On Monday, January 24, 2011 11:00:38 pm cogoman did opine:
> On 01/23/2011 02:14 PM, [email protected] wrote:
> > Yes on the surface this looks like an esc project. However the fact
> >
> > > that it has multiple interfaces supported such as CAN, i2c, pwm and
> > > serialmean that it can certainly send and receive the sort of data
> > > you are looking for.
> > >
> > > I am well aware that an esc is different than a cnc driver, however
> > > Piotr is a control engineer thus the commutation routines that he
> > > is developing are the latest and greatest in all respects. I have
> > > already discussed the idea of using it for cnc and he is certainly
> > > happy to help. The nice thing about Piotr is that he is not an
> > > amateur coder, thus adding pid loops around his various routines
> > > will not be an exercise in trying to unravel a ball of wool.
>
> If he can write code to use a shaft encoder to feedback position, and
> use that information (adjusted for 1000, 2000, 4000, or whatever counts
> per revolution) to fudge the equivalent of a hall effect sensor
> feedback, then YES, this would make a good BLDC controller for CNC.
>
> The next link shows a 6500 watt BLDC motor for around $99. That's
> around an eight horsepower motor for around $100 bucks. .130Kv times 50
> Volts gives 6500 RPM at 50V no load. I don't think you could build one
> for near that, though I've thought about that option. For bigger stuff
> you might try the armature from a vacuum cleaner motor. I've never
> tried taking one apart, but they are supposed to be universal AC/DC
> motors, so they might have laminations that would work. For the bell
> that you mount the magnets into, a stamped steel hole saw might come in
> a useable size.
>
> http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5142
>
> To give you an idea of how much power one of these motors supplies, some
> guys put 3 of them into a go-cart, and drive it through a centrifugal
> clutch. Watch the video, then look at the smiles when they come back in
> from a run!
>
> http://www.youtube.com/watch?v=vwODx028_Jw
>
Why the clutch? And its set so high that the cautious way he is driving,
that clutch will be 100% toasted in half an hour. Don't those motors have
any starting torque at all?
I don't believe it is even driving the rear wheel on the far (left) side at
all, so he is showing a lot of useless wheel spin in the right turns that
he thinks is cute. Give me a solid rear axle to drive both wheels and I
could have that rig for a low cal breakfast with a 6.1 CID McCullough
engine for power. Even at my age.
Now the other video of the 70kw kart is more along lines of what I was
driving in the early '60's. Wheel spin not quite at will, but still 25 mph
faster (on gasolene, it burnt that and booze/dynamite almost
interchangeably when I could afford the castor oil, that was even more
fun...) than the Olds 98 that towed me to get it started. No clutch, it
needed about a 15 mph tow to get that rotary valved 2 stroke to fire good
enough to pull away from that Olds. Top speed (circa 130 mph) was about the
same on either fuel because it was a deflector head engine and they run out
of breathing room at about 7700 rpm regardless of the exhaust tuning. But
it was noticeably easier to steer with the throttle in the corner when
running on booze & dynamite.
The ultimate rush, 130 mph with your butt 1.5" off the blacktop. ;-)
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Without adventure, civilization is in full decay.
-- Alfred North Whitehead
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