Sharpening Mower Blades

Eric in IL · Aug 25, 2011

I have not done the math on this, but I am guessing that at the ground speed I mow and the blade speed of my mower I'm probably only using about 3/8 of an inch at the tip of the blades.

Now I'm wondering why I sharpen about 5 inches of blade if I only use 3/8 of an inch. Sure would save alot of grinding time.

Has anyone tried it?

ShadetreeRet · Aug 25, 2011

When you pull the blades to sharpen, how far back are they dull? If they have nicks from rock or gravel, I'm sure you will find that these nicks go back more than 3/8 inch. (If you never nick a blade, you are either lucky or have an awful smooth yard!) I feel it's best to sharpen at least four or five inches just to make sure.

Jiles · Aug 26, 2011

Most of the Grass clipppings are cut MANY times before they are discharged!

Eric in IL · Aug 26, 2011

Well, if anyone was interested, I did the math today. I had a hand-held tachometer, so I found out my blades are turning 3500 R.P.M. Then I used 5 M.P.H. for the ground speed. If my math is correct I am using about 3/4 of an inch of the blade tips on the uncut grass. Actually .754 of an inch to be exact.

My original guess of 3/8 of an inch was off the mark. So much for guess work!

Jiles · Aug 26, 2011

(quoted from post at 02:45:58 08/27/11) Well, if anyone was interested, I did the math today. I had a hand-held tachometer, so I found out my blades are turning 3500 R.P.M. Then I used 5 M.P.H. for the ground speed. If my math is correct I am using about 3/4 of an inch of the blade tips on the uncut grass. Actually .754 of an inch to be exact.

My original guess of 3/8 of an inch was off the mark. So much for guess work!

If your research is correct----I would say that you have made a major discovery!!
Mulching blades are useless, even the curved blade design.

smallercrawler · Aug 28, 2011

Hi Eric, IIRC about 1962/63 I had a riding mower with about a 30/32" cut(single blade), don't remember brand, but the interesting part was the blade assembly. It had a shallow belled disc of about 30" O.D. X 5/16" thick solid steel with 4 or 6 replaceable short (1"?) lightly spring loaded free pivoting knives (similar to sickle bar mower type) that were mounted to the bottom edge of the disc at the periphery. The disc acted like a big flywheel and centrifugal force (and light spring load) would hold the knives extended. If it hit something the individual knife would fold back against the torsion spring. It cut extremely well, no blade stall/loadup, and the mower ran very smoothly with fairly high ground speed.
I believe it was marketed as a "safety blade". The relevance to your observation is that it only used a very short cutting edge. (The fact I can find no information on it makes me think it was not successful). Some current weedeaters use a similar setup today.

Eric in IL · Aug 28, 2011

That was an interesting read. Thanks for posting.

Sharpening Mower Blades

Eric in IL

Well-known Member

ShadetreeRet

Well-known Member

Jiles

Well-known Member

Eric in IL

Well-known Member

Jiles

Well-known Member

smallercrawler

Member

Eric in IL

Well-known Member

Similar threads