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Angle grinder, flap disks, mower blades

rlitman

LawnSite Silver Member
Location
Long Island
A smaller grit doesn't mean you can get a sharper edge. The courser the grit (lower numerically) the easier it is to get too sharp too fast which can lead to over-heating etc. The material used for the grit matters the most IME.
Over-heating comes from too much grinding time. If you're dwelling on one spot because you have too fine a grit, then you'll over-heat. It's pretty hard to overheat with too coarse a grit, because you're rapidly grinding through the heated part.

40 is about as coarse as you want to go. 60 is good too. 80 is too fine for a mower blade.

But I much prefer hard grinding wheels to flap discs. Look into the AVOS wheels where you can see through the wheel at what you're grinding.
 
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Ben Harms

LawnSite Member
Over-heating comes from too much grinding time. If you're dwelling on one spot because you have too fine a grit, then you'll over-heat. It's pretty hard to overheat with too coarse a grit, because you're rapidly grinding through the heated part.

40 is about as coarse as you want to go. 60 is good too. 80 is too fine for a mower blade.

But I much prefer hard grinding wheels to flap discs. Look into the AVOS wheels where you can see through the wheel at what you're grinding.
Makes sense - Fine grit with come in contact with the "face material" more often while the coarse grit wont because it shave off that "face material" quicker.
 

Ridin' Green

LawnSite Fanatic
Location
Michigan
Over-heating comes from too much grinding time. If you're dwelling on one spot because you have too fine a grit, then you'll over-heat. It's pretty hard to overheat with too coarse a grit, because you're rapidly grinding through the heated part.

40 is about as coarse as you want to go. 60 is good too. 80 is too fine for a mower blade.

But I much prefer hard grinding wheels to flap discs. Look into the AVOS wheels where you can see through the wheel at what you're grinding.
That is true if you are using grit fine enough for you to labor at a given spot, but anything up to 100 gets the job done perfectly fine and doesn't cause over heating. I stand by what I said as far as the grit material mattering more. Grit that wears down/off fast makes you work at it harder/longer. Grit that lasts for the life of the wheel cuts fast and clean and saves you both time and money in the long run and won't over heat your work material. 100 grit is pretty good size for the thinner blades used on a lot of mowers like the .203/.205 blades as long as the grit is up to the task. For thicker blades like my JD uses, I like 60 or 80.
 

Garrett1234

LawnSite Senior Member
I like to use 80g. If I have “Miss used” my mower like a brush hog, I’ll take a grinding wheel first to get the shape back and biggest gouges out then hit with 80g flap disk
 
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