[GBC] Momentum Launcher – Proof of Concept

[jijik111]

I have always been fascinated by GBC modules. Whenever I came across a video showing multiple modules connected together, I immediately clicked on it and found it completely mesmerizing to watch. What I enjoyed most were the modules that introduced truly original mechanical ways of moving the balls from point A to point B.

At first, even simple lifts felt fresh and exciting. Over time, however, it seemed to me that genuinely new mechanical transport principles became less common. On the other hand, the visual themes of modules have become more and more creative and original. This made me wonder whether it is still possible to come up with a completely new approach - something where the balls are not lifted by a marble pump, not moved by a brick-built wave, not pushed by a spiral, and so on.

Eventually, I came up with an idea that I would like to share with you.

Momentum Launcher – Proof of Concept

This module spins a ball to build up momentum and then releases it onto an inclined track, allowing it to travel upward into a basket. Almost every aspect of the module still needs refinement. The feeder is currently quite improvised, the ball tends to bounce while being accelerated, and the biggest challenge will be achieving reliable placement of the spinning ball onto the track.

Even so, the concept already shows that the idea is workable and could become a nice GBC module with further development.

Unfortunately, I have a limited number of parts and even less time, so progress toward a finished module is quite slow. The original idea has been in my head for several years, and only recently I managed to build at least a partial proof of concept. That is also why I decided to share it here even in this unfinished state - so that if the idea catches someone’s interest, they might continue exploring and developing this principle further.

 

Edited April 5 by jijik111
link fix

[aeh5040]

That's a very interesting and original concept, congratulations!

It already seems to work well, which is always the main challenge.

It looks as if the balls could go considerably further, which would look even cooler.

For my tastes it would be nice to see the feeding done purely mechanically, rather than programmatically.

Edited April 5 by aeh5040

[ord]

It's great to see new and innovative GBC modules like this. Nice work! 

I wonder what the different behaviour of different ball types might be...

 

[2GodBDGlory]

Very cool and unique indeed! 

I wonder if you can send the balls rolling up some curved or inclined track, for more drama?

[yqc]

I really like the design, it nearly looks like magic there. As said by @aeh5040qlready, I think a more mechanical was to let balls through would indeed be better, so the power supply would matter less. I'm thinking this could work by a rotatable beam (similar to a rail crossing) which would get repeatedly get pushed up by some circular rotating from any motor and then fall down by gravity again.

[jijik111]

Yes, you are all of course right that a purely mechanical solution would be better. At the moment, it is controlled by software mainly because this is still a prototype and I wanted to focus on the mechanics of launching the ball. Initially, I had it designed so that the rubber-tired wheels did not spin continuously but instead accelerated gradually once a ball landed on them. However, that approach seemed too complicated to redesign into a purely mechanical version, so I postponed it for the prototype stage. Later, I realized that the module would be too slow and that I needed to handle the balls faster. As a result, the wheels now spin continuously, so the only remaining issue is the feeder itself. Because of that, a purely mechanical solution might not actually be that complicated - similar mechanisms have already been built many times before.

2 hours ago, 2GodBDGlory said:

Very cool and unique indeed! 

I wonder if you can send the balls rolling up some curved or inclined track, for more drama?

I would also be interested to see whether it could handle a curved path. The ball is spun in one specific direction, so my intuition tells me that any turns could be problematic, but perhaps properly positioned guide rails could help direct it correctly. At the same time, it might need a slight amount of slip on the surface in order to turn, which is somewhat different from my original goal, where I wanted to maximize friction with the surface as much as possible.

In any case, the only way to find out is to try it.

[yqc]

47 minutes ago, jijik111 said:

I would also be interested to see whether it could handle a curved path. The ball is spun in one specific direction, so my intuition tells me that any turns could be problematic, but perhaps properly positioned guide rails could help direct it correctly. At the same time, it might need a slight amount of slip on the surface in order to turn, which is somewhat different from my original goal, where I wanted to maximize friction with the surface as much as possible.

In any case, the only way to find out is to try it.

Possibly a half pipe design could work as well, so the ball would run along the side of it and doesn't really need to change direction, but always runs (for itself) forwards.

Thinking of it, a full tube might work as well, do we have something for this in Lego? (I'm kinda inexperienced in GBC, so don't know exactly what's available)

[Divitis]

This is very interesting!

 

To add a complication, you could try adding rotational momentun on another axle as well, and that should have the ball run away on a curved path.

 

One possibility would be to accelerate the balls on a spinning disc, thus giving them momentum both forward and left.

 

Another, to add a tire on the feeder arm, probaby to the right of the ball, so as the feeder pushes the ball out, the lateral momentum is added.

 

Keep up the good work.

You make me want to continue working on my centrifugal GBC.

 

 

[aeh5040]

Did you consider making the surface that the ball initially falls onto something soft like rubber? That could both reduce the impact and perhaps increase the speed at which the ball fires off. (Not sure what to make it out of though, since most rubber parts are not flat.)

