First beetleweight robot

[DaveB]

Hello there,
This is our first post on the site so wanted to say hello. Have been following some of the threads here with interest and have picked up lots of great information. After going to see an extreme robots show my son and I decided it would be fun to have a go at building our own robot and so have designed and built a beetleweight as a project together. We've signed up for the battle in the 'burgh event in a few weeks time and are really looking forward to trying it out! We've done our best to abide by the necessary rules including a removable link fuse and light but I thought it would be worth posting a couple of pictures here and asking some of you kind folks if you would be kind enough to have a look and see if you can spot anything obvious that we might have missed or might cause us problems passing a tech check, given that we are completely green behind the ears. It would be disappointing to make the trip only to find out we can't take part for any reason. As you can probably tell, it was a bit of a struggle to get it down to 1.5kg! We can run it with a lifting blade on a 2s lipo or with some jaws which are a bit lighter on a 3s lipo. Not expecting great things for a first time out but at least hoping to get off the starting blocks! I'm a bit concerned about the link. We went for a removable fuse to save weight and a first it was a very tight fit but is loosening with use. Would it be allowable to put a velcro strap over it, still removable by hand? Incidentally we live in the north east. My son is 10 and I wish I still was! Many thanks indeed,

[Retroman]

As far as I know, The fuse being the link is acceptable (I do this with my ants and have designed it into my feather) so long as removal renders the robot dead you should be fine, and the rules stipulate that it must be removeable by hand and without tools, there are many using things to hold them in like straps and things, nothing says you can't. I have a brilliant bayonet fitting that I plan on using if I can make it fit.

Although for the fuse, is that a fuse holder? I use a pair of insulated female spade connectors as I find they tend to stay tight for longer, maybe a thought for the next build.

2S lipo might leave you a tad sluggish, but you should be fine, if anything I prefer a bit slower as my driving is a bit... pants...

Just make sure the battery is well protected, bit of foam to stop it rattling about as a minimum, and I think you should be good to go! If you have any serious concerns you could try to contact the Event Organiser directly and ask them, they can give you the definitive answer for a particular event.

Looks a decent first build and I wish you luck in the first event!

Finally, WELCOME!!!!!!!

[Albear]

Welcome! That looks like a really solid effort for a first go, you should be pleased!
I've seen fuses being used as links in smaller classes but someone with a bit more experience may be able to set me straight as to whether if its ok in a beetle.

[James Williams]

Hi David

Firstly, I don't see using velcro to hold the link in place being an issue, however if a tech checker hypothetically did take issue with it then you would be allowed to simply remove the velcro & carry on. One good thing about tech checkers is even if something does fail they will allow you to change it on the day so you still get to fight, plus there will be plenty of other roboteers around to help & give advice.

To be honest though, as long as your fuse is rated lower than the max current discharge for each battery setup I'm sure you'll be fine. It looks like a good bot, I honestly wouldn't have believed it was a 1st attempt.

[DaveB]

Thanks both. Its encouraging to know we're not too far off. The fuse holder is a medium sized one we picked up in Halfords. Its the first thing in line of the positive side after the battery which I think is right. Will definitely look at spade connectors next time round as we've quickly found out that every gram counts! I think a velcro strap to help keep it in will be a necessary precaution. I'm not sure how much punishment the front blade will take as its only 3mm aluminium. I'd looked at steel but couldn't figure out how on earth you could afford that within the weight limit. How do others manage it? I think perhaps our wheels are on the heavy side but I'm struggling to see where else we could shave off that much weight. Lack of experience I expect. I'm looking forward to seeing some others 'in the flesh' and picking up some tips! Thanks again.

[Retroman]

Yeah, the position of the the link is spot on there my dude, and to be honest we are talking shaving a few grams, it's probably more of a last ditch effort ha

Depending on which aluminium you've used it might surprise you with what it can take, 6061 t6 is good stuff for example, I've pulled varying qualities of alu from skips for my builds and it's still half decent.
For reference Firestorm in robot wars was made from 6mm.

Those wheels are pretty chunky, but they look perfect in the proportions, and I'd imagine will be pretty grippy when they've worn in a bit, and getting you're first build finished and within weight is an achievement in itself.

As for those with steel in their builds, if you want something enough you can build around it, the weight system will force you to compromise, you could have a steel blade but only 2 wheel drive for example, a 4wd pusher can be a very effective tool though.

