Sharpen Brush Hog

[Tom_H]

If this model is Heavy Duty, then I agree with Roy Jackson. I could see sharpening the blades on a light duty. On a Medium Duty, I'm not sure. On a Heavy Duty, the blades function more like hammers than like knives; using the tremendous inertia, they simply break (or "pulverize" as Roy puts it) material rather than cutting it. Thus a sharp edge isn't all that necessary on a Heavy Duty model.

 

[greg_g]

C'mon guys. Does anybody here believe there's such a thing as a heavy duty four foot rotary cutter? With the right tools and technique, it should be a simple matter of putting a new edge on the blades off the machine.

//greg//

 

[John_Mc]

If this model is Heavy Duty, then I agree with Roy Jackson. I could see sharpening the blades on a light duty. On a Medium Duty, I'm not sure. On a Heavy Duty, the blades function more like hammers than like knives; using the tremendous inertia, they simply break (or "pulverize" as Roy puts it) material rather than cutting it. Thus a sharp edge isn't all that necessary on a Heavy Duty model.

I'd agree with that if you are actually cutting brush (e.g. saplings and the like). If you are cutting grass, having some sort of edge gives a much better cut. As someone else mentioned, when my blades get really beat up or rounded off, I'll grind them back to about a 1/16" edge.

John Mc

 

[Highbeam]

I don't consider the heavy vs. medium vs. light duty nature of the mower to make a rat's poo of difference IF you are cutting a normal pasture. If cutting known pasture then I tend to want the sharper blades just so that the finish is nicer. If cutting heavier trash like saplings and bushes then the bluntness of well worn blades is not a problem.

I do like Sandman suggests before I go to a pasture mowing job and grind the blades as they hang off the back of the trailer. The dovetail of my trailer allows me to get good access with the mower deck firmly dropped down onto the trailer and even chained down. There's plenty of room between the blades and the deck to get the typical grinder in there and I see no need to remove the blades for sharpening. That said, if I have to remove the blades for some other reason then it is really nice to sharpen them in the vise with the same 4" grinder.

 

[lopezian]

All, What about balance? Do you guys worry about getting the two blades to balance out? That would be especially hard for those of you who don't take the blades off to sharpen them.

If you do balance them, how do you do it?

 

[JerryG]

I know several post about sharping BH blades here all the time, but I have never sharpened a set. I use them until they are worn out and then put new blades on. I usually put new blades on each spring. The amount of rocks maybe the reason that they are completely worn out in a season. Flint rocks are hard on cutter blades.

 

[sandman2234]

Balance a blade that spins at 540? I guess you can, but I never have. I just try to cut about the same amount off each side, but for some reason, I don't think it matters. I bought a bush hog many years ago and wondered why it seemed out of balance. Turned out to have two different sized blades on it. Not even close to each other. I bought a new one and installed it and it was fine from then on, dispite the fact that one had been sharpened several times by the time I added the new blade to the other side. Maybe I am lucky or just don't notice it as much as others do.
David from jax

 

[Farmwithjunk]

Here's what works for me. Your results may vary.

4-1/2" right angle grinder will do the trick. It takes a little "elbow grease" every now and then. A new disc helps. I've rejuvinated some mighty beat up blades that way. I can't recall ever removing a blade to grind it. By the time I get out all the tools, I can be done grinding them in place. Generally do the task with mower hanging over the end of a trailer, or raised with 3-point hitch and jack stands/6"X6" timbers supporting mower. I NEVER allow myself to get more than one arm under the mower, and that's once it's properly shored. I hold the blade with a pair of 16" Channellocks. (Grinder disc's will do a number on flesh)

I replace blades every spring, obvious need for it or not. I've seen what happens when a blade breaks. Gruesome is too mild of a word.

The frequency of need for sharpening depends of course on how much you mow and under what conditions. I'm in rock country. Blade edges get hammered. The trick is to keep them touched up and NOT let the blade get too far out of shape. Excessive grinding is avoidable.

I don't see the difference in light/medium/heavy duty mowers and how the blades are ground. I grind my blades to one profile no matter what sort of mower I'm using. It's far easier to be accurate with a certain degree of consistancy from blade to blade. Just like swinging a golf club. The same exact way every time.

I've never balanced a bush hog blade. No need.

 

[kenmissouri]

It's a cheap light duty hog but still works like me. It appears most others use the same 4 or 4 1/2" grinder I have. My uncle had the brush hog before me and used a 9" grinder (way, way too dangerous for my tastes). Sharpening off the end of a trailer works sort of unless you have one of those mesh lift gates. They make it hard to block up the hog or get a stool in. The hog does pulverize more than it cuts, granted. That said, cutting grass in a pasture, sharp blades make a better "cut, flail, beat, pulverize".

I do have an FEL but almost never have it on the same time as the hog. It's too dangerous to have that extra front end versus rear weight in uneven situations, even with filled tires.

Does anyone know the correct torque for the blade bolts? Half inch drive is the largest impact wrench I have, 120-150 ft lbs +/-. That way a major reshape (or that expensive word I have trouble with "replace") could be done every couple years.

 

[N80]

I don't remember the specifics, but getting the blades off my JD LX-6 seemed like too much trouble and I don't think I have the necessary tools. Don't remember details but there is a nut somewhere that requires a lot of mechanical muscle to get undone.

I sharpen mine occasionally. I just tighten the top link all the way, back under the skinning rack, raise the mower as high as it will go and chain it to the top of the skinning rack for safety. It is a little cramped but I've had no trouble using the 4 inch angle grinder. Like others, I don't really sharpen them, I mostly just take the big dings and bulges out.

As for mowing with the FEL on, that's the only way I do it. It is easier to maneuver in tight places with it off, but I think it is actually safer with it on, both in terms of balance, and finding objects in the mower path. And its great for knocking down ant hills before the mower hits them. This, in turn, helps keep the blades sharper over time!