Questions/builds thread.

[Ellis]

Re: Questions/builds thread.

Well the amount of soldering and such involved was daunting, that's for sure. I somehow expected it to take hours. Between me making the short wires up and my dad soldering, we did all of the so called daunting stuff in mere minutes!

Also, for the record, the bottle thing works a treat. I think I saw it on a video for making a cheap battlebot (American video) by RoboGames on YouTube. Standard hairdryer and an old bottle or two and away you go. They're remarkably solid too. Impossible to buckle or twist. Once the stuff shrinks, it's shrunk! Nothing you can do about it.

[gizz]

Re: Questions/builds thread.

I agree, altho using a big model of a soldering iron would help alot, i struggled a bit using my small one when making the FW pack

[Ellis]

Re: Questions/builds thread.

Still waiting for wheels, but today was pretty productive. We cut out the two side bulkheads and angled the base-plate's edges to fit. The material is astonishing, in a bad way! It's sort of... self healing. We passed the blade through the material 4 times, yet the material remained joined. It was like magic!

Anyway, after much fiddling with the speed and sanding and fretting, we battered something into shape. It's a really bizarre material to work with. We made endless amounts of mess on the drill and scrollsaw. WD40 + what look like toenails, and at other times it was like weird papery snowflakes.

So we cut our 20mm (in theory) 6cm (also in theory) strips, then shaped the back and angled the front. We shaped the base-plate and angled the two ends, then effectively eyed-up our wheel positions. With our lack of knowledge when it came to the material, the material itself being really imprecise (it's 20mm thick in places and I kid you not, 15mm in others), our limited precision tools etc, we got something to within a few mm of precise. Good enough for a first robot. We will definitely use more formal materials when we come to upgrading.

Pics are here: http://s1088.photobucket.com/albums/i32 ... elentless/

--------------------------------------

Quick question, what grub screws do we need to lock up the drills? Our homemade ones are functional but big, ugly and... for not much we can do better. Thanks.

[harry hills]

Re: Questions/builds thread.

yeah most plastics have that healing bit if you try and cut them too fast.

looking very good so far, and STOP DISSING CHOPPING BOARDS

[mattsdragons]

Re: Questions/builds thread.

im with harry on this, look at bitza, used chopping bords and was 10th at the last FW champs, and was build for something stupid like £100

[jonny]

Re: Questions/builds thread.

looking good, if you think working with chopping boards is a pain in the asp you've obviously never worked with nylon robot is coming along really nice though!

[Ellis]

Re: Questions/builds thread.

Thanks guys.

Well today we ended up screwing the bulkheads down at about 85 degrees instead of 90, so we set about rectifying that. We wedged washers under one edge to straighten the pieces, and sort of succeeded. We wanted to make that permanent so we decided to ram glue into the gaps. We ended up using the wrong glue and using some sort of cement like stuff.

*facepalm*

Anyway, if we're not lucky enough for it to work anyway, we'll pull it apart tomorrow and do it properly.

------------------------

Today we also decided that this material is officially the most awkward material ever. Nothing really sticks to it, it melts really easily, it varies in thickness by 5 mm, it's got holes in it and it's relatively heavy.

So,

Why don't I see robots made out of plywood? It's half the weight, a good deal stronger, cheaper, REALLY EASY TO WORK WITH and readily available. The only logical explanation I can come up with is that it's the psychological side of things. Knowing you're pitching wood against hardox must play on your mind. And not only that, if painted it's really obvious when you've lost a chunk of armour or bulkhead or what have you. Does that mean that even if you're structurally as sound as you were to start with, and fully functional, it looks like your robot is in tatters and therefore you lose points?

We're seriously considering dropping the chopping board and using plywood, I just wondered why no one else does that? Is there any immediately obvious reason?

Thanks.

[PJ-27]

Re: Questions/builds thread.

Yeh Bitza was only £100 to build and came 10th.

The chopping boards were very cheap and seriously tough, but still go destroyed by Little Hitter so don't underestimate the power of other people's bots.
Also although the chopping boards were advertised as 'High Density' Dave (Satanix) advised me that actually they were LDPE.

HDPE has an incredibly high impact resistance, which is what makes it so popular, I'm pretty sure Plywood doesn't compete on any level.

Wanna use Plywood though make a Wooden robot!

[Ellis]

Re: Questions/builds thread.

Today has kind of reinstated my trust a little. Wood is on hold for a while, haha.

