Following lengthy deliberations, our expert panel has agreed that our advanced robotic lawnmower shall henceforth be known as the Genuinely Autonomous Garden Assistant – or GAGA – and it gets a sidekick too. That sidekick takes the form of a blade-testing runabout to which we can fit a variety of blades in order to show us how …
how about.......this blade? http://www.fightingmaster.com/actors/snipes/photos/snipes.jpg
A "sinning blade"?What has it been up to?
GaGaPaint It PINK and call it Lady...
OrEnsure it's radio controlled, and call it Radio GaGa. Y'know... where she stole, sorry, took inspiration for her name.
Why not a decent drum mower?Don't just go with the wee wires, use what real people use, out in the meadow: A drum mower that will leave your cut grass conditioned for haymaking. Or if you feel a bit more concerned for fleshy things (even of the small furry kind), try a rake cutter. Bl**dy effective and doesn't easily get stuck. The tricky bit will be to stear well clear of auntie Gertrude's tulips, though! :->
Bah!An electric drill won't spin the strimmer (US "weed whacker") cord fast enough to be of any use. Have any of your "technologists" actually ever *mown* a lawn? I would have thought that such experience would be a quick way to eradicate idiotic options like spinning weed whacker cord with a Ryobi 18v electric drill and expecting a result. Tsk. Must try harder.
Most efficient cutI've used six different cutting heads: rotary plastic blade or string, rotary metal, flail metal, cylindical reel, rotary metal with small swinging blades (essentially a giant string trimmer with five 1/2 meter heads and three 140mm blades on each,) and sickle bar. The last two are the most efficient, but the sickle bar suffers from weight. The plastic blades on the string trimmer work very well, and should be sufficient for one or two mowings of a home lawn before needing replacement. I recommend two heads in echelon to provide coverage without greatly increasing weight. Our Worx 18 volt cordless trimmers provide about 45 minutes of run time, and their Ni-Cad batteries are very inexpensive from the factory. If Worx is not available, Ryobi's are about the same price, probably from the same factory. My wife also made horse hay for two summers with a sythe!
Bill Ray is mounting blades to a wooden test rig. If you send your wife over I'm sure he'll do his best to mount her too.
3D printing?Why don't you work up prototypes by 3D printing? e.g. http://www.bbc.co.uk/news/technology-16503443. Surely that is a more future-driven approach for any project you undertake? When you finish, you can publish the design, and anyone will be able to make one...
Test bed needs a few gears!You'll probably want to gear the test bed up a fair way as I'm not convinced your drill will spin it fast enough for a really good cut.
2 counter-rotating metal plates with teeth cut in them. For a start, use table saw blades.
It would be simpler than a scissor mechanism but would only require rotational motion, not the more-complex reciprocating.
Or for additional safety, only the bottom plate rotates, providing some protection against feet getting into the cutting surface.
This also benefits clipping elimination, since all the clippings are on top of the blade for easy collection.
I recall a sci-fi story where some youngsters were getting into rocketry and because of their budget they used highly polished steel as a mirror since it was cheaper to replace that than to replace the camera. Gives you the option to mount the camera above the board yet still watch the action.....
And so much simpler than, say, an actual mirror....
An electric drill in a bag lady cart?? Seriously?!?
And the drill doesn't even look like it's cordless!!
I expected more from the Special Projects Bureau! Like maybe a laser-based mower or genetically-mutated goats or something.....
I can see it now:
You've made a very good point in jest. You don't actually *need* a power-hungry, noisy robotic lawnmower if you keep a goat (or a sheep.) That would make for a fairly boring SPB report though, so please do continue along the incredibly dangerous course you've started on :)
No way that horrible little box is going to work with a mulching blade - the cowling needs to be tight against the blades so that enough lift is generated to make the cut ends fly up a few times to get recut. Seconding what other commenters said too - it's never going to run at the right speed and the right torque. I've got 5 bucks on the drill motor catching fire the first time you put a real man's mower blade on it.
This isn't really rocket science - start with a regular gas mower, take off the handle, and then spend your robotics knowledge on how to steer it. Personally, I'd start with a small riding mower instead of a push model - easier to rig up servos, and even the smallest one has lots of cutting power.
Don't even think about electric mowing, you'll never be able to carry enough batteries to get a decent run time, once you've mounted a motor big enough to spin the blade right. Electric mowers just plain suck, even for a small lawn.
Will you be trying two or three blades in combination?
I would have thought something like a sharp metal or plastic blade or two at cut height and a strimmer-style blade above at 90 degrees could provide some "mulching" without resorting to fancy blades. Or for safety you could even go for blunt-ish plastic blades at the bottom then a strimmer wire then some metal for mulching?
I do echo the sentiments above about rotation speed though. Wouldn't a modified cheap strimmer make a better testing rig?
If we are gunning for power tools
If the drill aint going to be fast enough how about a couple of circular saws or angle grinders. Maybe a bench cross cut saw canabalised, comes with a nice big blade as well and the slide action may come in usefull for covering a wider span in one pass.
5 blade laser
How about a laser that points across under the mower from left to right, then is reflected by a tiny mirror slightly forward and slightly upward, repeat as needed to mulch the grass. It would cut the grass long then shorter and shorter with the different passes of the laser.
I don't know how powerful the laser would need to be, but I heard that a DVD burner laser is powerful enough to start fires if used (im)properly.
You can pay me in eBeer :)
For the video...
... you could try with Aee MD80s...
As a cutting implement, the Scythe is still unbeaten.
The blade is only part of the equation for a mulching lawnmower. The shape of the mower chassis has a large effect on how the grass blades are lifted, cut, and chopped.