There is something of a zen-like quality to forcing hardened steel to bend to your will. Welders and metal workers have some of the most intriguing jobs in the world today. These folks work with materials which will stop most bullets today, bending, twisting, and joining; they seemingly create life from lifeless metal. How they create is unique to each worker, so there is no “only way” to transform those box beams from sticks to a rigid trailer frame capable of hauling farm equipment. While there are general rules, of course, if you speak to ten welders, you’ll get ten approaches, each unique in its own way. So, how do you analyze what’s best for the general field when there are so many opinionated DIY’ers out there? Simple. You give your opinion. This is my opinion on the best angle grinders for welders.
Angle Grinders (aka Side Grinders or Disc Grinders)
Angle grinders are standard tools used in welding and most all metal working. These power players of the metal-transforming world remove material and rust, smooth welds, and polish surfaces in preparation for painting. Their use is dictated only by the disc being used, making their versatility an invaluable asset when performing metal work.
They come in varying sizes and amperages, from 4-inch to 12-inch, and from 5-amp to 15-amp. The larger the amperage requirement, the more likely we’re talking a larger grinder. The larger the grinder, the more likely you’re working with large, thick metal plates. In 99.9% of DIY cases, we’re only going to need a 4-1/2” angle grinder in the 6 to 10-amp range. If you’re welding thick steel plates, the 7 to 9” sizes at 15-amps will be the go-to.
What to look for
First and foremost, a spindle lock is essential. This feature allows the user to lock the spindle in place while changing the disc. If you’ve ever changed one without it, you’ll understand why most consider this to be an absolute necessity when considering a new angle grinder. They’re almost standard now, but make sure it’s there before you buy.
Second, what size do you need? 4-1/2” is the most common disc size out there, followed by 4”, then 7” and 9”. If you go with a 5” or 6” angle grinder, be prepared to find Waldo when searching for discs without special ordering or visiting a specialty metal shop. They can be quite difficult to find in a pinch, so when you get discs, save them and keep that stock up.
Third is arbor size. As with circular saw blades, grinding discs have arbor sizes, with most being in the 5/8”-11 range (the “11” being the thread count for threaded holes). That said, there are some off-brands which carry “special” arbors. This translates into “special” discs needed, and that means “special” costs. For simplicity, stick with standard arbor sizes of 5/8” and 7/8” bore. 5/8” will usually be threaded (as stated earlier) and 7/8” bore will usually be smooth. The smooth bore discs will fit a 5/8” arbor due to the washer holding against the shoulder of the disc. Beware of metric (M10 and M14). They’re rare, so beware.
What to watch out for
First things first: price. Just because it looks like a steal at $15 doesn’t mean it’s a good deal. These are usually very cheaply made with very cheap materials. They’ll burn up on you the first time you sharpen those mower blades. Buyers beware.
Secondly would be the weight. The larger grinders are, by nature, heavier. If you’re going to be grinding for any length of time, you need to consider your own stamina. You have to balance the needs of the job with the practicality of the tool. A 15-pound 9” angle grinder being used to brush some rust off a trailer fender is likely not the best tool for the job. Consider the toughest job you may encounter and work backwards from that point. More than one grinder may benefit you.
Third warning is the amperage draw. A 15-amp, 9” grinder may trip that 20-amp breaker in your garage upon startup due to the initial power load. You might need to switch the breaker out for a 30-amp or wire a new circuit. Again on this note: do you have a need for a grinder that size? If so, make sure you’re prepared.
Best Angle Grinders I like
When it comes to metal working, I like to at least attempt to cover all our bases for the DIY crowd. While the professional metal workers in the audience will already know the majority – if not all – of this information, I’m geared to the DIY’ers who are just looking for a little advice.
General metal working
I suggest the Makita 9557PBX1 for jobs like sharpening mower blades, removing light coats of rust, cutting tin or other thin metal, grinding down edges of thin steel plates in preparation for welding, and general smoothing/polishing of smaller metal surfaces in preparation for painting.
- 7.5-amp motor
- 4.5 lbs in weight
- Switch locks on for continuous operation
Heavier metal working
I recommend the DeWALT D28499 For jobs such as grinding thick steel plate edges in preparation for welding, removing large areas of mill scale or thick rust, cutting thick steel I-beams, polishing/burnishing large metal plates in preparation for painting
- 15-amp motor
- 15 lbs in weight
- Tool-free guard adjustment
- Rotating rear handle
- Automatic shut-off feature when the brushes need to be changed
What about the discs?
Every grinder is only as good as the disc being used. When it comes to discs, there are two roads of thought: cheap and reliable. The cheap road is usually best used by the DIY’er with only the most occasional call for use of an angle grinder. The reliable road is the road less traveled, and usually only by those with a need for regular use of their grinder. When shopping for discs, do you just want to get it done, or do you want to keep the disc forever? In our experience, even the cheapest discs have some use, but be warned:
Discs have been known to come apart! Inspect your disc carefully before use. When your grinder is spinning at 6,000 rpm or higher, the danger presented by an exploding disc can NOT be overstated. Cheaper doesn’t equal better if your budget is destroyed by a hospital stay!
Grinding discs are the general-use discs seen on most angle grinders. They come in varying grits, just like sandpaper. Be aware that the lower the grit, the larger the chunks of metal coming off your workpiece. While the job may get done quicker, your skin may not like the hot metal chunks flying around.
Flap discs are used for sanding metal, removing sharp edges and burrs from metal cuts, and chamfering metal edges. Again, they come in varying grits, like sandpaper.
Cutoff wheels, as their name implies, are for cutting metal. They are thin, so they are NOT used for grinding. They’re meant to cut metal just a saw blade would, though the use of an angle grinder for this purpose is not recommended. While it’s possible for the angle grinder to do the work, the DIY’er should use every precaution in preparation for the work. This is the most dangerous wheel for an angle grinder. Being thin, it is more likely to shatter and send chunks of brittle wheel flying in every direction.
Wire wheels, usually with threaded arbors, are best for removing surface rust and paint. Their cousins, the “rose bud” wire cups, remove mill scale extremely well. Thick, twisted bristles are best for removing rust and paint quickly.
If you’re going to be doing any metal working with an angle grinder, wear your safety equipment! As mentioned a moment ago, some discs have been known to shatter when used. The shrapnel is just as dangerous as any found on an active battlefield. The following safety equipment is absolutely invaluable when it comes to use of any angle grinder.
Safety glasses – wrap around and shatter proof. Protect those peepers!
Face Shield – indirect vents, clear lens, and rated for high impact. Protect that mug of yours, too!
No bystanders – send the kids in the house and put the dog away. Don’t take chances with those you love!
Take care and use your head when choosing the size of your angle grinder. Don’t overthink the work you’ll be performing and always, ALWAYS work with safety in mind!