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Andy



People Skills: 1662
Registration date: 2010-04-16
Location: South Park, PA

PostSubject: Drive motors?   Fri Apr 16, 2010 11:59 pm

Alright so I was at the SWPA bots iq competition today (15 lb class) and I noticed tha a lot of teams were using castle creations brushless motors with a 26:1 banebots gearbox gear ration. I considered using a monster max brushless for drive myself. However we ran out of time and money for those so we stuck with the stock brushed motors with a 16:1 gearratio. This leads me to my question...I also noticed that a lot of the more experienced or better teams were using the stock brushed 540 drive motors as well instead of highend brushless motors for the drive. Does anyone know why this is so? Is there a perfomancething I don't know or was it just that the brushless were too expensive for those teams?
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tb1h



People Skills: 1639
Registration date: 2010-04-10
Age: 20
Location: center township

PostSubject: Re: Drive motors?   Sat Apr 17, 2010 6:30 am

i would say a mamba max would kinda overkill for a drive motor also the regular mamba we have the 550 motors in our bot and the have tons of power and its a little to quick its hard to control which would lead me to believe that a mamba would be twice as fast and even more hard to control
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Frisco
super contributor
super contributor


People Skills: 2237
Registration date: 2009-11-01
Age: 42
Location: Brownsville, Pennsylvania

PostSubject: Re: Drive motors?   Sat Apr 17, 2010 7:29 am

Banebots for the drives.
And either a Brushless that has good torque and over or near 1000kv or the mamba for the weapons.

Stop over and talk to me about it today.

Frisco (advisor for West Mifflin)
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Andy



People Skills: 1662
Registration date: 2010-04-16
Location: South Park, PA

PostSubject: Re: Drive motors?   Sat Apr 17, 2010 5:25 pm

Your right it probably would be overkill and especially not worth the price. Thanks for the advice guys.
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Dan Curhan
Admin


People Skills: 2897
Registration date: 2009-03-14
Age: 23
Location: Sarasota, FL

PostSubject: Re: Drive motors?   Sun Apr 18, 2010 10:29 am

I have no experience with brushless drive, but my one comment is this:

DC brushed motors have maximum torque at 0 RPM. Brushless motors have very little startup torque in comparison.

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Andy



People Skills: 1662
Registration date: 2010-04-16
Location: South Park, PA

PostSubject: Re: Drive motors?   Mon Apr 19, 2010 7:23 pm

Ok thanks guys! I'm gonna try and do some r&d and see what works for us.
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rdubard
mega contributor
mega contributor


People Skills: 2467
Registration date: 2009-06-10
Age: 49
Location: Ransom Everglades, Miami, FL

PostSubject: Re: Drive motors?   Tue Apr 20, 2010 6:23 am

Dan's got the right idea--too much load on a brushless before it starts and you get cogging (unless it's a sensored brushless, which it seems no one is using), but a simple brushed DC motor has max torque on startup, always.

Brushless systems are generally also expensive, but to compensate they have amazing efficiency, so you might be able to get by with smaller batteries.

Overall, brushless drive doesn't seem like a great idea to me.

However, most of the brushed drive motors that come with the gearboxes are really cheap junk. (We have continued to use them anyway, because my students have been too busy to research alternatives) I know that Team Jag/rjw has found some quite superior aftermarket hobby motors but it seemed dishonest of me to peek to closely at the fruits of their labors, so I cannot make a specific recommendation.
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Cody
2000+ club
2000+ club


People Skills: 4649
Registration date: 2009-03-16

PostSubject: Re: Drive motors?   Tue Apr 20, 2010 9:06 am

i've only ever seen one robot use a brushless drive. It was team from meadville and the bot was a major fail in my oppinion. The kid just kept talking about his batteries when I tried talking to him lol

Brushed drive is the tried and true way to go.
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Andy



People Skills: 1662
Registration date: 2010-04-16
Location: South Park, PA

PostSubject: Re: Drive motors?   Tue Apr 20, 2010 12:44 pm

is everybody using the banebots brushed motors or is anyone gettin high quality rc car brushed motors?
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rjw
Chief Bottle Washer
Chief Bottle Washer


