[mowbot] Re: Gotta have gas to cut ??

KEN_REED nospam at hp-boise-om2.om.hp.com
Thu, 6 Mar 97 11:46:14 -0700

BAJ wrote:

--snip--
>1) Electric powered blades.
>2) Gas powered blades with a clutch - which standard lawn mowers do not have.
>For good cutting we need real power.

--snip--

Pardon me for saying so, but I'm not sure that is true.

My experiments have shown that small dc motors will cut the grass just fine.
My test cuts were done using a single dc motor, 12v nospam at 0.6 amps while cutting,
will turn a 5" aluminum disk approximately 2000 RPM. The aluminum disk has 4
X-acto knife blades sticking out 1/2" that do the cutting. The cuts were clean,
and seemed easy enough. Now bear in mind that I didn't cut overgrown grass, but
cutting off < 1" was easy enough.

My LawnBot will use two such electric motors/cutters to provide a 12" cutting
path.

Its also my recollection that the commercial robot lawn mower used such a
system, and it is solar powered. There is a link on the Mowbot Webpage to this
commercial mower.

I've also done experiments with the cutting blades on my Lawn Tractor. I
flattened them out so that there is no flip up on the ends. It turns out that
the flip on the ends takes most of the power used by my Lawn Tractor to cut.
Of course with out the flip, the grass is not thrown out into the catcher very
well, but the power required, and the sound created were reduced by about 60%.
The flip is there to move air, thus transport the clippings out of the cutter
deck and into the catcher. I tried pushing my Lawn Tractor while mowing to find
out how much power is used to move the tractor. The power used to move the
tractor is minimal compared to that used by the cutting blades. What I learned
from all this is, don't move the air with the cutter assembly.

This is why I'm using a flat aluminum plate to hold the cutting edges. It uses
the least amount of power to move air, and thus cuts very well using only a bit
of electrical power.

Has anyone else done cutting experiments??


bye for now
ken reed
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