Rotary cutter vs flail cutter

J Hamilton · May 10, 2020

Can anyone tell me any advantages/disadvantages between using a rotary (bushhog) cutter and a flail cutter. I only have experience with rotary cutters and have been reading about flail cutters but would like to know some first hand experience and suggestions about them. I mostly do monthly field mowing in fescue.

BobReeves · May 11, 2020

I use a John Deere flail to cut 7 acres that I started cutting with a rotary. Flail does nicer cut without leaving windrows but has trouble cutting the real heavy or tall stuff. Easier to maneuver as it sticks out less in the rear. If you cut often enough you can cut nicer and faster with the flail.

MarkB_MI · May 11, 2020

A flail mower in general does a nicer job. The knives of the flail lift up the grass that's been flattened by the tractor's tires, so you get a nice, even cut. Cuttings are distributed across the mower width, rather than left in a windrow. Highway departments often use flail mowers because they don't tend to throw rocks and debris to the side, reducing the hazard of hitting passing cars.

The biggest disadvantages of the flail are that they're more expensive than equivalent rotary cutters and usually require more power to operate. Also, most flails aren't intended for heavy brush, which is where brush hogs shine.

If you decide to get a flail, there are a few options to consider. In addition to differing widths, there is an offset option that's good for mowing around trees or other obstacles. You typically have a couple of different knife styles to chose from, depending on what sort of mowing you'll do. And some flails can be ordered with "reverse" rotation, where the cutter shaft spins opposite the direction of travel for better mulching.

Alamo (Mott) is the best known maker of flail mowers, but there are many others.

showcrop · May 11, 2020

There are two very different types of flail mowers. There are the ones with very light but sharp cutters for lawns and heavy grass, and then there are the ones with heavy cutters that are used for very heavy grass weeds and brush. They are the ones that you see on hydraulic arms being used for roadside mowing. They will bounce off rocks and keep going.

Bob Bancroft · May 11, 2020

I had an MC flail mower which was reversible. One direction for short grass,[finish mowing] and the other for tall grass. The idea being that tall grass would lay over and the flails wouldn't get a hold of it. It was a very rugged machine. But this is a stony area, and no matter how careful you are, you're always hitting stones, so you had to check for damaged or missing flails often. I was trying to do multiple jobs with one machine. As time went on, I acquired several different mowers, and sold the flail.

Traditional Farmer · May 11, 2020

I have several flail mowers, a Ford which is pretty bad all around then 3 Matthews Corp mowers the two have heavy flails one is for cutting hay the other is for basically mowing fields as it pulls behind both work the same.The third MC mower has the lighter flails and a compartment on the rear of it to collect the clippings if I want or to switch the door and just let them hit the ground.I use the collector on it to make mulch for the garden the nicest mulching material you'll ever find.All the flail mowers have to be operated at a much slower speed than a typical brush hog and take more HP.

Farmer Rock · May 11, 2020

I don't know why some are saying there not good for heavy brush,because i have a 90 inch alamo on a 52 pto hp tractor,and it really is the perfect match and i typically mow 10 acres ever two months of 4 feet high thick brush.i would say speed is right where i like it,i usually use 1st gear in high stuff just to see where i am going an know the gopher holes aren't under my wheels,but i could use 2nd if i was in a rush.flail mowers whoop the pants off a rotary mower.

JMOR · May 11, 2020

(quoted from post at 09:04:30 05/11/20) I don't know why some are saying there not good for heavy brush,because i have a 90 inch alamo on a 52 pto hp tractor,and it really is the perfect match and i typically mow 10 acres ever two months of 4 feet high thick brush.i would say speed is right where i like it,i usually use 1st gear in high stuff just to see where i am going an know the gopher holes aren't under my wheels,but i could use 2nd if i was in a rush.flail mowers whoop the pants off a rotary mower.

robably comes down to a person's definition of "brush". Wild berry vines, etc. or 1 to 1 1/2 inch wood, tree sprouts, etc.

MarkB_MI · May 11, 2020

> I don't know why some are saying there not good for heavy brush,because i have a 90 inch alamo on a 52 pto hp tractor,and it really is the perfect match and i typically mow 10 acres ever two months of 4 feet high thick brush.

If you're mowing it every other month, then it's not what I would call "heavy" brush. Not all flail mowers are the same, but I know mine starts breaking its cutter rings if I try to mow something too heavy. Such as two inch saplings or small stumps.

