bigest cause of uneven cut is bent blade, poor deck level, mismatched tire sizes right to left, mis matched tire pressures, missing/extra spacer between blade and spindle...Anything else????
I would like to know the anwser to that question also. After I installed new blades I notice I too miss a few blades. I thought I read somewhere, even with good equipment you will miss a blade and have to go back. I have a Honda mower with new blades and it miss cutting sometimes, and it's less than a year old.
speed is a factor as well....the faster you go or the slower the engine turns the better chance of missing spots.... Ideally you'd want to go slow with the blades turring as fast as they can....but no one wants to walk behind a mower all day long creeping along. Mulching mowers can sometimes miss things as they are double and triple cutting the grass it coudl very easily miss a spot or two...
I think this time of year its easy to see if your mower is cutting uneven. The grass is growing very thick where your blades are cutting it. If the blade is slightly off then you will see it. In grass that isn't growing as thick, you wont notice as much. The middle blade on my mower was slightly bent and I noticed a lot on some lawns. Others I barley noticed.
MarcSmith is correct. I my experience the most common cause of uneven mowing is a bent mower deck. It will be, most likely, lower in the front than the back. It is caused by the attachment points becoming bent forward on the upper part of the deck. Take the deck off and use a heavy hammer to pound them back in to the proper position. It may take several tries. Use a bigger hammer if you must. Keep a welder handy. Work on a flat surface and measure the blade height at several positions, but mainly front and aft. If you have adjustable front supports you don't need the hammer for the first few bends. Decks get bent when something hard is hit and stops the whole machine from moving forward. In other words, the deck stops the machine from driving forward. Bent blades are perhaps the second cause of the problem. Make sure you get the correct blade for the mower and balance them. Dull blades will just cut ragged and push the longer grass/weeds over. Missed grass blades between two blades is common. Sharp and newer blades help. The best mowers are single blade mowers but they don't have the width. As with everything it is a compromise between speed and quality.
Around here the main cause for an uneven cut is uneven ground. We use 60" mowers and some places we mow are so uneven that those big decks just wont fit in there and they don't do a good job.
