h a l f b a k e r yExperiencing technical difficulties since 1999
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Had to trim the hedge the other day. Being a perfectionist, I spent hours trying to get it *exactly* straight, level and square. Ho hum.
That gave me plenty of time to think about better ways to do it. Like having rails and moving blades and a...no, wait - level, straight, square? It has to be a laser-level!
High-powered (or high enough to singe off the sticky-up bits), on a levelled tripod - aim, fire it up, and sweep the beam across the top of the hedge - there, perfect!
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I always thought hedges looked stupid (or fake) when they were perfect. I would think that a laser that could cut a hedge would do a number on everything around: you, the neighbors porch, the cat... |
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Why not use a couple of poles and a string? |
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Ah, MoreCobewell, why do you always have to simplify the halfbakedness out of it? Poles and strings for topiary uses are already baked, and already a pain in the posterior. |
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Poerhaps a couple of poles and some monofilament razor wire at least... but that would not be laser topiary. |
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This idea has a lot of potential for simplifying my life. Granted, a bush trimmer might work just as well, but that is not so exciting. |
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Before Laser topiary can get off the ground, a few serious issues must be looked into though. Namely, avoiding ignition of the bushes, and preventing damage from stray shots. |
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A hacksaw shaped device with a mirror on one end to send the laser back into it's output, or to some other safe point might be wortwhile to prevent stray shots. Adding a water sprayer could prevent this from making burning bushes... if that turns out to be a problem. |
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Just for safety, you might also design the laser to specifically target cellulose, or some other plant material, so that when I'm working too close to a rough wall, or my arm, or the neighborhood pet... well, you get the idea. |
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An obvious idea, really. Cutting a straight line? Use a laser. |
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To make this anything but a wish, it needs to have some hint of how to make it work. For instance, vegetation looks brighter in infra-red photos, so we know an infra-red laser would reflect. Obviously, a green laser would reflect also, as plants reflect green light. Therefore, an ultraviolet laser would be best for this cutter. See? |
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That isn't right, by the way, but at least it makes an attempt at halfbaking an invention. Until this "idea" has something more than a wish, I'm fishboning. |
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...maybe he meant *razor*? |
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high powered laser on a tripod. Now, Bring me a shrubbery! And be careful with the laser! |
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So we can get the two level effect with a little path running down the middle. |
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Did I say laser? I, of course, meant A Herring! |
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Yes [baconbrain], it does need a bit more detail, sorry. |
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As [ye_river_xiv] said (thanks), with cellulose peak absorption (at 680 and 700nm), a ruby laser (at 694nm) would be the closest, but I suspect not available at a suitable power. Possibly krypton ion (see link), Nd-YAG, but certanly CO2 lasers with sufficient power are available - but down in IR wavelengths |
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I'm not sure that wavelength would be critical, as you just need heating rather than excitation. A visual wavelength would be an advantage, so you could see where the beam was. |
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You're probably going to need something fairly high powered. Laser cutting machines for woods and plastics output typically 50W, focusing the beam down to around 0.2mm, which gives about 1.6kW/mm^2, but that can cut through tens of millimetres of wood. For a laser with a raw (unfocused) beam diameter of 1mm and divergence of 1mrad (which seems typical) that would mean a 3kW+ device to cut the hedge over a range of a metre. That's well within the range of industrial cutting lasers - but would need a seriously hefty power supply, and water cooling too. |
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As for setting up - a mirror placed at the back of the hedge, deflecting the 'unused' beam into the ground (oops, sorry worm!), and the laser head placed on a tripod, or something else, that allows you to set it level, and pan the beam across the top of the hedge. |
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Oh, and a hose to put out any fires - best to spray the hedge first, to damp it down a bit too. |
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Ofcourse, you could use a computer-controlled galvanometer mirror, to carve your hedge into pretty shapes, instead of boring old 'straight'. |
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YEAH! now you're halfbaking! |
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I don't know about sending the beam to the ground... Might vitrify it, or mess up the cement a little. |
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Better than hitting the stucco of my house I suppose, but you'd want to aim that end too if you did it like that. |
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I have a privet hedge on my property.. a big one. This sucker is about 70 feet (22.5 meters) long, about 7 feet (2.2 meters) high and 5 feet (1.5 meters) wide. It takes me 3 to 4 hours to cut it with a electric trimmer. Each time I cut this monster, I design and build the laser cutting system described above in my head. If you build one some day, I will buy it... really, I will… a bun for you |
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