Bush hog blades not cutting

[RoyJackson]

"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."

Run it at 540 RPM... It's important to keep those RPM's up, but the cutter blades are designed to operate at 540. It's unsafe to go much above that.

 

[have_blue]

Since you and the other posters covered the usual suspects, I will cover some more unusual things it could *possibly* be.

*Some grasses are thin and fibrous, and do not cut well when dry. You would need a very sharp blade and/or very high RPM to avoid the raggies. Shorter grass may even be worse than long grass when thin, fibrous, and dry.

*The Rhino and the KK may have different blade tip speed. All things being equal, the blade with the greater tip speed will cut cleaner.

*The deck may be clogged on your problem cutter, causing air turbulence that irregularly blows the grass down against the ground.

*Your blade may be worn out, and have a double bevel. That is to say, the bottom of the blade may not be perfectly flat right up to the cutting edge as when new. This would not be a problem on thick grass stalks and weeds, but may be a problem on short, fibrous, or dry grasses.

When you de-bug the problem, please let us know what you found!

 

[have_blue]

</font><font color="blue" class="small">( 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. )</font>

All you have to remember is to cut while turning left.

I always trim along my roads and trails with the right side of my cutter so they will stay free from clippings.

Question is, WHY does the right side of the deck stay cleaner??? I guess it's one of the mysteries of the universe. /forums/images/graemlins/smile.gif

 

[Freds]

That's interesting, Jerry. I didn't know that would affect a rear discharge like a rotary cutter. I'll try yo pay attention and see if it helps.

It may be the blade speed. I've cut taller with my old KK and it all cut cleanly, same area, too. Maybe I'll stick it on and see if there's a difference.

I'll have to take a drive out to my Rhino dealer and maybe he will have some insight, too. Maybe it is the blade bevels (or whatever that is /forums/images/graemlins/grin.gif ) and again, maybe I didn't do the job I thought I did when touching them up.

Dave/gatorboy, /forums/images/graemlins/confused.gif
I would love a constant pto speed, but I thought it was directly related to engine rpm and other loads that may be on the tractor.

On the 560 PTO speed I run. I figure this digital readout is a lot more accurate than the dial on my old B7500 and 20 rpms above is probably closer to the "correct" PTO speed than I used to run. Seems to make more sense than constantly adjusting the throttle to make sure I don't lug it.

I'm still thinking it's the grass not coming up in time to be fully cut. With a heavier tractor and loaded tires.... I'm just not used to this.

Thanks again guys!

 

[Bird]

</font><font color="blue" class="small">( All you have to remember is to cut while turning left. )</font>

And I probably did 99% of my cutting with rotary cutters going clockwise around fields, turning right, and with the uncut grass and weeds on the right. No particular reason except that I liked to go along fences and other obstacles with them on the left, and maybe because when I cut hay, the haybine was offset to the right.

 

[have_blue]

Bird,

There's no particular reason I go left. It could be a NASCAR thing, a lawnmower habit, but most likely I get less motion sickness going left. /forums/images/graemlins/laugh.gif

 

[PM1]

There is a difference between clockwise and counterclockwise mowing that might explain a cleaner cut in one direction. As you pass over uncut grass with the tractor tires, the grass is bent forward -- often pretty low to the ground -- before the cutter gets to it.

On one side of the cutter deck, the blade is rotating forward when it gets to the bent grass. That might make it easier for the grass to stay under the blade without being cut (blade could skim over the whole grass stalk on that side, especially since rotary cutter blades aren't very sharp). On the other side of the deck, the blade is rotating backward when it gets to the bent grass. This might make it easier for the blade to get up under the tip of the grass stalk and cut it -- sort of like shaving "against the grain" on your face.

Finish mowers are typically dual-spindle designs with counter-rotating blades. That means each side of the deck behind the tractor tires can have a blade rotating backward to "lift and cut" grass that has been mashed down. Finish mowers also have much sharper blades, which should help the situation as well.

My rotary cutter always leaves a cleaner cut behind the left tire tracks. Some tall grass is always left (mashed down) behind the right tire tracks after mowing.

Parker

 

[have_blue]

Parker,

OK, you've made me think. I usually try to avoid that!

My cutter blade moves FORWARD on the right side. In other words, the same direction in which the grass is bent. The deck and blade are moving toward the grass. The blade is going faster relative to the grass, and the right side of the deck is the clean side. Hardly any clippings are left on this side.

My cutter blade moves REARWARD on the left side of the deck. Clippings accumulate and are left behind on this side. Although I have my deck height tilted low at the front, the right side clippings are re-cut to a slight degree on the left side. Clear as mud? /forums/images/graemlins/smile.gif

Right off the top of my noggin, I see no advantage to cutting going left or right. I do see a great advantage to trimming finshed areas on the right side (clean side) of the bush hog.

 

[JerryG]

I use to know the why of this. After doing it for years, I read some print that explained it and it made since. I don't remember where I read it. I know that I wish that it cut as good going clockwise. I don't like cutting going counter clockwise. It just doesn't seem natural to me, /forums/images/graemlins/crazy.gif but it does give a cleaner cut in thick grass.

 

[Gerald]

OK have blue you have got me thinking too. How about the level
of the blades front to back? I think I saw the specs on my snapper,
said the rear should be 1/2" higher than the front. Maybe something
to play with.
We have been getting so much rain here you can hear the grass growing.
Getting a lot of seat time on the tractor. /forums/images/graemlins/smile.gif
Gerald