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/

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!

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

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!

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

Very impressive, looks like it drives nicely.

I noticed your using what looks like a 1/4 jack for a link, neat idea that I've often considered, just remember it won't be up to much current.

Thanks for the interest fellas! PJ, the reason we went for a jack and not a deans or something similar is for its mountability (is that a word?). It's hard to solidly mount a deans into a chassis, but the jack socket has a screw thread and nut.

However, as you say, we have been having one or two problems with it getting hot. My dad is adamant it shouldn't. It's like a nail going through the middle, much thicker than the thinnest wire we're using for testing (our positive line, the grey one) and that doesn't get even remotely hot. Still, all can be changed and modified, so if needs be we can change it for something with a higher rate of flow.

Right now we're stopping for a refuel (dinner) and then we're off out to the workshop again. We have taken the whole thing apart. The inner bulkheads are now modified so that they can just slide in and out if necessary. All we need to do is do some unscrewing and they're out. We've also mounted some small fans into them, to try and combat the massive heat generated by the cheap drill cells. Also thinking about the lifter geometry as we go. Any pics worth taking will be posted!

Quote:

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Originally Posted by Relentless

My dad is adamant it shouldn't.

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Well go tell him he's wrong! (Go on, you know you want to :rofl: )

Jack plugs are used on microphone or guitars etc all of which use cables which are designed for low current and high impedence so that's essentially what the jcak plug is designed for. OK they're used for speakers which have a higher current but that problem I assume is why the SpeakON connector was developed.

If you're concerned about mounting a deans connector Robochallenge do a nice mount for them http://www.robochallenge.co.uk/Events_a ... rical.html

Andy

My dad agrees completely having been in the music business for about 106 years (producing music and playing) it's not the ultimate solution but for now it's convenient.

-adamant dad :lol:

I'm pretty sure mountability is a word...... If not I'm going to make it one!