What features should you look for?
Not all grinders are created equal when it comes to safety. About the only thing that’s standard on a grinder is the guard. And even then they’re different between manufacturers and models. OSHA says that a guard on a grinder is a requirement. There are exceptions to this rule, but for the most part you’re not likely to encounter them in everyday use. You can read about the requirements here [OSHA 29 CFR 1910.215 – Abrasive wheel machinery] and here [OSHA 29 CFR 1910.243 – Guarding of portable powered tools]. If a grinder doesn’t have a guard, it is to be taken out of service until it is repaired, i.e. a guard put back on it. The thing to look for in a guard is ease of use. A guard that’s hard to use will be more likely to be removed and not put back on. Some of the better grinders have guards that are easily adjusted by hand. And they stay in that position until you move them. Others require tools to position them, or move after you’ve positioned them by hand. There is a huge variance in quality of the guards between manufacturers. There isn’t much that’s more annoying than having to stop every few minutes to readjust a guard, not to mention unsafe.
One of the best safety features I’ve seen on a grinder is a safety clutch. As an example, I often use .040″-.045″ cutting wheels. These are excellent wheels for slicing through sheet metal or pipe, and when the conditions are perfect, they work very well. But the problem with them is that they’re prone to binding in the metal as you’re cutting. When this happens, it’s immediate and the grinder starts to rotate instead of the cutting wheel. This is a very dangerous situation known as kickback and it happens rather abruptly and violently. Especially if you’re not expecting it or not used to it. A safety clutch greatly reduces this and lessens the danger considerably. I’m really surprised that it’s not an OSHA requirement yet. I expect sometime it will be. It’s saved me hundreds of times.
Another great feature, although not very common yet, is the blade brake. Much like the brakes on wood miter saws, the blade brake stops the blade shortly after the power is shut off to the grinder. This is another feature that should also be an OSHA requirement. Since most grinders spin up to such a high RPM, the inertia of the wheel keeps them spinning for quite awhile after you shut them off. When you shut the power off, you often let your guard down, and can easily get nicked by a spinning wheel. It’s a pretty new feature, and I’ve only seen it on a few of the Metabo grinders.
Paddle switch or regular switch? I’m not a fan of paddle switches at all. As a matter of fact, i hate them. Some people like them, although i can’t understand why. There is usually a safety built into the paddle switches. A little spring loaded arm that stops the switch from being depressed. This is usually the first thing that breaks. Then, all you have to do is brush against the paddle switch to start the grinder. They also seem to require a more deliberate grip on the grinder. I’ve found that squeezing the paddle while holding on to the grinder wears out my hands sooner than a trigger switch or thumb switch. It’s harder to finesse a cut when you’re required to hold a grinder a certain way. If you’ve ever needed to prep a field weld, way up in the air for instance, you’ll understand this. I also can’t recall any paddle wheel grinders that you could lock on. Although this may have more to do with the way that i deliberately try to avoid them. With a thumb switch or a trigger you have the ability to lock it in the on position. This comes in really handy if you’ve got a lot of grinding to do. Your hands will get tired much sooner if you have to squeeze it constantly.
Variable speed is another feature that’s found on a few different grinders. It would be very useful when using a grinder as a buffer or polisher, since they require much lower operational speeds. There are also some wheels that require a slower speed, and metals that cut better at slower speeds. It’s a nice feature, but for normal use it’s not an absolute requirement.
On the electrical front, another great feature is soft start. This lets the grinder slowly ramp up to speed as opposed to starting at full power. This practically eliminates jerky, abrupt starts that can be dangerous. It also limits the inrush current to the motor helping to extend the life of the grinder. It’s a great feature that I’d highly recommend.
Ergonomics. A grinder is something you’ll become intimately familiar with. It’s completely hands on, and because of that you should be sure that you like the feel of the grinder. If it’s not comfortable to hold on to, you’ll hate using it. Grinders have come a long way in the past 20 years when it comes to fit and ergonomics. When they first came out, ergonomics were an afterthought. Today they’re smooth and contoured, and much consideration has been given to the feel. Something that’s comfortable to use and doesn’t tire you out quickly is inherently much safer to use. Along these lines, something you should pay attention to is the smoothness of a grinder as it runs. As an example, if you’ve ever used a cheap grinder, you’ve probably noticed how noisy they are and how much they vibrate. A good grinder doesn’t sound like it’s going to blow up, and is smooth and vibration free. Vibration will tire you out quickly and over the long term can damage your hands.
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