Finish mower blade sharpening?

pennwalk · Jun 1, 2003

I was using Bo's method till my cheap alarm went off. It was costing me $3 a blade and we have several mowers. So I have been experimenting with several different sharping systems. What I like best is the craftsman 4 inch belt sander using number 60 or 80 belts. What I really like about it is that it is almost impossible to burn the blade. My bench grinder will burn the edge in a heartbeat. I guess that getting the exact angle isn't esential as long as you are in the ballpark. I have never been able to find out what the exact angle is anyway. I suspect that the outside tip of the blade is the most important. On my blades the outside edge is always rounded off by use (rocks). I wonder what is the best way to keep it sharp?

Chris

djradz · Jun 2, 2003

I gave up on the bench grinder years ago and purchased a 4" / 4-1/2" angle grinder. Our local shop used one and it looked pretty easy to me, so ever since, I've used one to sharpen all the mower and even the brush hog blades. Just last year I moved up to a 7" angle grinder for the brush hog blades, just to speed up the task.

Kaon99 · Jun 2, 2003

Speaking of sharpening blades on a brushhog (aka bushhog), how important is it? I know that sharp blades give a nicer cut on a finishing mower, but how about on a brushhog where you are usually cutting heavy stuff? The way I use my brushhog, the blades don't stay sharp for long, so I don't even try to keep them sharp. Am I making a mistake? Since I don't have much seat time (yet) with my brushhog, I would appreciate any advice from folks with experience. Thanks. Ken in Mississippi

Bird · Jun 2, 2003

( Am I making a mistake? )

Nope, not as long as it's doing what you want it to do. How sharp is sharp? The sharper (thinner) the edge, the more quickly and easily it'll get dinged up, so if you're cutting brush and saplings, too sharp is not good. If you're only cutting grass, you might want it sharper. In fact, if you're cutting small trees and saplings, the duller blade may shatter the stump instead of a clean cut and cause it to rot out faster, meaning duller is better.

djradz · Jun 3, 2003

You really mean, aka: rotary cutter don't you! /forums/images/graemlins/grin.gif Anyway, Unless I know I'm off to cut an area with lots of bolders, I try to keep them reasonably sharp. Nowadays, I'm not doing much clearing and mostly am just maintaining trails and fields, with the occasional small tree that works its way into my path. For this, I keep the edge a little duller than my RFM and sharpened at a blunter angle. The blunter angle helps the blades to last longer yet allows me to keep it pretty sharp. Especially in high grass and weeds, I think the sharper blade greatly reduces the load on the cutter and tractor and leaves a much cleaner cut.

BillyP · Jun 3, 2003

The sharper the blade the better but... The sharper the blade, the faster they dull.

On a rotary cutter, sharpness isn't that important. You're not looking for that manicured look.

On a finish mower, sharpness is more important. The sharper the blade, the better the cut. But remember, the sharper the blade, the faster it dulls. I know some people who sharpen their blades after each mowing. It all depends on how often you want to buy blades.

pennwalk · Jun 4, 2003

Ken,
When I bought the new blades for the KK rotary cutter from TSC I was surprised to find that the edge was flat maybe as much as 1/8 inch. When I compared the old and new I realized that the old weren't that bad so I have a set of backup blades now. I guess if all you ever cut was grass you could sharpen them.

Chris

OkieG · Jun 9, 2003

...and always checked and adjusted the balance of the blade.

A slightly out of balance blade will put lots of stress and vibration into the bearings and deck, although you may not be able to feel it.

The first couple sharpenings I would use a nail clamped horizontal sticking out the side of a vice as a pivot to set the newly sharpened blade on. I have decided this method is not very precise. The blades always tested out as balanced. There must be some degree of imbalance, but it hasn't shown up for me with this crude method. So, I basically don't bother anymore. I would bother, though, if I had a better way to do it.

What did you do to test blade balance? There must be more accurate methods.

OkieG

djradz · Jun 9, 2003

Most stores that sell replacement blades for any mowers will also sell a simple little blade balance. They cost less than $5 and lool like an upside down toy top.

PBMAX · Jun 9, 2003

That was part of my ? I've seen those kits at the depot with the blade sharpener and the balancer. But I us a grinder on my scott mower if the blades are worth the time. But not having a RMF mower yet (but am looking for a good used one)I was wondering if the blades would be to thick for that little sharpennig stone in the kit? Has any body tried one? Sence it is double sided it would be nice... /forums/images/graemlins/grin.gif or is a nice paper wait?