42 in. Deck 19.5hp Lawn Tractor

I have a model 917.255430 riding craftsman mower.  After cutting the lawn, there are lines in the lawn and it is obvious that one or both blades are cutting at an angle rather than straight across.  There is a strip of higher grass left after cutting.  I thought it might be because blades needed sharpening but the problem still exists after sharpening.  If the blades are not level, how do I fix?
Experienced gardeners share their insights in answering this question :
Its not the tires it is the blades don’t line up.One blade is three-quarters of an inch lower.Is there a shim for the star fitting.

How to Identify and Fix Common Gardening Problems ?

We provide a variety of viewpoints on how to identify and fix common gardening problems. Our sources include academic articles, blog posts, and personal essays from experienced gardeners :

Sharpening or replacing the mower blades is also the answer if grass tips look ragged or tattered instead of cleanly cut. Blade vibration also causes an uneven cut. To eliminate vibration, replace unbalanced blades and worn mandrels. Replace a worn blade belt because a worn belt won`t spin the blades correctly.
These could include a dull blade, incorrect blade height, or an uneven terrain. To ensure a proper cut, make sure that your blade is sharp and that it is set to the correct height. Additionally, if you are mowing on an uneven terrain, you may need to adjust the blade height to a lower setting to ensure an even cut.
For most effective results, a lawn mower deck should have a pitch, or height difference of 1/8-inch to 1/2-inch between the front of the deck to the back of the deck. Naturally, this makes the sweet spot about 1/4-inch of pitch, depending on the mower model.
Identify if Your Lawn Mower Blades Need To Be Balanced

So to ensure that your lawn mower blades need balancing, look for unbalanced lawn mower blade symptoms like your lawn mower is not giving your grass a quality and even cut, as well as vibrating and making odd noises while running.

The causes of uneven cuts from your lawn mower are worn or dull blades, incorrect tire pressure, bent blades, or a clogged deck with grass. Also, due to the deck not being leveled, having an uneven spindle, or the belt may be in bad shape or at low speed.
Some dermatologists say the five-blade design smacks of overkill, because more blades mean more friction, and friction irritates the skin. “When you add more blades, there`s a greater chance of nicks and razor burn,” said Dr. Ezra Kest, a dermatologist in Beverly Hills.
Uneven Deck Joists

Your deck might look wonky if the joists were not adequately leveled at the time of framing and squaring, or they may have become weak over time. You might be able to remove the deck boards over the problem area and plane down or replace problematic joists.

Dual-lever, 6 position height adjustment makes it easy to change cutting heights from 1.25″ to 3.75″ high.
A strip of uncut grass left in the middle of mowing rows could signal that your lawnmower`s blades are unbalanced or that one or both of them was installed the wrong way. Lawnmower blades are beveled and specifically designed to attach in a certain fashion.
While there are several reasons this might happen, it is most commonly the result of an uneven deck or misaligned blades. Make sure the blades are facing the correct direction and are not warped. Check the mower spindle and repair it if necessary. Check if the deck is level and if not repair or replace it.

Discover Relevant Questions and Answers for Your Specific Issue

the most relevant questions and answers related to your specific issue

Uneven grass cutting
ANSWER : I have seen dull blades, blades not installed right and an un-level deck cause that.Hope this helps.

42 inch mower cuts uneven, what is the problem?
ANSWER : Several things here could be the problem. Check to see if mower deck is level, measure distance on both side on a level surface. Check tire’s for low air. If you’ve replace the mandrel’s lately, some have a left & right side & if not put back together properly this will cause uneven cutting

I have a craftman 42 in dual blade riding mower. It it cutting my grass unevenly. I have change the blades and bearing on the blade housing. please help.
ANSWER : Either the deck is uneven or one of the blades are upside down

Mower deck is cutting uneven how do you level it out?
ANSWER : Raise the wheels on one side?

One blade on deck gives an uneven cut
ANSWER : Hi..my name is Keith..and most times..when your problem happens..either the deck is bent down from runing into something or stepping on it..or the deck hanger is bent, worn or out of adjustment..or the blade on that side is bent..and i hope this will help..if not..please write back

Mower cranks and runs smooth until i try to engage blades or put mower in gear. it then stalls out
ANSWER : The seat switch is not making. You can start the mower but if you try to move it or cut, the switch is acting as if there is no operator present. Find it under the seat.

Gary

Mower blade on one side spins free and will not cut grass
ANSWER : Check the bearings in that spindle.

Cutting unevenly Changed blades now the tractor cutting the grass unevenly.
ANSWER : Set the mower on a known flat piece of concrete. Now look at the deck and the support connections where the deck hangs from from the mower. Should be adjustments such as pins with clips or threaded bolt hangers which will allow you to raise or lower the corner of the deck which is low or high. Conversely you could have put a blade in upside down or left out a washer making one blade higher than the other. Usually an owner’s manual will detail this process. As you just changed your blades, as opposed to wear and tear, likely you did not put it back together exactly as you took it apart.