Rotary cutting

[BuzzardA91]

I am buying a rotary cutter for a 3-4 acre field but have never used one. I know how to size the hp but how size the width? The width of my tractor is 66". Can I go with a 5' or is a 6' a must. I will miss a few inches in tight spots with the 5' or can you off set the cutter a few inches by locking the lower arms off center on the 3 point? I don't care about saving time.

Also my 3 pt hitch is rated for 2,200 pounds 24" out. Obviously a rotary cutter is rather large, heavy and long. What weight would be safe to get?

 

[nuffer460]

I am running an IH 411 6' rotory mower. Very heavy unit. I put it behind my NorTrac 254 Tractor. It is at the very limits of my tractor. My tractor is gear drive, not a hydraustat. So I don't lose allot of hp at the pto. I would not have tried this if not for a local Bobcat Dealer. He said that the frame size and tire size are good for a 6' rotory. If the engine temp goes up a little. I just cut a narrower swath. I do have to stop every so often to clean off the radiator screen. I also don't actually lift the whole unit off the ground. It runs down the road on the rear tail wheel just fine.

 

[Soundguy]

if you have the pto hp and safe weight capacity both on the 3pt and fram for a 6' and don't have obstacles.. go 6'

 

[Mark Page]

You don't mention the tractor's horse power. The rule of thumb is 5hp/ft, this would call for a 30 horse machine with a 6 foot hog. I used to use a 6ft mower with a 35 horse Massey and never had a problem. I could lift it all the way up and back down on multi-flora-rose bushes.

 

[Mark Page]

You don't mention the tractor's horse power. The rule of thumb is 5hp/ft, this would call for a 30 horse machine with a 6 foot hog. I used to use a 6ft mower with a 35 horse Massey and never had a problem. I could lift it all the way up and back down on multi-flora-rose bushes.

 

[Jerry/MT]

Conservative rule of thumb is 5 hp per foot of mower width.( If you are not going to cut four foot high weedy fields, 3.5 hp per foot will most likely be adequate.)
Get the width that covers your rear track, probably around 6 ft. That imples ~21.5-30 pto hp. ( A five footer would require ~ 17.5-25 pto hp.)The lightweight mowers are around 450 -500 lbs, the medium duty ones around 700-750 lbs and the heavy duty go 1000 lbs and up. You have adequate capability to raise any of these with the three point hitch but remember the heavier the mower the lighter the front end becomes unless you ballast the front. The price is proportional to the weight.
You can't off set the usual rotary cutter however you can probably find an offset mower but you'll pay a premium for it.

If your just mowing normal high grass( 2-3 ft tall) on 3-5 acres, the light weight will probably be a cost effective solution for you. If you have rocky ground and tall weeds and grass, the medium weight 5 foot model might be a better solution.

Your $'s, your choice.

 

[BuzzardA91]

Thank you. I didn't mention the HP because I did not want to cloud the issue, that part I understand.

I more wanted to know what the disadvantages of going with a 5 foot MX5 vs the 6' frontier. About the same price and weight but the MX 5 is way heavier duty. Mow time would be longer but what else? The width is 66" of the tractor some would be 3" short on each side. Is that going to be a problem?

My field the Frontier will be fine but I may want to do others and am worried about hitting something or thicker stuff.

Also JD doesn't list my tractor under the MX6 but it does the 6' frontier and the MX5. Not a HP issue, I have 32.5 PTO hp. I'm guessing it is the weight difference? Or it could just be a mistake, I have found several in the JD brochures.

 

[deere5105]

Go MX5 and be done. Will last you many years. If you are cutting anything thick, the MX6 will likely be a HEAVY load on 32.5 PTO HP.

 

[BuzzardA91]

Thank you. What about being 3" short on each side of width of tires? Is that an issue, I have never used one.

 

[TerryR]

I will miss a few inches in tight spots with the 5' or can you off set the cutter a few inches by locking the lower arms off center on the 3 point? I don't care about saving time.

I have my tires set at max width because of the significant side-hills on my field, so my cutter is about a foot narrower than the wheels. I do as you suggest, pulling the arms all the way to one side so the cutter matches the wheels on that side. Thus I have uncut wheel tracks only on the first cut through a place. It works fine - just a bit of trouble to re-adjust the arms after mounting or dismounting the cutter.

Terry

 

[deere5105]

Thank you. What about being 3" short on each side of width of tires? Is that an issue, I have never used one.

I have run a 5' behind a JD 5205 without noticeable issues.

 

[Oldstuff]

Buzzard- I am in the exact situation as you. I have a Ford 2000 and while it will handle a 6 footer that would put the cutter 3 inches outside of the wheels, I went with the 5 footer that puts the cutter 3 inches inside the wheels and am very happy with it since trimming up close in not needed for me. I have had this setup since 2010 and do not regret it.

