Rough cut mower size

BoonDoc · Sep 16, 2018

Hello all. Been ages since posting. I've been searching advice on sizing a rough cut mower but see a few things that contradict each other. A video on size selection on one supplier's site mentions to always buy wider than your tractor or risk a lousy looking cut. I can understand that. Many on this forum say the same. Another site notes staying within the HP guidelines is by far the most important consideration. Still more caution on weight. If I stay true to all that, I'd be running a 4 footer, not much wider than a John Deere riding lawn mower. A visit to sites like Northern Tool show 72 inch King Cutters with 40HP gearboxes that require a minimum of 40HP. I always thought the gearbox was max HP a cutter could handle. Another ad shows a 72 inch that requires "25 o 40" but a quick look at the link to the manual contradicts that with far higher numbers. Confusing for the consumer. Yet another model, only 48 inches, needs 25 HP minimum. In theory, even that 48 inch King is too large for me.

My tractor is a NH Boomer 30 with FEL and loaded tires. TractorData has it weigh in around 3000lbs but not sure if that includes the front hydraulics and bucket. Add for filled tires That might put her at 4500lbs. PTO is 22.5HP. Tractor Data Width is listed as 64 inches but I'm not sure if that's overall or tread width. PTO capacity is 1800 lbs. So ideally, I'd be running a cutter at least 64 inches wide, preferably 72 but would be very limited by HP. Weight isn't an issue as capacity is good at the PTO lift. Problem seems to be power. I'm cutting a nearly level field a few times a year with 1 to 2 foot weeds and grass in spring, 1 foot grass otherwise. I don't mind making partial passes if the conditions are heavy, nor do I mind first gear. I was once thinking of a 5ft as a good tradeoff size-wise but that would mean my tires are rolling over the edges of each pass. How important is that? Any advice appreciated.

oosik · Sep 16, 2018

I COMPLETELY understand your quandary there BoonDoc. Fortunately - I have little or nothing to cut on my 80 A. However - my Operators Manual is completely confusing. I've upgraded to a MUCH heavier rear blade - to work on my mile long gravel driveway - in the summer when it sets up like concrete. In order to get the necessary offset to plow snow in the winter and the weight to penetrate the surface in the summer - I've exceeded the width that Kubota recommends - but not the weight. My rear blade - Rhino - 96" and 1050 pounds. Kubota says - nothing wider than 72" but weight can go up to 1200 pounds. There is no way in God's green earth that I can offset & plow snow on my driveway with a rear blade that is only 72" wide. In order to get a 72" rear blade that weighed 1200 pounds - I'd have to ask the local welding shop to build up a custom blade.

And this weight/size incongruity is spread thru all the examples given in my Operator's Manual. Leads one to the belief that Kubota is ULTRA conservative.

I'm fortunate here - there is a ADM(Archer Daniels Midland) facility, granary, in the little college town near me (12 mile drive). I have FEL with heavy Land Pride grapple - beet juice in the rear tires - heavy rear blade on the 3-point. Three years ago I made the trip into ADM and their grain scales. My M6040 weights - 10,100# across the grain scales. Soooo - - my four tires are fairly well planted on the ground.

If I were to ever purchase a brush hog - it would be a 60" - heavy duty model - like Brown 415. Everything I have to cut is either dead grass/weeds or Buck brush(max diameter - 1/2"). I have no beautiful/fancy bright green meadows to mow. Least of my concern would be stomping down the dead grass and not having the mower catch/mow it.

Even though I have no mower - I've seen plenty cutting fields in our area. That's the second reason I do not have a cutter. My tractor is open station - the dust/crud/trash that a cutter gets airborne is utterly amazing. I would almost need a full Haz-Mat suit to do much cutting on my property.

Get out there and measure your rear tread - outside to outside. You could be in for a surprise. Tractor data web site lists mine at 73" - - it is actually 80" outside to outside.

The real decision you must make - do you want a cutter that is wider than your rear tires or not. I would opt for one narrower but much heavier construction - JMHO.

