Box Scraper Rotary Cutter & Box Blade Questions

   / Rotary Cutter & Box Blade Questions #1  

volunteer

Bronze Member
Joined
Dec 24, 2006
Messages
61
Location
Auburntown, TN
Tractor
1991 Ford New Holland 3930
Hoping to take delivery of my "new" 1992 Ford 3930 4x4 tractor with two rear remotes this weekend. Had new ag tires put on & turned out, fluids changed at local dealer. Back of rear wheels measures 94" across.

Going to use to keep 17 acres cut plus 1/10 mile + gravel drive maintained. Land is 95 to 99% cleared. Land has large hill in center where house is being built. There are a few trees on side of hill and perimeter of property. Driveway is approximately 12' wide.

Read tons of posts on both box blades, rotary cutters, and rear finish mowers. Now comes the time to make decision.

If I go with box blade to maintain drive, what size and features? Driveway has already shown signs of washing due to rain.

Land was bush hogged twice last summer but has, since winter, weeds stayed relatively short. Remaining weed "stalks" on ground are hard to walk thru even with boots. Would like to keep cut short but cannot decide if I should buy bush hog or rear finish mower. Any help on choice, size or features greatly appreciated.
 
   / Rotary Cutter & Box Blade Questions #2  
Typically, you figure a foot of rotary cutter for each 5 PTO horsepower. But I don't know of any nine-footers. So that makes me question the 94 inch rear track. Since the 3930 has an 84.5" wheelbase, that makes you wider than you are long. That further makes me suspect that a previous rear owner widened the rear track, perhaps for sidehill stability. At a minimum I'll bet the rims are scalloped out.

I say this, because an 8 foot rotary cutter is barely wider than your current rear track. I like my mowers to be wider. That's even more critical with a boxblade. 50hp might be sufficient for an 8' BB, but unfortunately that too barely covers your tire tracks.

I don't have original Ford/NH specs on that machine, so I might be all wet on this. But I'm thinking you should investigate the rear wheel width before proceeding into implement selection

//greg//
 
   / Rotary Cutter & Box Blade Questions
  • Thread Starter
#3  
Yes, the max width listed in manual with Ag tires turned out is 93.5". Due to my concerns about cutting on hill I had tires turned out for max stability. I had dealer measure since I have to get hauled from dealer to my small farm. Specs on tractor for PTO are 45 hp.
 
   / Rotary Cutter & Box Blade Questions #4  
volunteer said:
Yes, the max width listed in manual with Ag tires turned out is 93.5". Due to my concerns about cutting on hill I had tires turned out for max stability. I had dealer measure since I have to get hauled from dealer to my small farm. Specs on tractor for PTO are 45 hp.
Ok, safety first. And I know your question is about implements, but permit me to address the stability thing. If you didn't widen the front track proportionately, you may have actually reduced overall stability. The most stable 4 wheel platform is achieved when front and rear tracks are identical. What you've got now forms an oblong box, disadvantaged at the front. Sidehill tendency will now be for the tractor to roll (fold) in the direction of the downhill front wheel. Not as bad as a tricycle front end, but that design was intended for row cropping anyway.

Is it possible to widen the front track on a 3930 without unnecessarily exposing the drive hubs? If not, you might reconsider setting the rears quite that far out.

//greg//
 
   / Rotary Cutter & Box Blade Questions #5  
Lee,

Here is my take. I have cleaned my pasure of all brush and plan on keeping it that way. I was going to buy a rotery cutter for my newer tractor but I have decided to get a rear dishcharge finish mower instead.

Take the rhino rd rfm. The blades are 3/8" steel. I think the blades on my bh are also 3/8". I think that is heavy enough to mow down a decent size scrub tree mowing my pasture once or twice a year. If your pasture is fairly clean, does it need a bush hog type mower. The power needed for a rfm is about 25% less than a rotory cutter. Rhino has a 100" rfm that is ratedfor 35+hp. Some folks here say you can get a nice looking cut with a rotory cutter. Between my rc and rfm, I think the rfm gives a MUCH better looking cut.

The only problem I see with a rfm is the price.
 
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   / Rotary Cutter & Box Blade Questions
  • Thread Starter
#6  
greg_g said:
Ok, safety first. And I know your question is about implements, but permit me to address the stability thing. If you didn't widen the front track proportionately, you may have actually reduced overall stability. The most stable 4 wheel platform is achieved when front and rear tracks are identical. What you've got now forms an oblong box, disadvantaged at the front. Sidehill tendency will now be for the tractor to roll (fold) in the direction of the downhill front wheel. Not as bad as a tricycle front end, but that design was intended for row cropping anyway.

Is it possible to widen the front track on a 3930 without unnecessarily exposing the drive hubs? If not, you might reconsider setting the rears quite that far out.

//greg//

Thanks for the tip. I plan on going to dealer this afternoon and I will check this out. I believe all four were done but good reminder!
 
   / Rotary Cutter & Box Blade Questions
  • Thread Starter
#7  
kossetx said:
Lee,

I have cleaned my pasure of all brush and plan on keeping it that way. I was going to buy a rotery cutter for my newer tractor but I have decided to get a rear dishcharge finish mower instead.

Take the rhino rd rfm. The blades are 3/8" steel. I think the blades on my bh are also 3/8". I think that is heavy enough to mow down a decent size scrub tree mowing my pasture once or twice a year. If your pasture is fairly clean, does it need a bush hog type mower. The power needed for a rfm is about 25% less than a rotery cutter. Rhino has a 100" rfm that is ratedfor 35+hp. Some folks here say you can get a nice looking cut with a rotery cutter. Between my rc and rfm, I think the rfm gives a MUCH better looking cut.

The only problem I see with a rfm is the price.

Not that price is not important but I want to buy implements that are going to be used. If land is essentially cleared and weeds are currently in check, then it seemed to me that rotary cutter (bush hog) would not be needed unless I let the grass/weeds get out of control. Is this a correct assumption?
 
   / Rotary Cutter & Box Blade Questions #8  
A "bush hog" is a versatile implement in that it can mow and shred. With good blades, I've used mine for years to mow fairly close to the house (I use a riding mower for the closest 50' or so) plus I'm constantly tackling heavy brush and small trees too. But it really depends on what YOU are looking to do.
 
   / Rotary Cutter & Box Blade Questions #9  
Actually on the stability thing, the tractor won't tip until it's CG is outside the box formed by the contact patch of all 4 tires. So setting any pair out farther will slightly extend your tilt limits.
 
   / Rotary Cutter & Box Blade Questions #10  
It depends on the type of soil you have there in TN. From the info you have given you could run a six footer on either one of the implements and be conservative. There are things that make a lot of difference such as the weight of the rotary cutter. Some are much heavier than others. The soil if it is clay or sandy means you could not pull as much with one as the other. SO, I would say a general estimate would be six on each of them and you might get by with more width. I know that isn't to great of an answer. But, there are variables that one has to take into account. You might pull an seven foot mower or a longer box blade depending on the make and so on. I know that tractor will pull a seven foot mower, was just thinking of the brand and weight. Same with the box blade. Hope this helps some.
 
 
 
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