Oldstuff

 

[the6shooter]

If your tractor has the 2 pcs. wheels you can ajust the wheels in to make a narrow tire track pattern then go with the 5' cutter. if you don't have ajustable 2 pcs wheels then you can still go with the 5' cutter.
It doesn't matter, you still have to run the cutter and over lap, on every pass. it doesn't matter you still have to make the over lap no matter if it's 5' or 6' and 10' makes no differance.
david

 

[LD1]

Thank you. What about being 3" short on each side of width of tires? Is that an issue, I have never used one.

No, it wont be an issue. As you said, the only problem is mowing close to something, you will loose 6". But being narrower entirely why. Cause you cant "scrub" your tractor tires tight up against things anyway. And you can offset as you mention. The 5' will also be more manuaverable, shorter (which will make it easier to trailer if applicable), and may be light enough with the weight in close enough to not require the FEL to stay on like a 6 footer "may", this would make it even more manuaverable, and being narrower, you dont have to worry about catching the corner of the bushhog on a tree or something.

And a 5' cutter wont necessarialy be slower mowing either. Speed is a function of how much power you have. a 6' cutter is 20% bigger, but that would also mean going 20% slower for an equal cut without bogging down. So by going to a 5' cutter, you may be able to mow a gear higher to make up the difference.

 

[soulasphil]

Some cutters can be easily offset to cover one side of the tracks completely. Such is the case with mine which can be hitched either in a centered position or offset to the right (very convenient along walls or hedges).

 

[newbury]

Only to slightly hijack -
Any links or pointers to how best to set up a rotary cutter on the three point? My cousin just loaned me his 30hp Satoh again, this time with a JD cutter attached. He was running it with the cutter at an angle (left side lower than right) and at full lift it only clears the pavement by a few inches. I'm wondering if I should adjust the top and side links.

 

[Jerry/MT]

Tractordata .com lists the '86 Ford 1710 at a shade under 24 pto HP @540 rpm. (Tractordata.com has been known to be wrong.) You quoted 32.5 pto horsepower. You'll need to make sure that you really have 32.5 pto hp @ 540 ptto rpm before you get a 6 footer.

Initially you said you were going to mow 3-5 acres. If you're going to do mowing for hire, I'd lean to the medium weight units (700-750 lbs) because you inevitably are going to get into "dirty fields" with things in them you can't see from the seat and will hit with the cutter. Heavier would be better in this circumtance.

If you really have 32.5 pto HP at 540 pto rpm the stick with a 6 footer medium weight unit. If you only have 24 pto hp @540 pto rpm, in my opinion, go with a medium duty unit at 5 ft width.

 

[LD1]

Only to slightly hijack -
Any links or pointers to how best to set up a rotary cutter on the three point? My cousin just loaned me his 30hp Satoh again, this time with a JD cutter attached. He was running it with the cutter at an angle (left side lower than right) and at full lift it only clears the pavement by a few inches. I'm wondering if I should adjust the top and side links.

Depends on the cutter. But all of them should be level left to right. and when mowing, the tail should be an inch or two higher than the front.

When you say fully raised it is only clearing by a few inches.....is it a ridgid mount cutter, or does it have a swinging shackle for the TL, or does it use chains like soulasphil's pictures??? And is it the front or rear that is barly clearing?? If it is the rear that barley clears, and it uses chains or the swinging TL, then the TL needs shortened. Because you are using up most of your raise travel just taking the slack out of them.

 

[joshuabardwell]

And a 5' cutter wont necessarialy be slower mowing either. Speed is a function of how much power you have. a 6' cutter is 20% bigger, but that would also mean going 20% slower for an equal cut without bogging down. So by going to a 5' cutter, you may be able to mow a gear higher to make up the difference.

I've heard this said, and my (limited--admittedly) experience leads me to question it. On the fields I have bush-hogged, the limitation on speed has been either the thickness of the brush or the bumpiness of the ground. And when I say, "thickness of the brush," I don't mean how fast I can go without bogging down, but I mean how well I can see what I'm getting into so I know if I'm about to drive into a ditch or mow over an object. In these circumstances, I found myself wishing for a bigger cutter, since my PTO hp was not the limiting factor in my speed. I could have driven at the same speed, but covered more ground.

I have run into some cases where the brush is thick enough to bog down my engine, in which case I agree that it doesn't matter what size you're using. But when the brush is not thick enough to bog down the engine, other factors may limit speed in a way that mean you could use a larger cutter without tradeoff. I don't know how typical my results are, and like I said, my experience is limited.

My preliminary conclusion was that a larger cutter was better because, in the thick stuff, you could always slow down, but in the thinner stuff, you could go as fast as the terrain would allow and cover more ground than if you were using a smaller cutter and going the same speed.

 

[LD1]

If power is not your limiting factor, they you are right, size would matter.

But when doing something regularly, where you know whats out there and dont let it get overgrown (just pasture grass), the grass gets really thick. And even though it is under 2' tall, the grass will bog a cutter down in a hurry. These are the times that size dont mater much.