New roboteer looking to get started

Hello there! I'm looking to get started in the wonderful world of Robot Fighting!

Ever since I was a child, I watched Robot Wars with my grandmother and we both loved it, dating back to the first series with Jeremy Clarkson back in 1998.
Unfortunately my grandmother passed away just weeks before the BBCs revived show came back on air last year, and I was inspired to have a go. Unfortunately since then I've had health issues of my own, but now I'm ready to finally give it a proper go, and hopefully at age 27 I can still make my way into the fighting bot life. I know some people doing it have been in it for decades!

My personal experience with electronics is fairly slim, I've only ever worked on low voltage / low current things, no more than 16V and a couple of amps max (model trains mostly and the little circuitry within them), other than DIY modification to lights, changing a flourescent tube lighting to a circuit suitable for LED tubes instead and the basic replacing an old mains socket / plugs and building PCs. I've also played extensively with Arduino and little coding stuff there. I'm always eager to learn new stuff, which is handy because the only thing i have experience with outside of basic electronics is a hammer, nails, screwdrivers and a piece of wood - hardly winning anything there. So i'm not sure to what, if any degree, my past electrical knowledge / tinkerings will help? All I know is, electronics is my forté and everything I've really done with it has just come naturally and I learn that area of things a lot faster than most things I try! So that'll probably be my strong point in it all.

Something I do pickup on during Robot Wars and YouTube videos of battles is the sense of community between the roboteers, the TV shows try to work up intense rivalries between specific bots, but I'm almost certain its producer fabricated really. So hopefully I can find a place in the community and get some help, and give help back when I'm in a position to do so!

Is there anything the FRA offers, like some sort of basic 'qualification' or basic "this guy knows how to kill robots and not humans" safety stuff, something that I can use to later on show i'm serious, and not trying to waste anyones time? I'd love one day to be part of a team or builder for a heavyweight category bot, but I know that a lot smaller (probably featherweight?) is where I need to start by myself at least.

Pricing for such things is leaving me a little lightheaded, i've checked out things like Ranglebox and general stuff on eBay. Not sure how much I can do with my budget (around £250 to £750, but can go higher if I think i'm onto something with potential) - the low budget things I see on TV / YouTube usually rapidly end up being comedic relief rather than anything else (not that there is anything wrong with a bit of comedic relief, of course!)

I'd be very greatful for any help on the above notes, or ideal starting points - I've come across some featherweight 'kit' stuff, but i'm not sure if they're of any real use or if I should start by entirely doing it from scratch. Looking at every possible avenue to go down, its quite hard to know where the best place to start is!

(good grief, this post came out pretty long!)

If you're starting out with basic tools and a simple-ish featherweight design, £500 should easily get you a decent robot, that you could compete with. I know it can seem very overwhelming at first, but take a look at some of the many many 'newbie' posts over the past month or so (and even before) and you should be able to learn a lot. After you've done that, you'll be able to ask more pointed questions and get specific answers. As I've said to others, you're bound to waste quite a bit of money on your first robot, on parts that either don't fit or break before you've finished the machine. This is one of the reasons why people recommend starting with a featherweight, because £20 lost on a part is no big deal, but £200 really is for most of us.

As for qualifications, the best qualification you can have is a reliable machine that you've built from scratch, has been in a few fights and lived to tell the tale. Though, obviously experience can still be gained from 'going home in a binbag' as they say. If you can show that you've built a decent machine and clashed swords with some of the experienced roboteers here, that should be enough of a qualification for most people really.

Your electronics and programming experience could come in useful, though a lot of the electronics are somewhat plug-and-play. My featherweight uses an arduino to manage the limit switches on its modified linear actuator, and Danny B from Team Shadow Robotics used one for an automatic self-righter a while ago. So if you really want to put your electronics skills to the test, go for it (I suppose you could even build your own ESCs if you're good enough like Rory Mangles).

I don't know about the kits, I think they do work ok, but I'd invariably want to make my own machine from scratch rather than building a body and weapon on a pre-existing base. It's up to you, but I don't see many roboteers using them.

For the Budget and Tool question:

I've just finished my first Bot, a somewhat Gabriel-style thwackbot in the 6kg Raptor class (don't know if that is popular in the UK or just a german thing).
Would be really easy to make it bigger/sturdier and work as a Feather, internals could stay almost the same (just motors/gearing would need a change).

