brushless motors for drumbot

hi guys,

as you all probably know, im building a drumbot, iv got the basic chassis drilled and bolted together now, so now its time to do the weapon :twisted:

seeing as its going to run off a123's i have the power to use a brushless system for the drum motors :twisted:

iv been looking around and have found out that the align motors look pretty good for their price, iv been looking on ebay and found this:

http://cgi.ebay.co.uk/Align-BL500-L-Bru ... 2a070745de

however, i can only find one of them, and im really looking for a 2 motor system, so would i be better off usng 2 of these?

http://cgi.ebay.co.uk/Brushless-Motor-A ... 3efb8b40ab

or should i just stick to that one motor?

or in fact would any of those be suitable? iv never used bushless on this scale so any help would be great :D

jack

p.s: if youv got any recomendations for motors please pst a link :D

is this for the drum your making your self using the bolts as teeth?

Neither, on 24V the first motor will spin at around 38400rpm and the second around double that. That means some serious gearing negating the reason for going brushless over brushed.

The Kv rating tells you how fast the motor will run per volt you run through it. Like I told you on msn if you are going brushless you want to use an outrunner not an inrunner. Lower Kv ratings and higher torque ratings.

calum: non :P, that was yonks ago lol, im going to get it properly machined this time :)

gary: thanks for that,il take anougher looksie :)

jack

That Align model is similar if not the same as the brushless I was running in Drumroll occasionally and that I'll be using in the next build (to begin with anyway). As Gary's mentioned it's got quite a high Kv; I was running mine at 19.2V on a 5:1 ratio and that was still capable of theoretical top speeds of 6500-7000rpm which is just too fast to be effective.

The only reason I'm using it is because it was donated by Kenny. It may well not last many fights, and when it comes to replacing it, I'll probably opt for the Scorpion HK range of outrunners, as used by Dave in 360 and now in the latest Little Spinner. I'd give them a look if I were you, definitely seem to be the most capable brushless motors out there at the moment in terms of putting up with the rigours of robot combat:

Something like that would probably suffice, although whether one would be enough or not I'm not sure.
http://www.scorpionsystem.com/catalog/m ... K30-880KV/

I can only recommend the motor we used on Touro Feather (Robogames 2010 champion, two times Brazilian Champion):

http://www.hobbyking.com/hobbyking/s...idProduct=4936

It is a good motor, that can gel really good with some modifications, like gluing with epoxi the coil to the outer shell, drilling some holes on the front and back plates to aid cooling and above all, supporting the end when mounting the motor.

An 150A BESC is used on the following bases: a 2.5:1 ratio, stainless steel drum with S7 single tooth, weighting around 4Kg.

All I can say is that it is really impressive! :twisted:

Cheers.

When working out what brushless motor to use for your spinner you first need to ask yourself these 4 quetions;


Whats the weight of the drum you intend to use?

What speed do you want the drum to reach?

What voltage do you want to run the machine on?

Whats your budget?

hi dave

1: the drum should weigh about 2-3 kg depending on how many teeth i go for and the width of the robot, i need to get it all measured up befor i can say for sure but thats the rough estimate

2: 4000rpm? im not exatly sure what the average speed is for a drum

3: i was origionaly going for a 36vsystem but after talking to leo iv decided to go for 24v

4: hmm, well i guess its best to spend a bit more and get better results but id like not to get to ott...around £150-200 methinks but it depends on whats out there.

jack

Better than weight, if you can estimate/calculate the Moment of Inertia, even better.

Also, don't forget to pay attention to the belt stiffness, that costed us a couple of fights on Robogames 2008, the belts were too stiff and the motor didn't have enough start-up torque. The problem was solved switching from 3L to 2L belts, increasing the transmission ratio - was almost 1:1! - and using a lower KV motor (2300Kv to 1200Kv). With those changes and some re-design we managed to replace the Aluminium drum for a Stainless Steel one, even more MOI.

Cheers,
Eduardo

http://www.castlecreations.com/products ... x_ice.html ice 100
£96 ish

Id deffinatley go for a speedo like that, its worth spending abit more if you can spare it, The esc will help you improve your machine with the onboard data logging as shown in my build thread. and spending more in the short term will definatley save you money long term (TRUST ME :sad: )

When it comes to brushless id deffo say the speed controller is the most important part of the machine. I use the bigger castle ice 160's- im not sure if they are producing them yet for sale, or if they discontinued them, Joe ford at castle nocked mine up and shipped them out as a special in time for the gadetshow, and ive been impressed with them since.

Ive only blown one up- and that was due to drawing to much current which melted a soldered joint.

Castle creations also offer a repair service- which most companies dont.

And the Castle link software is terrific.

just a thought, you may be able to save a bit of cash by getting a power set for a very large heli (trex 500, 700e) I dont know much about brushless so im not sure if the kv of as heli motor is suitable. Can i also echo, get a good esc first time around, found that out the hard way, 50 amps my arse!