# Disc Mower Blades - How Long Do They Last?



## NewBerlinBaler (May 30, 2011)

I've put about 120 acres thru the new Kuhn disc mower so far. And now I see streaks of uncut grass here & there, not everywhere but it appears to be missing patches where there are tougher stems The blades still look good - at least they're not beat up as they would be if I hit something. So now I'm wondering, how many acres does everyone typically get out of a set of blades? Should be more than 120 acres, I hope.

Gary

P.S. Crop is primarily orchard grass / red clover mix - with a fair amount of weeds.


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## hog987 (Apr 5, 2011)

Granted I got rocks. But I have a 10 foot kuhn and have gone anywhere from 25-75 acres on a set of blades. It all depends on how thick the hay is. How many mole hills there are and how many rocks I hit.


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## Tim/South (Dec 12, 2011)

I usually flip them at around 100 acres. If I am cutting Bahia they do not last that long.

The set I have on now are at around 75 acres. They leave little ridges in the short grass in much need of rain. In tall grass they are alright. I start on some Bahia fields tomorrow and will put on a new set. Can't prolong the inevitable when in Bahia is next in line.


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## Grateful11 (Apr 5, 2009)

The thing with Kuhn blades is if flip them the bevel is reversed. They grind the same side of each blade. I don't like the bevel being down, you still have the twist angle correct but the downward bevel on the bottom seems to me like it create some amount of downdraft. Though it might be less susceptible to rock damage with the bevel down. NH blades have the bevel up each time you flip them.

I'm amazed at the people we know that say the blades still cut even when they're really dull and worn down.

Here's what I say to that, a set of 14 blades cost about $28. I figure our hay worth $50-60 a bale. If we leave even one bale worth of uncut crop in the field due to dull blades we've just lost more in hay than the price of a new set of blades. The moral of the story is: no need to go to the field with questionable blades. If they're sharp and still cutting fine go with it, if not spend the time to change them out.


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## Rodney R (Jun 11, 2008)

120 acres is too many, those blades should have been at least flipped by now, and if they were here they'd be lying in the scrap pile. You want to cut the hay, not rip the hay, so once it starts getting some rounding on an edge, it's time to flip them, or dress them with a grinder. Many times, we flip them when several get rounded, and/or get some sort of damage from a rock/dirt. I'd guess that on average we're getting about 50 acres on one side.

Rodney


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## ARD Farm (Jul 12, 2012)

Of course I'm the odd man out, I run a NH Discbine and on my last blade change I went with the new NH designed serrated blades. I used to flip at 50. With the serrated blades, I'm still cutting clean at almost 90 but I will flip them this winter when I pull the turtles to check for stray poly and change the gear olil. In that respect, I believe the serrated blades will go one season at best.

I think it depends entirely on field conditions, trash, how aggresive the cutter bar is (angle of attack) and blade design. I run on mostly heavy ground with a bit of sandy loam. I believe if you run mostly on sandy ground, your blade life will be shorter, much like a lawnmower. My yard and homestead is built on sanfy loam and I replace lawn mower blades yearly, not from hitting things, but from the abrasive act of the sand.

I've never resharpened a blade. Guess you could if you weighed each one on a postage scale to get the weights even....


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## mlappin (Jun 25, 2009)

I put on a new set before starting second cutting normally, run those the rest of the year and do first cutting the next year on the same edge then flip em before starting second again.

This year seems horrible for moles though and since it always seems to be down since we've had so much rain, I've already installed a new set right after first and those need flipped already. I don't have rocks or a lot of groundhogs to deal with though.


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## Colby (Mar 5, 2012)

Blades on a smaller disc cutter won't last as long as a bigger cutter.

Our senerio is quite different down here than most, we have very abrasive conditions. 
1 side on a 13' mower last 100 acres. While only lasting 60 acres on a 9' mower.


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## slowzuki (Mar 8, 2011)

We have rocks, they sometimes last 0 acres with no chance for a flip as its destroyed or been thrown. Probably more like 25 acres on average.


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## somedevildawg (Jun 20, 2011)

Bout 75-80 acres and flip here....only cut Bermuda


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## hog987 (Apr 5, 2011)

I envy the guys who can flip blades. I have had my kuhn now 3 seasons and I have only flipped a handful of blades. Mine end up being a dull moon shape and that is after straighten a lot of them. But beware you can only straighten them about 3 times before they break.


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## TJH (Mar 23, 2014)

Take a 4" grinder and put the bevel back on them. If you do this about every 35 to 40 acres they will last awhile. I stop a little before they are half gone and then flip. If your careful it's not too hard to keep them in balance. No more than they weigh a few grams is not going to matter. Keep in mind they don't have to be razors, just have a bevel. Never try to straighten them if they get work hardened they will become brittle.


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## ARD Farm (Jul 12, 2012)

Never sharpened any but sounds interesting. I guess like a lawnmower blade, no sharp edge, just a tiny flat. I may give it a shot this time around. My NH Serrated blades are pretty cheap for a full set.


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## MFred (Nov 29, 2013)

slowzuki said:


> We have rocks, they sometimes last 0 acres with no chance for a flip as its destroyed or been thrown. Probably more like 25 acres on average.


I was just thinking this. I've put a new set on only to go half way around a field, pick up a rock and promptly need to put a new set on.

Usually go 50-75 acres on a new set. I keep the good ones from the change for spares if I hit something and need to swap.

I will say quick change blades make the job wicked easy. Full set in about 2 minutes.


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## Lewis Ranch (Jul 15, 2013)

I used to flip around 100 acres on my trail mowers, I'm now getting closer to 200 on the sp before flipping.


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## Tim/South (Dec 12, 2011)

I touched up my last set a little and got some more use out of them.

I used a floppy type disk on the angle grinder, was quicker than flipping the blades.


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## krone.1 (Jul 28, 2013)

180 acres. Minor sharpening twice on the mower. Need to be flipped now. Very few rocks.


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## ARD Farm (Jul 12, 2012)

Colby said:


> Blades on a smaller disc cutter won't last as long as a bigger cutter.
> 
> Our senerio is quite different down here than most, we have very abrasive conditions.
> 1 side on a 13' mower last 100 acres. While only lasting 60 acres on a 9' mower.


Lets quantify that a bit...

The only reason blades would last a shorter time on a smaller cutter is it has to run more hours to achieve equal acreage to a wider one.

However, some times a smaller width cutter is an advantage, especially on odd shaped fields which are the norm around here as hay is usually an afterthought and planted on fields incapable of supporting large equipment turns.

Input blade tip speed is about the same.


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## Lewis Ranch (Jul 15, 2013)

Tim/South said:


> I touched up my last set a little and got some more use out of them.
> I used a floppy type disk on the angle grinder, was quicker than flipping the blades.


I used to carry a cordless grinder with the floppy disk, works absolutely great but I have found that sharpened blades do not seem to last long enough to be worth the time.


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## urednecku (Oct 18, 2010)

I tried flipping the blades on my Kuhn GMD700 last seaason. Just didn't seem to cut right, so after about 1/2 hour I came back to the barn, flipped & sharpened. (Trip to town for new would have taken at least an hour.)


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