Pulverizer Build Diary

[Mega Masher]

Would two of these be ok?
http://www.scorpionsystem.com/catalog/m ... 4015-1450/

[archie2000]

the kv of a motor is like RPM per VOLT.
in this case we have 1450K/V
if you run this on 20v (to make the maths easy)
you will get 29,000 RPM
which is quite a lot.
Say you run this on some 5inch wheels (to keep the maths easy)
you get 455530 inches per minuite.
Is it just me or is that about 432 miles per hour.
The maths is probably completley wrong but the message is.
Thats WWAAYY toooo fast.
Im not quite sure what you should aim for as an rpm.
Also bear this in mind.
speed can be changed by gears.
simple.
However gearing systems can be quite expensive and be huge and weigh tons.

Tips
If there is something that possesses you to waste money on a brushless drive get a low kv one
Also if you are in the states can you just edit your location to say U.S.A or someting.
We can probably link you some parts from america in $ for the future.

WOW thats a long post.
Good luck with the build anyway

[Ellis]

In any case, you will need gearing. Unless you have an absolutely huge motor and small wheels a featherweight scale machine won't even move without some sort of reduction.

[typhoon_driver]

Ignore brushless for this application. It's not as simple as turning on and off a mosfet as with a dc motor. They also don't like being stalled or turned on and off quickly. Either on full or off for brushless. You have to remember you can't just hook them straight up to a battery to get them to work.

Stick to brushed motors for a melty brained machine

[Mega Masher]

Thanks for the replies, yes i was planning to use a gear box.
Typhoon Driver, if it HAS to be brushed, then which brushed motor do you suggest.
Archie2000, brushless is not a waste of money and i don't live in the USA.

[typhoon_driver]

Are we looking at feather or beetle?

[Mega Masher]

This is my beetleweight:


And the scorpion motors would be for my featherweight. I will plan to use 75mm Robochallenge wheels, a gearbox made by erm...me, and it will be controlled by an Arduino Uno and an Arduino Proto board onto which i will solder my own motor control circuit. I know you keep saying to go brushed, but only 2 brushed motors i know of will do the job: ampflow motor (too big and expensive), and 2 Astroflight 40 cobalt motors (extremely expensive). If you have any ideas of any brushed motors, please tell me.

[Eventorizon]

Speed 900's might do it. However they are no longer in production. People have been seeking out alternatives and have found some that are pretty much identical. I don't know what they are called but the only S900's were dam good for their size and not ridiculously expensive either at £35 each. There is a thread somewhere called speed 900's alternatives but I cant find at atm.

[Max]

viewtopic.php?p=138153
There is a topic on using brushless for drive- I don't know what ever came of the idea.
I imagine you would struggle to break and accelerate and control a brushless motor fast enough for a melty brain robot and you will probably spend a fortune on gearing it down.
If you do go for brushless then you want a very large gear ratio so the motors can spin at maximum rpm easily and so draw little current- you don't want them under high strain.
It could be a possibly to connect 2 motors together but that also has its problems, for instance 2 gimson motors per wheel

[typhoon_driver]

And you are able to control a 3 phase motor?

http://www.active-robots.com/motors-whe ... 0-150.html

Or if you want a really powerful cheap motor then look at something like motorcycle starter motors. Although these will draw large currents.