Rotary Cutter 305 Bush Hog 5'

[SPYDERLK]

Old thread, but correct.

How well it cuts light grass is all about blade speed and how sharp you keep them.

Good heavy duty cutters, people tend to use cutting alot of thick brush with. And in doing so, you DONT want sharp blades as it turns all the saplings into little spears that will go right through a tire. Dull/blunt blades shatter and splinter them, no spear to go through a tire.

I'v seen cutters with as low as 10,000 FPM blade tip speed and ones as high as 17k. And anything in between. The higher speed dont really gain you much if cutting brush, saplings, briars, etc. But helps tremendously on grass.

Another huge help is high lift/suction type blades.

I agree in principle but have not been able to detect it in practice. I have experimented cutting at 540 and 748 pto speed in alternating circuits of a field. I can see no change in the characteristic of the cut. ... Strange. :confused2:

 

[SPYDERLK]

The 305 and 306 are heavy duty cutters rated for 3" diameter material. You're gonna cut 3" brush that kind of HP IS a requirement. Cutting light grass will obviously not require that kind of power.

Yes, and to go a little further grass can take a lot of power but you can always slow down and make do fine with much less HP. Cutting trees OTOH causes huge retarding impulses each 180 of rotation and lots of HP is needed to keep blade speed up and the knives robustly extended. ... Of course, with that HP you could cruise through thick grass pretty fast too.

,,,In my experience 9 HP per foot does fine with 4" trees. 12 would certainly be better.

 

[msjanket]

Yes, and to go a little further grass can take a lot of power but you can always slow down and make do fine with much less HP. Cutting trees OTOH causes huge retarding impulses each 180 of rotation and lots of HP is needed to keep blade speed up and the knives robustly extended. ... Of course, with that HP you could cruise through thick grass pretty fast too.

,,,In my experience 9 HP per foot does fine with 4" trees. 12 would certainly be better.

Makes me wonder about the effect of blade shape at the tip. If the leading edge of the blade is advanced at an angle from the bulk of the blade farther back, does this create a holding influence on the blades of grass and weeds, perhaps brush, and does it thusly cut "better". A very rounded edge that falls away from the leading edge can't cut as well as the one I just described, can it? Looking at the blade from the "top" of same would show an angle of at least 15 degrees ahead of the bulk of the blade farther back. Has any manufacturer considered this alteration in blade shape? Or, am I barking up the wrong sassafras?

 

[Turbys_1700]

Yes, and to go a little further grass can take a lot of power but you can always slow down and make do fine with much less HP. Cutting trees OTOH causes huge retarding impulses each 180 of rotation and lots of HP is needed to keep blade speed up and the knives robustly extended. ... Of course, with that HP you could cruise through thick grass pretty fast too.

,,,In my experience 9 HP per foot does fine with 4" trees. 12 would certainly be better.

Couple months ago I hogged an area that was left alone for over a year and a half. Small pine trees, heavy brush. blackberry bushes, ETC... Pretty extreme conditions. I used my Workmaster 50 and Brown 472. My tractor has 45 PTO HP which equates to 7.5 HP per foot of cut. That combination worked great but at times the tractor certainly "knew" what was going on when cutting those trees. I think that 4 to 5 HP per foot of cut is fine for clipping pastures.

 

[LD1]

I agree in principle but have not been able to detect it in practice. I have experimented cutting at 540 and 748 pto speed in alternating circuits of a field. I can see no change in the characteristic of the cut. ... Strange. :confused2:

Lift blades, and how fast your ground speed is play a part as mentioned.

If your accustomed to mowing at 3-4 MPH, then no I dont imagine there would be much difference between 12k and 15k blade speed.

12k vs 15k is a difference of blade RPM of 750 vs 950 on a 5' mower. 4 MPH is ~350 feet per minute ground speed. So even at 12k/750RPM blades, You are making over 2 full revolutions of the blades for every foot of ground covered. Which works out to advancing the cutter into the uncut material less than 2.5" for every blade that comes around. Plenty good enough to leave a good cut even at lower blade speeds.

Try mowing at 6-8 MPH and there is a big difference in my real world experience, using a 306 bushhog with 10k blade speed, a KK and bushhog 5' cutters both with ~12.7k blade speed, a 6' IMC cutter with close to 15k blade speed, and a woods DS96 with close to 16k blade speed. They all cut well at the more normal 3-4 MPH. But if testing all of these cutter to see how fast you can go and leave a clean cut, (assuming you have sufficient HP), I find the max speed is directly related to blade speed.

Oh, and I cut plenty of 2-3" saplings with my 306 and L3400.

 

[Ultradog MN]

I just came across this old thread searching for something else. Very interesting and I'm glad to see the BH 305 and 306 getting such good reviews - by the experts no less.
I had a 305 for several years then found a 306 at a reasonable price and about tore my pants getting my wallet out. Sold the smaller one.
They're great mowers!
Now if we could just get everybody to stop calling their tin can rotary mower a Bush Hog. Maybe we need to revive the quip from the Packard Motor Car ads:
"Ask the man who owns one."