Choosing the right grinding wheel for your needs can be a bit more complicated than you think. I found myself in this situation just last week. The wheel that came on my new grinder was finally too low to actually use, so I had to start shopping for another.
I bought my grinder from Harbor Freight and it came from the factory with a 36 grit grey straight grinding wheel with a max speed of 3700 RPM. I went into the store to pick up a new wheel, and they did not carry one that could actually work on my grinder. My grinder is rated at 3600 RPM, so if I got a wheel with a lower rating it could be a safety issue. Grinding wheels always have a risk of exploding, and I do not want to help it by getting the wrong wheel.
I looked all over our little town and the highest I could find was a 3,350 RPM, close but not quite close enough for me to be comfortable. So I headed to the internet to see what was out there, and I was met with an almost overwhelming amount of information.
I am not making this video for someone that already has a handle on what they are doing, but I am making if for the average person that my need a few tips. I run a grinder, but that doesn't make me a professional in all things grinder.
There are several different types of grinding wheel characteristics to choose from. There are a variety of colors and compounds. In the video I touch on the most common which is Aluminum Oxide.
Aluminum Oxide comes in several different colors, which are also unique to what they are used for.
Brown and Grey are the work horse. The most common wheels that are often used for everything from a softer steel to high carbon steel.
Pink and White are for finer work and temperature control. They let you work on harder steels that also need to control the temperature to not effect the temper.
Ruby Red is more expensive and mostly used for tool steel
When it comes to the wheel you use there are several things to factor in. The size of the wheel you need. The RPM that the wheel needs to handle. What material you are mostly grinding. How fast you want the material to come off.
Each wheel is rated by the aggregate and how course the grain pattern is. The lower the number, the courser the grit. So if you need to remove material quickly then the lower grit is the best. If you need more control and a nicer finish, then the higher grit is the way to go.
Also something to consider is how the wheel is made. When I chose my new wheel I chose a brown wheel that is vitrified. That means that the compound is glass based.
The aggregate that makes up the wheel is very important when you think about how fast the wheel will refresh. Grinding wheels are consumable, meaning they are going to get smaller and need replaced. As you wear down the wheel it will expose a fresh surface, and the bond will determine how quickly that happens.
In the end I chose a brown 60 grit 4100 RPM wheel. This should give me the control I need when I am profiling knife blades, and it shouldn't were down too quickly.
I hope these how to tips are helping you, and if you have any questions please leave it in the comments below. If you are a professional that knows alot about grinding wheels, feel free to add more tips to help in the comments!
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