View Full Version : Blade Sharpnening

05-10-2002, 06:39 AM
Hello I have a question few questions and hope someone can help:

I have heard many opinons on using a 1/2" grinding vs a 1' grinding wheel and any comments on this which is better and why? Also I have heard that a 7" wheel is as good as an 8"wheel
any input here?

Also which grit on a grinding wheel is best for lawn blade sharpening?

Is it true that a blade should not sharpened if it is more than 75% worn? Because after that there is a chance of the blade breaking?


05-11-2002, 01:25 PM
Hello, and thank you for your question.

Please first understand that all of your questions are of a VERY general nature, and therefore i can only give VERY general answers. The choice of grinding wheel sizes, grit size, etc is all determined by the type of material you are grinding and the machine driving the wheel.

There are no easy answers to your questions, since it is so tied to the application.

1/2" vs 1"
The difference between these wheels is the amount of force that can be put on them. The 1/2" has a smaller surface area therefore it is easier to push material into it with less force. The will feel like you are cutting more faster. Where the 1" wide provides more resistance with the larger surface area. The choice of 1/2" or 1" is dependant more on the application. For example our MAG-8000 uses both 1/2" and 1". The 1/2" is used for getting over the curves in mulching blades, where the 1" is used for straight edge blades. You could use the 1/2" on the straight edge blades but you would use up the 1/2" wheel faster. WARNING, when using thinner wheels, a higher SPEED RATING is required to add strength to the wheel. The wheel has 1/2 the mass so it requires more strength to be safe. ALL MAGNA-MATIC WHEELS ARE SPEED TESTED TO 5500 RPM, FOR YOU AND YOUR EMPLOYEES SAFETY!

7" dia vs 8" dia
Again we have the same problem of application. The diameter of the wheel chosen is relative to the motor speed of the grinder. The diameter of the wheel directly affects the surface speed of the grinder. Surface speed is one of the most important specs of a grinder. The surface speed is calculated with the motor RPM and diameter of the grinding wheel.

Please review some of the info in our TECH INFO section of our website.

The grit size of the grinding wheel is also chosen by the application, for our sharpeners we use 46 grit becuase it is aggressive in metal removal and still puts a nice finish on the ground blade edge.

With any lawnmower blade you can sharpen it until you get to the lift of the blade or run out of flat edge area on the blade. There is no information that we know of where blades break after any percentage of sharpening.

In closing, please understand that most of the questions that you have asked are very general in nature and the answers are dependant on MANY other variables that you have not given. Also, understand that there is usually almost never a quick fix to modifty a grinder to be more productive (like changing wheel specs). Grinders/sharpeners are designed for use with a specific wheel or specific range of wheels, you must be VERY careful and consult manufactures when making such changes to your equipment.

Thank you,