and it will uncurl back to being straight when power is applied. So obtain them pre formed so they return back to coiled springs, less the power. Apply power they they will expand. That would be the type to obtain. When the machine is shut down, the two springs will come to resist each other as they cool down and the box should just about self-level.