BoonDoc · Sep 16, 2018

Hello there Oosik, thanks for the reply! You've given me some food for thought. First, I do believe that tread width is used, center of one tire to the center of the other. It reasons, therefore, that it doesn't take into account half the width for each tire. That, by my guess, would mean actual width is one tire width larger. It also means that by your argument, I'd ballpark actual width as close to 6ft across (I'll measure when I'm up at camp again). A cutter would need to be quite wide indeed to avoid my tire paths. Your point is well taken. Like you, I'm currently using a 6ft box blade on the rear and the edges of the box line up well with the tire edges. I've yet to try a cutter. Sounds like I'll be needing a scarf around my throat and mouth with a pair of goggles

The small John Deere I use for the 3 hours of cutting I do already kicks up dust in spots like a stampede in August.

I had to chuckle when I read, "I have no beautiful/fancy bright green meadows to mow. Least of my concern would be stomping down the dead grass and not having the mower catch/mow it." It got me to thinking, neither do I really. In fact, I don't care that it's closer to rough than finish. A smaller cutter could also come in handy on saplings and thick brush should some grow, or hills, should some appear :laughing:

I went down this road of questioning around 5 yrs ago and for some reason I can no longer remember, thought the 60 inch was the right choice. Looks like I'm remembering why.

Thanks again!

Before and After. 3 hrs later, time for a beer or two.

John Fitzgerald · Sep 16, 2018

I use a standard duty 60" on mine with no problems cutting grass, weeds, and occasional yearling sprouts. Watch the RPM. If it slows, slow the tractor down. On your tractor, I would get a medium duty 72". If I had the 48", the tires would hit about the same time as the cutter. I prefer the cutter to stick out a little so I can trim close to trees and other obstacles. Small tractors will pull a bigger cutter than "suggested", as long as they can lift it OK. Simply have to go slower.

boomer1025 · Sep 16, 2018

One thing about MMM and rear mowers, your always going to be running over wheel tracks.

leonz · Sep 16, 2018

BoonDoc said:
Hello all. Been ages since posting. I've been searching advice on sizing a rough cut mower but see a few things that contradict each other. A video on size selection on one supplier's site mentions to always buy wider than your tractor or risk a lousy looking cut. I can understand that. Many on this forum say the same. Another site notes staying within the HP guidelines is by far the most important consideration. Still more caution on weight. If I stay true to all that, I'd be running a 4 footer, not much wider than a John Deere riding lawn mower. A visit to sites like Northern Tool show 72 inch King Cutters with 40HP gearboxes that require a minimum of 40HP. I always thought the gearbox was max HP a cutter could handle. Another ad shows a 72 inch that requires "25 o 40" but a quick look at the link to the manual contradicts that with far higher numbers. Confusing for the consumer. Yet another model, only 48 inches, needs 25 HP minimum. In theory, even that 48 inch King is too large for me.

My tractor is a NH Boomer 30 with FEL and loaded tires. TractorData has it weigh in around 3000lbs but not sure if that includes the front hydraulics and bucket. Add for filled tires That might put her at 4500lbs. PTO is 22.5HP. Tractor Data Width is listed as 64 inches but I'm not sure if that's overall or tread width. PTO capacity is 1800 lbs. So ideally, I'd be running a cutter at least 64 inches wide, preferably 72 but would be very limited by HP. Weight isn't an issue as capacity is good at the PTO lift. Problem seems to be power. I'm cutting a nearly level field a few times a year with 1 to 2 foot weeds and grass in spring, 1 foot grass otherwise. I don't mind making partial passes if the conditions are heavy, nor do I mind first gear. I was once thinking of a 5ft as a good tradeoff size-wise but that would mean my tires are rolling over the edges of each pass. How important is that? Any advice appreciated.

======================================================================

A used John Deere 25A flail mower or a new JD290 flail mower is well within your power band as my father used a
25A on his ford jubilee for years.(7 foot finish cut)

They come up for sale quite often on tractor house and in other rags and you can just google used flail mowers to look as well.

Turbys_1700 · Sep 16, 2018

I had the earlier version of the 30 in a New Holland 1720. The specs are nearly identical. Like you I had a FEL with loaded rears. The tractor was around 2800# dry and 3300# loaded. With FEL it was in the 4300# range. I was right at 60" rear tread width with AG tires.

I would get a light to medium duty 5' cutter in the 600# range. Anything heavier you will get light in the front unless you want to put additional weight in the bucket.

At the time I bush hogged with it I ran a light duty squealer and it handled it just fine. This was before the FEL was added. Later I got a 6' Brown and it was too much cutter for the tractor with the FEL attached. The Brown was a little over 1100#.