Project Squirrel

[Outlaw]

Alright, so drills, HDPE, a Sabertooth Dual 12A for movement and a Botbitz 85a V2 for the weapon ordered... I know where to get an RC, and now I just need some connectors, screws and batteries. And a soldering iron.

Question is... should I go for some ec3 or ec5 connectors to connect all my wiring together? And what thickness of wiring would be the best? 12 awg? 14 awg?

Also, on another side note... which side of the battery should the safety link go on? The + or the -? It's been a while since I've done any wiring of the sort.

[lowndsy]

The ready made fuses sold by Gimson go on the red side, so my money is on +
https://gimsonrobotics.co.uk/categor...tomotive-fuses .

[Maxamuslead]

i had asking which side to mount the Link as well, it doesn't matter but people prefer on the positive side

http://www.fightingrobots.co.uk/thre...t-robot/page20

[Outlaw]

Oh boy...

So, I got the Botbitz ESC, the Sabertooth ESC and the drills in. Just waiting on the HDPE to come in. But (here it comes), I've looked at the little sheet that comes with the sabertooth, and although it says on the technobots website that it's good for 30lb combat robots, on the little sheet, it says at least half of that. This is the thing I'm talking about. Did I make a big mistake buying this? Or is it suitable for what I want to do, which is power two motors for the movement of the robot?

[Outlaw]

Forgot to add on here, thank you for the help on the safety link Steve and Mark. It's very much going to go on the positive side.

And the reason why I ask this now about the ESC is that it looks a little small, considering what it needs to do.

[Theo]

I'd say they would work relatively okay for a featherweight. They were used very frequently a while ago, and they used very similar motors. I just wouldn't run them on 18v. There are better ESCs but given the lead time of feather2s, and that they cost the same as one Botbitz controller and half the price of a scorpion, their advantages outweigh their shortcomings.

[RogueTwoRobots]

12A per side is on the low end of handling capability for featherweights but it would probably manage. I've never used Sabretooth controllers (and never will) but I ran a 2WD drill drive robot on a Scorpion XL for several years - they're also 12A per side - and it coped fine. It does have current limiting, so if your motors try to draw too much current, the speed controller will prevent them from doing so rather than blowing up. Best thing to do though is test it out in practice once you've got a functioning drive setup. Run it for a few minutes at a time to get a feel for it and see how it copes.

[Outlaw]

Well if that's the case I would've gotten myself the 25A instead, haha. Thank you Theo and thank you Jamie for the insight. If it doesn't really work that well, then I can at least use it for... like a distraction bot just for silliness, I guess, and I'll have to dive back into the wallet for the 25A one.

So with that out of the way, I'm just waiting for the HDPE, then I'll make a list of what else to buy.

[Theo]

I think Antazz is/was selling one for £60. I saw it in an old for sale thread (about a year old by now) but it didn't say it was sold.

[Bodge Job]

I've got one of those ESC's and it seems to cope with two drill motors fine. If I were you I'd add an additional heat sink/fan, just to keep the heat down. And there a bit exposed/ delicate so I'd give it a cover of some sort (so bolts and other rubbish doesn't damage it) and shock mount it somehow.
Other than all that their really good ESC's, have lovely low speed control and lipo cut outs etc. There a fee different settings (like exponential ramping) so have an experiment with those and find what you like driving best.

[Outlaw]

I may have to look into that, thank you Theo, and thank you for the additional information Alex. I was planning to put it into a cheap, small Tupperware box with holes drilled out for the wiring to go through and such, and use maybe a couple of rubber washers to keep it steady and not shake itself apart when other robots smack into it.

Aaaand unfortunately I have to go back to asking questions about batteries... again. But instead of it being the batteries itself, the questions are for the chargers.

I found this thing from hobbyking, and I'm just wondering if that'll charge up say... this battery? Or are there any other battery/battery charger combos that're cheaper and get the job done just as well? Because I don't want to buy them and find out that they're utter... well, you know, haha.

[Al_]

I have the Accucell T100 charging that exact battery and a couple of other 5S packs. Not used it lots yet, but no trouble so far.

[Outlaw]

I just realised that the charger that I found is for 4 cell batteries... and the zippy's a 5 cell. Almost shot myself in the foot there.

So I'm still looking for a charger/balancer. There's one by Overlander that's around £45, so I could end up buying 2 of those so I can charge said batteries... And I tried looking up what Alan said about the Accucell t100 and it looks a little sketchy... Does anyone have any recommendations/thoughts upon this?

[Outlaw]

So I looked up some reviews on the Overlander charger, and suffice to say that a lot of people say that it's a good one. And I spied one that was about £5-£10 cheaper, so that's good at least. So I bought two of them, along with 2 Zippy 5 cell LiPos, a pack of EC3 couples, 2 LiPo bags, and 2 metres of red and black 14AWG RC wiring, along with a cheap Hobbyking 4 channel RC controller with receiver. All that's left are screws (would chunky wood screws work with 15mm HDPE? I can't remember), a soldering iron, grub screws, a multimeter, and some good ol' fashioned elbow grease.

Only question is... how thick should the countersunk wood screws be? And is it possible to get them from B&Q? Or would it be better to just find better ones somewhere else? Same question goes with the Grub Screws.

[overkill]

I recommend cross nuts (sometimes called cross dowels) over wood screws:



These are impossible to rip out until the plastic itself breaks and unlike wood screws, the thread doesn't wear out if you have to disassemble them.