The Chilli Daddy: A robot with a spicy rear 🔥

Hi all, quick write up on my latest beetle The Chilli Daddy.

The Chilli Daddy was born and took the shape he did for a few reasons:

  • First and foremost is my upcoming trip to NHRL, no way was I throwing my baby Luchador into that KE hot mess - with no pit and no OOTA, I knew I wanted something with a bit of KO potential to take (likely a spinner of some variation).

  • I wanted to make something vaguely viable/competitive but to have my own unique twist on things

  • If possible I wanted to build a robot that was as difficult as possible to hard counter via changing set ups.

  • Im generally a control bot driver, so while I wanted to ensure I had reasonable KO potential - I knew I also wanted something with a strong focus on solid drive and that could hold it’s own even if/when the weapon goes down.

After a bunch of iteration and abandoned ideas I finally settled trying to do a horizontal with a forked front and a butt spinner. The idea being to get under my opponent and then pivot/twist to hit them in awkward spots - not with a long thwacky tail like thagomiser, but more akin to Rotator vibes.

Here’s my initial concept sketch:

Most my robots start out like this at some point, a dodgy drawing on a random scrap of paper. Once in CAD though the realities of the actual scale (and weight) of things often see them change substantially - and in this process that sketch turned into:

This first version of The Chilli Daddy. veered away from the initial sketch in a couple of ways. It became a cantilever design rather than a mid-cutter - I realised with my idea of getting under people prior to hitting them - that this would ensure more consistent hitting ability.

And the weapon and drive became gear driven rather than belt driven - couple of reasons for this. Firstly the most common teething issue I see for spinners is belt related so this side steps that. Secondly not many people seem to do it here in the UK on weapons at least(which is always a great reason to try things imho). And finally I really like gears - look how many I have on this robot ! :stuck_out_tongue:

I have tons more I could say, but I need to get on with work. But will update further details as I go :smiley:


For my drive I’m running one 1806 diy rotalink conversion on each side. To the output I’m attaching a pololu mounting hub and bolting a printed gear to that.

Each wheel is a TPU printed hub with integrated double helical gears and cast PU tires running on oilite bushings on shoulder bolts.

Vers1. That ran at brawl had the shoulder bolts threading into inserts in the drive bulkheads.

Ver1.1 which I’m currently working on has these inserts relocated into the billet chassis, with longer shoulder bolts running through the drive bulkheads to reach them. This extra support of the axles combined with the inserts now being fully encapsulated - should result in much more robust drive

The Chilli Daddy uses a 6mm hardox weapon with an effective diameter of 165mm. Ive got a few options cut that range in mass from 220g to around 290g.

However to get into the US weight limit of 3lbs/1360g requires running the lightest of these, so the others will have to be reserved for UK outings post NHRL.

The weapon bolts through a printed double helical gear gear with six m4 bolts that then thread into an aluminum locking. It spins on the 8mm shoulder bolt shaft on two sets of skateboard bearings. The upper set sit snugly within the weapon it’s self while the lower set are recessed tightly into the lockring and gear.

I decided I didn’t want to risk simply running the shaft straight through the hdpe chassis. Concerned that the impacts might easily deform the soft HDPE on big hits. To reinforce it I’ve added aluminium top hat shaped inserts to each side. These then bolt together through the chassis with four m3 bolts. The m6/8mm shoulder bolt threads through the lower insert and finally a nut is added to lock the whole assembly.

The weapon is then powered by a 4108 which has a double helical bolted to the top that drives the whole thing with a small amount of reduction for a tip speed of around 190mph (theoretical).


It looked very promising at Feb Beetle Brawl! How did the gears hold up for the weapon from those fights?

Hey Thomas,

The gears I ran at brawl show no signs of wear after my two whiteboard fights, which was a big relief as that was certainly one of the bigger question marks going into this design. I didn’t experience any real weapon on weapon hits, so we’ll see how they fair with those kinda forces in the long run…

They’re fairly chunky - nearly 10mm thick with 2mm mod and double helical with a fairly extreme helix angle (which as I’m sure you know - puts more material across each tooth in the direction of load than a spur and spreads loads across multiple teeth). If I was starting again I’d probably consider going up further on the mod size for peace of mind - but not an easy thing to change at this point

They were printed in taulman bridge nylon for the motor gear and overture pa12 nylon for the weapon gear.

I do expect these to be fairly consumable however and do have spares.

Prior to brawl, I did attempt a test spin with some pla-st prototypes, which went comically badly resulting in very melty gears :joy:

So The Chilly Daddy. had another shakedown run at Chichester recently. It was a mixed bag for the bot.

On the one hand it really demonstrated that the principle of the build works and also proved the reliability of the weapon with it surviving multiple weapon on weapon hits against inferno.

However it did also highlight some issues I had not foreseen.

In three out of my five fights my diy brushless rotalinks failed in the same manner. The cans backed off the motors causing the pinions to disengage from the gearbox.

This isn’t a failure I’ve encountered before and I’m assuming it’s happening now due to the strong lateral forces of hitting with a horizontal.

After a bit of advice from the builder of Billy I decided to add some brass spacers between the pinions and the brushless motor to lock the whole assembly together.

I cut these from brass tube using a ghetto pseudo lathe :joy: matching the lengths to each motor

Because I made these doing a full shaft swap I didn’t want to pull the shaft or pinion for fear of introducing slip on either part so instead slitted them length ways and pushed them onto the shafts and crimped them down.

Having removed one that I made too short I was very reassured by how much of a ball ache getting them off is.

I’ve now done this to all of my motors (2 for each of the 2 copies of the bot and one spare).

Hopefully that should be the end of that particular failure. :crossed_fingers:
And this will now be standard practice for me on all future rotalinks conversions.


So since my last post The Chilli Daddy. has been to NHRL back in June and Rapture the following weekend.

Nhrl was a wild ride and The Chilli Daddy proved to be mega reliable, not once getting KOd and making it to the top 8 out of a field of 160! It did however loose the weapon in both its final two fights against Sea Dragon Roars (possibly my favourite fight I’ve ever had) and Jet lag.

At rapture TCD performed reasonably well, but lost its weapon again against gizmo.

It turns out that big weapon on weapon hits against powerful verts had enough upwards force to make the flange in my nylon weapon gears tear through!

So naturally this is where my attention has been focused recently and I’ve redesigned my weapon stack.

The nylon gear is no longer structural and instead just keys around a stack of 2d metal profiles. Aluminium spacers to hold the bearings and the middle retaining flange now being 3mm hardox.

Hopefully will be less inclined to fly off now :joy: