Ideal Blade Tip Speed?

[kweaver]

That is deceptive though because the blade will stick out a couple of inches from the disc. With the stated diameter and rpm it's 15708 FPM

By adding the 2 blades @ 2" overhang = 18849.6 FPM

 

[dtanner]

Ken
just what are you trying to figger out( speed ,travel for a great cut)? depens on the type of grass you have and moistue I think. After a rain the grass has swelled and cuts easier. when a drought the grass is tuff to cut smooth.Blades can be dull with a lot of moisture and sharp when its dry. What are we debating here lol?

 

[kweaver]

Donald - Ryan is trying to figure out why his hair has a nicer even cut when he sticks his head up under a Craftsman mower deck than when he has his hair cut by an <FONT COLOR="ff0000">I</FONT><FONT COLOR="000000">H</FONT> deck.

Really though , I think with his hair a weed whacker would be better.

That's my story and I ain't stickin' with it ...

 

[rwilke]

KENtuckyKEN,
Using Don's values of a 21" blade = 65.97" circumference.
So, at 3189 rpms, I calculate he's running a blade tip speed of 17,532 ft/min.

Using your posted New Holland cutter info, I also calculated the disc blade tip speed at 15,708ft/min.
However, as you point out, since the cutting edge sticks out more, the tip speed would be higher than that.

So, since all of these blades are running at a similar blade tip speed, this little bit of research between the disc, the Craftsman and the IHC blades is leaning the evidence
toward the tapered cutting edge blade design as being the major performance difference..... VERY interesting.

By the way, the applicable Oregon mower blades for a 42" IHC deck seems to be:
For the two outer blades (10.97") Oregon part# 91-321. ~$11 each.
For the center blade (22.365") Oregon part# 91-322. ~$15 each.

These Oregon blades have a single center hole of 0.755", 2.5" wide, 0.203" thick, and have the RH cut.
Ryan Wilke

 

[rwilke]

Don T.,
Go back and read my opening post --

Ryan

 

[dtanner]

Ken
There are so many verables here that ,how can you say depending on where you live as tp how grass cuts. Man this is to TEC for me lol.

Got 19.56 towing 8623.6 lbs this weekend, A long trip soon as the wife makes up her mind.I`ll have the truck ready lol. I might have to take a side trip .lol. What else do you guys need cause I`ll help if I can

 

[rwilke]

Don T.,
While you had your head under your Craftsman deck, what else did you notice is under there that makes it different from a 38" or 42" IHC deck that might allow it to cut better?

It does have straight cutting edge blades, correct?
Are the blades standard-looking or gator like?
Does the shrouding look any different?

Ryan

 

[dtanner]

Ryan D Wilke
I have grade 7 in school and I follow you.Since you ask for a math check it was easyfor me cause I had my cal right here. your good on the math. But thats how we overthink.Depends on drag and much more I would think. And just to get it moving and an 1" to that on a 21" blade as per rpm and ?

Now I think and I could be way off here,but here goes,The blade has a taper to help creat a force to break the stem of the grass long after they need a retouch (sharpened)

 

[jdiederichs]

I believe the f.p.m. speed is determined by the length of the blade, I think the ANSI/OPI standards specify that factor.

Sort of a way to factor in the "bat speed" in baseball terms in respect to objects thrown from the discharge chute. A fast "bat" hits home runs, a weaker bat simply pops up.

Did you know that one certification test involves firing 1/2" steel balls into the mower deck with it running at WOT! No kidding. These steel balls are lauched from outside the test cell( luckily for the tester) using air pressure to inject them to the deck. That is one interesting test. Cardboard is set up a distance from the discharge chute and hits are recorded, high flyers are grounds for immediate failure.

 

[dtanner]

Ok Ryan
What else did I notice that is different that IH did. Easy realy,The decks are flat in the back as to the cut and have a higher tunnel staring back center to right discharge,with gaters a finer cut at lower ground speed means finer cut. Blades can`t cut if the cut **** aint moving and a few recuts lol./ just my .02

 

[kweaver]

Somebody re-read Don's last sentence !

I just cut the front yard with the 50" and it's leaving clover blooms standing.

If we get to technical like Dennis was about to do with seal drag then we'd have to account for elevation , humidity , water grains , air temp ...

If it cuts use it , if it doesn't it was IH made !

 

[dfrisk]

KEN - When you have a finely tuned piece of mowing equipment like these old Cub Cadets you have to take into account things like water grains, air temp & humidity & density, wind speed & direction, track...errr I mean grass temperature, tire pressure, PTO clutch engagement.

