Attitude Adjuster - Build Diary

scott · 14 April 2024 23:11

I have decided to pick up my build log from where I left off on the old FRA forum: Attitude Adjuster (Beetleweight).

I’ll do a brief catch-up about what I can remember, and go into more detail about more recent things.

Let’s start with the last events for v1 of Attitude Adjuster! This was my first bot, made by hand out of HDPE, mainly using a table saw and a mitre saw. Heavily inspired by Snappy and This Is Not A Drill, with an axe/hammer because of Beta!

Euros 2019

The axe worked a bit more reliably for this event, I switched from the DYS + 25mm spur gearboxes to DYS + Rotalink conversions for the arm, after chatting to people at BBB. The idea behind it is that the planetary gearboxes are more reliable than the spur gears since the force inside the gearbox is balanced, so the gearbox doesn’t flex so much. This was pretty successful, I used the rotalinks in the arm until 2023.

The event was fun, I once again fought Joe with Crabsolutely Clawful and had a great time with some whiteboards. However the robot itself was still a bit rubbish, I faced a Fingertech beater bar that made me realise that the wedge front was a bit too thin and unsuited to fighting verts.

BITB 2019

Enter my first set of forks! I made a front attachment with some janky, handmade 3mm titanium forks. They worked OK, they were all slightly different sizes which actually helped to get under people.

For the first BITB I was a competitor more than an EO. I did OK in the tournament, I replaced the Fingertech pulleys in the axe drive with 3D-printed PLA pulleys that exploded every match as I didn’t really know what I was doing. Luckily I had plenty of spares. I also tried magnets, but they didn’t really work for me.

The robot shone at the Gladiator. The battery was way too big, 1000mAh 3S for a simple 2WD brushed drive and weapon, so my strategy was to stay out of trouble, not use the weapon so it couldn’t explode and out-last everyone else. With a couple of minor scrapes, it won its first trophy!

Attitude Adjuster v1 had been a good experience to learn on. It was a simple bot that I made by hand with basic power tools. I had encountered many issues and had iterated on it as far as it could go, with 3 separate designs for weapon bulkheads. I had travelled with it across the UK and made friends at events.

It had several major issues though:

It didn’t do any damage (not that I was expecting it to - it was deliberately not too scary)
The weight distribution was bad because the wheels were too far back, and in particular it had no traction when the arm was extended
The robot was too big so there was a lot of wasted weight
The armour was too thin, in particular, the front ti wedge
It was all handmade, so it was all a bit janky, I didn’t have too many spares and I was a bit too scared of it being written off as I’d spent a lot of time on it

I also wanted to retire it on a high and redesign it from the ground up.

I had planned to skip BBB UWE in Feb 2020 to go to some events later in the year (including September 2020 Norwalk) with a new design in mind. However, then the pandemic happened… This is as far as I got with my late 2019/early 2020 CAD before giving the robots a break for a year.

So that was the end of the line for this version of Attitude Adjuster! It still lives on my robot shelf, as a reminder of how far I’ve come.

scott · 1 July 2024 23:02

Attitude Adjuster v2

The pandemic happened, so I gave the robots a break for a bit. However, in 2021 I heard rumours of an event at Rapture Gaming Festival, which gave me something to aim for. In addition, I had been watching NHRL so I knew I wanted to do that at some point, especially since I have family around 3-4 hours away.

I decided to redesign the bot from the ground up, re-using little from the previous version. I made some design choices for the new version of Attitude Adjuster:

Replace the axe with a hammersaw - the axe was fun but I wanted knock-out power. I had seen Sawblaze have success with their hammersaw, so I decided to replicate it
Fix the weight distribution issues when the arm is extended by going to belt-driven 4WD
Use silicon hose wheels (like Bourbon) to give more grip than the foam wheels, with pololu hubs in the drive wheels
Go for Hardox forks as the primary configuration instead of the titanium wedge
Go back to full brushless for speed and power, using rotalink conversions instead of the brushed 25mm motors.

I decided to keep the same rotalink weapon motor and arm belt geometry, as I’d finally worked out the right number of teeth and distance between motor and arm. One major difference is that I now had a printer that could print nylon, so I could make the pulleys out of Taulman Alloy 910. I kept the HTD 3M pulleys and belts, and again modelled some custom pulleys with an unusual number of teeth for optimal belt tension, 15:43.

This is an early prototype, with some parts from the first AA and a 3d printed chassis and arm. It inspired the 4wd geometry but wasn’t used in the end. This chassis is a bit longer and wider than the final design but is about the same height.

I went in on a group Charles Day order to get my first waterjet cut Hardox parts - some disks and some forks. I went for a simple symmetrical design for my first spinner, as I didn’t want to complicate things. I designed two lengths of forks, as I discovered accidentally that if the forks were different lengths then it gives you two chances to get under your opponent. Fun fact - the short forks from this order were donated to Jevan at BBB Brawl 2024. I also had some forks that were designed to keep drums at bay.

I also designed a sportsman config, with a kinked aluminium axe arm and pointy hardox head. I donated one of those to David Harrison to use on Axe Wobba, and subsequently gave him the CAD.

I wanted to make two copies of the robot as I planned to take it to NHRL, so I decided to have the chassis CNC cut by Nat from Team SC, who did a great job. Using CNC meant that I wasn’t limited to 45 degree angles. It also meant I could make the robot black, which in my eyes is a bit cooler than white.

Here are the chassis and arm parts the day they arrived:

I assembled it into a pretendo-bot, with the hardox parts and some aluminium U-section as a fork mount.

The final chassis was put together with nutstrip. I used tee-nuts to mount the rear shoulder bolt axles and the armour mounts, with M4 bolts everywhere.

Wiring-wise - I used Afro 12A and 30A ESCs, as I had some lying around, and reused the battery from the first attitude adjuster. This started my tradition of not leaving enough space for the battery in my designs.

I decided to also make a 2mm titanium wedge for horizontals, with hinged nylon mounts. I still use this wedge for horizontals, it’s pretty sturdy. I cut it with a hacksaw and a Dremel, and bent it myself using a blowtorch and a vice. The bend in particular helps deflect spinners.

For the spinner motor I went for an Emax RS2205S with more belts, which Tweedy used in Toxin. They are powerful, but most importantly small and light.

These are the two copies of the bot, ready to go the night before Rapture. There were a few late nights to get to this point. I had a few weight issues with the hammersaw config, so the wheel guards had to drop to 3mm HDPE, and I had to make a last-minute change to use titanium bolts for the arm axle. But we were ready to make the 10-hour drive to Rapture!