I have two wooden spinners that I'd like to turn in opposite directions and they need to be concentric, so they're on the same axis. The setup I have now is a 30 teeth bevel gear mounted in each spinner and it sits on the axis with a couple of bearings. Then the vertical axis has a 20 teeth bevel gear that is the input to the whole system with a motor at the bottom. Here's a picture:
This technically works but I'm looking to improve by:
a) reducing the distance between the spinners. Currently this is determined by the diameter of the bottom gear + the height of the teeth of each spinner's gear. It's around 30mm and I want it to be closer to 10mm (or as close as possible really).
b) make the whole thing as silent as possible. I want to put this on my desk at work and it's currently making enough noise to be annoying. Most of it is coming from the motor that resonates against the wood at the bottom. The rest is coming from the gears.
I looked into spiral bevel gears and it looks like they might improve the gear noise issue but I don't know if it solves a). The gears in the picture were 3d printed off a model I found on a gear supplier's website. I don't think I've seen ones that are narrower than 20mm regardless.
I also looked into planetary drive and that looks like it could solve a), but I'm not sure how it would apply here. This arrangement seems better also in the sense that I don't need the perpendicular axis that isn't very aesthetic to begin with.
You could use a mechanism like for the hands of a clock which uses two concentric shafts. In a clock the minute hand is on the inner shaft which protrudes a little from the outer shaft (to which the hour hand is fixed). That would allow the two disks to be very close together.
It might also give you more freedom in the choice of gears to reduce noise.
If you are prepared to spend a little money I suggest getting some small ball bearings to carry the shafts and reduce friction and thus reduce the power that needs to be transmitted by the gears.
In this arrangement there's a hollow outer shaft (pipe) and an inner smaller one, is that what you meant? Then the motor spins the smaller one which has gears on it that also extend to the outer shaft?
idank:
b) make the whole thing as silent as possible. I want to put this on my desk at work and it's currently making enough noise to be annoying. Most of it is coming from the motor that resonates against the wood at the bottom. The rest is coming from the gears.
Gears are inherently very noisy, move to a belt drive if you want less noise - you can cross a belt over
to switch direction (so its figure-8), if you use circular section belt. This is commonly done for
Wimshurst machines: