Nelly the Ellybot Build Diary

By Sarah Malyan

“Hammers are terrible and no one should build them.” – Al Kindle, repeatedly.

Truer words were never spoken!! It is by no means the hardest weapon type to get to grips with, even for Noobs. But I’d be lying if I said this build process hadn’t come with a healthy amount of sailor language and several existential crises.

It’s not exactly like I chose an easy design aesthetic either!
An elephant. A bloody bonking elephant.  
As a noob to Battlebots I could have made it easier on myself and designed something a little less silly… But then again, we probably wouldn’t have been accepted, and I’m not one to let a little existential crisis or two get in the way of artistic robotic glory!

So… How to design a bonking elephant heavyweight for Battlebots. I’d like to take this opportunity to point out that heavyweights are also stupid. Our total build cost – including purchases and expenses made at filming – came in at just over £4k. This is poor-man’s money in terms of Battlebots, but a huge amount of money to a newbie team on a very tight budget. Experienced builders will inevitably read this diary and question many of our decisions. The most likely answer to most of these is that we didn’t have the budget for better and had to get creative!

I have laughable CAD’ing skills and have never used it for any of my previous bots, with the exception of a small wedge. Other team members are pretty good at CAD though, so this job – with a lot of frustrating input from me – falls to them. They deserve sympathy for this because I am not an easy boss, and artistic robotic glory requires..umm…dedication? (Madness)

They describes the CAD’ing process as “Hardox box that we attached things to.” Due to the size of the weapon, the ‘box’ had to be designed around that, which was an additional challenge. We had already purchased the LEM motor for the hammer prior to CAD’ing – owing to finding an absolute bargain on eBay – and said LEM was rather large…

Mounting the wedge took a significant amount of thought because we wanted to have it shock-mounted all over. We settled on hinged rails of wubs attached to thick hard-points that go through the front plate of the bot and attach to the base plate, hoping to provide the strength we wanted. On the sides we used bent pieces of Hardox to mount the wubs.

Finished Nelly the Ellybot CAD

After more all-nighters than we would like to admit to, we had an elephant looking bonk-machine and all the innards fit. We hoped. Time to start ordering parts and building the thing…

We hit a very frustrating hurdle at this point because two of the team were made redundant and a third followed soon after. We started a Go Fund Me campaign and this helped out loads and got things going again, but it looked pretty bleak at one point. Once the Go Fund Me money came in, we ordered SO many parts at lightning speed – all of the Hardox for the base and the hammer head, all the aluminium for the weapon and bulkheads, all the plastic for the heads, all of the electronics, all the- OH MY GOD THE BILL. So much stuff!! It all turned up on time, thankfully. But we were definitely clenched for a while.

Once the abundance of ‘stuff’ had arrived, we started off laser cutting the Hardox via our sponsor ASG, who also welded the base and the wedges for us. It took three days to get it all finished. While we were waiting for the aluminium in the weapon to be cut, we made a start on the drive system, and painting the parts we could.

Nelly is driven by two Ampflow E30-400G motors on Colson wheels. To control the drive we used Ragebridge 2s, and FRSKY receivers to go with our FRKY transmitters. The drive system mercifully presented no hurdles and was up and running in no time. With less than two weeks to go, this was something of a relief..

Nottingham University kindly allowed us the use of their waterjet, and we had the aluminium for the weapon arm and bulkheads cut there. When it arrived we began building the weapon. First we spent a fantastic amount of time swearing as we grinded out all the tapers. Assembling it wasn’t too difficult but we did have a massive six hour argument with her chain, and several smaller arguments with bushings. We won……… Eventually.

The Great Chain Argument:

The trouble with having a massive chain, is needing a massive chain-breaker to break it with! We tried several different shops and couldn’t find one big enough, and didn’t have time to order one in, so we had to improvise. This came in the form of using our hydraulic wire crimper to pop out the links…Except it wasn’t big enough to pop the link out in one go, so we had to use the crimper to push a few millimetres out, then grind of the protruding link with a dremel.  Repeat over and over until eventually the links were out. This was infuriating to do once. I feel there is little need for me to describe the vocabulary used when we discovered we’d popped out the wrong link and had to do it again on another one. Huff. Due to bad designing we also had to put a half-link in, so we ended up doing this process three times.
Time cost: Six hours
Emotional status: ANGERY!