People Skills: 4482
Registration date: 2009-03-31
Location: Miami

PostSubject: Re: Drive motors?   Tue Apr 20, 2010 12:55 pm

Andy wrote:
is everybody using the banebots brushed motors or is anyone gettin high quality rc car brushed motors?

mlec uses aftermarket motors on all but 1 bot, which is still using some bb's

Don't jumo too quickly tho....the higher end rc stuff is not without it's own set of problems.....I've seen bushes, brush holders, endcaps, etc all go south if steps aren't taken to prevent ...and they can get expensive.

do your research and

'AVOID THE PAIN'

jmo

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Cody
2000+ club
2000+ club


People Skills: 4649
Registration date: 2009-03-16

PostSubject: Re: Drive motors?   Tue Apr 20, 2010 2:28 pm

At the pa competition you are already a step ahead of most of the teams with p-60s and banebot motors
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jtm94
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People Skills: 1909
Registration date: 2010-04-23
Age: 20
Location: Clairton, PA

PostSubject: Re: Drive motors?   Fri Apr 23, 2010 7:25 pm

I must say that for our first year our team made THE worst mistake and bought some terrible, and I mean terrible, robotmarketplace drive motors. If it wasn't for that our robot may have actually been competition in the losers bracket.
At the competition at Century III I did notice that "most" of the robot failures resulted from awful drive motor gearboxes.
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rjw
Chief Bottle Washer
Chief Bottle Washer


People Skills: 4482
Registration date: 2009-03-31
Location: Miami

PostSubject: Re: Drive motors?   Fri Apr 23, 2010 7:45 pm

If you look around here, elsewhere and ask a LOT of questions, next year will be totally different. All teams go thru a weening period...do you homewoark and 'AVOID THE PAIN'

_________________
Ready to Rumble combat robots
Advisor to MLEC BotsIQ team...2010 BotsIQ champions (1st and 2nd places)
Spinning Tortoise...Possibly the World's first Brushless Melty!!
2010 Franklin Cup winner
Vapor bots..Ho
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jeeves_m_d
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People Skills: 2622
Registration date: 2009-04-21
Age: 21
Location: Sudbury, MA

PostSubject: Re: Drive motors?   Fri Apr 23, 2010 9:07 pm

RJW is right, my weening period has been the past 3 years Very Happy hopefully senior year i might know what i am doing
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rjw
Chief Bottle Washer
Chief Bottle Washer


People Skills: 4482
Registration date: 2009-03-31
Location: Miami

PostSubject: Re: Drive motors?   Fri Apr 23, 2010 9:25 pm

jeeves_m_d wrote:
RJW is right, my weening period has been the past 3 years Very Happy hopefully senior year i might know what i am doing

everyone easnt s to vuild the New LATEST AND GREATEST..but except for a few things, most of it has already been done.

No shame in steeling....or should I say borrowing stuff from other bots that actually works.

It's actually a compliment to whoever built the other bot. Plus, most mistake are made in how it is executed.

Many bots have drums or beaters and BIG AXI motors, etc but few matched up to Hummdinger....He had a whole package

1) Good design
2) Good choice of materials and components
3) Good driver
4) Godd execution of the design
5) Goos funding or sponsorship, in that large chunks of S7 and Ti aren't cheap

and more

Lolcano looked good, but perhaps you should have spent a bit more time getting your weapon tweaked before nat's...I know, I know...so much to do and so little time...

the point is, if you skip any steps or take shortcuts.....others will show up and be better prepared and will kick your robutt.....

Fluffy 2 was looking like it was going to be a heck of a bot, but I think that Will spread himself too thin with all the other bots he was working on...and to my surprise, Sting WMD got in a good hit, a couple of bolobat type bounces and it was basically all over.....

Sometimes the draw at these events will kill you..... affraid

fwiw: it will be hard (unless you have a hummdinger) to go to an event with 1 robot and compete against teams with 3 or 4 or more strong bots. Over time, attrition is a VERY big factor.

Until they change the rules and force teams to fight their own bots full force, there will always be an advantage to bringin more ...unlees they're all weak bots.

_________________
Ready to Rumble combat robots
Advisor to MLEC BotsIQ team...2010 BotsIQ champions (1st and 2nd places)
Spinning Tortoise...Possibly the World's first Brushless Melty!!
2010 Franklin Cup winner
Vapor bots..Ho
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