For the chassis i only used a Jigsaw, a cordless drill, a rasp (for wherever i didn't make the cuts good enough), a few nuts and bolts, a square tube of aluminium, a normal tube of ali with a wooden core and a steel plate, as well as some sheets of HDPE and some bike tire for the wheels. And duct tape. Cost... about maybe 150€? Got myself some spares and ordered some wrong stuff, so hard to estimate. could sure be done cheaper, but if you're building for a featherweight it could make for a rough guess.

Internals were a dual channel ESC from IBF (~120€), 2 Ranglebox Neptunes and fitting motors (72£. not really fitting to this bot due to it's huge wheels, but otherwise great stuff), LiPo should be choosen bigger than mine. Getting some good quality should be possible for around 50€ (a bit more if you want 4 motors and/or an active weapon, you'll need a bigger battery then). Plus some small parts like connectors, safety-LEDs etc you possibly got around anyway when you're into electronics leaves you at roughly 250€ for internals. Oh, and you'll need transmitter and receiver, but these are cheap on ebay if you wait for the right moment.

So if without already having any spares and such you could absolutely build a HDPE-based bot without active weapon (so a pusher, wedge, thwackbot, something like that) but with good internals for about 400€. Bit less in £.

Could go cheaper on the internals, but this is the easy-to-use-and-upgrade-version.
If i wouldn't have done so much wrong or have had to wait for parts to arrive (and if electronics wouldn't have been my big problem^^) i could have finished it within one week.


My first plan was a super complicated totally destructive featherweight vertical spinner. Too complicated for a first bot, and even more to finish in time for my first event. So i more or less made this one from what i already had as material for the feather, just to be there and learn from it. And i learned a lot. My bot was probably the only one getting stronger from fight to fight, because in the needed repairs (mostly putting wheels back on) i also upgraded a few parts. I got home not in a bin bag, but with a list of what could be made better so long i'll rebuild the chassis completely (this time using a buzzsaw and a drill press, upgrades, too!).
Hopefully, after the next 1-2 events i'll be happy with what i've made from that bot, and maybe give that vertical spinner feather another try. So yeah, don't overcomplicate it with your first bot... being there and having something driving gives you on one weekend more experience and inspiration than months of internet.
even as comic relief, my bot got stuck in the floor on turning twice, lost it's weapon and wheels (which had no grip anyway, making movements really difficult), and all in the first round. in the third round i at least punched a hole in the armor of a spinner (no real damage, but yeah, i did something!), and by the fourth and fifth round i wasn't the first to die. But it was something driving, it got potential, and i managed to carry all tools, spares and the bot in one backpack on the train. Can't get much simpler than that.

Ps: you gave us a long post, now take that!

Cheers for the replies so far! Glad to hear my budget is easily doable, I'm going to have to lookup motor stuff, as my only experience with them is the tiny diddy motors that model trains use, which won't be of any use here.

I'm thinking of trying to do a bot without any welding, as its not something i'm familiar with at all, and its a fairly expensive thing to get the stuff for. I live in a flat so i have no room for big tools, and my neighbours wouldn't be fond of the noise.
To overcome this, I was thinking of trying to build a no weld, nuts and bolts machine. I believe that Pulsar is one such machine. However i'm having trouble finding metal to do that with, i'm also a bit skeptic as to wether that'd put it overweight for intended 'featherweight' class, so i might end up using HDPE - this will also be a lot easier to work holes into for the nuts/bolts side of things I imagine. I looked up threaded bars too for easily joining things together, however Ranglebox has sold out of these, and i can't find another source of them?

Last thing I can think of for now. I note that a lot of machines appear to use LiPoly batteries. I personally have bad experience of LiPolys, in an imported smartphone the LiPoly battery failed in a rather mean manner, expanding in size, venting smoke and eventually breaking out into a short lived but intense fire. I'm not sure if the phone malfunctioned, overvolted or short circuited etc, but it does put me off them. Do roboteers use special stuff to ensure LiPolys are never overstressed? Should I avoid them until i'm more experienced?