[yqc]

2 hours ago, aeh5040 said:

Not sure what to make it out of though, since most rubber parts are not flat.)

A pure Lego version could maybe be done by putting a few rubber bands around a 1x2 or 1x3 beam.

[Divitis]

To create a surface with more attrition I would lay a fabric element such as a sail over tiles. The challenge might be to keep it in tension.

[jijik111]

2 hours ago, aeh5040 said:

Did you consider making the surface that the ball initially falls onto something soft like rubber? That could both reduce the impact and perhaps increase the speed at which the ball fires off. (Not sure what to make it out of though, since most rubber parts are not flat.)

This was actually another crucial step to ensure the ball had the right amount of grip, so I decided to use a rubber surface. I spent quite a long time searching for different LEGO pieces that could be used to build it, because all parts had to come from official LEGO sets. I experimented with making a track from multiple tires, for example, but they didn’t fit together precisely enough, and the joints between the individual tires caused significant speed loss.

Later, I discovered that LEGO had historically produced several types of rubber bands. I ordered some of them, and they solved the problem perfectly. In the end, I believe I used LEGO part #70158. The rubber bands were able to stretch to the distance you can see here, which made them ideal for this solution.

[Zerobricks]

Very interesting and original idea. I also agree that the release mechanism would fit more the GBC theme if it was mechanical.

[jijik111]

11 hours ago, Divitis said:

This is very interesting!

 

To add a complication, you could try adding rotational momentun on another axle as well, and that should have the ball run away on a curved path.

 

One possibility would be to accelerate the balls on a spinning disc, thus giving them momentum both forward and left.

 

Another, to add a tire on the feeder arm, probaby to the right of the ball, so as the feeder pushes the ball out, the lateral momentum is added.

 

Keep up the good work.

You make me want to continue working on my centrifugal GBC.

 

 

Thanks for your response. I’m not sure I fully understand your point. Even if I spin the ball in one direction and the entire spinning mechanism in another direction, after releasing the ball all the rotations will combine into a single resulting rotation around one specific axis (formed by combining the original axes). So the released ball would still travel straight, just in a different direction.

What could work, however, is spinning the ball the way I currently do, but then launching it with a much greater force, not the way I do now, where I just push it down from the tires, but rather shooting it forward more like a billiard ball. If the surface were non-rubber, the ball would actually follow a curved path, because it would take some time for the spin to affect its motion, since the ball would initially slip quite a lot. I’m concerned, though, that the additional motion caused by the spin would be relatively small due to significant losses. Is this what you had in mind, or were you thinking of something else?

[Wapata]

Well, in perfect condition the ball touch a table by only one point. You can spin it as you want but if you push it to one direction: it will only go is this direction, no curve. Test it in your desk 

That why billard pool are carpets.

But just a single loop like Sonic the hedgehog level layout can be cool, and catapult the ball super high too ! 

 

Your idea is really cool ! 

[Divitis]

10 hours ago, jijik111 said:

Thanks for your response. I’m not sure I fully understand your point. Even if I spin the ball in one direction and the entire spinning mechanism in another direction, after releasing the ball all the rotations will combine into a single resulting rotation around one specific axis (formed by combining the original axes). So the released ball would still travel straight, just in a different direction.

What could work, however, is spinning the ball the way I currently do, but then launching it with a much greater force, not the way I do now, where I just push it down from the tires, but rather shooting it forward more like a billiard ball. If the surface were non-rubber, the ball would actually follow a curved path, because it would take some time for the spin to affect its motion, since the ball would initially slip quite a lot. I’m concerned, though, that the additional motion caused by the spin would be relatively small due to significant losses. Is this what you had in mind, or were you thinking of something else?

You're right, sorry I misspoke 

[aeh5040]

On 4/6/2026 at 12:06 PM, jijik111 said:

This was actually another crucial step to ensure the ball had the right amount of grip, so I decided to use a rubber surface. I spent quite a long time searching for different LEGO pieces that could be used to build it, because all parts had to come from official LEGO sets. I experimented with making a track from multiple tires, for example, but they didn’t fit together precisely enough, and the joints between the individual tires caused significant speed loss.

Later, I discovered that LEGO had historically produced several types of rubber bands. I ordered some of them, and they solved the problem perfectly. In the end, I believe I used LEGO part #70158. The rubber bands were able to stretch to the distance you can see here, which made them ideal for this solution.

Sorry, I had not noticed the rubber bands - I thought it was just a different colour piece.  My original comment was intended as a suggestion for further investigation or development, but in fact you have done what I was talking about already!

Edited April 10 by aeh5040

[Stereo]

I wonder if you could simplify it by having the pair of rubber tires slowly spinning, so the ball launches when the tire 'in front' of it drops low enough.  More similar to the traditional water-wheel GBCs.  That way it's also launching in the same direction that it exits the tire so you're not messing with the momentum by pushing it sideways.

 

Using stacks of round profile tires (eg. the 3x3 pulley tire) might also help feed balls in without them bouncing a bunch?  As they'd have a groove between tires to settle into.