425: 6-Blade Kit

Red Zebra · May 29, 2008

I did it...I bout one. Was ordering a few parts...and thought, "why not?".

Just tried it tonight. Cool...very cool. It consists of a disk which you bolt 6 10" long blades. the disk and blade together are the same diameter as the brush blades.

Take the blades off and attach the disk. Flip the PTO switch and.....nothing.
That is other than the engine momentarily dropping RPMs there was no "klank", "rumble", and requisite start-up vibrations of the brush cutter.

It's not a finish mower but it is light years ahead of the brush cutter on grass and 30" tall grass/hay.

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RegL · May 29, 2008

Does the disk bolt on over the stump jumper using the original blade bolts? Some pics would be great.

TRUKFXR · May 30, 2008

Sounds interesting. Might be something I could use. Are the blades attached to the center fixed, or do they swing loosely like the big brush hog blades? I already know the cost. Wondering if it is something I could make?

woodlandfarms · May 30, 2008

Am I stupid (well, according both my ex and my current wife I sure am) but that said, do you have a link to this crazy contraption?

J_J · May 30, 2008

You did not give us enough data about the unit. What is the name , web site, and a picture would be helpful.

Years ago, Sears had an optional blade unit for their lawn tractors that had a circular disk and 4 swinging blades.

Also, years ago, a guy was selling a disk which bolted on instead of the blade had 4 holes around the perimeter that had very thin wire for cutting, they said it was a safety blade also. I probably still have it around somewhere as well as the Sears blade.

KentT · May 30, 2008

I think he's talking about PT Part #K177, Disc With 6 Blades For Grass, price $265, for attaching to the T3026, 48" Brush Cutter...

http://power-trac.com/pdf2008/508/tractorgasT8price051508.pdf

I've heard of these, but never seen one. Pics sure would be nice -- hint, hint!

Red Zebra · Jun 1, 2008

Sorry guys...just getting back into town. Will get a photo later this week.

Yes, it's the kit from PT. Comes with new bolts. The disc mounts in the existing 4 holes of the stump-jumper. The six blades are rigid mounted equi-distance around the edge.

Trukfxr, It could be fabed up fairly easily. I did not have the time to attempt and likely the metal would have been 1/2 the cost....then cutting the blades, etc....just more work than I had time for on this one.

It's a heavy plate...at least 3/16"...but not 1/4". Used an ATV jack to lift it to the stump jumper....then hand turned two of the bolts a few turns until I could partially slide the jack out of the way to put the impact gun to all four. 15 minutes to take off the brush blades and install the plate....another 10 to add the six blades.

Red Zebra · Jun 7, 2008

Here's the under skirt picture of the brush cutter w/ grass kit/disc installed.
The angle of the pic makes it appear the blades are not evenly spaced....but they are evenly spaced.

TRUKFXR · Jun 7, 2008

I went ahead and ordered one too. I have it installed now and have tried it once to see how it works. From what I can see, this should work well cutting some of the rough areas I have. The only problem I can see is changing the blades back to the two-bladed brush setup. This new arrangement is heavy and awkward to lift and hold in place while you start the bolts. Since I am not planning on changing blades for a while, it will give me some time to figure out the best way to make the swap.
What is your opinion of the construction? One worry (I like to worry) is the disc that holds the blades. It is rather large and not very thick. If you were to hit a rock or stump and it was bent, even slightly, the result would not be pleasant.
Another observation I made while changing the blades; my mower does not have a grease zerk. I removed the center drum to see if it was hidden under that, but nothing there. When I asked Power trac they said that it should have one, but I just don't see it.

KentT · Jun 7, 2008

TRUKFXR said:
IAnother observation I made while changing the blades; my mower does not have a grease zerk. I removed the center drum to see if it was hidden under that, but nothing there. When I asked Power trac they said that it should have one, but I just don't see it.

The grease zerk on mine is accessible from the top of the deck, between the hydraulic motor and the deck.

BobRip · Jun 7, 2008

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 · Jun 8, 2008

BobRip said:
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 · Jun 8, 2008

BobRip said:
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 · Jun 9, 2008

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 · Jun 9, 2008

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 · Jun 9, 2008

J_J said:
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 · Jun 9, 2008

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 · Jun 9, 2008

BobRip said:
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 · Jun 9, 2008

Red Zebra said:
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 · Jun 10, 2008

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.