A 'no weld' featherweight is more than doable. Whilst I am a newbie like you, I would hazard a guess that a fair few of the featherweights out there do not have any welding on them. My first bot has no welding on it and is primarily aluminium and HDPE construction. I have used barrel bolts to hold together the HDPE to HDPE joins, available cheaply at lots of places online. For the HDEP to aluminium, or the aluminium to aluminium joins I have used the square section bar with threaded holes in as you are planning. You don't have to source them if you don't want to, you can make your own out of some square section aluminium (again, available cheaply online at lots of places), a drill, a hacksaw, a vice and a tap.

As for batteries, I think the thing with Li-Po is to just be sensible with how you use them. For example, make sure you charge them in a Li-Po sack, in the robot make sure they are well protected and shock mounted if possible, also don't use them any more if you notice bulging or swelling on the pack and so. I think that Lithium Iron Phosphate batteries are used by some people as a less potentially volatile alternative but it's not something I have personally used. However I'm sure someone more knowledgeable then me on those can tell you more about them.

Good luck, and have fun with your build.

These are really good starting points - if you are looking for something easy to work with then I would totally recommend HDPE, held together with bolts and barrel nuts. I used this and 12mm HDPE for my robot and it held up super well to non-spinner combat - it's robust, but still easy to cut with a jigsaw, and cheap enough to replace if something breaks. I don't have any experience fighting spinners but I'm stepping it up to 15mm/20mm HDPE for those.
Just be aware that cutting HDPE can be pretty messy if you're cutting it inside. I think I will be finding little bits of HDPE swarf round my house forever now. :p

For motors I believe a lot of beginners use 12v Argos value drill motors - they're ideal since they are cheap, powerful enough and the gearbox they come with uses metal gears, so they are relatively robust. I used 4 of them running on a 4S LiPo and they made the robot surprisingly quick for something so cheap and easy to implement. Having said that Argos just released a newer model which is a little bit more expensive and needs to be hacked differently to make it appropriate for robot use. I haven't used these before, but there's a whole thread which talks about it here:

http://www.fightingrobots.co.uk/thre...ide-and-review

The key to LiPo's is getting a good battery and a cheap but high quality charger.

I build everything with a drill and a hacksaw and bolt it all together. They are basic and boring but good fun to fight.

Yeah I haven't had any LiPos explode on me yet, or even puff up. You're required to have a flameproof LiPo charge bag for competitions anyway, and as long as you get a decent balancer and charger to keep the cells in check, you should be fine. If they get punctured or overheated, that's when they can set on fire (a la Chompalot), but as long as you protect them well enough, that shouldn't happen.

And even on fire due puncture or overheating, that will happen in the arena, so rather safe for the people watching the great show.

Of course, the wallet isn't as happy with that.

Makes me wonder what my phone was doing to trigger a major failure in the LiPo, seeing as you guys seem to very rarely come across it in much more hard working environments!.


I'm intending on making the outcome of my first attempt legal for fights should the opportunity fall my way. I'm not entirely sure how HDPE will hold up against spinners, i've no idea how powerful spinners of featherweight design can be? Found a supplier local for HPDE and they stock from 1mm up to 30mm, can get a one large sheet and cut it down to size and probably have some left over so i can shape some spare parts - next decision would be how thick I want it to be. That itself might be a learning curve of getting the perfect thickness for defense without too much hassle on weight / slowing things down / awkwardness of tinkering with and quick repair if needed to be done in a hurry.
Although at the end of the day, even if it comes home in a bin bag, fun would have been had and things would have been learnt, so not that bad of an outcome really! Think that's the best way to look at that very possible outcome...


Side note, just got confirmation of some tickets for the Robot Wars next season filming in May. Looking forward to that!

It's common advice but before you build anything read thru the build threads and get to a couple of live events so you can talk it all thru first. You will learn a load.

Feather spinners can be... well... i don't think there is any material left nowadays that is strong and light enough to take a good hit from one of the really good spinners and still don't take serious damage.
So it mostly depends on the angle. If your armor is 90° to the spinner, or even having some pointy bits standing out, you'll possibly get shredded. If i remember right, there were feather spinners ripping through 8mm armox. And as soon as you want an active weapon, even 3.2mm of that stuff all around might be too heavy.