Anyway, we removed the glue/concrete stuff we used by accident because it hadn't set at all. We bought a hot-glue gun yesterday, and so we glued the gaps between the bulkheads and the base-plate. It's pretty rigid now and we're on the kind of angle we want, far closer to 90 than we had hoped in fact. We put the wood screws back in and after just letting the glue sit for a moment it's suddenly massively rigid. No upper support yet, but still, plenty strong. Success, I think. As long as I don't jinx it!

We also put in the motor mounting brackets. We had a bit of a fiddle with it but they're well and truly in now. It's gradually starting to look less like a chopping board and more like a... a, thing.

Not much new to see, but I uploaded a few pics.

http://s1088.photobucket.com/albums/i32 ... elentless/

Next stop is the inner bulkheads, then front and back support. Then well put the motors in and wire them up. We're still waiting on the wheels, ordered over 6 weeks ago!

[Ellis]

Re: Questions/builds thread.

Today we made the bulkheads. I wish it were as simple as just making them, lol. I won't go into too much detail but in short, we spent hours doing something so technically simple because of the unique properties of the material, and the end result isn't that great in truth. We managed to use pretty much every tool in our arsenal, and we had to break our scrollsaw blade to remove it from the material, which had melted and dried solidly around it. It was interesting, to say the least.

Anyway, yeah, the two inner bulkheads are cut. Need to be refined a little since one is significantly shorter than the other, then mount them. Photos below!

http://s1088.photobucket.com/albums/i32 ... elentless/

[Ellis]

Re: Questions/builds thread.

Hi again.

It's been a while. My dad has been busy for the past couple of weeks but last night we got a small bit done. We cute the holes for the motors in the inner bulkheads. With some packing pieces, we should be able to get the motors sitting roughly square. Right now they're all over the joint! Also amazed by how heavy this thing suddenly is. It's not even got it's front battering ram, weapon or armour on it yet.

Pics with its drive innards and wheels more or less in place on the photobucket...
http://s1088.photobucket.com/albums/i32 ... elentless/

[Ellis]

Re: Questions/builds thread.

About time I updated this!

The robot is coming along quite nicely. We have decided on a 4bar lifter afterall, for simplicity, cost and weight allowance. We have also plugged everything in so to speak and got it driving, as you can see here:

http://www.youtube.com/watch?v=5t3f-8X_pPA

This video is at 12v onto a single drill battery. The machine will run on two 18v (we have tested it at 18v, as is to be expected it's an entirely different piece of kit next to 12v) drill batteries in parallel, giving us 2.6Ah. This isn't enough we don't think (opinions? What's your average battery capacity in a FW? This is 4x 12v drills at 18v and a motor or two of some sort for a lifter mech) but we can't find a suitable replacement yet. As I am sure is the case with anyone building a bot, we have to juggle size, weight, cost, capacity, voltage, max. discharge rating and charging. We reckon these cheap 1.2v 1.3Ah NiCd cells are capable of around 10c? Does that sound right? If so that means we have a max. discharge of around 30A, which we feel isn't quite enough. Again, opinions on this?

Also, does anyone have any experience with these cells? - http://www.ebay.co.uk/itm/4-x-C-Recharg ... 2a14e8e3c7

They seem like a brilliant deal. Cheap, very high capacity, etc. We asked someone selling them for a max. discharge rate, and they replied with 3c. Does that mean that if we had 2x 18v battery packs made up of these cells wired in parallel, we would get 19Ah and around a max. discharge rate of 54Ah? Is that correct, and if so, what do you think? Good/bad brilliant/terrible fantastic/useless?

Sorry for all of the questions, feel free to watch the video and leave, lol, although some info on our current drill cells and the linked ebay cells would be brilliant!

[Anttazz]

Re: Questions/builds thread.

Uh-oh, house is busted up, play time over

[RogueTwoRobots]

Re: Questions/builds thread.

I'm impressed

Looks a bit like a featherweight Stamper (although that never got finished) but it's certainly agile and pretty nippy, and I imagine it would be more so on 18V. 2.6Ah is a bit lower than I'd normally go (3Ah or over for me) but it might actually be alright, as I'm sure several robots only use around half their capacity in a battle. Also depends how long the battle lasts of course!

[ewan]

Re: Questions/builds thread.

If I were you I'd go for a 14.8v or 18.5v lithium polymer- you can get ones with over 20C discharge rating at 3500mah+ that will still save you weight over drill batteries. Here's a pretty good range http://robotbirds.com/catalog/index.php?cPath=63_469