Rotary cutter blade pics, advice?

[Bullwinkle123]

I've read the various threads. I know we don't want them too sharp, that dull blades are arguably fine.

After my first field clearing I thought I'd just touch up some rough spots with a file, but man, these look more like they need to be put on the anvil and hammered out. Normal? Just leave 'em alone?

The field cutting definitely seems sub-par now compared to when the blades were new. Pics are of new blades after about 15-20 hours of use.

 

[Roadworthy]

My rotary mower blades are ugly, too. I've used the mower for sixteen seasons and never sharpened the blades, even after the occasional rock. I don't cut my fields to be pretty, more for wildfire prevention. If I wanted a nice even cut I'd probably have a finish mower. You won't touch your blades up with a file - you'd need a grinder. I'd just leave well enough alone.

 

[deserteagle71]

The blades on my mower look MUCH worse than that. I've been using it mowing desert (lots of dirt mounds from ground squirrel and badger burrows) for the past 22 years and the blades have never been off and never sharpened. One of my projects for this coming winter is to see if I can replace the blades - I'm afraid they are getting to the point one of them might disintegrate - but I'm not sure if I can get them off. May have to use a cutting torch.

 

[/pine]

Just guessing from the pic...but it looks like the blade edge has lost some temper...possibly from heat generated by grinding ??

 

[jaxs]

Piney is right,from the way blade edge is bent,the metal is soft. The blade also appear's much thinner than usual. I wouldn't sharpen that blade but I'd certainly compare thickness to other mowers and take note how blades normally wear and chip but don't distort.

 

[Bullwinkle123]

Just guessing from the pic...but it looks like the blade edge has lost some temper...possibly from heat generated by grinding ??

Nope, that's a brand new blade with its first season in my field, untouched by me. The damaged edge is _very_ thin in places now, I don't know what it looked like new, I didn't bother to see.

The only grinding it's had is the the occasional rock in the field.

 

[MF243RedTop]

That's a lot of rock grinding right there, whether you hear it or not from the seat.
Can you get a pic from above or from the end of the blade edge? That will help in determining what's left of them.
I use a 7" grinder on mine.

 

[oosik]

Odd, very odd. I can see by the posted picture that Bullwinkle's blades are MUCH sharper than the OEM blades on my cutter. My blades have 48 hours of use.

Mine are blunt, quite a bit thicker and sharpened at a much steeper angle.

 

[Bullwinkle123]

I'll see if I can find a picture I took after only about 2 hours last spring, though it wasn't very good, maybe it will show more about the original blade shape.

I'm wondering if perhaps they're in worse shape because my blade is angled too steeply forward. If I recall correctly they recommend only an inch in height difference between the rear and front, it's quite possible mine is more than that and that I need to take the rear wheel adjustment so that the deck is down a notch.

Still, seems like that would have had to have been a _lot_ of grinding, and not just the occasional blade hitting the crown of a rock before the jumper gets to it.

 

[ovrszd]

Nope, that's a brand new blade with its first season in my field, untouched by me. The damaged edge is _very_ thin in places now, I don't know what it looked like new, I didn't bother to see.

The only grinding it's had is the the occasional rock in the field.

I'm with Pine. Exception being, I don't think that blade was ever properly tempered. What brand cutter is this?

 

[Bullwinkle123]

I'm with Pine. Exception being, I don't think that blade was ever properly tempered. What brand cutter is this?

Landpride RCF2072

 

[Tinhack]

Wow, that edge does looks too "keen". Mine are at about a 45 degree angle with about 1/8" thick edge. I've always tried to keep them that way. I've never seen the type of damage you show. And I sure hit my share of stumps and rocks. Even concrete and rebar once.

 

[ovrszd]

Can't tell from the pic. Are your blades flat blades or lift blades? Are they simply a straight blade with no elevated rear edge? Or are they slightly dropped out at the cutting edge and have an elevated rear edge to create "air" lift?

 

[MF243RedTop]

Can't tell from the pic. Are your blades flat blades or lift blades? Are they simply a straight blade with no elevated rear edge? Or are they slightly dropped out at the cutting edge and have an elevated rear edge to create "air" lift?

That's why I asked for pics from above or the end of the blade.
To get a better perspective of what's going on here.
I've seen blades like that damaged also from high rpms and fast mowing speeds. But rarely as bad as his.

 

[Jim Nelson]

I have an old Woods finish mower that I bought cheap so one of the first things I did was buy new blades. As others have said the new blades were thicker, guessing 3/8" and the angle to the cutting edge was closer to 45 degrees. Our place is real steep with lots of gopher mounds and a few rocks so they get nicked up a little but nothing like yours. Ocasionally I will hit them with a 4 1/2" angle grinder and try to keep the original angle. They are real hard steel, nothing like what yours look to be. I do run pretty slow because of the steep grade and use the top & tilt to keep the front higher than the rear to avoid dirt build up.
I think you got some bad blades that weren't properly hardened.

 

[Bullwinkle123]

Here's some poor pics I took when the rotary cutter was almost new. Other than a big divot in one blade, they seem reasonable to me.

 

[Tinhack]

Yeah, those are lifting blades. Great for grass but I cut brush and trees with mine. As they used to say at the race track; "Run what you brung".

 

[ovrszd]

I think they simply aren't properly hardened. Not sure how to fix that. Kinda surprises me from LP.

 

[Industrial Toys]

I have a lot of different mowing machines. Some blades are quite soft and some are really hard as nails. The toughest are on my most expensive CUSHMAN mower. The guy that used to sharpen them always complained about their hardness.

 

[Bullwinkle123]

Having just spent several hours again in my field picking out rocks, I've come to the conclusion that nearly an acre of my field was used to dump schist which was dynamited out of the ground across the property to build a large building. Every single bit of rock I pulled today was schist, not another type of rock in the bunch. I always knew it was likely a dumping ground for it based on old satellite photos of the place when the building was under construction, I just didn't know it went quite so far down the hill. (Or ... it actually _is_ the hill, I think, in part).

Anyway, the thing about this schist is that if you hit it with anything it breaks into smaller pieces. Even my mattock trying to disloge them causes them to break. I'm thinking a blade that hits this stuff just turns it into successively fine abrasive material. Though there wasn't that much exposed, I'm probably making it worse trying to dig out the big surface pieces, it looks like a very large gopher has been making a home in the field.

Anyway, I hear "lifting blades" and will ask the dealer about it (i.e. the alternatives). He's saying the blades don't look abnormal and that I should get another year out of them, but I was kind of expecting more than two years out of blades for such a small field, even though I knew it was going to be a rough first cut.