So your best bet is to not give them 90° to bite into, but make it angled, so they will more "scrape" on the armor than to "bite" into it. You might even deflect a blow (mostly from the horizontal ones) so the spinner itself will get bounced and possibly having his energy backfiring at him.
Now the really hard thing is... how do you make it all angled from all sides, with the possibility to get flipped? But that's something you have to find a solution, or more likely, live with something "the best you could do".
Could also be a good idea to shock-mount the armor, but really depending on the kind of armor and all.
basically, any metal-based armor tries to deflect hits without actually absorbing any energy, and "tries" to stay as one, flat surface. Once it is bend or ripped, it will stay so and be a perfect weak spot for any hits coming after that or even locade your drive or such.
HDPE is more like "oh, you took a part out of me? so? try again, i've got some left". parts can be chipped out, but they won't be bend out leaving something for the enemy to "hook into", and won't be bend in and press against your drive or stuff like that. It will stay in shape, but get chunks get cut out of it. And that most likely with every hit, where some metals might just take a scratch, if even that.

What actually is better in a feather... depends on where and how it is used, and what you can work with.



With HDPE, you got two options:
Making the chassis from Ali or stuff like that, just enough to put all the electronics etc. together, and then put HDPE on that as the armor.
Or if you'd want to go with all HDPE, i think 20mm for the armor and 10mm for internal structures should be enough. Maybe even less for internal stuff, depends on what and where.

But: Never try to drill and tap into HDPE. The bolts just get ripped out.
For me, i do the screwing depending on if i likely need to screw/unscrew here often.
If the screws are mostly once in, never out again (like internal walls to base plate, or internal walls to other internals) just wood screws. And not just a few.
But can't do these for Top to Armor and stuff like that you'll likely want to open and close a few times (or in case of the armor: might have to swap for new parts to repair). After a few times of screwing and unscrewing you'll just have a big hole to look through, and any screw gets ripped out easily. So either take barrel nuts as mentioned above for these parts, or try to melt other, big nuts in sideways (didn't try that, but could work), or if the bot is flat enough, you could do what i do: drive-in nuts.
If it is box-shaped in any way and not too high, they work really nice. Just screw the box together with only a few wood screws (just to hold everything in place). Take a drill (ideally a drill press or a straight, steady hand) and drill 5mm holes through top plate, any walls, and bottom plate in one go. now make the holes 6mm on the first cm on one plate, and sink in the bolts from the other side. Now you can hammer in the nuts through the 6mm holes, or, what worked better for me: take one longer bolt and a washer from the other side, and just drive those nuts in. they get straighter that way, saving you trouble later on.
Take out the wood screws from the side where you sinked in the holes and not put the nuts in. I'd leave the few next to the nuts, just so not the hole chassis falls apart once you remove the bolts to open the top plate.
Might want to step it up a bit on the bolt size, i just used M5 because i had those around.

Downsides i found so far for that way:
-swapping side armor is not that easy without a drill press or having the parts pre-made. the holes have to be on the same place in the same direction.
-if the nuts don't go in straight, instead of bolting into them you could just push them out, and will have to try again. gets annoying.
- since sinked in bolts get flatter than the nuts, it could be wise to make the bottom plate removable, not the top, so you don't get stuck on the floor with these nuts. it's just 1mm or such, but could be enough. But gets a bit confusing with wiring the motors etc., and could leave you drive in the wrong direction when you turn the bot around again ;)

In quiet some characteristics HDPE behaves like wood, so what's used to hold wood together or give wood the form you like, will likely also work for HDPE.

Anyway, it is definitely possible to make a working bot in a way you only need HDPE as material (maybe 10 and 20mm, if you have weight left more at least for side armor is better. if you stay with mostly rectangular and triangle shapes for the parts it is really easy to calculate the weight even without CAD or stuff like that. make an excel-sheet with all the surfaces of the parts added together in cm², once for the armor parts and once for internal stuff. now you can experiment and multiplicate those numbers with 0,5 to 3 or whatever. whatever you get from these numbers will be your weight in g. But don't forget screws, those are really heavy...)
Tools for this you'd only need some kind of saw (any saw will do, but some will better than others), a drill (preferably a drill press, too), maybe a few screwdrivers and stuff like that, something to put the electronics together. With some luck they're mostly plug and play, as well as some duct tape and zip tie, a knife and a hammer (you can always need those. The knife comes in handy, since you can even carve HDPE with it.) Possibly some hot glue.
You can even saw out round pieces of HDPE and screw bike tire in them as wheels.
So, with one spare sheet of HDPE in each thickness you use, you can make all the spares you might need (except for gearbox etc.) without too big machines to carry with you to an event. Big plus compared to guys who need a mill and wielding and whatever for their spare parts.

