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evil_dan2wik



Joined: 05 Oct 2013
Posts: 20
Location: QLD


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How does sportsman work, Like is there tape on the ground to push them out of or is it an endurance battle or what is it?

Post Mon Oct 07, 2013 8:16 pm 
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Jaemus
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Joined: 01 Apr 2009
Posts: 2674
Location: NSW


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If you are going to do a spinner, the brushless you've picked is pretty small for a featherweight, I have one not much smaller than that (3530) in my beetleweight. Unless your weapon blade will also be quite light (and therefore ineffective) you may want to consider going with something bigger, at least a 42mm brushless with > 1.0kw of power and an ESC rated above it for safety as Chinese 'amps' can be conseratively stated.

Such motors will generally run at higher voltages more compatible with your drivetrain. Aim for 4S at a minimum.

Otherwise one of the following will happen with a heavy blade:

- motor burns out
- ESC burns out
- spins up extremely slowly (tactical disadvantage)
- wont spin up at all

You also want the biggest shaft size you can get for the size of motor you're using, to help protect it against torque from impacts being transmitted back into the shaft and breaking it.

I concur with Angus tho, get a moving platform rolling first and worry about spinners later.

4AH battery seems like massive overkill for drills and the small brushless you've linked. Even with the larger brushless I've suggested above 3AH would be plenty. Catastrophe runs a 2.25Ah battery (although that is probably smaller than it should be). Make sure you get one with a high enough C rating to cover the startup current from your weapon motor as well as driving at the same time
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<Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls

Post Mon Oct 07, 2013 8:38 pm 
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Jaemus
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Joined: 01 Apr 2009
Posts: 2674
Location: NSW


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quote:
Originally posted by evil_dan2wik:
How does sportsman work, Like is there tape on the ground to push them out of or is it an endurance battle or what is it?


Works exactly the same as the unrestricted class, 3 minutes, win by KO, immobilizing the opponent or on points for control, aggression, damage. Arena is the same although may be smaller
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<Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls

Post Mon Oct 07, 2013 8:54 pm 
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evil_dan2wik



Joined: 05 Oct 2013
Posts: 20
Location: QLD


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Thanks.

Post Tue Oct 08, 2013 8:34 am 
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tetraPark



Joined: 07 Oct 2013
Posts: 62
Location: Brisbane / Ipswich


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Hi chaps,
Inaugural post here! I'm in similar situation to evil_dan (in fact I think we may have talked to eachother at the Nationals in Ipswich just recently). At the moment i'm looking for wisdom about what parts for a first machine.

I've poured over most of the how to / getting started forums (damn fine stuff for noobs such as myself), and so think I have a pretty good general idea of parts and costs.

I intend to build a featherweight and stick pretty close to the type that Angus and Steve have provided instructions for... with a few exception Wink

I am hoping to use 4x 18v drill motors for drive (1 per wheel), and was wondering ( first question ) what the best esc choice would be. I'm not intending this to be a push bot. Cost considerations are important to me, but I'm willing to spend a little extra if it will mean less chance of killing components. So 4x 30amp, or larger?


Bit of context for next question: I would ultimately like to experiment with mecanum wheels on this machine. Long story short, to do this using the HK 2.4Ghz 6Ch Tx, I will end up having not enough mixing channels (it comes with 3, not the 4 needed) to control the drives in all directions.
Thus my question : I have read around the net that it is possible to y-spit a channel output from the rx between 2 escs without any trouble (meaning, the motors powered by said escs ran basically with equal power to eachother, with seemingly no performance loss; ie like a mixed channel). Does anyone have a dissenting opinion from this. Otherwise this would seem to solve my little problem, and that is radio package I will purchase. Razz


Finally, last question , I'm a little confused as to where to look for the next event (I know I've offended the gods of thread posting by asking this here...). I live in Bris (workshop in Ipswich though), so just keep my eyes on the QLD Arenas thread? Hope to meet with some folks and talk shop at the soonest opportunity.

Cheers!

(p.s. I like your concept design dan Smile )

Post Mon Oct 28, 2013 3:06 pm 
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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4X 18V drills = use a pair of BotBitz 85A's, they will handle them with ease and saves you having to fiddle with y connectors for the RX.

For the TX, SPEND THE EXTRA $$$ AND BUY THE ORANGE T-SIX!!!!!!! . You will thank yourself forever afterwards.

Next event hasn't been planned yet, everyone will probably be in hibernation till early next year Razz But don't let that stop you from building stuff and asking questions!!!
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Post Mon Oct 28, 2013 3:41 pm 
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Valen
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the case is a worthy addition for $11 or whatever it is from the .au warehouse for the orange tx.
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Post Mon Oct 28, 2013 9:40 pm 
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dyrodium
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Joined: 24 Aug 2004
Posts: 6476
Location: Sydney


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Hey and welcome!
There is strong suspicion among aus robot folk that the Kmart 18V drills are actually just 12V motors with 18v packs slapped on... which may explain some of the spectacular smoke and fire from them in some robots. Personally, I've only ever run the 12v ones and even up to 5S have worked for me. Just a heads up!

