How often do you sharpen or replace mower blades?

[sixdogs]

My current mowing setup is a 7 ft pull type Woods RD8400. Recently I put new blades on and the difference in the grass quality is amazing compared with the "before" blades. I mow at 3 1/2". The mower also doesn't clump the grass clippings any more either but distributes them evenly. I'm now sold on sharp blades.

I know to sharpen them when they are dull and need it but how often is that for most people? And do a given number of sharpenings mean you replace or do you just keep sharpening as long as there are no nicks in the blades? I hear everything from four times a season to every four years. What do others do?


Also, the owner's manuals say to not sharpen the blades to an edge but, in effect, leave them with a dull radius. Why? It doesn't sound right so it that advice just a liability issue?

 

[k0ua]

My current mowing setup is a 7 ft pull type Woods RD8400. Recently I put new blades on and the difference in the grass quality is amazing compared with the "before" blades. I mow at 3 1/2". The mower also doesn't clump the grass clippings any more either but distributes them evenly. I'm now sold on sharp blades.

I know to sharpen them when they are dull and need it but how often is that for most people? And do a given number of sharpenings mean you replace or do you just keep sharpening as long as there are no nicks in the blades? I hear everything from four times a season to every four years. What do others do?


Also, the owner's manuals say to not sharpen the blades to an edge but, in effect, leave them with a dull radius. Why? It doesn't sound right so it that advice just a liability issue?

This is just my opinion.. so take it for what it is worth. I don't mow a large amount now where I live so I sharpen the blades once a year. But my mowing is about 12 hours per year. When I had a large place to mow, I would mow about 12 hours in two weeks. I would sharpen the blades in about the same time period or at least every 20 hours of usage.

Dont sharpen them razor sharp, Just a decent edge, but not sharp enough to slice your skin if you touch them. The best way I have found to sharpen blades is with a hand held 4 1/2 inch angle grinder with an 80 grit flap wheel. I will never use a bench grinder again for this task.

If there is a bad nick I leave it, and concentrate on keeping the overall straight configuration of the edge and sharpen to a moderate edge. In other words, don't grind off a ton of metal to get that one nick out.

 

[Mikeeemo]

Ditto!

 

[RandyT]

Oregon, the largest mower blades manufacturer in the world has what they call the 30-30 rule. Which means sharpen the blades at a 30 degree and and leave a .030 blunt edge on the front. A thin leading edge will dull very quickly, which results in the .030 edge anyway.

You want to remove enough metal to produce a uniform edge but nicks and chips will have little to no effect on cut quality. Most grass is cut with the last 1/16" of the blade tip.

 

[ovrszd]

The blade will hold it's edge longer if sharpened to a dull point rather than a razor sharp edge. The cutting edge is thicker and will wear off more slowly.

For the past 5 years I've been mowing with a JD 2210 MMM. I bought it used with 100hrs on the clock. The blades were sharp. I mowed all that Summer without touching them. The next Spring I took the blades off to sharpen them. I then realized they are hardened. They had some nicks but were still relatively sharp. I put them back on without doing anything to them. I ran them for the next 3 years never sharpening them. I replaced them last Winter when I inspected them and noticed they were wearing thin where the blade curves up at the back edge to create lift. Eventually the raised edge was going to break off. I don't know what they make those blades out of, but sharpening is a thing of the past for me now. I mow 4 acres.

On my brushcutters the cutting edge is blunt. I never sharpen them. My little 6' Rhino leaves a very well cut look. Not lawn quality, but close. And that's with a blade that you couldn't cut yourself with if you tried.

 

[ovrszd]

Most grass is cut with the last 1/16" of the blade tip.

And this is confirmed when you look at an old blade, the outer 1/2" of blade is always worn away more than the rest of the edge.

This is also why going too fast starts pushing the grass over and not cutting it properly. When your forward speed is faster than the outer end of the blade can make the circle and come back around to cut again without leaving a gap. You then begin to cut with the inner part of the blade and efficiency is lost.

 

[Kyle_in_Tex]

My current mowing setup is a 7 ft pull type Woods RD8400. Recently I put new blades on and the difference in the grass quality is amazing compared with the "before" blades. I mow at 3 1/2". The mower also doesn't clump the grass clippings any more either but distributes them evenly. I'm now sold on sharp blades.

I know to sharpen them when they are dull and need it but how often is that for most people? And do a given number of sharpenings mean you replace or do you just keep sharpening as long as there are no nicks in the blades? I hear everything from four times a season to every four years. What do others do?


Also, the owner's manuals say to not sharpen the blades to an edge but, in effect, leave them with a dull radius. Why? It doesn't sound right so it that advice just a liability issue?

First off, your tractor is way too clean.

I like to even have sharp bush hog blades, but not so easily kept up with. I have flint rocks that are up to large potato size. I try to pick them up, but they keep spawning. They take their toll on the blade's tip, rounding it off where you need it sharp.

Sharp blades cut through grass easier and save fuel. In Bahia grass, I have to slow down as it lugs down my 4310's 25 pto hp. Sharp blades help it cruise right on through.

 

[sixdogs]

Tractor not quite that clean. Date shown in photo is 4 years earlier.

But I do wash them either once a year or every other year and I am fundamentally (wife says) pretty sloppy otherwise. This tractor is a dedicated lawn mower. Used to be I used the 6' belly mower but the 7' rear blade does a better and faster job.

 

[JohnWhayne]

After Dinner......

 

[EddieWalker]

I tried sharpening the blades once. It worked find, but I found that they got dull really fast and when I took them off again to sharpen them, I changed my mind and just bought new ones. For the time and effort it takes to sharpen them, I've come to the conclusion that I'll just buy new ones every year.

I start out the season with last years blades, then when I have everything under control, buy new ones to keep everything nice for the rest of the year.

Eddie