How often do you sharpen or replace mower blades?

[SPIKER]

I mow about 4~5 acres on/off till I finish and start all over again & like others I have spare sets of blades that I sharpen & swap out. However I just did BOTH sets at one time as I had not sharpened the old set from last season. I usually do one or two mows in spring as the winter grows rocks or sticks & then I swap them out for sharp set. I agree grass cut will tell when to sharpen & having a sharp set will cut with less power required as well as leave a better cut.

I LOVE the GATOR style blades (dont have them for the NEW mower) as I have not had chance to get out to buy them but when I need a new set that is what I will buy. They last a LOT longer between sharpening and cut is much better as well. I also sharpen my brush hog blade once a year after 2nd cut but only cut the rough stuff a few times a year.

I also have had a set of the hardened tip blades which worked great however sharpening them is hard (requires hard disk not flap wheel) but I mostly use a hard disk anyway as it leaves a longer lasting edge from what I can tell a flap wheel sharpening only last 2 cuttings till it suffers whereas the hard disk can last 5 or so cuttings.

Mark

 

[Kyle_in_Tex]

Don't forget you can balance them on a nail (by placing them horizontally in the center hole). Grind a little more off of the low hanging side.

 

[RalphVa]

I do my bush hog and mower blades once/year as long as the mower blades haven't hit a rock. Bush hogs hit rocks quite frequently, still once/year on them. If I've knowingly hit a rock with a mower blade, they get sharpened.

Mower blades, like chain saw blades, seem to go forever if something isn't hit to dull them. In the case of chain saws, it's dirt or a metal object will dull them. For mower blades, rocks do it. Otherwise, they'll go for the 4 years that maybe some claim. Doubt you can go 4 years without hitting something that shouldn't have been hit though.

Ralph

 

[Complete Turf Care]

I've been in the commercial mowing business for 13 years, and here are some general observations about blades.

New blades will need to be sharpened at about 20 hours of use. And then at about every 10 hours after that. And they will need to be replaced at about 50 hours.

We use a commercial blade sharpener which is a glorified bench grinder. It sharpens them to a 30 degree angle. And the owners manual recommends to be careful not to overheat the blades while sharpening them, which tends to happen more with an angle grinder.

 

[oosik]

I mow about four acres. One acre of lawn and three acres of meadow. I sharpen the blades once a year and the blades on my riding lawn mower are nine years old and still going strong - nicks and all.

 

[RandyT]

I've been in the commercial mowing business for 13 years, and here are some general observations about blades.

New blades will need to be sharpened at about 20 hours of use. And then at about every 10 hours after that. And they will need to be replaced at about 50 hours.

We use a commercial blade sharpener which is a glorified bench grinder. It sharpens them to a 30 degree angle. And the owners manual recommends to be careful not to overheat the blades while sharpening them, which tends to happen more with an angle grinder.

which is the reason most lawn mower repair shops are changing over to the Burrking type belt sharpeners. Faster sharpening with a lot less heat. Can sharpen the average lawnmower blade in under a minute after cleaning the dried grass off the blade.

 

[Gary Fowler]

The main reason for using a hand grinder is so you can see what you are doing. You cant with a bench grinder so you are just making a pass and then looking at what you did. I also like the sanding pads, I call them Tiger Paws after one of the brand names. They cut fast but don't overhead like the abrasive disc do. I resharpen mine similar to original edge, which is sharp edge, not razor edge but sharp and on a 30 degree angle. If I wanted to have a 1/16" edge, I would just leave them dull and never sharpen. Why waste effort after sharpening to a sharp edge then dull it to a 1/16". Normal wear will displace the metal fast enough. A sharp blade will use less power to cut thru heavy grass than a dull one. 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.

 

[k0ua]

Ok, I gotta ask, having never heard the term "crawfish mounds" does this refer to mole hills"?

We are not that far apart geographically, and we have a lot of southern colloquialisms here in southern Missouri, but I have never heard of "crawfish mounds". :confused3:

 

[rswyan]

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.

I'm still on the original set of blades (2) for our Simplicity CFC 18. At one point, it was the primary mower (for 6 acres) ... before we got the Kubota. It now does probably an acre or so (mostly around the house) every mowing.

The lift wings are almost gone on 'em and the blade itself is getting pretty worn down ... but they still cut good when sharpened ... and they have lasted almost 30 years now

 

[SPIKER]

my 1st mower has gator blades that are wore pretty good but probably over 1000 hrs on them blades in 13 years...

I loose more to sharpening than for the wear from grass & gravel & mole hills...

 

[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