Just some basic changes to the master sketch upon further review it seems there are bigger issues most likely require deeper revision. It all stems from changing the motor diameter it changes center to center distances in the belts as well causes a whole slew of issues.
The physical butterfly module is fully assembled. While FTC Team 26000 used a different wheel layout, this design places one larger wheel in the center of the module. This configuration centers the 104mm mecanum wheel and uses the GT2 belt reduction to link it to the first stage, maintaining a balanced center of mass.Master Sketch CompletionThe master sketch for both the main chassis and the butterfly module is finished. Mapping all geometry in a single master sketch ensured that the 96.24269 mm center-to-center distance for the 20T and 28T pulleys aligns precisely with the packaging constraints of the 8:1 gear reduction stage. This layout locks in the axle positions and gear mesh clearances before manufacturing the final plates.Next Steps: Efficiency and AssemblyWith the core architecture defined, the focus shifts to two main areas:Mechanical Efficiency: Optimizing the module pivots and belt alignment to minimize friction losses from the 5000 RPM motor. This includes pocketing parts to remove unnecessary material weight.Connected Assembly: Finalizing the top-level assembly in CAD to verify clearances for the deployment mechanisms, electronics, and structural brackets across the full chassis.Oh also cool aside this should put me as # today in hackclub hours!
Butterfly Drivetrain DevelopmentThe butterfly drivetrain, or “switch-drive,” is a configuration that allows a robot to switch between two different types of locomotion. In my current build, I use this to alternate between high-traction movement, using 72mm hogback wheels, and omnidirectional maneuvering, using mecanum wheels.My design features a two-stage reduction system. The first stage uses an 8:1 gear reduction to power the hogback wheels directly. The second stage uses a GT2 belt system to further reduce the speed for the mecanum wheels. This ensures both wheel sets maintain consistent surface speeds despite their different diameters.Inspiration: FTC Team 26000My implementation of this system is heavily inspired by FTC team 26000. Their work on the butterfly drivetrain showcases a clean, efficient way to package two distinct movement systems within a compact chassis. I studied their design to understand how they optimized the mechanical linkages for deploying the secondary wheels. This helped me solve the challenge of integrating a 5000 RPM motor with the high torque required for a multi-wheel system.By applying these concepts to my own robot, I am building a versatile drivetrain that adapts to different match conditions while maintaining precise control over wheel speed and grip force.
I spent sum time stress testing the parametric model and goofing around with the chassis model to see if I can fit it in.
I followed the readme rules more seriously and came up with a new version of a readme along with a more specific section that explains the math and mechanics more in depth.
I just made a quick draft of my read me before I go sleep today side note im #11 hacktime bum in canada. I wanna be number one in da world before end of summer!
Just finished the parts list for my gearbox project! I spent a decent amount of time sourcing everything from Amazon and really tried to keep the budget under $100 total.
My recording ended early on accident again today 🥀. I still logged about 40 minutes of work though. I spent that time finishing up the casing and adjusting the main assembly. I also added heat set inserts so putting the physical parts together will be much easier.
I accidentally ended my recording early today lmao. It cuts off while I was right in the middle of working on a lightweight and thin footprint for the gearbox assembly. I was still able to get a lot done. I finished the new pinion gear and started setting up the parametric model. I also thinned out the three wave plates even further to save space. The whole design is getting much more compact. Also short breaks from cad where I looked into different bearing and hub types online.
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I spent an hour setting up a parametric design so I can easily change dimensions on the fly.
The main goal today was shrinking the overall footprint. I need the entire assembly to fit inside a 56mm parallel plate drivetrain. The wheel takes up 38mm and the two side plates are 6mm each. That leaves very little room to fit the gearbox internals and the outer cage.
I spent the session making all the gear layers and housing walls much thinner to squeeze into that remaining gap. Since the parts are getting so thin, standard printing might fail. I am now looking into SLA printing for these parts to make sure the fine details and tight tolerances actually hold up.
I worked really hard today and finally fixed the issues I was having with the metal rod pinion gear holder and the cams. Those parts were giving me a lot of trouble.With that out of the way, I built a full outer shell to enclose the gearbox. I also put together a complete assembly and made an exploded view to show exactly how all the pieces fit together. It is looking really good and is almost completely finished.I just need to add a little bit of polish to the final assembly. After that is done, my next goal is to work on a parametric version so I can easily change the gear ratios and tolerances without having to rebuild the whole file.
Currently on a bus to Toronto, fighting bad Wi-Fi and smelly passengers just to work on this! I managed to spend 30 minutes tweaking my settings and finally designing the casing for the gearbox. Progress is slow, but moving.
I’ve been fighting with my robot’s drivetrain for a few weeks, and to be honest, I’ve been losing the battle against traditional belt systems. In FTC, we have to deal with very tight space constraints, specifically fitting everything inside a 43mm U-channel. My goBILDA motors are fast at 5000 RPM, but turning that into 435 RPM at the wheel using belts is a headache. Either the gear ratio is too small, or the pulley is so big it hits the floor. Plus, belts tend to strip whenever the robot hits a wall. I wanted something better, so I started working on a 3-phase cycloidal drive. It’s a completely different way to move power. Why I’m using a 3-phase cycloidal drive , Traditional cycloidal drives are cool but fragile. They usually rely on small internal pins and bearings that are hard to line up. This “inside-out” 3-phase design is different because it uses an epicycloid curve to grab pins on the outside of the plates. This gets rid of those tiny, weak pinholes that break in 3D printed gearboxes. The other cool thing is that it uses three plates, each staggered 120 degrees apart. This keeps the plates supported and stops the mechanism from getting stuck in dead zones where it would otherwise lock up. It’s a smooth way to get a lot of torque in a small package. getting the CAD right hasn’t been easy. I’ve been testing different pin counts and eccentricity settings. I’m aiming for an 11-pin setup to get a 10:1 ratio. If you push the eccentricity too high, the gear profile loops over itself in the software, which means it won’t work in real life. Finding the right balance between high torque and making sure the part can actually be manufactured has been a big learning process.