I'll agree mowing clover blooms is "Iffy" with a 50C, best to spray them. ROUNDUP works but that kills everything. My Buddy's looking for some spray His neighbor says works really good on clover. I have so-so results with Weed-B-Gone, Weed-Stop makes it grow faster. Stuff my buddy's looking for is a real Ag chemical, for keeping weeds out of hay & pastures.

RYAN - I'm pretty sure ANSI could care less how well mowers mow. They probably prefer that mowers didn't have belts, blades, pinch points, etc because then nobody would get hurt.

 

[dtanner]

Recuts are smaller Ken and the motion of the blades adds air to the cut ,You can blowe dry grass with any deck with a 3.5" cut. Woks here.

 

[kweaver]

Dennis -
<font size="+2">I LIKE CLOVER !!</font>
You clover murderer !

 

[dfrisk]

KEN - The only clover I like is Sweet Clover, at least that's what we called it. Very tall plant, would get 4-5 feet tall, little yellow flowers, and pollen, LOTS of yellow pollen. I was clipping hog pasture one afternoon with the Super H & bush hog. My tractor almost looked like a Minny-Mo with all that yellow pollen.

But about a day or so After you mow sweet clover is when it smells the best.

I have a couple areas where the clover smothers out the "good grass", the Kentucky Blue Grass.

 

[wshytle]

I like the clover too for the insects, mostly honey bees. There aren't that many left around here. It's probably something to do with BP.

I like the way my IH decks cut. I don't follow any height rules; I just mostly scalp hoping the grass will slow down its growing.

 

[kweaver]

My yard was a white carpet before I mowed today , should have took a pic. I like White Clover.
I did see one Red Clover bloom in the backyard a while ago before the 2166 nailed it.

 

[rwilke]

Don T.,
I don't know. Maybe you're correct with your idea that, "The blade has a taper to help create a force to break the stem of the grass long after they need a retouch (sharpened)".
I think it would have be neat if we could have gotten an explanation from an IHC 'mower deck blade' engineer, but that isn't likely I guess.

Your observation of grass cutting easier when it's wet is an interesting one.
Now I was told if you cut when it's wet, it'll tear it rather than cut it???
I usually don't cut when the grass is wet because I don't like the way it packs up under my deck.

Your observation of the IH deck having a higher tunnel area may mean something...it seems to me that by having a higher tunnel area would cause a pressure drop in that area, which in turn would reduce the transport velocity (speed) of the passing air & grass, which would reduce the distance the clippings get tossed out the side shoot; which would be more apt to produce windrowing and a less than ideal look. Hmmmm....


Jim D.,
Yeah, it makes sense that the blade tip speed is limited by some gov't standard.
However, some of these newer mowers sound like their spinning their blades like helicopter blades! MUCH faster than our Cub deck blades.
Maybe the gov't has been paid, er, 're-considered' the issue and raised the limit.

I know your opinion is that the "Crapsman" decks aren't any better than the IHC decks; I don't have a vote, since I haven't one to compare my IHC deck with...

Interesting fact re: the "steel shot test". There sure are a lot of tests for a lot of stuff....


Dennis F.,
Yep, as I once told my boss, "The best way to ensure no one gets hurt at this (manufacturing) Plant is to send everyone home." A few years later, that is exactly what management did.


Well, unless someone has any other thoughts or ideas on the subject, I'd like to thank everyone that contributed - I appreciate all good input!
Later Guys!
Ryan Wilke

 

[aschumacher]

All this investigating has led to some interesting concepts...Ryan, I dont think its completely over just yet. People are gonna search the Net for more info.
Now, my deck did this and his deck did that... My Husqvarna walk behind took down a whole oak forest this afternoon! Tied up the side chute door and let it fly...it was a beautiful thing.

...<font size="-2">Tooth picks anyone??</font>

 

[wheinsohn]

I will not say that blade speed helps but when I worked at a green dealership, the first thing I noticed with the newer decks was that the wing was at a larger angle which caused more suction. This suction is the noise that you hear from these decks more than blade speed. When I went from the 5" to the 4.25 driven pulley on my 50" deck, I could hear the difference in sound but the sound also was less after I installed the Gator blades. The Gator blades do make smaller clippings so you do not see them on the lawn but I also noticed it had less suction and would streak easier and not cut the dandelions as well.