Unlimited Gear Ratio 3D Printed Planetary Gearbox

Added: 2026-05-12

[00:00:00]This is the most popular model I have ever designed in my life. And I think for two main reasons. It's easy to build and it works. In matter of fact, it works so well that this is downloaded thousands of times and have appeared from other YouTubers videos. But also, this planetary gearbox is not perfect. I had some small design flaws. Some of them I noticed and some from the feedback that you guys pointed out. Now improved planetary gearbox is stackable.

[00:00:28]This is also the reason why it has been so popular. Simply saying, you can print this gearbox with one stack and having 3:1 gear ratio or two stacks having 9:1 gear ratio or three stacks with 27 to1 gear ratio and so on. If you want, you can stack this gearbox to the moon. But before we can start building, first we have to print all the necessary parts.

[00:00:50]This time I'm going to print this stackable gearbox with resin by using my new Heygears Ultra Reflex 2 and their high quality engineering resins. To be exact, I will use two different type of resins. The housing will be printed with transparent paten resin and will be coated with their new gloss glaze. These make the transparent printed parts actually transparent. Paten is actually extremely tough resin, one of the toughest resins you can use for mechanical purposes. and the planet carriers and gears will be printed with friction resistant resin P AW10. I was considering also ultra dough resin. Both of them would work, but because I have printed and used this gearbox before, and thanks to your guys feedback, the friction resistance is more important in this case than the toughness. If you have watched my videos, then you know that I'm not the biggest fan of resin printing, but I'm more than happy to do it because the Hey Gear printing environment is just so good. They know their products and only thing you have to do is to select what printer and resin you are going to use. All the settings and other stuff is already figured out by Heyge Gears and you just have to start to print. I'm using their latest printer Ultra Reflex 2. There's also a pro version that is a little bit bigger than this one. It has some upgrades and new features compared to the previous models. Most noticeably the scraper. This mixes the resin before every print and make sure that the resin is evenly heated throughout the resin dunk. Also, they have improved the print speed and quality. User comfort is same as the other printers because this was already spoton. My first print with this printer were gears and spacers for the gears. After removing supports, washing and curing them. The result is well, you see by yourself. When I finish printing all the dings with PAW10, it's time to move to the transparent resin. And this one is interesting. Look, I told before the gearbox casing will be transparent when I finish the printing. First, I again wash and cure the parts, but at this moment, you cannot really see through them, and this is completely normal. But hey, Gears have now new product, gloss glaze, and this will make the transparent parts truly transparent.

[00:02:56]So, I took the brush and painted the outer and inner walls with gloss glaze.

[00:03:01]Be note that he recommend to spray the gloss glaze instead of brushing it. But I don't have other choice right now. So I have to use a brush.

[00:03:10]When the first step is done, we have to cure it. So it goes to the cure station and we will bake this with 60° for about 3 to 4 minutes. And then the result is here. This is clearly way more transparent than it was before. Because I used the brush instead of spray. The uneven brush marks distort the result a bit, but still it's way better than before. But now it's time to assemble all those things to one stackable planetary gearbox. It starts by press fitting 4 * 13 * 5 mm bearings to the planetary gears. Note, you can go around them if you don't have those bearings for some reason. You can print the gears without pairing slots or use the spacers as a friction bearings, but don't do this when you FTM print this gearbox.

[00:03:53]This wouldn't work. This is the moment when the extra friction resistant racing comes in handy. But because I have access to those bearings, I'm just going to use them. So, if this step got nicely done, I connected the gears to the planet carrier with M4* 20 mm bolts and lock nuts. It's important to use lock nuts, by the way.

[00:04:14]This should look like this. I repeated this more few times. Now, we start with stage one. Place the planet gears to the first stage housing. Then secure the stage two to the stage one with M4 * 40 mm bolts. It's important to use those holes where the bolt heads can fit in.

[00:04:32]Then again place the planet gears to the stage two and repeat till you have your desired amount of stages aka gear ratio.

[00:04:40]Like I already told I use three stages to finish this off. We need the end cap again. Three M4 bolts and the gearbox is completed almost. Currently, we don't have input. So, I decided to borrow this from the old version. This area didn't got redesigned, so it's completely fine to use this one.

[00:05:03]And I think we are all set. Let's see.

[00:05:06]Does it even work?

[00:05:11]Well, right now there is a problem. I didn't lubricate the gearbox because I just forgot. I do the gearbox apart and assembled again after I added some silicon oil. Now it works way better.

[00:05:44]Like we saw the gearbox works, but there were no load. So let's torture it a bit.

[00:05:59]Gearbox is mounted to the wood plate and it will turn 20 mm aluminum shaft which is connected to the gearbox output. When the gearbox moves, it will turn the rope that is connected to some amount of weight. Gearbox will be driven by 4S lipo battery and the speed controller.

[00:06:15]If the weight leaves the ground and gearbox won't break, then the test is passed. If not, then not. We start with 5 kg. Let's see will three stack gearbox can lift this up.

[00:06:33]This didn't look like a problem.

[00:06:35]Increasing weight to 8 kg.

[00:06:45]No difference. Next 10 kg.

[00:06:57]I had to give a little bit more power to the speed controller, but still not touching the limits here. Next, let's do a bigger jump. 18 kg.

[00:07:13]Okay, definitely harder. Still best, but we are getting close to the maximum load. Let's add another 10 kg, aka 28 kg in total.

[00:07:42]Yeah, this is too much. But still, it managed to lift weight from the ground, which is already pretty nice. But it was too much because look the smoke.

[00:07:52]Moving on to test two. Test is torque test. I connected one piece of wood to the gearbox output. You see the markings on the wood. Every line shows every 5 cm from the center of the shaft. I apply 5 kg to the first line and then move the weight farther away by 5 cm each time starting with 5 kg at 10 cm.

[00:08:19]Next 5 kg at 15 cm.

[00:08:26]5 kg at 20 cm.

[00:08:38]5 kg at 25 cm.

[00:08:45]5 kg at 30 cm.

[00:08:54]This was harder, but still it passed the test.

[00:08:57]Now 5 kg at 35 cm.

[00:09:01]This is on the edge of passing the test, but I think it's fair to say 35 cm is the limit here. But still, I tried 40 cm too. And yeah, this is clearly a failure. So for the torque test, the limit is 5 kg between 30 to 35 cm. Guys, don't forget this model is free to download. So if you need 3D printable gearbox, give this a shot. Also, big thanks for Heyge Gears for making this video possible. But for now, thank you for watching and see you guys next time.

[00:09:32]Bye.