quote:
maybe the left motor has a lot of internal friction?
when doing the mock up/building of the spinner the motors in question were used in the bot as can be seen in the pictures. All the drilling of the metal swarf ended up in the motors they were later tapped up but was too late they were covered in fillings....so that may well be the culprit.
quote:
Is the left motor harder to turn by hand than the right motor?
Yes.
quote:
Does the left side ESC get noticeably warm compared to the right side?
Neither ESC ever get's that warm at all, they have never been too hot to touch, unlike the motors the motor's which get very hot, after pushing another bot around for 3 minutes.
haven't had a chance to swap ESC's yet I did however run the bot for 3-4 minutes on a stand 6 times and the above issue seemed to stop? the thing is now when the 4S 2.65Ah drops below 4.00 volts per cell power output at the wheels diminishes almost instantly where previously it still had decent power down as low as 3.80 volts per cell with the old 18v dump motors.
Hey Steve, had a read of it the other night, mite play around with it when I get a chance otherwise the hex file on Launchpad works perfectly fine, did for me/has done so.
Sun Oct 05, 2014 7:21 pm
Tim
Joined: 30 Oct 2013
Posts: 247
Location: QLD
Mental did exactly what it was designed to do, for me personally a great design solution! for the given criteria also driving in the full size arena was fun made it through the whole weekend and only had to replace one 18v drill! Below pic after the rumble, Demon, Scissor Hands and Cavitation all took bite or two out of Mental Bot over the weekend, thought i would have lost those wedgelets in one hit from a spinner however not so they are there.....a little worse for wear atm.
Sun Oct 05, 2014 7:43 pm
Jaemus Experienced Roboteer
Joined: 01 Apr 2009
Posts: 2674
Location: NSW
Congratulations Tim! _________________ <Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls
Mon Oct 06, 2014 8:10 pm
Tim
Joined: 30 Oct 2013
Posts: 247
Location: QLD
Thanks Jaemus, it's a good feeling big weekend great time! learned a lot!
Mon Oct 06, 2014 8:56 pm
Tim
Joined: 30 Oct 2013
Posts: 247
Location: QLD
Mental bot
Damage other than cosmetic.
After I lost a drive during a round against demon (after a really big hit that sent us both flying ) and tapping out curiosity got the better of me so pulled said motor apart the autopsy reveled the following -
The motor was full of crap so that's no surprise but the gear box....missing a pin @ 4 o'clock?
Found it!
Same box, the pin seemed to be friction fit it just popped back in? not that I'll be using it again it has served it's purpose.
Inertia Build
Well I certainly learned a lot, Inertia is far to fat so I've pulled out the drills in favor of the NTM 580kv brushless. Total saving of 200mm / 100mm either end, if I go down this path which seems to be the logical thing to do seeing as I have all the nessary parts ie. motors/esc's/battery's/metal/pollycarb for the top protection/wheels 4"x2" Colsons hook up great....anyway here is a few mock up idea's to get rid of metal and hence weight. I'm sure there is many other obstickals to overcome yet but getting closer....and yeah I'll need a smaller belt lol.
mocked up with red wheels/drills = wider wheel base, pound for pound roughly the same as the colsons 1kg per drive
mock up with colsons looks menacing better traction is the key when a round turns into a pushing match makes sense to have a lager foot print....to me at least.
In the above pic's you can see how dramatically the wheel base would change with brushless! I intend to mount the brushless drives exactly as the brushless pully drive is mounted (with support bearing also) I really question weather 4 x M4/M5's high tensile countersunk screws is enough to hold the drive together....say after hitting the arena wall and landing on the wheels unlikely but could happen.
With the LiPo/batt/wheels/motors/everything you can see, and all that extra metal that will have to go, Inertia sits at 15.4kg there has to be 2kg of dead weight there, After studying Demon there is very little to nothing in Demon that does not need to be there. So I shall do the same
The NTM 580kv can theoretically make 1kw on 5S which would make it a reasonably powerful lil monster using a 5S Nanotech 5Ah LiPo
Question...how do brushless go as a direct drive for the wheels (I'd be inclined to use a bearing support seeing as they save drives/releave stresses on the drive system) are they slow off the mark? burn out quick? of what should I know good peoples of the robot world
Cheers Tim
Wed Oct 08, 2014 6:29 am
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
We tried the NTM 42/35's 750 KV on Caliope mated with a 6-1 gearing to 100mm wheels.
