How often do you sharpen or replace mower blades?

Kyle_in_Tex · May 10, 2015

There is another thread about throwing a bush hog blade. Check your blade bolts carefully and replace them at signs of abnormal wear. You could easily kill or destroy something. I think a 6' blade weighs maybe 20 lbs?

I know it probably doesn't last long, but I apply a bit of high temp copper or titanium lube to the bolt journal. It might would help to polish the ID of a new blade's hole.

C4Ranch · May 10, 2015

Agree that sharp blades help reduce lugging and improve efficiency. I sharpen abt once a yr and cut 2acres around the house.

I balance the blade by hanging off a nail in a vice to make sure it hangs level.

rswyan · May 10, 2015

The blades on our 6' Kubota MMM came from the factory with a blunt edge 1/16" or so wide. I don't sharpen them any sharper than that because, as k0ua suggests, a very sharp blade will dull pretty quickly.

We probably mow about 4 acres every mowing with the Kubota (we have a smaller Simplicity that gets used to do the area around the house) Our mowing usually cycle varies between every 5 to every 10 days, depending on weather ... mainly how much rain we're getting.

Blades usually get rotated out at the start and the mid-point of the mowing season, although last year I ran a single set for the entire season.

I use a flap disc in an angle grinder to clean up the machined angle on the blade unless it's really chewed up and then I use a grinding disc ... and I'll leave any really bad nicks. I use a flat file to put the actual edge on the blade and keep it straight.

Gary Fowler · May 10, 2015

I have two sets of blades for each mower and change them about 3 times per season. I have lots of crawfish mounds that take a toll on the blades + the occasional rock that gets hit. I use my FEL to jack up the mower then my impact gun to remove the bolts. It takes maybe 10 minutes to complete the change out including time to get the tractor FEL chained up. I then sharpen up the spare set so it is ready for a swap out. I mow about 6 acres at a time normally about once per week but this year what with all the rain, it has been about every 4 days.

I sharpen them using a flapper wheel on my 4.5" grinder. I don't try to keep the end square as it tends to round up a bit, so I just sharpen to the blade contour out to the end. As said, all the cutting is on about 2" of the blade with most being right on the tip so not much to sharpen except on the last 2" of blade. The lift fin usually wears out before the rest of the blade. I have used weld metal to build up the transition zone where it starts to bend up as that is where they will wear thru at. This seems to work well using 6010 rod and the wear pretty much stops at that point. One does need to keep the weld metal the same on both ends so they stay balanced.

Ed of all trades · May 10, 2015

I have a commercial lawn mower blade sharpener. I sharpen for myself, I mow about 4 hr's a week, two neighbors that mow around the same and the other a lot more and a simi pro that has 8 or 10 yards, We all do it the same, the grass tells us when we need to sharpen. when the quality of cut starts to go down it is time to sharpen. I leave less than a 1/16 edge on the blade and if I get a spot sharp trying to get a dull place I dull it with a file. I sharpen my blades once or twice a year but could do it less if I would pick up sticks more often and did not mow along a state gravel road. I have run these blades for 5 years and expect to run them for another 4 or 5.

sixdogs · May 10, 2015

It's interesting that most people seem to use the abrasive flap disc rather than the grinding wheels of years ago.

k0ua · May 10, 2015

sixdogs said:
It's interesting that most people seem to use the abrasive flap disc rather than the grinding wheels of years ago.

You have much better control, It is much easier to maintain the angle, and it does not seem to heat up the blade.. A Win Win Win, situation.

sixdogs · May 10, 2015

k0ua said:
You have much better control, It is much easier to maintain the angle, and it does not seem to heat up the blade.. A Win Win Win, situation.

Good thinking. I'm also going to get a backup set of blades or maybe just replace annually as EddieWalker suggests. These big blades are $125 a set, however and I can't find an aftermarket maker.

Kyle_in_Tex · May 10, 2015

sixdogs said:
It's interesting that most people seem to use the abrasive flap disc rather than the grinding wheels of years ago.

I actually mounted our bush hog 6' blades in a bridgeport type mill presenting the ground edge to the side edge of a 1/2" carbide endmill. I needed to remove a lot of metal. Moving the X and Z axis, they actually came out really good. Then I touched them up on the 6" wide belt sander with a 40 grit belt. 1/32 to 1/16 small flat on the edge.