Whether you're heavily into your DIY and are merrily slicing through metal sheets, bolts, and bars to knock together your own furniture, or managing an enormous steel manufacturing project where the end product is a ship, the main issue will always be how best to cut through the metal. Taking into account factors such as the thickness of the metal and the precision required, it's important to choose the right machinery for your needs.
Traditional techniques include the metal-on-metal approach, where screeching noises from the rotating blades and flying shards of metal create a pretty unpleasant and dangerous workspace. Additionally, the final cut will require smoothing on the edges, which can further reduce the accuracy in size and shape, often crucial when fitting pieces together.
Laser cutting is a modern technique offering greater precision and energy efficiency when applied to sheet metal, but can prove expensive on thicker metal with high power consumption in relation to the work done. It's also very sensitive to external disturbances and the process risks being halted mid-flow unless the parameters are constantly monitored by human operators.
This is where the slightly futuristic sounding, yet well established plasma cutting technology holds its own, offering near-laser precision through any conductive material, up to 50-mm in thickness. So how does an intangible physical state provide a tool for cutting through an extremely solid element? Put simply, an inert gas is blasted at high speed from a nozzle (thickness varies) with an electrical arc running through it and connecting to the target material surface. The extreme heat melts through the metal and the speed of movement blows molten metal away from the sliced edge, meaning that little or no finishing is required. The increased accessibility and size of plasma cutting machinery mean that home hobbyists can just as easily get their hands on the perfect metal cutting tool as the industrial steel workers.
Note that using a plasma cutter still requires strict safety precautions, such as leather gloves and aprons, hearing protection, and eye goggles to protect from debris and limit the risk of "arc eye," which is similar to snow blindness, resulting from the overexposure to UV rays. Finally, with any plasma-cutting machinery purchases, it is recommended to assure ongoing servicing and maintenance from the supplier as such complex equipment should only be tampered with by the professional engineers.
Emily Banham holds a 2:1 BSc Physical Geography (International) from the University of Leeds.
But when I needed a beer brewing kettle (I forget what they are called) I used a saber saw to take the top off a discarded keg. I used the same saw to round some corners on wood shelves the other day. To the point, I have two ten year old boys. I am not teaching them about bandsaws or plasma, everything today is vacuumed bagged and mostly carbon fiber. Although I must say a carbon fiber bridge, now that may not fly.
Yes, CNC plasma cutter prices are out of this world. I am surprised someone hasn't taken those portable plasma cutters ($500) and combined it with a CNC router (some at $500 as well). Perhaps it is due to the frightening accidents that could happen? Or the routers not able to withstand the heat? I don't think I would want to use a DIY/hobbyist made CNC plasma cutter for those reasons.
I guess I'm about to qualify as a serious hobbyist. You can tell by my tag what one of my hobbies is.
In street rodding, plasma has become the preferred cutting method, especially for sheet metal. The minimal heat distortion and accuracy reduce the amount of 'massaging' needed to realign the metal. This is particularly important when chopping or sectioning the body.
As it looks like I'll be 'slicing and dicing' a '32 Chevy sedan next, it's time for me to buy a plasma cutter.
I have not experienced significant distortion when making plasma cuts. Quite the opposite. The plasma jet is *so* hot and so localized that the work material is liquified and blown out of the cut before the remainder of the work piece can be affected. Anything that touches the plasma is removed, and anything not touched by plasma is left behind. Overall heating of the piece is much less compared to cuts using an oxy/fuel process. On thinner material (<1/4") you can *almost* handle the pieces within a few seconds of completing the cut, though obviously that is not recommended practice. The kerf (width of cut) is also significantly smaller than with oxy/fuel, and the cutting time is less as well.
For what it's worth, the History Channel has a Modern-Marvels episode where they show 3" steel plate being cut by robotic plasma cutter at the Newport-News shipyard. The plate is actually submerged under water to suppress the fumes and ensure there is no thermal distortion, which would be impossible with an oxy torch.
While this method sounds like it has promise, one thing stuck in my mind. The plasma stream is energized and creates heat. Is the heat high enough to distort the workpiece? If so, this would affect the aciracy of parts produced by this process.
While this method sounds like it has promise, one thing stuck in my mind. The plasma stream is energized and creates heat. Is the heat high enough to distort the workpiece? If so, this would affect the aciracy of parts produced by this process.
Aside from the quite toxic fumes, which I had not considered, a plasma cutter is quite hazardous due to the very high temperature plasma, which is able to deliver a whole lot of heat energy to almost anything almost instantly. So while they can produce very good cuts, it is mandatory to keep in mind the whole process at all times. There are lots of ways to get into trouble very fast when using a plasma cutter. This article did address a few of them.
Cabe; I haven't found a Laser cutter anywhere near the 'affordable' range for a home hobbyist or a small shop. Plasma works well, but is fairly expensive, it only works where there is power and compressed air, and it only cuts. I've gone back to oxy/acetylene. I use it for cutting, heating, brazing and occasionally welding where power isn't available. The edges always need grinding using hand held Plasma or oxy. The major benefits of plasma are the ability to cut stainless, starting holes in the middle of a sheet or piece of pipe, the narrow kerf, relatively clean cut and less heat distortion. If I was running a shop, I'd use plasma for every possible cut but as a hobbyist I can't justify the space or cost.
In the past several years, economical rigs from Hypertherm, Miller, and others have started to make plasma-cutting affordable to home/hobby users. I have a 60-Amp unit that works fine on plate steel up to around one inch. One safety consideration that new users must not forget is a good respirator. Even when cutting ordinary steel, the plasma process produces a fog of microscopic rust particles that is miserable to breath. Users should visit their local welding-supplier and consider purchasing a disposable N95 welding-fume respirator. I wear eyeglasses so I prefer a respirator with a valve (eg 3M #8515) so moisture does not fog my lenses when I exhale. If I cut any galvanized steel, then I also rely on the welding respirator to filter out any zinc particles which are known to cause "metal fume fever" if inhaled. Anyone cutting stainless steel should be aware that the plasma process creates "hexavalent chromium" particles, and anybody who saw the film "Erin Brockovich" can relate to what chromium-six does to people, so stainless-cutters will want to have respirators that are rated for hazardous materials such as chromium. I use a 3M #8212 in this case. I have listed my personal preferences (from 3M) but several other manufacturers offer suitable products as well. I buy them in small quantities from my local welding supplier for under $20 each, a small price compared to the expense of treating bronchitis, or worse, cancer.
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