A bench grinder consists of powerful grind wheels that are used to carry out different tasks. The grinding wheels come in different sizes, generally from 6 to 10 inches and with varying grits for doing a variety of functions. This powerful machine can be bolted or installed on a bench or work table where the workpiece is held against the grinding wheel to allow for a varying degree of sharpening or shaping.
There are a couple of things that you’ll need to consider before you choose a bench grinder for your workshop or home. Choosing the correct wheel size is crucial as it will have an impact on the work you can do as well as the speed of operation. You may also want to consider speed variability, safety, cooling mechanisms, and more.
Key Bench Grinder Parts and Functions
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The motor occupies the middle part of the grinder, and it determines the scope of work a grinder can handle depending on the amount of horsepower. The horsepower will affect the number of revolutions per minute (RPM) that the grinding wheels will have with the average speed range being 3000-3600 rpm. Generally, the high higher the RPM, the faster you can get the job done. This is especially important when you are working on hard materials such as steel.
Also known as spark deflectors, the wheel guards helps to prevent fragments of an exploding wheel from flying towards you. When running a grinder, it tends to emit a lot of sparks and wood fragments out. Covering the wheels will help contain these fragments, and it is prohibited to run one without the guards. The guards should cover about 75% of the wheel. The guards also keep your fingers or any other object out of the grinding wheel.
This is yet another protective feature that is mounted right above the grinding wheel to make sure that the scraps do not come into contact with your face or eyes. However, you will still need to wear eye protection when working with your bench grinder.
Bench Grinder Tool Rest
The tool rest is used to hold the workpiece when grinding. It needs to be tight and within 1⁄16″ to 1⁄8″ of the wheel to prevent the workpiece from slipping down. The tool rest is also used to hold the workpieces momentarily when you need to change the wheel or adjust the speed of the wheel.
The wheel is the part that is involved in doing the real work, and they come in different types. The wheels will have the maximum RPM rating printed on the cover, which must never be exceeded. Over speeding the wheel can make it explode and cause serious injuries or death. Also, the wheels are made of different materials, and also they will have different grit to serve different functions.
Uses of a Bench Grinder Machine
Bench grinders are generally for removing quite a bit of material quickly using grindstone wheels. The grindstones typically come in different levels of coarseness. As the grindstones are used, the front edge wears out, and it may be clogged with the metal. As such, it is vital to dress your grindstone periodically for better grinding efficiency.
Also, the grinding stones that are designed for hard materials such as steel should not be used on softer materials like aluminum. This is because the metal can get lodged in the wheel and explode later with the heat of grinding. This can dislodge the grinding wheel and cause injuries or damage the machine.
While grinding, it is crucial to move the material back and forth to avoid heat buildup. Also, using a coarse grit will help prevent the metal from overheating as it will enable you to work quickly. In addition, you can dip the metal in a can of water if it starts to heat up.
2. Sharpening Metal Objects
Another primary function of a bench grinder is to sharpen metal objects. All you need is to set the right speed, preferably a slower speed, to enable you to work with more precision. It is useful when it comes to sharpening lawnmowers, chisel, saw blades, and cutting tools like knives and other household metals.
Another reason why you should run the grinder at a slower speed is that it helps to reduce the chances of overheating the edge of the tool. Many cutting tools are made of steel, and it usually is hardened by heat treatment. If you use too much heat, this can undo the heat treatment, thus exposing the softer metal.
Also, a low-speed grinder includes white grinder wheels, which do an excellent job of sharpening than their gray counterparts found in high-speed grinders.
A bench grinder is widely used for cutting hard items as well as wooden objects. The process involves holding the piece firmly onto the tool rest while rotating it towards the grinder surface gently. After the grinder makes contact with the spot you want to cut, you will be required to keep turning the material until it splits into two. Turning the piece will cutting will ensure a clean cut while also preventing the chances of catching fire, especially when dealing with wood. The material is then dipped in water to temper the hot ends and to achieve the desired smoothness.
Buffing is a standard process carried out on metal products to ensure that they retain their texture and that they don’t get blunt. This is done by ensuring regular cleaning using a buffing wheel on the bench grinder. The motor is lined with a cloth that scrubs off the dirt as the wheel rotates. When buffing, you’ll be required to dip the metal piece in water to cool it off as you continue to buff.
5. Removing Rust
Metals parts tend to rust quickly, particularly if they are exposed to humid conditions. The good news is that you can use a bench grinder to remove the rust, which can then be then followed by sharpening. To avoid damaging the tool or the material you are working on, always set the motor at a low RPM. This will also allow you to eliminate all the rust. This is particularly useful for preparing small areas for welding and other fittings. You can then increase the speed if you would like to perform other functions.
6. Shaping Objects
When it comes to shaping metal or other objects, you’ll be required to place the piece you want to carve right on top of the wheel. This should be done gradually in a back and forth motion, especially if you intend to grind off some parts off. A bench grinder will make it easy for you to smoothen up the surface of your workpiece more than other shaping tools would.
The object to be shaped should be held firmly against the grinding wheel and work slowly to enable a varying degree of shaping or finishing. It will also ensure that the material is not dislodged while being shaped. When shaping metal, ensure to dip it in the coolant frequently to keep it cool.
Polishing helps you to achieve a fine finish on your metal and wood pieces. The material to be polished should be firmly held and moved toward the wheel while ensuring that you maintain a firm grip throughout the process to ensure that the polish is evenly applied. You should, however, be careful when polishing wood material as it can catch fire easily.
Tips for Using a Bench Grinder
Select the right wheel
When using a bench grinder, you want to be accurate as possible while also be comfortable while using it. The first and most important thing is selecting the right wheel for the job. After that, you should set the right speed and guide the workpiece gently into the grinding wheel to achieve the desired results.
Set the Right Speed
As stated, you’ll need to make sure you are running the grinder at the right speed based on job requirements. When doing this, you’ll need to factor in both the wheel material and the material you are grinding. The wheel tends to overheat when working, and this can make the wheel wear or explode. Although you can use coolants to counter this, the best option is to set the wheel at a slower speed or use a bigger wheel as the bigger the wheel, the slower you need to operate.
Use the grinder upright
For the best results, ensure that you set the grinder upright and that it is tightly secured on the bench so that the wheel does not get displaced. You should also ensure that the wheel is balanced and the tool rest is in place. Clear the area of debris or any other object to ensure that there is enough space to push back and forth the material you are working on.
Use the correct angle
Always use the recommended angle depending on the material and the task you are performing. You’ll need to use a sharp angle if you want to produce a sharp edge. However, other tasks such as polishing or sanding may not require as much of an angle.
Ensure to dipping your materials in a pan filled with water to help with friction and overheating. With this, you don’t have to wait for the metal to cool down while you grind it. You can also use a rolling pan to cool the wheel as it spins, thereby cooling the tool.