Sharpening Blades

[James]

I too have used a bench grinder, file, angle grinder as well. But I think the I will try the belt sander the next time. I have not tried the hanging the blade on a nail to check for balancing, I need to do this for sure.
I also find that mowing the first time in the spring it is best not to have sharp blades because of stones and other debries in the yard from pushing snow in the winter.

 

[Mike's grass cutter]

When sharpening blades I never use a stone as the metal gets hot quickly and will turn blue. You are taking the temper out of the steel, which will allow small yard stones etc, to dull it much quicker, making it worthless.
The belt sander is better for those not familiar with the grinder. The nail balancing plan is also a universal solution, used for many years at lawn mower shops.

Keep the heat down by using a squirt bottle of water or an old towel soaking wet, apply often throughout the sharpening process. It's you best bet for long life of the blades. Grind stones not used propery will also quickly make the balance go bad as the stones eat steel up fast.

 

[KennyV]

how can you tell when you've heated the blade too much, and what are the operational and life consequences

Welcome to the Forum...:thumbsup:
You can tell when you have heated steel too much by the color... that shine of silver will start to darken and go brown and then blue... It is toast with any color change. That part will be pushed off the blade by continual striking grass, leaving notches worn into the cutting edge. Most will think it is a stone chip but almost all the notches in a sharpened blade are caused by burning the steal.
The best indicator of how hot is too hot when using a stone or grinder, If you can not hold it in your hand ... it's too hot, frequent quenching with water helps, but the best method I have found is alternate ends of the blade. Do not be in a hurry and use water to cool...
Belt sander is great... :smile::smile:KennyV

 

[MikeSp]

I have tried all methods but commercial grinders that are very quick. My favorite is to place a 5 gallon bucket half full of water beneath my floor-mounted 48x6 inch vertical belt sander and install an 80 grit belt. I have scribed a line on the platform in front of the vertical belt where a block of wood is clamped which provides the correct angle when the back of the blade is sat against it and the business side of the blade is pressed against the spinning belt. The Rockwell hardness of the JD and Toro commercial blades that I use is hard enough that nothing less than 80 grit will do much. After a couple of minutes of grinding, I place the hot end into the bucket and grab another blade and repeat. Then start over with the first blade that has cooled and was dried either with compressed air or a shop towel. This puts a razor sharp edge that is perfectly straight and the same angle as the original and does not take away the temper if care is taken. Of course the balance is checked before finishing both ends of the blade. YMMV

MikeSp

 

[Ric]

I sharpen all my blades with a grinder and balance with the table top cone. These guys say different.

Welcome to Magna-Matic Corporation | Magna-Matic Corporate Site

The nail-in-the-wall measure of balance is so inaccurate that it simply has no value in reducing blade vibration.

A nail in the wall is not a balancer! | Magna-Matic Corporate Site

 

[CQ_DX]

Many individuals just have yet to learn the PRO way to process a blade. What's the correct angle? Do you know? Industry standard (by average) is 30 degrees. Got an ExMark? then it's 28 degrees. Do you FIRST perfectly clean the blade(s)? After sharpening, do you use an accurate bearing balancer? Or do you red-neck hack it with a nail? All of this we all have done - or at least until we were educated with the why nots ....

Here's the real deal:
http://www.lawnmowerforum.com/gener...ade-sharpening-pros-perspective-part-1-a.html

 

[KennyV]

I sharpen all my blades with a grinder and balance with the table top cone. [/URL]

That will work perfectly ... If needed wire brush it before you sharpen it...


MikeSp .. your method is great... belt sanders are :thumbsup:...
:smile:KennyV

 

[supertech]

When the edge turns blue your staying in one spot to long, I use a Makita hand grinder with a fiber disc, for ball fields I give it a much finer edge and then check the grass clippings after mowing. You want it to cut not rip the grass blade. Frayed leaf blade can cause grass to get disease , will also turn yellow or white tips on leaf blade.

 

[bertsmobile1]

Note . most here are talking about bar blades.
So if your push mower has a single bar that is fine but balance has to as near to 100% as you can get and if you feel it vibrating then do not use it.

Domestic bar blades will get hot really quick because they are a lot narrower & thinner than a ride on blade so I would be wary of anything other than hand sharpening and a diamond hone or oil stone is perfect it you have not let them get too dull.
Get some glass proof gloves because sure as night follows day you will slip and pt a gash in your hand.
This can be fatal as there are a lot of bacteria that inhabit grass and are no problem on sound skin but can become a drastic problem in the blood stream.

If you are doing swing back blades they need to the the same weight +/- 6 gram.

On a push mower there is no such thing as "too sharp"

 

[reynoldston]

Do you sharpen your blades yourself when they get dull or do you just replace the blades or the mower? If you sharpen them how do you go about it?

I wonder how many replace the mower? It might get a little pricy with a commercial mower.