Mowing What a difference that 1/2 inch makes!

[RaydaKub]

I bought new gator blades last spring for my 60 inch mower. The old ones were rounded off almost to the discharge bevel. The first several cuttings I was really impressed with them. As the summer went on July and August got dryer and I decided to let the grass grow a little longer and with the number of times I took the mower off I changed the cutting height from 3 to 3 1/2 inches. The grass isn't all that thick. I figured the blades were getting a little dull because it was leaving quite a few blades of grass sticking up. I wasn't all that impressed with them anymore if they were that dull already.

This week I put the mower back down to the 3 inch cut. It looks great again even though I didn't sharpen them yet. I can only assume that the 1/2 inch makes a huge difference in the vacuum the blades create under the deck. I would never have believed it could make that much difference. It's like a brand new mower again.

Just thought I'd post this simple but significant observation.

 

[AceDeuce]

I've noticed the same thing. Running at full RPM and slowing down your forward speed also increases the quality of cut. More opportunity for the blades to do their job. Worst case, running back over the previously mowed area in the opposite direction will get anything left standing.

 

[Larro Darro]

In thinner grass it does do better to lower the blades. When it is thick enough, the grass will stand up to be cut. But it always helps to sharpen the blades. And to slow your forward speed.

 

[RaydaKub]

Wide open throttle, foot on the floor in low range. The only difference was the mower height. And based on the quality of the cut, I think the blades are fine without a sharpening yet.

 

[Ken45101]

Sharpening blades? What's that? I just sharpened the blades on my B2710 MMM. It's had about 500 hours of use and we have had it since 2000. I'm not sure the blades really needed the sharpening, but since I had the deck off (first time), I went ahead and sharpened them up.

 

[Gale Hawkins]

I am coming to the mind set about the only thing sharping a push mower to bush hog blade does is shorten their productive life span. We only have about 150 hours on the ZTM blades but it has been 36 years on the bush hog without sharping. Those red sparks are good metal saying Bye Bye.

 

[Gary Fowler]

While at the NH dealer a week or so ago, I saw a mower blade that I couldn't believe was still mowing. The cutting edge was ground almost to the center mounting hole so it had about 6" of beveled edge which made no sense. The 3" at the end was worn down till it had no edge, just a rounded profile the same thickness of the blade, the last 3" showed very little wear which showed plainly that there was no need for more than about 3-4" of cutting bevel needed. The lift fins were worn completely away also. Maybe this was a Gale Hawkins owned blade. I suppose that the blade was still beating the grass down with a big sacrifice in fuel usage and mowing speed but a sharp blade will allow a much faster travel speed and neater cut. I sharpen my blades at least once during the season or more if I hit a lot of rocks which are plentiful on my place. Damned crawfish mounds eat on the blades too everytime I hit one it is a mini-sand blast to the edge and I have a bunch of them in the lower part of my yard. I wish there was a way to kill those suckers.

 

[Ken45101]

a sharp blade will allow a much faster travel speed

IDK about a "much faster travel speed". A fast travel speed moves the cutter forward a certain distance. If that distance is greater (per rotation) than the cutting section of the blade, it doesn't have a chance to cut. Maybe if you are lucky, it will cut on the rear of the mower.

Bush hog type blades are not supposed to be "sharp" (according to the manual). Finish mowers, yes, rough cut mowers, no.

 

[LD1]

Here is some fun math...

My ZTR goes 10 MPH and rotates the blades @ 3600 RPM (drive pulley is the same diameter as spindles).

10MPH is 880 ft per minute.

880 fpm is 176" per second.

With the blades spinning 3600RPM, thats 60 revolutions per second.

SO....60 revolutions only needs to cut 176" of grass. Or.... less than 3" of grass with each revolution.

With 2 cutting edges, yea, I can see how only the last 1-1/2" even needs to be sharpened. So with about 4-5" sharpened, I guess you can say each blade of grass sees a sharpened edge at least 3 times.

 

[Gale Hawkins]

I find fine edge on a sharpen blade has a half life of nano seconds.

A ZTM is a pain to remove the blades vs the old 20" push mower.

It is my theory that grass beat off with a dull blade is insulted and will not grow as fast.

Knew a guy once that would grind out each rock gap in his blades. They did not last very long either.

For physical reasons typically I do not pick up dead limbs before I mow so a more rounded cutting edge mulches them better I find. I will do the same with the bush hog on highly decades limbs up to 6". It makes a lot of noise but the pieces get smaller each time I bush hog them.

Having a tool and die background at one time I over sharpen all of the time. Now a chain saw should be very sharp 100% of the time in my book but that is a different subject.