Once eventually assembled, we wired it up. The system was pretty simple and our handy hydraulic crimper made this a fairly easy job. Regardless, firing it for the first time is always a somewhat nerve-wracking experience. The hammer is powered by a LEM 200, controlled by an ALBRIGHT SW202 contactor. We chose a contactor because it was easier and cheaper than an ESC. But it does increase the demand of the discharge on the batteries, so that was something to watch out for. The controller for the Contactor was a custom piece by Rory Mangles. (Monsoon) The battery bank operating it was 8.8Ah total capacity at 12S, comprised of 4.4Ah 4S Nanotech batteries. From the motor to the output we had an overall ratio of 8:1 which was achieved with two chain-stages and one gear stage. The gears were waterjet cut from 20mm Hardox. Clutch was a Comintech DF1.70. We have regrets over this clutch, but more on that later!

Prior to installing the weapon system

So what happened when we fired it for the first time? IT WORKED! WOOHOO! Our early tests were halted by some good old British rain, and with only a couple of days until shipping, this was a big source of anxiety. But it eventually let up and we had a couple of successful weapon tests. This was one of the biggest moments of relief for us now that both the drive and weapon were working. We had a few bits left to do, but the hardest part was done. Finally, we painted her up – which was no easy job either – and then packed her up in the crate for her trip to the US! It was looking like she was well within weight too – Phew!

Shove it all in for a pre-head weight-check

Due to the delays in weapon testing, we didn’t have time to make the heads before we left. On arrival in the US, we cut out the plastic for the heads and used two heat guns to bend the HDPE panels into their rounded shapes. (Too large for an oven..) Once the heads were made, we painted them and fitted our humongous 3D printed googly eyes into them.

Eye see you!

The eyes came from our other sponsor 3D Print Direct UK and were made from SLS Carbon Fibre Nylon. At 180mm diameter, they’re definitely the biggest googly eyes that Battlebots has ever seen.

If anyone subsequently breaks this record, know that I will make every effort to claim it back!

With the heads and eyes fitted, Nelly was ready to rock (bonk?) and we come onto the biggest source of anxiety of the whole thing; tech check. I expected it to be a somewhat overwhelming experience for a team of Noobs anyway, but when you’re in the presence of so many other fantastic robots and builders, it’s absolutely terrifying. We were pitted close to the likes of Bite Force and Tombstone along with many other experienced builders. Literally everyone, to us, looked like they had their sh** together a lot more than we did. By no means did anyone intentionally make us feel small, but I felt shorter than usual with my derpy purple bonker next to such awesome machines.

My anxiety over tech-check was neither the fault of the tech-check crew either. They knew we were new and were patient and explanatory. Our nerves were probably a little frustrating to them, but they never showed it. With all the fantastic machines around me, I was just praying that our little (large) elephant did the thing. It didn’t help that our drive and weapon check drew a crowd, either. For all my bravado, I’ll happily admit I was punched in the face by nerves (as well as jetlag) at tech-check. Kudos to my team for keeping me grounded!

And after all that anxiety…. She passed!! I drove her around the little test arena and we gave that test-tyre a god bonking!

Mid-Bonk. Photo credit: JCRB Photography
Photo Credit: JCRB Photography

I noticed a few impressed raised eyebrows in the crowd and felt a burst of pride for our bot and the team. I can’t begin to describe the relief of passing tech-check. Honestly after this point, I didn’t care if we won or lost, as long as the bot worked and we put on a good show doing it. The bot worked at least, and to find out if we put on a good show or not, you’ll have to watch Battlebots on Discovery!!

I will add further updates as-and-when we can while the season airs!

In the mean time, presenting Nelly the Ellybot!!


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