Motorsport Fabrication Fundamentals: Bench Grinder
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Bench Grinder
04.21
| 00:00 | - The bench grinder is a staple tool in just about any decent workshop. |
| 00:04 | This indispensable item is sometimes also known as a pedestal grinder when mounted on a stand free of the bench. |
| 00:11 | The bench grinder has remained almost unchanged for the last 50 years and uses an electric motor to rotate 2 grinding wheels on either end which can then be used to remove material or polish components depending on the specific wheels fitted. |
| 00:25 | They're available in a series of different sizes ranging from small hobby grinders at 100 mm through to large industrial machines measuring more than 300 mm in diameter. |
| 00:35 | The size reference is the diameter of the wheels that fit to either end of the spindle within the standard sheet metal guarding. |
| 00:41 | Like an angle grinder, we must retain the factory metal guarding as this ensures the correct sized wheel is used on the bench grinder. |
| 00:49 | Running a wheel larger than the wheel the machine was designed for can have catastrophic implications as the RPM limit of the larger wheel may be exceeded if run on a smaller bench grinder. |
| 01:00 | Attached to the sheet metal guarding will be a clear eye shield and a tool rest and before using a bench grinder it's extremely important to have a brief check that the wheels are in sound condition. |
| 01:10 | An overloaded wheel can cause it to heat up and expand, resulting in cracking of the bonded stone. |
| 01:16 | Cleaning a grinding wheel is called dressing the wheel and this is the process of removing a small amount of material from the wheel in order to expose a fresh and straight cutting surface. |
| 01:26 | Tools to do this come in a few different styles, the first being a sintered diamond dressing tool that uses an exremely abrasive face, pressed up against the running grinder to wear away the grinding disc and expose fresh grinding material. |
| 01:40 | The second is a rotary wheel dresser and this uses a consumable hardened steel wheel that's mounted at 90° to the handle and is run backwards and forwards across the grinding disc. |
| 01:50 | It's important to note that the process of dressing a wheel also trues the wheel, removing any ridges that may have formed in the wheel surface and this can also eliminate nasty vibrations from coming through your machine. |
| 02:02 | Once the surface of the wheel is prepared, we need to reset the tool rest so that it's within 1-2 mm of the wheel surface. |
| 02:10 | This helps prevent anything becoming jammed between the grinding wheel and the tool rest. |
| 02:15 | If you don't know what wheel is attached to your grinder then it may be a good idea to remove the guard and inspect the product information located around the mounting spindle. |
| 02:24 | Most grinders will be sold with a universal wheel that's made from vitrified bonded aluminium oxide which is ideal for general use on ferrous metals like mild steel, cast iron and stainless steel. |
| 02:35 | Something to note here is that bench grinders aren't designed to remove non ferrous metals like aluminium because the RPM is far too high and the wheel is incapable of clearing out the build up. |
| 02:46 | Using this style of grinding wheel with aluminium will quickly clog the surface of the wheel, rendering it useless until the surface is dressed and clean again. |
| 02:54 | This actually can also be quite dangerous as the heat that is built up during grinding can cause the material clogging the stone to expand which in turn can cause the stone to crack and even explode at high operating speeds. |
| 03:07 | It's a good idea to have two different grinding wheels on each side of your bench grinder. |
| 03:12 | For instance, we have a universal grinding wheel on one side for various grinding tasks and then a finer grit silicon carbide wheel on the other for sharpening specialty tools like drills. |
| 03:22 | Keep in mind that a bench grinder won't necessarily have to use a stone wheel for grinding, there are other attachments that'll allow for various other tasks to be performed. |
| 03:32 | Wire wheels are a popular addition to many bench grinders, making it easy to stip and clean your work piece. |
| 03:37 | These wheels are available in a number of different grades that can roughly strip or gently finish your work piece depending on your desired results. |
| 03:45 | Another popular addition to a bench grinder is a buffing wheel which is made up of a soft material and can be used for polishing. |
| 03:53 | These are available in a number of different grades that allow us to start by roughly polishing the material and the move to a finer grade buffing wheel to finish the part. |
| 04:03 | As you can hopefully appreciate, the bench grinder is a fairly universal machine that can be used for many different tasks and it's not uncommon to have multiple bench grinders in the workshop, permanently set up for different tasks, such as buffing, polishing, sharpening and grinding. |