But, if you want to go anything wedge-like, you should consider make the top/bottom plate (partially) from some kind of metal. you'll just get a way sharper/sturdier edge with it. Hard to get under the enemy when you rammed the wall a few times with an edge from HDPE.

Quote:

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Originally Posted by Runsler

Feather spinners can be... well... i don't think there is any material left nowadays that is strong and light enough to take a good hit from one of the really good spinners and still don't take serious damage.
So it mostly depends on the angle. If your armor is 90° to the spinner, or even having some pointy bits standing out, you'll possibly get shredded. If i remember right, there were feather spinners ripping through 8mm armox. And as soon as you want an active weapon, even 3.2mm of that stuff all around might be too heavy.

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My original design had an elongated slanted edge around all sides of the machine which contained no electronics, just sacrificial HDPE and air behind it so there was room to be massively gashed by a spinner but still come off with theoretically no internal damage, and that's if the slanted angles didn't undo the spinners attack enough. this however may be too expensive (and large) with all the sacrificial HDPE that'd end up being... well sacrificed. Depends how often it came up against something devastating to HDPE. It does seem to be one of the cheaper materials though, and certainly one of the easiest/quickest to carve out replacements for.


I'm yet to decide what I want to do for weaponry. My original idea was to try adding a hunk of slanted HDPE to the front and get some powerful motors and try to make a simple ramming / pushing bot, however I don't think that's going to hold up to modern opponents and I'm going to have to splash the £££ on an active weapon...

As for screwholes getting weaker. Don't think I'll get that issue, as i'm planning on basically holes with bolts running through it, and everything held in place with nuts. Although I'm not sure how much i can do with just that, and i'm not sure how flimsy that sort of design would be when it came across a violent throwing into a wall. Only one way to find out for sure I guess. Trial and error!

Perun, our raptor, is milled out of a massive billet of HDPE. (doable with a router)
The lid is held on with bolts right trough that block.

wedge all around... now i'm thinking of a design many full body spinners have.
Sure good to deflect blows, and sacrificial HDPE is.. well... that stuff is, compared to anything else useable in that weight class really cheap. if you even shock mount the electronics, that will be one shell hard to open.
Only problem: what happens when you get upside down? you'll need to either stick the wheels out through the top (needing bigger wheels) to drive on your back if needed (but the wedge would be turned around then, too). Or get some self righting arm or such to pop up.
Well, not really need, but would sure be a good addition if something gets under you and turn you around, since as mentioned pure HDPE-wedges get blunt fast, so you don't have much hope to get under another pusher, flipper, lifter etc. Even many spinners stay low to the ground as defense against these.

Anyway, the way i see it the meta is like this for now:
big spinners, have massive energy stored and causing others to really think about their side armor.
heavy armored pushers to charge into the spinners before they spin up and push them into the pit or whatever.
flippers to get anybody who isn't low to the ground and get a self righting arm or can drive on both sides.
Hammers/Axes to remind everybody top armor is needed, too.
grabber, lifter etc. for everybody trying to have an active weapon, but maybe easier to build than these high powered ones.
Crusher... just the occasional few to remind people internal structure is needed, too.

And at least from the one event i saw that's also about how often they appear/how dangerous they are, from top to bottom.
(But that one was in germany, so might be different for you).
Anyway... something well armored and able to push definitely is competitive, if you can drive it well. And that just needs practise.
Your motors won't even have to be too powerful, since mostly traction is the bigger problem. And getting really good wheels... well, there are some threads about that, a science in itself.
So with that design:
A inner shell, as compact as possible from thin HDPE to house the electronics.
And around that the wedge with some air pockets. sounds good to me.

