Do lawn mower blades need to be timed?
I have had mower blades that require timing, usually blades on larger machines. I prefer blades that do not need timing as they make my life much easier, but occasionally, they are necessary, and I will tell you why.
If you use a stock standard domestic push mower, you do not need to time the blades. Timing is usually required when blades overlap, so it would first require an extended deck running more than two blades in sequence. This is normally found on lawn tractors and zero turns. Your average domestic lawnmower is not going to have overlapping blades.
Why would a lawnmower need overlapping blades?
There is a simple reason for overlapping blades. This is part of the design, so they do not leave a strip of grass between the cuts when mowing, so you end up with a nice level cut. This is great when everything is going fine, but it can be a bit of a nightmare when things go wrong.
This walker mower in the photo above has timed blades, and as you can see, they are set in opposite directions so the blades do not collide. As you can imagine, if you were to hit a stone, it could throw off the timing, and one blade can hit the other.
I have had this happen to me more than once, and more often than not, it does a lot more damage than just bending a blade. Whenever this happened to me, I walked away a couple hundred dollars poorer.
Some mowers nowadays even have spindles mounted in the deck that prevent the blades from hitting each other.
What can go wrong with a timed blade?
Yes, because you are running a timing belt, it can be subject to wear and tear. If your belt stretches over time, it can affect the timing of the blades. You need to keep the belt taut for it to perform correctly.
A broken belt does not usually damage the blades as they stop turning. Then, it was time for a trip to the mower shop for a new belt.
What is the correct lawnmower blade position?
Should mower blades be parallel?
The manufacturer sets the blade orientation when the machine is assembled, and alignment pins hold the blades in place.
A lot of blades are set parallel, but a large number of machines run their blades in north and south positions. (as pictured above with the walker)
Do mower blades have to be lined up?
Blades are lined up when they are fitted to the new machine and held in place by the spindles and the pins, so you should not have to touch them. The way they are set up when they leave the factory is the setting needed to give the best possible cut.
If you have an older machine and are unsure of the orientation of your blades, you should be able to find this information in your instruction manual.
One suggestion that I would make is that if you are working on the blades, you pull them off one at a time. This will help you with placement when returning or replacing the blade.
How do you know if your blades are out of alignment, and how do you fix it?
The most obvious sign that you need to check your blades is generally bad-looking mow. This can include missing bits between the blades and a general scruffy cut.
This will mean that your blades may be out of alignment or have blunt blades. If you care about getting scalping or an uneven cut, it is more likely to be issued with your deck wheels.
Do all ride-on and zero turns have timed blades?
Some machines do not need timing as the blades do not cross over each other. There are a lot of different machines available, and many contractors prefer non-timed blades because the belts are half the price, and they are a lot easier to fix.
The most common cutting decks are the two and three-blade versions. We have discussed the two bald decks, so I will now talk about how a three-blade deck works.
What is the ideal three-blade mower orientation?
It actually doesn’t matter. When a mowing deck has three blades, it does not need timing. This is because there is no chance of the blades hitting each other.
Whereas a two-blade deck can have overlapping blades so it does not leave an uncut area. A three-blade deck has a third-cutting deck, which covers any overlap.
Some people feel that a three-bladed deck does a better mulch mow, but remember that a third blade will always equal 33% more spent on blades and associated parts. They can be heavy mowers and have been known to scalp lawns if they are lumpy.
The video below is a 3 blade deck in action. This is actually a John Deer Mulch deck, but it works exactly the same as a standard deck as far as the blade movement goes.
Does lawnmower blade balance make a difference?
The manufacturer will tell you that it is as important as a sharp blade because an unbalanced blade can put undue stress on an engine. As this might be critical with a helicopter, I don’t think it is such an issue with lawnmowers.
In 30 years, I have never had an engine issue that has been connected to an out-of-balance blade.
During the first few years that I sharpened my own blades, I used to use a blade balancer, but I don’t use one anymore. I have been sharpening push mowers and ride-on blades without any issues for years now without balancing them.
I must mention that when I sharpen the blades with my grinder I do count the strokes and keep both sides even, That’s about as far as I go.
Over the years, when I have serviced mowers, I have seen some horribly unbalanced blades (some with fins missing). This has never been noticeable while mowing unless one of the blades is damaged or bent.
I should also point out that I have always serviced my mowers every 33 mower hours, so an unbalanced blade left for an extended period may be a different story.
Conclusion: Do lawn mower blades need to be timed?
In Conclusion, it depends on the kind of mower and how it is set up. Your everyday domestic push mowers are unlikely to have timing. However, it becomes a necessity when looking at larger machines such as lawn tractors or zero turns with overlapping blades.
While timed blades offer better cutting efficiency, they come with a downside. They are usually a lot more time-consuming and expensive to fix. A blade that goes out of sync can cause much damage before you hit the kill switch.
Given a choice, I would rather have standard blades that don’t require timing, but as you move onwards and upwards to bigger and better machines, they become a necessary evil.
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