Glad my guides could be of some use Very Happy double recommend the TZ85a's they'll run drills all day.

Mechanum eh? Cool Do you mean the slanted roller variety or the perpendicular kind?

If you mean the first kind... alcoholic stepfather was an amazing robot which used them: http://youtu.be/TrWF0eucc-c

The tricky part is getting ones tough and grippy enough... Those ones were custom milled titanium construction. Shocked
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Post Mon Oct 28, 2013 10:20 pm 
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tetraPark



Joined: 07 Oct 2013
Posts: 62
Location: Brisbane / Ipswich


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Yo guys, thanks for the prompt responses!

Unfortunately, I don't believe the mecanum drive setup will let me run only 2x escs: to strafe, the wheels on each side will need to contra-rotate, as well as operate in the same direction for normal differential (tank drive) movement.
Here is a crappy image that is more articulate than my explanation:
http://www.emeraldinsight.com/content_images/fig/0490330405007.png

It would seem therefore that 4x escs is a minimum for this concept... I would love to go for the Botbitz 85s. It kind of sounds like the AK47 of escs (rugged and reliable), however if I have to go for 4 of the buggers on drills, might that not be a bit overkill? I'm not sure what stall amps the escs would be dealing with...

The orange T-six looks cool but also seems to have max of 3 channel mixes. Crying or Very sad
Good vid find Angus, thats the drive set up I'm contemplating (slanted). Going to do some experimentation this week. I'll post pics of progress if anyones interested. Should be good for a laugh. Razz

Post Tue Oct 29, 2013 12:39 am 
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Ellis



Joined: 21 Jul 2012
Posts: 129
Location: Shopshire, England


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Should be possible to tell if certain drills are just 12v drills sold as 18v by finding out their rpm. Assuming standard 36:1 gearboxes are used; if the drills are sold as capable of 550ish rpm, they're using regular motors at their designed voltage, if they're sold as capable of up to 825ish rpm then they're overvolted roughly by 1.5x their nominal v. I'd be surprised if they are just putting 18v stickers on some motors, but not that surprised, lol, yay mass production!

Also, the robot combat world needs more omniwheel(ed) robots, will be following your build, good luck!

Post Tue Oct 29, 2013 2:10 am 
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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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Lets just say in 6S lipos the drill motors were emitting fire. Not like sparks.... actual fire.
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Post Tue Oct 29, 2013 7:27 am 
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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Ah, I missed the Mechanum OMNI bot part Razz
You will struggle to find a radio where you can mix more then 3 channels for less then $500. If you want to run an mechanum, your better off doing the mixing on a micro controller in the robot itself.
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Post Tue Oct 29, 2013 8:18 am 
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miles&Jules
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Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD


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Hi all..great to hear new robot discussion!

Any local builders (bris /ipswich) are welcome to come and play with some of the drills and other robot bits we have laying around at our house...Pm us if you want to visit
(we are in Booval)

My recommendation for drills is ...what ever you use 12v/18v have at least 2 spares per wheel at an event... and use only a 4 cell battery ....thats what we are doing now....its just two insane running drills higher i reckon....especially after kojak and Pokey ate like 20 drills when they were in Syndey.(8 new 18v kmart drills al got eaten on 6cell)

We have actually made a promise never to use drills again...but plenty of champion robots do so they can rock.
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-Pickasso- Vivid Sportsman champion 2015

Post Tue Oct 29, 2013 5:13 pm 
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Valen
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Joined: 07 Jul 2004
Posts: 4436
Location: Sydney


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if you limit them so you don't feed 24V into a 12v drill its not so bad.
IE limit the servo travel to 50%.
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Mechanical engineers build weapons, civil engineers build targets

Post Tue Oct 29, 2013 7:12 pm 
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evil_dan2wik



Joined: 05 Oct 2013
Posts: 20
Location: QLD


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I have 2 drill motors prepared for use from a 9.6v drill. It seems that the regulator was the voltage limit in this case since it exploded spectacularly when I connected it to 12v.

I am not sure if these are 6v motors but the motor heats up enough to cook the oil in the gear box after about 1 minute of constant 12v. I have had to pull apart, clean and re lubricate the gear box because of the crunching from the burnt oil. It seems to be working ok for now. Should definitely survive a fight though.

I am thinking of using an old rackmount UPS as the base for the armour. I even have the display board for the front which can run up to 30v, Expect some neat flashing LEDs on the front.

http://imgur.com/rMeEriW,51xV0hB

Post Tue Oct 29, 2013 9:40 pm 
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