How often do you sharpen or replace mower blades?

[4570Man]

I have blades with over 1000 hours on them. They have been ran hard cutting rocks, sticks, and dirt. They are in pretty bad shape. The cut quality probably suffers after a few hundred hours.

 

[SPYDERLK]

Anyone getting 5 or more years from a set of blades must have a perfect lawn and small with no rocks, sticks or sand to be sucked up by the mower. Dirt and sand will wear out a blade fast. As for my yard, I have crawfish mounds in the low lying portion that require me to resharpen fairly often. They often contain some small rocks in addition to dirt and sand. On my mowers and especially my brother in laws blades, the wear out at the bend where the turn up to produce lift. Anything travelling over that junction, making the abrupt turn, wears heavily on the blade eventually wearing completely thru the metal.

You said it. ... The blades on the BX 54" MMM dont get sharpened, but replaced each fall to renew the "lift wings" for leaf pickup. These blades have a hard life and are pretty worn at the ends by then. The steel is very good so I straighten the old blades on a press and use the metal at critical positions in projects.
larry

 

[OrangeToys]

I have blades with over 1000 hours on them. They have been ran hard cutting rocks, sticks, and dirt. They are in pretty bad shape. The cut quality probably suffers after a few hundred hours.

Best results are sharpening every 8-10hrs. I cut commercially and I change/sharpen every 2-3 days depending where I've been. I'll go longer in the summer months since the grass isn't as tough to cut. I use a magna matic 9000 it's designed for leaving a 30° angle

 

[LD1]

I have found a set of blades I really like. I am at 80-100hrs and still havent sharpened them (allthough they are about due). And I am not easy on them at all. Doing alot of construction around my new place and same at the old with living in a woods. Always running over rocks, sticks, dirt clods, dragging one edge into the ground running down the ditch, etc.

After the first season with these blades I took them off to sharpen, but didnt and put them back on as they were still sharp.

They are Gator Magnum blades with Fusion. Standard blades for my ZTR are 2.5" wide and 1/4" thick. The magnums are 3" x 5/16" thk. Fusion is a coating added to the underside of the cutting edge that is like a layer of sintered carbide. Its on the underside so as you sharpen, you dont grind it off. I was really amazed at how well they held up after mowing countless dirt clods and scalping after I had the pond dug.

And I too use a flap disc, but dont leave a blunt edge. If you maintain the 30 or whatever degree angle, they wont dull any quicker per-say. IE: if you sharpen to 1/32 and consider 1/16" as dull. Making them sharp wont result in dulling down to 1/16" quicker. But they will wear down to that 1/32" blunt edge quicker, but from there on, they would dull at the same rate as if you started there.

 

[Dr_Zinj]

I sharpen my blades when the grass looks like it's being beaten and ripped instead of cut.

 

[Industrial Toys]

I have a lot of mowers on the go. The bigger ones have nine and seven blades respectively. Smaller ones have the typical three. So blades are a huge on going PITA (and expense) for me. Worst part is, we grow stones!

Is it an absolute known truth about the last 1/16" doing most of the cutting? This is news to me!

Usually a guy, I barter with does my blades. He always complains about the hardness of the commercial blades on the one particular mower but makes them look new. The commercial blades seem to smash limestone rocks almost without injury to themselves unlike other ordinary blades. This guy sharpens with a hand grinder and by eye. Having said that, you could SHAVE with these things. Is he really making them too sharp? I think he may get his fur up, if I ask him to sharpen them less.

I was once told, that the sharper, the better, just for liability reasons, places don't sharpen them that much. I have a scar accross one palm from a wrench slipping off the blade bolt from such a sharpened blade as a kid!

I did just buy a wack of those super industrial blades and notice that they are quite, and I mean quite sharp!

 

[Sysop]

Once at the beginning of the season. Pop it in the vise, 25 strokes with a rough cut flat file, 25 strokes with a finer cut following the existing blade angle. Leave any nicks. Too many nicks, replace the blade...

 

[Sawyer Rob]

I don't keep track of hours when I sharpen, I pay attention to how the deck is cutting... With the electric deck lift,

it makes it so easy, when it needs it, it get's it. I impact the blades off, hand file them back to like they were when new, and they go right back on!

By paying attention and sharpening them often, it's very fast/easy to keep them sharp with a file, no grinder needed!

SR

 

[Creamer]

Nobody mentioned heat treating them. New blades are only hardened at the cutting edge so that they are not brittle and dangerous. I sharpen mine about every 10 hours - the grass just looks better. After I have sharpened them 5-6 times the hardened edge is worn off and so I heat the first 1/4" from the sharp edge red hot and then quench them leaving the rest of the blade soft for safety. I only change them when about a third of the blade is worn away..

At the speed I mow I know the first 1/16" does not do all the cutting. The blade wear does not indicate that either.

I have never worn the lift part of a blade off. You guys must be mowing a lot of sand.

 

[SPYDERLK]

Is it an absolute known truth about the last 1/16" doing most of the cutting? This is news to me!

No. ... It is a simplism. The bigger circle swung by the tips has more area of course, and guarantees that they do more cutting. This does not equate to "most". How much of the blade is used depends on the travel speed and the refresh rate.
,,,Independent of the above issues a tip, inherently sitting proud, will experience more wear even in a uniform circumstance. Slice sand with a knife, watch square shovels round off at the corners, check out how bucket teeth wear, etc.
larry