First CHoice mower leaving uncut streaks

nhman · May 18, 2004

My first choice mower is leaving noticable streaks of uncut grass between the center blade and the two outside blades. Any idea on how to fix this? I sharpened the blades and have made sure the belts are tight. That somewhat improved the problem, but it is still happening. I am ordering new blades. I was wondering if it's how the blades are installed, i.e., should they all be installed parrallel so when they spin they are almost touching. ALso, seems like I have quite a bit of clearance between my blade sunder the deck, almost a quarter of an inch. I this the problem?

thanks for any help

theboman · May 18, 2004

Try again..

Could a blade(s) be upside down?

Check the deck for buildup. Keeping the mower from lifting the grass to cut.

Wet grass? It's hard for a mower to lift wet grass.

On my 60" Kubota MMM the center blade sits forward to the side blades. This allows the blades to overlap without touching each other.

markie61 · May 18, 2004

What size mower? (for my own curiosity)
Rear or side discharge? (side discharge seems to have more problems)
What engine speed? (if PTO not at 540rpm, try speeding engine up)
What ground speed? (if too fast, the blades can't keep up)

No matter where you install the blades, they will slip on the belt and change position relative to each other eventually.

Sometimes, the grass is just too wet or just too tall to get everything. The rule of thumb is to take no more than 1/3 of the grass height off in one pass.

Mark

sweettractors · May 18, 2004

I agree with all the other posters. In addition, check to be sure the blades are tight on the quill spindles on the underside of the deck and also, sometimes reducing ground speed helps (Continue to run at FULL PTO speed)--Ken Sweet

Sweet Farm Equipment LLC *New First Choice 5 ft Sickle Bar Mowers for CUT tractors*

paccorti · May 18, 2004

What do you mean by a 1/4" clearence? There is a 1/4" clearence between 1 blade touching another or 1/4" between the blade and the deck?

Peter

nhman · May 19, 2004

The deck is a 72" rear discharge
I am running it at full 540 rpm and slowing my ground speed.
The distance I was speakig of is the distance between the blades when they pass each other. Whne I slow my ground speed to very slow, the streaks get better, but are still there.

My Kubota 60" mmm cuts the same grass, same conditions and does not leave the streaks and I can cut at a faster ground speed. Does the MMM spin at higher revolutions? ALso the distance between the blades on the MMM is less than that of the first choice which is why I asked about what the distance should be on the first choice. Ken is sending me the new blades I ordered from Sweet Farm and I will be interested to compare them to the set I have on the mower now that came with the mower last year when I bought it from Sweet Farm.

Thanks for all responses

kevincook · May 19, 2004

My guess is that compared to your mmm, the rear tires are also compacting the grass and with the typically wetter springtime grass the mower just doesn't have enough time to suck the grass up to be cut.

If I cut very frequently I have less of this type of problem. Unfortunately, that means every 3 days this time of year.

Don't feel bad, I was down on the town/school sports fields last night and they have the same problem with their brand new $70,000 mower /forums/images/graemlins/blush.gif

Many of the professional mowers over at Lawnsite.com complain of having to double cut everything this time of year.

Good Luck,
Kevin

theboman · May 19, 2004

MMM PTO 2400 RPM
Rear PTO 540 RPM

Dozernut · May 21, 2004

You said you just put on sharpened blades, heres something simple you might check. On most mowers when you put the blade back on, you have to fit the blade onto an extended stub. If you don't get it on the stub properly and tighten it down, it will feel tight and you think it is properly installed. When you start mowing the blade will move onto the stub leaving around 1/8th inch of free play. The blade will in effect slow down when you encounter thick grass, leaving streaks in your cut. I have done this when I got in a hurry and didn't double check my work.

have_blue · May 21, 2004

NHMan,

Are the blades original equipment, or after market? Even 1/8 shorter blades could lead to a streak of unmown grass.

Measuring blades is usually done "cross corner". In other words, if your mower is 72", then your blades should be just about 36" cross corner. (Assuming 2 blades)

Running wet with mud buildup around the perimeter of the deck can cause the blade tips to be ground down shorter. If the corners are no longer square (rounded off) this can certainly cause the streak.