How to build a feather weight?

**daveimi** · 11th November 2013, 19:57

Hiya! Welcome! There are a few people and sites that make all the hard-to-make bits pre-packaged. I've literally just started entering my first featherweight after a year of building. My advice as a new builder would be get to some events and just keep it simple at first, there's a lot more to it than I first realised.

For motors / wheels

www.gimsonrobotics.co.uk
www.robochallenge.co.uk

Batteries - ebay

Speed controllers -the range is endless and everyone has their fav's, I use these

http://www.technobotsonline.com/moto...ntrollers.html

erm and my transmitter / receiver is these

http://www.giantshark.co.uk/product/...e2-transmitter

This is all uber budget but thought it might help!

Dave

**Flag Captured** · 12th November 2013, 03:55

For the parts, it depends on how much spare cash you have... I'd fully reccommend the BotBitz 85A's (just drop that into Google) by way of Speed Controllers, they'll set you back about £110 at most for the pair, but I've heard nothing but praise for them, and they've served me well so far. Motors, Gimsons do some ready-to-mount ones as Dave said above, alternatively there's the drill motors that can be easily modified to be decent enough drive motors - TeamExpat on Youtube (the Tormenta 2 team) have some very informative videos on that, there's numerous others about on there too.

You can get wheels practically anywhere (look for castor wheels of about 100mm diameter) but as Dave says, Robochallenge are pretty good for those too, since they do ones with a threaded insert purposely for mounting onto drill motor shafts.

The more commonly used transmitters from what I've heard are Spektrum DX5s or similar from that range. The budget one above will also do too (I use that one, myself, but I'm looking to upgrade)

As for batteries, it depends on your drill motors, you'd be best going with either a 3000mAh 3s or 4s LiPo, or a 12v NiMh if you get 12v drill motors, step it up to bigger batteries if you get higher voltage ones obviously, but it's a decent enough starting point. You can find those from www.hobbyking.com as you can with plenty of parts these days, they're not bad price-wise but it seems to add up on postage...

Finally, some advice regards putting a flipper on - if you know what you're doing, then by all means go for it, but I'd suggest you stick to making a moving box for now until you get an understanding of how it all works, and then go for the flipper - it's easy to jump ahead of yourself and be a bit ambitious which is what I did/am doing, but it does all come along soon enough. If you really want a flipper though, perhaps you could design a lifting mechanism that incorporates a high torque motor and later adapt it into a flipper? Might be a good idea to create a test platform out of wood or something that you can bolt all your parts to to see if your system works, always a good way to get the ball rolling.

**JakeButler** · 12th November 2013, 16:01

what are the different plastics you can use? names?

**razerdave** · 12th November 2013, 16:15

HDPE, polycarbonate (sometimes go by the trade names makrolon and lexan) or Nylon.

**Flag Captured** · 12th November 2013, 16:46

HDPE is the most commonly used I think, you'll probably want about 15-20mm to make it hard-wearing from what I've seen, but then again I've never worked with it. Directplastics.co.uk are a decent enough place to buy sheets of that.
YOu can always get creative though, make it out of scrap parts, I've heard of a few people making machines out of chopping boards, they're not spinner proof but if you're on a tight budget and you have some available then they could be an option I suppose.

**razerdave** · 12th November 2013, 20:29

Chopping boards aren't axe proof or rammer proof either. They shatter. They're crap. HDPE, not LDPE. Remember that.

**RogueTwoRobots** · 12th November 2013, 21:07

Of the three main plastics, Nylon and HDPE are currently the more popular ones. Polycarb was used a lot more in the past and still can be effective and useful but if buying new, it can be more costly than Nylon and HDPE.

Nylon is the stronger of the two materials, and the more expensive. It's good for making structural or load-bearing parts in your robot, such as bulkheads or mounts. I've tried various other plastics for these parts in the past (HDPE, Polypropylene, RG1000 etc) but always end up back at Nylon as it's the best for the job.

HDPE is better used as armour. It is quite soft in comparison to other plastics, which may sound bad but it actually makes it well suited to standing up to attacks from spinning weapons. When a blade hits, the plastic flexes which helps to dissipate some of the energy of the attack, and you're usually left with gouges in the material, but they can be easily cleaned up. Metal armour would bend and deform and you'd have to get a hammer out to re-shape it but because it flexes on impact, HDPE is more likely to retain its shape and if it does get deformed, heating it up with a heat gun is usually enough to allow you to correct it.

That said, HDPE doesn't have to be used solely for armour and you can make bulkheads, supports or mounts out of it too (one of my robots Onyx uses it for the central bulkheads). It's also worth mentioning that your armour is only as strong as its mounting. You could have the toughest armour in the world but if it's mounted poorly, it'll just fly off when a spinner hits it. In terms of thickness, a lot of people use upwards of 12-15mm thickness. That is fine, but personally I find it can make robots look bulky or cumbersome. I tend to use 8mm HDPE for my armour, and have never had a problem with it getting penetrated. You can also leave a gap between the armour and internal components so that if a blade or other weapon does get through the armour, the gap might be enough to stop it damaging any of your expensive parts.

**RogueTwoRobots** · 12th November 2013, 21:11

And without wanting to bombard you with too much too quickly, it's also worth just mentioning when it comes to the overall design of your robot, make sure that it's relatively easy to get to all your internal components for you to work on them. Time in the pits to repair your robot can be limited and you don't want to waste a lot of that time having to dismantle half of your robot to get to a small component in a hard-to-reach place that's causing you trouble. Always design with ease of maintenance in mind; at the very least it makes competing at an event much less stressful