How and when to sharpen Rotary BH blades

[Farmwithjunk]

I just walked in from the shop to cool off. (93 degrees and 65% humidity) I sharpened 2 sets of blades (2 different mowers) while they were still mounted on the mowers. I've got everything it takes to pull 'em off and sharpen 'em in a vice, but that's a waste of time IMHO. In the case of a 3-point hitch mower, I simply raise the mower as far as the tractor will lift it, put jack stands under the skids, use a vice grip welders clamp to hold a block of wood against the rear skirt of the mower for the end of the blade to rest against, and reach under with the 4-1/2" angle grinder and go to work. It takes about 10 minutes per blade, even if they're beat up bigtime. (which these were) I use 'em until there isn't enough meat left to grind away any more. My oldest batwing probably has 6,000 to 7,000 total acres of cutting on the original set of blades. They're still more'n servicable, with a few more years of life left in 'em. They do an excellent job still. With the batwings, I run the rear wheels up on a set of 12" tall ramps I made to get additional clearance to get under the middle section. The wings I do while they're in the raised position.

We aren't talking a precision instrument here.....So long as you get a decent edge at roughly the correct angle, all is well.

Everyone has their own way of doing things. Any way you can SAFELY get the job done is a good way in my book.

 

[LoneCowboy]

I
If it didn't matter if the blades are sharp or not why do the new ones come with a sharp edge?

Because it's easier than explaining to 90% of the people why it doesn't matter.

 

[pitt_md]

The reason that people sharpened bush hog blades, is that they do want a better cut. When you get a new bush hog and cut a field with out a lot of debris, it does a very good job, and as the blades wear from use, it does start to tear and shred the grass. You could even use a flat faced blade, and it would cut better than a rounded off blade. Some people say they never sharpen, but to each his own. You won't get into balance problems unless you grind more off one blade than the other. Most of the blades start off with a slight edge to them. You all should know by now that a sharp blade cuts better, in any situation. When to sharpen, is your choice. I have even thought of welding some hard surface on the first 2 in of the blade, to reduce wear. It should work.

I agree with the above. I don't know that it makes a difference when wading through thick brush but I can tell you it makes a lot better cut on tall grass/clover when sharp. It still is not a "finish" quality cut but its pretty darn good.
If it didn't matter if the blades are sharp or not why do the new ones come with a sharp edge?

 

[scrapironford]

J J has the idea on blades. If you cut much Pensacola Bahia grass it will eat up blades real quick. We have been useing hard surfacing rod or even 7018 rod on ours for years. Last year bought a new mower ,unloaded it ,put jack stands under it removed new blades , welder time. Three sticks hard surfacing,touch up blades with 41/2 angle grinder put blades back on. Have mowed about 60 acres,sharpened one time, blades look almost new. We also do this on our lawnmower, just have to balance them. Went from one set of blades a year, to three or four years on a set,still have to sharpen them after about three or four acres. scrapironford

 

[GreenLawnFarm]

leave blades on and use angle grinder. i am surprised with how well a brush mower cuts. other than not following the contours well, it cuts very low and even if it doesn't cut the grass evenly, it grows back.

 

[rbcsaver]

Took my blades off the other day and did a touch up on them. Weighed them, one at 8.000 and the other at 8.005 think Im good to go this time around. Used a floor jack to reinstall, worked like a champ.

Can you please explain how you removed them? I have a Bush Hog and was able to remove the nuts through the deck hole, but couldn't get the bolt through the pivot point. I even whaled on it with a mallet. Did protect the threads. How did you get yours off. Any pics.
regards,
Steve

 

[J_J]

To get the bolts out, loosen the nuts a little and smack the nut with a brass rod if you have one. Otherwise, use an old 1 in bolt to knock out the blade bolts.

 

[have_blue]

Since I removed all the brush 8 years ago, all I have left is 8 acres of grass. So I use my BH for a finishing mower. Therefore, I touch up my blades every time I mow, right on the mower. It takes 15 minutes to disk grind them very sharp. Cuts great, smooth, and quiet at reduced RPM. As blades dull, I can hear the noise increase under the deck and hear the tractor engine loading up a bit. I have to increase the RPM a little, or take a break and touch up my blades.

If you're cutting rocks, dirt, or heavy brush, sharpening does little good. It's a good investment in time to remove everything that can damage your blades or be thrown. It may take a year, but you can chip away at it. It's worth it, and you'll feel better about it.

 

[J_J]

I have noticed in my many years, that you can only change, some people minds. We all seem to be set up to know what we know, and change is not easy, especially if it can not be proved. Logic is supposed to work most of the time, but there are exceptions. Cutting a field with dull blades as an example. Some will say it doesn't matter, but that is because they have been slashing that field forever. I say let them be and do what they have always done. If I can see some good in a change, I usually will comply.

 

[Charlesaf3]

educational thread. Somewhat surprisingly for a subject that's been covered a lot. I'm now going to buy new finish blades, as the tips of mine are rounded from finding stones etc.

Still not going to sharpen my shredder blades. Not because I don't see the advantages for mowing grass, but because I use mine to mow woods. Seems like the biggest issue in sharpening/not sharpening is intended use. Good for grass, why bother for shrubs and vines - might even be bad/make sharp stumps. Pretty much standard one size does not fit all...