It was a disaster. Nothing, nothing, Liftoff. With 1 motor starting way earlier than the other. if it would have been the same motor everytime again we could have compensated electronical, but alas.
Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD
Cool...looks better smaller ….Are you planning to put gearboxes on those brushless drives? _________________ Miles Blow - Julie Pitts
www.mulesfilm.com.au www.wombokforest.com.au
-Pickasso- Vivid Sportsman champion 2015
Wed Oct 08, 2014 12:47 pm
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
Without sensors the outrunners have no chance, they won't be able to find their position with that much load on them, even if they're capable of moving the bot once spinning. You could however definitely go with some smaller outrunners (or the same) and some kind of compact reduction. _________________ ( •_•)
Ah Ha! thought there was more to it than just whacking a wheel on a brushless motor. watching weapon drives spin up tells a tail of delay that I figured would be the case
quote:
We tried the NTM 42/35's 750 KV on Caliope mated with a 6-1 gearing to 100mm wheels.
It was a disaster. Nothing, nothing, Liftoff.
That's what I was afraid of, not put off by it yet.....just new to brushless.
So assuming I wish to experiment with brushless drives despite the apparent associated problems what type of gearbox and reduction ratio are we talking about?
@Miles that what I thought smaller the better, sounds like gearboxes are not optional so yep.
@Angus going OT for a second, thanks for the help with Mental bot worked out well where do I find suitable gearbox reduction components for a 50/50 580kv NTM (I figure HK?) would not know where to look, also what are these sensors you speak of and where do I find them? is there associated software I should be aware of to avoid what maddox said re: " With 1 motor starting way earlier than the other."
Drills work a treat however the space I could save with brushless is greatly needed.
@Aaron, of that I was not aware, for the sake of the thread continuity I'll leave it as is atm when It's finished or I think of another name I'll edit the thread.
I'm thinking of naming it Momentum (the bot formally know as Inertia) if that isn't taken.
Thanks for the heads up guys
Wed Oct 08, 2014 9:41 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
I don't think there is really going to be all that much difference in size for a brushless or brushed drive system to be honest. For your first bot like this an experimental drive is probably not going to give you the best bang for your buck.
If you look at the vertical spinners out there they are all managing with drills or larger motors. I feel you might be best served looking at other areas you can save weight and perhaps a re-shuffle of the insides to save on size. Take a close look at the other vertical spinners for ideas on packaging and component selection.
(I'd also strongly suggest weighing the hub you have there, its really pretty massive at least visually) _________________ Mechanical engineers build weapons, civil engineers build targets
Wed Oct 08, 2014 11:04 pm
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
quote:Originally posted by Tim:
quote:
We tried the NTM 42/35's 750 KV on Caliope mated with a 6-1 gearing to 100mm wheels.
It was a disaster. Nothing, nothing, Liftoff.
That's what I was afraid of, not put off by it yet.....just new to brushless.
So assuming I wish to experiment with brushless drives despite the apparent associated problems what type of gearbox and reduction ratio are we talking about?
Caliope's drive was a variant on the MSR12-72 gearbox. A Z12 mod 1 gear on the motor, and a Z72 bolted on the 90mm wheel running over a "dead" 12mm silversteel axle.
In Nebelwerfer2 we used a way faster inrunner with a GR02 24-1 ratio (batterydrill with fancy structural plates) and 120mm wheels. ESC's, Trackstar 25A. And that drives almost as the standard sets.
Now we made the same but with the longer inrunners and the original speedo's from Caliope (Trackstar 60A v2) and that's in Hannibalito 3.2.
And with 8 kg load that drives nice.
Thu Oct 09, 2014 1:03 am
miles&Jules Experienced Roboteer
Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD
You could always put some of those little 550 sized brushless in runners on he back of drill gearboxes…they are like $20 from hk Daniel tells me. _________________ Miles Blow - Julie Pitts
www.mulesfilm.com.au www.wombokforest.com.au
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