Cleaning old tools nowadays is not problematic. Do you want to extend the life of your old tools and make them look like new again? CNC (Computerized Numerical Control) sharpening can do that. That's why you buy a bench grinder, which can easily handle almost any sharpening task. What are the benefits of CNC tool sharpening? How to do it? We write about it below!
The most important rule when using a bench grinder
The key step that should be taken first is to prioritize safety. Eye protection is paramount, so you should wear certified safety glasses, followed by proper tight gloves to protect your hands. Additionally, use both hands when sharpening tools to ensure that you are not applying too much or too little pressure. To learn more about tool sharpening, read our post to the end!
Using a bench grinder for tool sharpening
If your tools are very dull or seriously damaged, skip the files and other hand tool sharpening options and go straight to the bench grinder. It will easily handle any tool sharpening task and save you valuable time.
Here are some tips to help you sharpen old tools on a bench grinder:
- Match the wheel to the metal you want to sharpen — this is the right tool for the job, which always applies. For older tools, you can use an aluminum oxide grinding wheel with a 60 grit and medium hardness.
- Put the tools into a not too hot oven - the optimal temperature is about 350 degrees and leave for 2 hours. This procedure will help prevent cracking during sharpening.
- Mushroom tip - it will help you feel the sharpening. Use the edge of the wheel to make a short work resembling a mushroom, and then start from this place.
- Patience - don't try to remove all the metal at once. Take your time and make several passes. Be careful of any hot metal flakes that may fall off during grinding.
- When sharpening, try to achieve a good edge and don't use too much pressure.
- Remember to immerse it in cold water, oil, or other cool lubricant. Overheating the tool will only work against you.
- At the beginning and end, use a wire brush to remove rust from old tools and prevent unevenness from forming.
Bench grinder for sharpening lathe tools
A tip that may help you when sharpening lathe tools is that using a grinder is very similar to using a lathe. The techniques are also very similar, almost the same. However, you will find that sharpening lathe tools requires many accessories and can be done quite meticulously.
Required tools:
- 6 or 8 inch low-speed bench grinder
- V tool tray
- Grinding wheel with 80 grit
- Diamond wheel puller.
- Protractor
- Permanent marker
It should be noted that different lathe tools require slightly different techniques. This is due to the purpose of each tool. The following instructions apply to diamond cutting tools.
- Use a protractor to set the tool support angle so that the bevel aligns with the circle.
- Place the splitting tool on top of the rest and align it with the circle.
- Mark the straight lines with a permanent marker. This helps to keep the tool straight during grinding.
- Press the tool directly into the wheel.
- Continue until you achieve the correct edge angle.
For the lathe scraper:
- Adjust the lathe knife handle to the blade angle.
- Use a permanent marker to color the edge of the spatula.
- Touch the wheel with the scraper. Adjust the tool grip until the grinding wheel is in the middle of the bevel.
- Holding the scraper flat, gently push it into the wheel. Follow the shape of the edge.
- Everything ends when sparks start to fly and fall on the scraper blade, and you feel the edge.
For the bevel chisel:
- You need flat bevels on both sides of the tool.
- Let the bottom part of the tool touch the wheel first, then the top part.
- Do this on both sides of the chisel.
- You want to end up with a bevel from 35 to 40 degrees on both sides.
- Pressure is not critical, so gently move the chisel towards the grinding wheel.
Grooving
This requires practice if you want to insert grooves around the wheel at the same time as you move them up the wheel. For the best results, do not use the tool grip for stabilizing the lathe tool. You need a bevel from 25 to 30 degrees with concave edges.
Rough spindle grooving:
- You are looking for right angles between 40 and 55 degrees.
- To do this, set the rest so that the tool's bevel touches the grinding wheel.
- When the chisel touches the wheel, hold the tool with one hand and slowly rotate it with the other.
- When you move to the other side, reverse the direction and do it again.
- Keep the tip perpendicular to the circle at all times.
Sharpening lathe tools requires some practice. You will need patience and a steady hand to re-sharpen the tool. The key is to make sure that the angle is correct and to continuously adjust the knife grip.
Safe sharpening of CNC tools
When sharpening tools on CNC machines, always ensure the safety of both yourself and your surroundings. Proper use will help you avoid injuring yourself, those nearby, and the equipment. Here are some safety tips:
- Remember to have enough space - without it, you will not be able to properly sharpen, for example, a tool that is too long. You need to be able to move freely.
- Remove contaminants and flammable particles — to ensure safety for yourself, your workplace, and your acquaintances, remember to clean the grinding area. Sparks can cause a fire and damage the area around you.
- Earplugs are fine – bench grinders can be loud, so it's best to wear earplugs or noise-canceling headphones to mute the noise. We've talked about protecting hands, eyes, and face. It's also important to protect your hearing.
What is a CNC grinder?
This is a device that uses computer numerical control (CNC) to create precise parts and tools. By using various rotating grinding wheels to remove material from a part or tool, it is often used for sharpening and improving the edges of drills, end mills, and other non-standard cutting tools.
How does a CNC grinder work?
The grinding wheel is mounted on a rotating shaft, moving up and down to achieve the desired cutting angle. The wheels, powered by the engine, allow cutting the material at a very high speed. When the grinding wheel cuts into the material, it generates a lot of heat. To prevent this, abrasive oil is sprayed to maintain a constant low temperature, thereby protecting the integrity of the cutting tools. During each work cycle, it is constantly filtered and cooled, which is supposed to ensure the reliable and correct operation of the device.
What are the benefits of using a CNC grinder for tool sharpening?
CNC grinders offer four main advantages over traditional methods of sharpening and finishing tools:
- They provide more precise and repeatable results than manual sharpeners.
- They allow for quick and easy adjustment of the sharpening angle to achieve the desired effect.
- A CNC grinder produces less waste than other methods, saving money, especially if you're working with sintered carbides or other expensive metals.
- Damage to the tool or part, caused by high temperature is less likely due to the grinding wheel and grinding oil.
- The operation involves maximizing the full geometry of the tools.
How to fully utilize the capabilities of a CNC grinder
Here are some basic tips to help you maximize the advantages of your CNC grinder:
- If possible, try to use a dedicated CNC grinder for sharpening tools. This will help achieve better results and avoid potential machine damage.
- Always use the same wheel for sharpening tools. Switching between wheels can lead to inconsistent results and damage the mechanisms.
- Use coolant when grinding metal. This will help keep the tools at the appropriate temperature and prevent thermal damage.
- Always check or test a sharp tool on a piece of scrap before using it on the workpiece. This will help ensure that the tool is working as expected and does not require further adjustments.
Do I need to buy my own CNC grinder for sharpening tools?
Purchasing your own CNC grinder is a profitable investment, but it's important to answer the most crucial questions before making a decision.
Here are a few of them:
- Does your workshop have enough space for a grinder and a cooling system?
- Do you have sufficient funds to cover the price and operating costs? Buying and maintaining a CNC grinder can be very expensive.
- Do you have the necessary qualifications and skills to use this machine in a convenient, safe, and efficient manner?
- Is there someone in your establishment who can assist with operation and maintenance?
If you answered no to any of these questions, it's best to leave tool sharpening to a professional company.