Possible problems:
- weight. Wedge in all directions needs a lot material or steep wedge. But can be done, if no active weapon needs weight.
- most wedges have two driving wheels somewhere in the back, and one point of the wedge (or close to the wedge) slide over the ground to stay as low as possible. could be interesting to get all sides low.
- if someone get under you, you'll be left with wheels in the air as soon as one side leaves the floor (since the opposing side gets stuck on the floor, wheels will hang in the air between them). So no way to retreat and free yourself.
- pure HDPE wedge doesn't hold up long, possibly add a steel tip to it. nothing fancy, maybe like this? http://forum.roboteers.org/gallery/u...48e3-large.jpg
- what to do when you're upside down?

Cheers for the reply Runsler.

I completely forgot that if the bot is upside down, the angle is reversed and doesn't have any effect on bringing down potential damage from spinners, oops - that minor oversight ruins the whole running upside down thing. I find that sometimes the best defense against spinners is to be as quick as possible and ram them front on before the spinner has time to get up to a meaningful speed, and push them around from there. Although some spinners get up to speed incredibly quickly compared to some. That tactic is more than likely a "do or die" scenario. Either it works, or you get torn to shreds.

I think i've also worked out a schematic where I can control it using an Arduino, and to keep costs down incase replacements are needed frequently, wouldn't even need to be a genuine Arduino, just a compatible clone you can pick up for $5 - I've used a few clones and never had issues with them.

Steel tip sounds rather good, although I'm not sure how i'd do that, I'd need to look up stuff moreso than the rest, as i've literally never worked with any metals before.

Possible solution:
Make the wedge from HDPE.
Take a sheet of steel , and screw it on the HDPE in a way it is a bit longer where the tip will be. now if you want, you can try to sharpen it (from the floor side, to keep the angle sharp) a bit more, but that's all you'd need. And it doesn't have to be a big sheet, maybe more like a stripe.
Some shops get you stuff like that cut for really cheap, or you could ask a local metal working company (not the really big ones^^) to do that for you, and also let them make you a few spares.

I would only use that on front and rear end, since the wedges on the sides are defensive, you can't really use them to get under someone. There you can also get a little bit closer to the floor, since you won't get stuck with the sides as easily as with something in driving direction. So no use to keep them as sharp.

Another idea: it would be a bit more complicated, but a lot more effective to make the base plate octagon shaped, not square. just to avoid the 90° angles on the wedges, the smoother and flatter those are, the less the spinners got to bite into. but i'd treat that as extra, depending on how you can work with the material and stuff like that.


Plus, if you're going to use an arduino anyway and like electronics... possibly ask Rory Mangles how he made Nuts spin around and still be controllable. i could imagine this working for your bot, too. But again, that's an extra that would effectively convert a push/wedge bot into a full body spinner. And then you'd need fast motors^^

ps.: well, it would still have some effect against horizontal spinners, they'd make you go up (possibly turning you back again) and, depending on their balance, maybe make their blade go into the floor... whatever effect that may have, depending on the bot.
vs. horizontals... if they're weapons radius is bigger than your height, they'll land a big hit, definitely flipping you (but how often) and bend or rip the wedge on that point. If their weapon is smaller, they'll scrape on the wedge just like they did when you were the other way round.

Just going to reboot this thread I started a while ago with some more questions!

Is there a huge advantage between using a chain for drive instead of a belt? I find that chains can destroy themselves with enough force to pierce your battery packs if they've not been heavily shielded, belts don't seem to potentially wrecks the inside as badly if it fails.

So another question. Does anyone know any very fast motors suitable for featherweights? I'm hoping to build something supremely fast, simply trying to ram, knock & drag opponents until something inside comes loose and they become immobile or they find a hole to be pulled into. Not a good plan, but its the taking part that counts, at least until I get experience with more complex things. Ideally the motor needs to be capable of the same speed in reverse as it is in forward, so both ends of the bot can be used to the maximum instead of one being weakened due to motors not liking to reverse. I'll be trying to pack the bot with the maximum weight allowed for featherweight, so it hits with some force.


Also, something that amused me. In the Robot Wars rules, it mentions hovercraft. Now I want to try doing something like that as I've never seen anything like that before - could be the first, but all these silly things tend to do very poorly, like the walkerbots from the old series of Robot Wars, so horrendously slow and did nothing of value. Good laugh though...