425: 6-Blade Kit

[BobRip]

I don't understand why the six blade kit would cut better. I guess more blades would do more cutting per revolution, but the tip speed is the same.

 

[MossRoad]

I don't understand why the six blade kit would cut better. I guess more blades would do more cutting per revolution, but the tip speed is the same.

This thing is for the brush cutter. The original brush cutter blades are really thick and do not do well in grass, but really destroy woody stuff. This thing looks like thinner blades that could be sharper than the originals and cut grass well, but not the woody stuff like the originals.

 

[J_J]

I don't understand why the six blade kit would cut better. I guess more blades would do more cutting per revolution, but the tip speed is the same.

Bob,

Although blade tip speed might be the same if the blades are equal in weight. If the 6 blade kit weighs less, maybe more power and blade tip speed, and taking little cuts would have it's advantage. I believe the blades would also have a sharper edge, compared to the brush cutter.

 

[catsco]

I believe that the improved cutting might be a result of the portion of the blade(s) which are cutting are moving a a high speed compared to the original arrangement where the actual blade speed near the hub is quite low.

For example, for a four foot DIAMETER blade:

Circumference is 12.56636 feet (2 * pi *radius)

At 500 rpm (just picked a number):

The ENDS would be traveling at 6283.18 feet per minute.

The MIDDLE of the blade (at the 2' radius) would be traveling at 3141.59 feet per minute.

Four inches from the HUB (at the 0.33 radius) the blade wouild be traveling at 1047.1 feet per minute.

With the large disk there is no cutting edge that is NOT moving at a high velocity so the blades would cut much better. The additional short blades make up for the lack of length of the cutting edges with fewer blades.

From an engineering standpoint, this makes sense to me.

Other opinions?

Regards,
Mark H.

 

[J_J]

At the same rpm, the two bladed bush hog will make two cuts per revolution, while the six blades will make 6 cuts for each revolution. The six blades are thinner, and will give a better cut. The leading edge does most of the cutting anyway. It also depends on the ground speed.

 

[BobRip]

At the same rpm, the two bladed bush hog will make two cuts per revolution, while the six blades will make 6 cuts for each revolution. The six blades are thinner, and will give a better cut. The leading edge does most of the cutting anyway. It also depends on the ground speed.

I finally got a finish mower, and I could have just got this. Oh well. No big deal.

All of the comments seem to make good sense to me. Thanks again fellows.

 

[Red Zebra]

Yeah,.... what Catsco said.: : ....

Overall I think the kit weighs more than just the two brush cutter blades. Trukfxr, Back me up on this or call me out when you get your kit in. I did'nt weigh them but judging from the weight of just the disc I had to use the ATV jack to hold it up long enough to install the first two bolts.
(I also like having something between me and heavy stuff when I'm under it.) Using the ATV jack again, I estimate a blade change in approx 15-20 minutes. Not something I want to do more than 1 or two times per year.

I ran it over some rough ground (dry clay with gravel and some grass in other areas) scalping/gouging the lanscape nicely . The picture I uploaded is the "after" picture. I spun it by hand and could not see any distortion by watching the edge referenced against a fixed location.

Decent cut on the lawn grass without pushing the grass over.
It definitely cuts hay/tall grass much cleaner and faster than the brush blades without bogging the engine. BUT...An unknown stump or big rock could defintely grenade the smaller blades. Just my .02 ...It is what it is.

Jim

 

[Red Zebra]

I finally got a finish mower, and I could have just got this. Oh well. No big deal.

All of the comments seem to make good sense to me. Thanks again fellows.

We were posting about the same time....

No, I don't think you did wrong by getting the finish mower. I like a "rougher", almost unkempt look to my (ok, hers ) place. Think "wild" and you get the idea. So the cutter kit works best for me. If you prefer a more "manicured" look, then the finish mower is probably best.

Still, I was surprised at the cut as compared to the brush cutter.

 

[BobRip]

We were posting about the same time....

No, I don't think you did wrong by getting the finish mower. I like a "rougher", almost unkempt look to my (ok, hers ) place. Think "wild" and you get the idea. So the cutter kit works best for me. If you prefer a more "manicured" look, then the finish mower is probably best.

Still, I was surprised at the cut as compared to the brush cutter.

I take it that the cut is much better with the six blade?

Yes, I am OK with the finish mower. It seems to work well and certainly better than my old 12hp Sears mower with the "postive scalping feature ". No regrets and the price was fair.

 

[TRUKFXR]

Well I found out what happens when you hit something with the six-blade setup. I used mine to cut some heavy grass, and brush and broke 4 bolts holding the blades. (there are two bolts holding each blade). I can't blame it on the mower, because I hit some hidden stumps that were just slightly above ground level. If that is all that happens, I can live with it. Consider it a safety valve......
I have the 60'' finish mower that I use on lawn. The brush hog is great for the really bad stuff, but it doesn't cut as nice as this six-blade disc does in the heavy grass.