Bush hog blades not cutting

[Freds]

I noticed the other day that the areas I keep trimmed low for walking paths were looking a little shaggy, so I touched up the blades on my Rhino SE5 with a hand grinder. The blades didn't look too bad, a few nicks and gouges, nothing like the blades looked on my 4' KK that I had never touched up.
Yesterday I went to cut down a 3' high field with grasses and weeds in it. The brush hog left clumps all over of grass that was still a foot long. It looked like the blades pushed it over and then ripped it off.
I never had a bit of this with my old KK and wondered if there is a difference in blade materials, taking an edge, keeping an edge... why would duller blades on the KK cut better than sharper blades on my Rhino?

The blades seemed sharp, or as sharp as I would expect them to be on a brush hog, PTO speed never dropped, changing my travel speed didn't help, everything was relatively adjusted the same as far as height and angle and I don't recall having this problem last year. /forums/images/graemlins/confused.gif

Thanks for any ideas...

 

[JerryG]

If the grass it tall and thick, your RPMs need to be high and / or the ground speed needs to be slower. These things will cause what you are describing.

 

[Indydirtfarmer]

Check the angle at which you have them ground. I'd suspect the ones not cutting as well will have just a tick LESS taper than the ones cutting well. Most bush hog blades are ground right on that thin edge between too "blunt" to cut, and just barely enough. They don't have to be razor sharp, but they DO need to have adaquate "ramp". I also (ever-so-slightly) give them a bit of "hollow grind".

 

[RoyJackson]

Cutter blades shouldn't be sharp...not like a finish mower. Also, maintaining PTO speed is important. Per the Land Pride manual, lower RPM can result in a ragged uneven cutting, which reads like your problem.

 

[EastTexFrank]

</font><font color="blue" class="small">( <font color="blue"> It looked like the blades pushed it over and then ripped it off.
</font> )</font>

That may be exactly what is happening ... tractor tires laying it over and it not springing back up in time to be cut or the grass being layed over by the cutter and being too tall to sit up and be cut by the blades. I don't think it is the cutter or the blades. It may just be the conditions. It sounds as if it is going to be a really slow job or you'll have to make a second pass.

 

[Gatorboy]

<font color="blue"> I went to cut down a 3' high field with grasses and weeds in it. </font>

Don't expect very good results when cutting something that tall. A second pass over it a couple days later should take care of it. As previously stated, the grass is way too long to be able to spring back up after the tires, mower etc. run over it. I don't think the blade edge had anything to do about it.

 

[Freds]

I will try to look at a new set of blads and compare my sharpening job to them. I did not get them near as sharp or as tapered as I would a finish mower, they seemed adequate for their intended use.
Even though the grass is dry... maybe this high humidity is deceiving me and it's acting like wet grass, so maybe it is the tires, but it appears to happen mainly on the right side (left side looking back).
I run my PTO around 560 to allow for any drop in rpm when I hit a dip or incline, you think maybe I should run it higher when in thick stuff? Like I mentioned, slowing down didn't seem to help any.

Thanks for the replies. I may be expecting too much and grown too accustomed to just cutting the low stuff.

 

[JerryG]

Freds,
Another thing. Try cutting with the uncut grass to the left of the tractor and the cut to the right. The cut will come out cleaner.

 

[Gatorboy]

<font color="blue"> ( I run my PTO around 560 to allow for any drop in rpm when I hit a dip or incline ) </font>

Correct me if I'm wrong, but I don't believe it will ever exceed 540, no matter how fast your run your engine.

 

[JerryG]

<font color="blue"> I don't believe it will ever exceed 540, no matter how fast your run your engine.</font>
Why not?