[DaveB]

Thanks. Ordered the aluminium from metals4u but didn't know there were different grades. I imagine the proof of the pudding will be in the arena. We're now looking forward to seeing how it gets on against other robots. Its OK against a 1.5kg bag of flour (although my wife wasn't massively impressed to find us bashing that around the kitchen and with hindsight she probably had a point!). Cheers. Dave

[Ocracoke]

Welcome to the forum! Nice looking bot.

Fuses as links is OK, I've seen this in the Featherweight class. 3mm aluminium will stand up to most things in a BW arena, better than mine did :P

[McMullet]

Looks great! Congrats on your first build and hope it does well in Edinburgh.

I think it's been covered pretty well already, but I've also seen both fuses as links and velcro covers. The key thing for the link is that it has to be safely accessed and removed by hand, so you're fine on both counts. Just make sure the people running the event know where it is and how to get at it.

One thing I would say about the link... that cable tie doesn't look very secure! If it gets hit by something relatively minor the whole thing may come loose inside, which might then rattle the fuse loose. I guess that might also be a tech issue, since if losing the cable tie would allow the link and holder to fall inside the machine, it could then not be removed, i.e., it would no longer be a functional removable link. So might be an idea to either cover up the cable tie with a plate on the outside, or better have the fuse holder secured inside with something a bit more robust.

I think coming in only-just-overweight is a great achievement. You've obviously planned everything out carefully! I'd say the reason you're on the limit here is you've started with a high mass drive system, 4 motors and big chunky wheels. There's not much left once you've built a box around that.

[DaveB]

Thanks all, that's really helpful. We'll have a look again at the fuse holder attachment. A couple of screws and clamp sound like a better solution. Perhaps a bit keen to get finished! I think shaving off a bit more chopping board (Boyes finest, choice of white, blue, yellow or green and the thinnest we could find anywhere at £4 if anyone is interested! Do they have Boyes in other parts of the country or is it a northern thing?) in favour of some velcro would be a worth while trade off. As for the planning, it was more of an 'evolve as we went along' approach!

[RogueTwoRobots]

To echo what others have said, that is a great effort for a first build, well done. Using a piece of velcro to hold the link/fuse in place is fine; I always put a piece of duct tape over the link hole on my feather to keep it in place.

As for securing the link/fuse mount so it doesn't disappear into the robot, I'll be honest that is something that has never crossed my mind. I haven't done beetles for a few years but on both of mine, the link mount just sits slightly loose in a section of the robot, with the link hanging out slightly (and with a cable tie on) so that it can be easily grabbed.

Could always attach something to your fuse (a piece of string etc) so that even if the holder ends up further in the robot, the fuse can still be gotten to courtesy of the string.

Best of luck with it, and see you at Edinburgh!

[Ocracoke]

In my Beetleweight robots, I have been known to glue down my removable links to the body but in The Honey Badger, I clamped it down with a small cut of polycarbonate. The XT60 connector in that needs renewing, it is quite loose and quite old. Larger weight classes, I use a bolt between the two wires and a oversized washer to hold it in place.

[firefly1]

It looks like a great well thought out first build!! 3mm aluminum (grade dependendant) will hold up well in beetleweights but I wouldnt expect it to last more than an event, maybe two at a strech. Steel is heavy on beetles, a few bots use HARDOX steel wedges however titanium (grade5+) is a very common wedge material. HDPE wedges have seen some success in the beetle classes aswell. If the robot feels sluggish then, presuming those are 12v 1000rpm motors, running them on 3s or even 4s (with approproate escs) gives those motors a huge burst in power.
Wish you luck in scotland!!

[scott]

Looking forward to seeing it in Edinburgh! I second the cable-tie around the link, my link housing is a couple of cable ties so it makes it easy to find the link when it disappears inside the robot.

Off the top of my head, when you're in the pits you might need some sort of locking bar for the weapon to make sure that it physically can't move, and you should also have a cradle so that the wheels of the bot are off the ground.

My cradle isn't too fancy, just a couple of bits of wood screwed together. However I did hear there might be an award for best cradle at this event

[DaveB]

That's great. Thank you all for the advice and encouragement. Now you mention it I recall the need for a cradle and will get on the case although unlikely to win any prizes! Similarly, it should be easy enough to drill a locking bar through the lifting mechanism. We have a lipo bag for charging and will bring a few tools and some spare parts too.