Oliver 500 Wa · May 11, 2020

I have an old (40 years?) Mott 60" wide flail. It's been an excellent piece of equipment, but reaching it's last days I'm afraid. Lots of holes rusted through the body. The gearbox splines are very worn and lots of slop. Parts are probably NLA. No worries, I've had it almost 30 years so the $700 I paid for it has paid itself back countless times.

Does a much nicer job than a rotary. Mainly because every rotary I have used, when you get in heavy grass stops cutting it and just kind of swirls and balls it up leaving a ragged clumpy mess behind. Definitely uses up more HP in heavy cutting than a rotary.

I've worn out a few sets of flails. That's no fun when you have to buy a couple hundred at $1+ per blade. Originally it used 3/8" hardened clevis pins and cotter pins to hold the flails. I switched to using 3/8 grade 8 bolts and nyloc nuts because the cotter pins would get beat up and fall out then the clevis pin and blades went shortly after.

Fordy20 · May 11, 2020

A flail does a much nicer job. But, if you get heavy duty one like in the photo, they are expensive. I would not buy a light duty one. A friend had a light duty John Deere flail and caught the back roller on something and bent it. I had a lighter one and hit a rock which made the drum out of balance. If you buy a used one, run it at operating speed to check the drum for balance. So, if you're mowing where you know there is nothing to hit, I would rather use a flail. But, if you don't know what's in the field, a rotary is less likely to be damaged and cheaper to repair if it is.

Mike Groom · May 11, 2020

I have a New Holland 72 inch heavy duty flail that works great on weeds and grass up to head high,I usually mow twice year the second time is not as high,usually I mow in June and then late August,in June I mow in 2nd gear and in August I mow in 3rd with my 1520 John Deere.The flail mower does a great job compared to the 6 foot Woods brush mower that I have also,as someone stated you can only cut up to two inch saplings with it and you don't want to hit any down branches,make sure any one that you buy has the one piece blades and not the little flail knives that attach with the rings,mine bolt on back to back with 3/8" grade 8 bolts and I go two to three years without changing any blades and then you can swap them from side to side and your good to go again.

3LFarms · May 11, 2020

Heavy duty flails exist. My 6.5 foot flail is rated for 3" material.

Downside is it costs close to $10k (unless you can buy one used from a county road maintenance auction) and will put a hurt on an 80 hp tractor in heavy brush. Upside is it will pure a cinderblock (done it) and will make make 1/2" rebar it s ***** (did that too).

Farmer Rock · May 12, 2020

Well maybe we got different brush but there is more 2 inch sappling than there is grass,i mow pine tree groves and over grown pastures,and let me just say its an ex highway setup,so any doubt you have,take it up with them.when it is too dry to burn,i back into the burn pile (usually 4 inch branches or less) and it just leaves wood chips,if that ain't brush i don't know what is Mark.

ikepieman · Jul 5, 2020

I was lucky to have found an old Mott flail that just needed a couple new bearings. It does an amazing job compared to the finish mower I used to use. Definitely a better cut over a rotary.

kcm.MN · Jul 5, 2020

I've never used a flail mower, but when I had my Howse rotary, I used the stock blades for years cutting both tall grasses and brush. It didn't do so well with the grasses.

When we moved up here I re-sharpened the blades to be much sharper. I had plans to buy another set of blades for cutting heavier brush, but the tractor I had then died and the replacement tractor was far too much hp for a 5' brush cutter.

When cutting stalky things like tree saplings, corn stalks, etc., you really want a more blunt blade that will not leave a clean cut. Stalky brush with clean cuts can poke through tires, as well as through feet. My wife learned that one the hard way when just a child.

Do not know what your needs or finances are, but I, personally, would choose to get another rotary and 2 sets of blades; one for grasses and one for stalky cuttings. My rotary had a stump jumper. I wouldn't have a rotary without one!

Rotary cutter vs flail cutter

J Hamilton

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BobReeves

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MarkB_MI

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showcrop

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Bob Bancroft

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Traditional Farmer

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Farmer Rock

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JMOR

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MarkB_MI

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Oliver 500 Wa

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Fordy20

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Mike Groom

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3LFarms

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Farmer Rock

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ikepieman

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kcm.MN

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