Rotary Cutter Shorten blades on rotary cutter to match tractor HP

[birdman13261]

I have the JD 1025r and it is 18hp at the PTO and I need a rotary cutter to clear some woods with multiflora rose and other tall weeds and briars. The dealer says to use a 48" mower abd they are in stock and look real pretty, but I want a cheap used one and I have yet to see one reasonably priced. So here is what I am thinking.....can I use 48" blades on a 60" (5') 3pt mower at 540 RPM? Either shorten (cut or grind) the 5' swing blades or buy 4'?

First post, thanks for any advice!

 

[amaxwell]

I have the JD 1025r and it is 18hp at the PTO and I need a rotary cutter to clear some woods with multiflora rose and other tall weeds and briars. The dealer says to use a 48" mower abd they are in stock and look real pretty, but I want a cheap used one and I have yet to see one reasonably priced. So here is what I am thinking.....can I use 48" blades on a 60" (5') 3pt mower at 540 RPM? Either shorten (cut or grind) the 5' swing blades or buy 4'?

First post, thanks for any advice!

I used a 5' cutter with my ford 1300 (13 pto HP) for several years . I just cut a narrower swath each time around the field. Now I use the same cutter with a 24HP tractor. As long as the tractor can handle the weight of the larger cutter you should be ok.

 

[Samuellm]

All the mowers I have worked on take the same leght blades it is the boss in the center that is differant have a look and see it is the same for your ones. I see no reason why not unless it is too heavy for the 3ptl

 

[birdman13261]

Thanks guys, I think I will check out 5 footer and see if I can mow with that and maybe use shorter blades for the thick briers. I can't take small passes since I will likely be backing over them.

 

[LD1]

I'd try it with the 5' first. 18hp at the PTO is probably similar to what an old wore out 9n/2n ford would be putting out. Go slow, and raise the cutter, back over, then slowly lower.

If that dont work, your best bet is to sell and buy a 4' cutter. By chopping the blades down, you really loose blade tip speed. Would still chew up the briars though, but would probably suck for grass and weeds once you get the briars under control.

Oh, and welcome neighbor. Centerburg is just a few minutes south of me, and I happen to pass through there quite often, usually on the way to the golf course.

 

[Capricious]

Not endorsing any particular supplier, but you can find a lot of dimensions for cutter blades here:

http://www.powellequipmentparts.com/rotary-cutter-finish-mower-parts_opt.pdf

 

[jeff9366]

Do not fool with design parameters for implements.

Instead, sharpen the blades on your used rotary cutter, then take a narrower bite.

Bayer Weed and Stump Killer herbicide kills Multiflora rose and other briars with one or two applications. Roundup requires five or more applications to kill same.

 

[gwdixon]

The momentum of the blades (due to weight) and their rotational speed (tip speed) is what does the cutting. If the travel is too fast and/or the foliage too heavy then the blades will swing out of the way and cutting width will be reduced. The blades effectively shorten themselves automatically.

With shorter blades on a larger machine the lighter weight of the blades would reduce momentum and tip speed. It would actually be harder to cut with shorter blades. This would be compounded if the gearbox is designed for a certain length blade and a shorter one is installed.

LD1 has pretty much addressed the issue well.

So in summary, I'd buy the larger mower and sharpen the blades to reduce drag (a controversial subject). Then I'd watch the engine RPM as it relates to the ground travel speed over the mowing area. Less bite, higher mower setting, more overlap, slower speed would be strategies that could be options (credits to LD1).

Edit: Credits to Jeff also, we matched posts.

 

[flusher]

Do not fool with design parameters for implements.

Instead, sharpen the blades on your used rotary cutter, then take a narrower cut.

Bayer Weed and Stump Killer herbicide kills Multiflora rose and other briars with one or two applications. Roundup requires five or more applications to kill same.

Right on. Sharpen the blades. Since I don't have any brush to mow, just weeds, the blades on my 6-ft Hawkline brush hog are sharpened to the same edge radius I use on my riding mower.

 

[Mendonsy]

Are you talking about using a mower (fixed blades) or a bush hog (swivel blades)???
That will make a big difference!! If you use a bush hog as gwdixon suggests you won't have a problem. A mower with fixed blades will not work well at all on heavy brush.