I made a tiny, squishy combat robot

When I last made a combat robot about 20 years ago, the thick cardboard and duct tape armour I used was borderline indestructible. Things have come on quite a long way, I see.

A suggestion from my side would be to actually make your build even more flexible by not having a single stiff PLA plate but rather have like 2 or 3 plates. They could give stiffness to the different components, but let the chassi as a whole be more resilient to crushing damage. If the rotation of your weapon causes too much flex by itself, you could stiffen it more by having a joint connecting the plates. Also it might be woth to replace the metal screws with plastic ones to save some weight.

Try to use one wheel in the center (like the ball that a computer mouse used to have) and in the case of an inversion - if the body is thin enough and the ball is protruding, it can still drive upside down

The biggest tip for printing TPU for combat robots is more walls. Infill you can set to like 2%, and then just bump up the walls as high as you can.

Cool build. My suggestions are rather than having the strengthening plate a solid piece it should have holes cut out where there's no board or anything to protect. It will keep the same strength but be lighter. Likewise skeletonised wheel covers could do the same. Looking forward to seeing the next version as this is a really restrictive category but that forces creativity.

This is funny, some drone frame builders, build a protective pod with TPU (as opposed to a top and bottom plate made of carbon fiber with standoffs in the middle). It is often heavier, but much more protective of your camera and other electronics inside. OpenRACER is an open source design that has a TPU thicker option, or a thinner PCTPE (nylon+TPE) blend. The squishy properties help it not to shatter in 90+mph hits. One tip we have is always bring multiple spare pods or covers for your robots to swap between rounds. For races we often bring spare pods, but also spare drones, i will usually take 5-6 for each race, more competitive racers bring 10+ drones. Take a look at week points and beefen all of those up as mentioned, and yes, motor protection for robots and drones is important, as nothing will keep you from taking off quicker, so beef that us as well. For some more rigid parts, we often get them cut out of carbon fiber. It may cost you a little in weight, but should also make it a bit stronger, im thinking 2.5-3mm for y our application.

So glad you're doing a video about the wonders of TPU, it's my favourite filament to design parts for due to its flexibility. Over the past couple of years I came up with designs to securely hold radio receivers & antennas on drones in ways nobody had thought of before which are very easy to print, those designs are now used by thousands of people. "Hoopin TPU Cable Tie" is another popular design of mine I created 8 months ago which is also very easy to print, it's very strong as demonstrated by holding up my 3D printer with a 100% scale print in the photos, and 150% scale print easily held 12kg weight.

Angus - What about running a 1mm steel wire embedded in the TPU for added strength around the perimeter of the chassis?

So some tips for making weight easier, carbon fiber top plate it adds the rigidity and is not heavy at all. you can probably get away with a 1mm thick one. ditch the heat set inserts, they weigh a ton you can use #4 plastice screws. the self cutting type. you can get really fancy with prusa slicer settings. like removing the top layers in the battery compartment, or changing wall line counts in areas you need more or less. also the more compact you make your bot the less it weighs. it looks like you could have reduced the length of pancake a good bit since you had a small diameter blade look at getting a blade made from 1mm grade 5 Ti its a lot lighter but very strong.

between the heavy weapon motor and the heavy electronics, the relatively thin connecting piece is always going to flex, no matter what you try. I'd design a certain amount of flex into the robot and give it an articulated top plate.

suggestion: paint/print it green and add googly eyes! the little guy has so much personality leaping around the arena that he DESERVES to be a cute little frog!

This seems like a great use for TPU. I recently did my first TPU print. What I was most surprised of is how hard it gets when you give it a few layers. I also was super surprised about how resistant it is to fatigue cracks. I've been using a print as a fidget toy. and even trying to get it to break, but it keeps holding its shape, with only the mildest deformation.

I literally said “holy f*****g s**t” when you said the weight limit was 150g. What an incredibly interesting weight class, I’m honestly astounded by the capabilities possible with such little allocation towards total weight.

You may want to try encasing everything inside a TPU case: print the bottom half, install the electronics, print the top half. This way you'll save weight on screws and inserts. Design your robot with disposability in mind, these tiny robots get so banged up in a weekend you'll end up printing another one anyway.

Builder here and I say tpu is God's gift to combat robots. I recommend a carbon fiber tpu sandwich for construction. Metal is only for weapons.

I make the Jolt! Kits for the 3lb weight class in the USA, but for that I use 7075 aluminum plates to give the needed stiffness to mount the spinny bits and TPU for the armor and squishy mounting to protect everything, so TPU can definitely work as both armor and a main structural component even at the larger insect weight classes

My thoughts include not using PLA as support for the weapon. Instead, let it flex, but to avoid cutting into itself add slight PLA or similar to the exact part that would bend for it to hit itself. Potentially is a rebar kind of fashion, with thin bars of PLA threaded inside the TPU to offer rigidity without adding much weight (Currently assuming PLA weighs more, otherwise printing sections in PLA (melted to connect to TPU) might serve even better). Or potentially even thread actual metal nails or mesh as rebar, if light enough. Instead of 1 wheel+1 weapon, use 2 weapons so it compensates for itself trying to spin like a reaction wheel. Then either have the weapons be the wheels, or add 1 wheel for "forwards/backwards" (with Yaw being set through modulating the weapons spin-ratio so one overpowers the other, turning the robot as desired as a reaction-wheel).

I would recommend plain Nylon instead of CF Nylon for that top part. The CF makes the part stiffer but also more brittle. Cool bot! Here in the US we have been using TPU for all sorts of things on combat bots for years now.

From personal experience with TPU combat robots, a few notes I have are to use plastites with undersized holes rather than heat-set inserts, use thin UHMW for top plate (I use 1/16” for a beetle), and print hot and slow to increase the strength of the TPU prints. Also, if you build a beetle or larger, you should reach out to NHRL and they might be able to sponsor you competing there

Mhh... Bunch of ideas that came to mind: 1. Single, steerable Drive Wheel in the Center ( biased towards the front but behind the Weapon ) with Skids on the back ( CG located between them ) - This should allow the single wheel to drag the Robot around in the direction you want while being protected deep inside the unit. 2. Avoid making the entire robot a rigid Unit like with your single Piece Top Plate - Consider making only the bare minimum necessary rigid ( like the portion immediately within the vicinity of the Weapon ) thus allowing for as much flex to happen if an impact occurs reducing the blow. Dunno... Just something that sparked my mind after your one wheel comment and the looks of all the broken parts 🤔