The best sanding discs for rotary tools are those that offer durability, versatility, and efficiency for various applications. Here are some top choices: 1. **3M SandBlaster Discs**: Known for their high-quality abrasive materials, these discs provide excellent performance and longevity. They are ideal for heavy-duty sanding tasks and are available in various grits. 2. **Dremel EZ Lock Sanding Discs**: Designed specifically for Dremel rotary tools, these discs feature an easy-to-use locking mechanism that allows for quick disc changes. They are suitable for detailed work and come in multiple grit options. 3. **Diablo Sanding Discs**: These discs are known for their premium ceramic blend, which offers superior cutting efficiency and durability. They are excellent for both wood and metal surfaces and are available in a wide range of grits. 4. **Norton ProSand Discs**: Featuring a premium aluminum oxide grain, these discs provide fast material removal and a consistent finish. They are designed for long-lasting performance and are suitable for various materials. 5. **Gator Finishing Discs**: These discs offer a good balance of performance and affordability. They are available in multiple grits and are suitable for general-purpose sanding tasks. 6. **Bosch X-LOCK Sanding Discs**: These discs are designed for quick and secure attachment to Bosch X-LOCK angle grinders. They offer high performance and are available in various grits for different applications. When selecting sanding discs, consider the material you are working with, the desired finish, and the compatibility with your rotary tool. Opt for discs with a hook-and-loop backing for easy attachment and removal, and choose the appropriate grit for your specific task.

1. **Select the Right Drum and Mandrel**: Choose the appropriate sanding drum size for your project. Ensure you have the correct mandrel (the shaft that holds the drum) that fits your rotary tool. 2. **Prepare the Rotary Tool**: Unplug the rotary tool or remove the battery to ensure safety. This prevents accidental activation while attaching the sanding drum. 3. **Insert the Mandrel**: Locate the collet nut at the end of the rotary tool. Press the spindle lock button to prevent the shaft from turning, then loosen the collet nut using a wrench or by hand. 4. **Attach the Mandrel**: Insert the mandrel into the collet. Ensure it is seated properly and straight. Tighten the collet nut securely while holding the spindle lock button to keep the shaft from rotating. 5. **Attach the Sanding Drum**: Slide the sanding drum over the rubber drum of the mandrel. Ensure it fits snugly. If the drum is loose, tighten the screw at the end of the mandrel to expand the rubber drum, securing the sanding drum in place. 6. **Check Alignment and Security**: Ensure the sanding drum is aligned properly and securely attached. It should not wobble or slip when the tool is in use. 7. **Test the Setup**: Plug in the rotary tool or reinsert the battery. Turn it on at a low speed to test the attachment. Check for any wobbling or unusual vibrations. If everything is secure, you can increase the speed as needed for your project. 8. **Safety Precautions**: Always wear safety goggles and a dust mask when using the rotary tool with a sanding drum to protect against dust and debris.

For wood sanding, the choice of grit depends on the stage of the project and the desired finish: 1. **Coarse Grit (40-60):** Use these for initial sanding to remove roughness, old paint, or varnish. They are ideal for shaping wood and removing material quickly. 2. **Medium Grit (80-120):** These are suitable for general sanding purposes. They help smooth out the surface after using coarse grits and prepare the wood for finishing. An 80-grit disc is often used after the initial rough sanding, while 120-grit is good for final smoothing before applying a finish. 3. **Fine Grit (150-180):** Use these for the final sanding before applying a finish. They help achieve a smooth surface and are often used between coats of paint or varnish to ensure a smooth finish. 4. **Very Fine Grit (220-240):** These are used for sanding between coats of finish to remove any imperfections and ensure a smooth, even surface. They are also suitable for final sanding of softwoods. 5. **Extra Fine Grit (320 and above):** These are used for ultra-smooth finishes and polishing. They are typically used on hardwoods or for final touch-ups on high-gloss finishes. Start with a coarser grit and progressively move to finer grits to achieve the best results. Always sand in the direction of the wood grain to avoid scratches.

Yes, rotary tool sanding discs can be used on metal. These discs are designed to sand, grind, and polish various materials, including metal. When using sanding discs on metal, it's important to select the appropriate grit size for the task. Coarser grits (e.g., 40-60) are suitable for removing rust or paint and for shaping metal, while finer grits (e.g., 120-240) are better for smoothing and finishing surfaces. When using sanding discs on metal, ensure that the rotary tool is set to the correct speed to avoid overheating the metal or wearing out the disc prematurely. It's also crucial to use the right type of disc material, such as aluminum oxide or zirconia alumina, which are effective for metalworking. Safety precautions should be taken, including wearing protective eyewear, gloves, and a dust mask to protect against metal particles and dust. Additionally, ensure the workpiece is securely clamped to prevent movement during sanding. In summary, rotary tool sanding discs can effectively be used on metal for various applications, provided the correct grit, disc material, and safety measures are employed.

1. **Safety First**: Unplug the rotary tool or remove the battery if it's cordless to ensure safety. 2. **Locate the Collet Nut**: Find the collet nut at the end of the rotary tool. This is the part that holds the sanding drum in place. 3. **Press the Shaft Lock Button**: Most rotary tools have a shaft lock button near the collet. Press and hold this button to lock the shaft in place, preventing it from rotating. 4. **Loosen the Collet Nut**: While holding the shaft lock button, use a wrench (often provided with the tool) to turn the collet nut counterclockwise. This will loosen the collet and allow you to remove the sanding drum. 5. **Remove the Old Sanding Drum**: Once the collet nut is loose, pull out the old sanding drum from the collet. 6. **Insert the New Sanding Drum**: Take the new sanding drum and insert its mandrel into the collet. Ensure it is seated properly. 7. **Tighten the Collet Nut**: While still holding the shaft lock button, use the wrench to tighten the collet nut by turning it clockwise. Make sure it is secure but avoid over-tightening. 8. **Check the Drum**: Ensure the sanding drum is firmly in place and does not wobble. It should be straight and secure. 9. **Test the Tool**: Plug the tool back in or reattach the battery. Turn it on briefly to ensure the sanding drum is properly installed and rotates smoothly. 10. **Ready to Use**: Once confirmed, the rotary tool is ready for use with the new sanding drum.