Sharpening brush hog blades:

What's the best way to sharpen a 6' rotary mower blades? Can I sharpen them while still on the machine or do I have to attempt to remove the blades, that have been on there forever? There is a hole on the top of the deck with access to the nuts on the bolts that hold the swinging blades.
I'm sure it easiest to remove the blades and sharpen but if the nuts are not easy to take off, what's the best plan of attack? I'm sure you guys have been through this many times so you will have some good advice.

Thanks,
Dick

Most of those types even though they have a nut on the bolt; the bolt will be keyed and some of them tapered to the stump jumper too. When you loosen the nut, leave it flush with the top of the bolt and place a large punch or round piece of stock on top of the bolt and nut and hit it hard with a sledge hammer. After the bolt is free remove the nut and blade and sharpen with a disc grinder and replace the same way it came off. Don't forget to place a support under the Cutter frame so it doesn't fall on you. I've had two friends who died that way. One died of head trauma and the other was pinned with his face in the dirt and died because he couldn't breath. Tractor hydraulics can fail suddenly.

One of my elders told me these blades shouldnt be sharpened like a regular lawn mower blade..should "sharpen" with a blunt edge not sharp edge.. maybe some others can shed some advise on this?? Ive never had to sharpen mine. I have a J.D. Mx7.

About the best and safest is to lift it up on its side and then chain it to a tree or other such thing that is not going to move other then by an act of God and go at them. Never depend on hyds to hold any thing up that your under or you may not be here to do it the next time

The easiest way I've found to sharpen the blades is to raise it up with a engine hoist while attached to the tractor. Then I get under it with an angle grinder and sharpen the blades.

I too never have sharpened brush hog blades. I figure that as many rocks as I have here to sharpen them would be a waste of time and work that would go bye bye the first time I did much cutting

Like stephen said but with blocks under it. Sharp edge; no. With a sharp edge any rock, large or small will remove metal and gouge the blade.

are you from florence colorado???

I"ve removed most all my rocks, so I use my bush-hog to just cut grass and weeds. I raise the body up, then lower it down on solid secure 6x6 wood blocks. I just stick my hands under the left-side forward corner, and grind away til the edge is really really sharp. i like a little roughness to it, but a lot of sharp. Mows like a champ.

That is the quandary, try and get those blades off by yourself, without removing the blade holder or stump pan,(see photo below of one removed).

The easiest way to get those blades where you can remove them or sharpen, without being underneath, its to flip the mower upside down, and remove the castellated nut, and cotter pin, pry the stump pan off the tapered shaft, also allows you to inspect the bottom of the gear box for a leaky oil seal around the shaft, and if you are diligent, you can point the filler plug down to a pan and change the lube in the gearbox, letting it drain while you deal with the other things. I welded a hook to one side of my deck, centered and lift it with the front end loader, to flip it. The blade bolts are or could be shoulder type bolts with left hand thread, (turn right to remove) and they have nylon coated nuts to prevent thread disengagement, shoulder bolts on mine are meant to shear, which I have done and was like $40 for new ones last time I bought a set. I have hung my mower from the front end loader, on its side, and braced the lift arms with 6x6 timbers, leaving the mower with one edge on the ground and tilted back, again I NEVER stand in its path where it could fall, I reach over. I have put a ratchet with a cheater pipe on the top side when situated like this, and had a wrench in the other hand, straddling the deck, but not in its path, to remove the blades, I think its easiest and safest to flip it over like mentioned above.

If you have no means to lift and flip over, then I would suggest appropriate hardwood, cribbing, blocking, for the mower to rest on, don't go to high, and remember blocking can roll so take that in consideration when blocking it up, square hard wood timbers are best, leaving enough room to get an angle grinder on the blades, I reach in with my arms, but I NEVER put my head under the deck even when cribbed up.

If they are not trashed, bent, gouged up heavily, you can sharpen them. The profile of one one of these blades if you look at in section, shows the edge square, not pointed like a knife, not sure what the dimension is, its slight, thats how they are when new. I sharpen mine to a point or dull point, I don't see a difference in when cutting thick, tall grasses, maybe there is, and they are as described when new.

If the blades look trashed, its time for a new set, they can be bent and out of balance, makes a difference in efficiency, that and properly adjusting the mower to the tractor, front lower about 1" than the back and level side to side, with sharp, balanced blades, cuts much better, easier, and not as hard on the tractor.

Here is a stump pan of my 6' SE-6 Rhino:

Rocks definitely suck and don't mix with these, I have laid both blades, and all the hardware down after getting a decent size rock in there once. Also had a tail wheel fall off, and hit it on the next round, was dusk, last round too, always figures, and that did some damage. Fortunately at one place I had an excavator for a weekend and took all projecting boulders out, no more gouged, or bent blades.

I used to do as you mention, naah, just run it, its just a rotary cutter, they're tough, and I will admit, though having run one of these since I first was able to run a tractor, I did not know the first thing about them, 'cept how far one could fling a softball sized rock!

Barring rocks, unseen junk and so on, when in areas I know there are rocks, I just lift the deck up high, not worth it, bent, broken blades, sheared bolts, damaged deck etc.

When I finally got around to changing the blades on the mower, and adjusting it up nice, it made a huge performance difference in tall thick grasses, I picked up another gear on the 850 ford, and the mower ran smooth, none of that shaking when you first engage the pto. I thought it was well worth doing, was funny to compare the old blades to the new, and see so much more grass fly out, and a better job done by it.

A lot of people don't really take care of these and you can sure get a beat up, wore out one 2nd hand, but I went through mine, kept the gear oil changed, blades recent or sharp, adjusted right, tightened the bolts on the gearbox to the deck and on the gearbox itself, no more leaking, so far the lower oil seal on the output shaft is dry, its an older, probably mid 80's, but with a little effort, it cuts and performs like a new one.

Years ago I had a blade fly off of the brush hog I had at the time. The thing all at once started to shake so bad the tractor was about to shake me off. I stopped the PTO and tractor and lifted the hog up to have a look see and one of the blades was missing. That was at least 10 years ago and I have yet to find that blade and I have hayed that field for years after that and still no blade

I broke a blade on my BH 305 model a couple of years ago and had to buy 2 new ones. The new ones were definately not sharp. That had about a 3/32" flat on the cutting edge. I never sharpen mine as I don't use it like a finish mower but for grinding up brush and heavy weeds.

Conway Arkansas!

I have always taken pretty good care of my bush hogs. I have always put neversieze, on the blade nuts, when I have the pins and blades out. Agree with others that they don't have to be razor sharp, I try to mock the edge you get, on a new blade. I would try to get the blade pins out, while the b-hog is on the ground, attached to the tractor. Try to turn with a 3/4" breaker bar, and cheater pipe, to increase leverage. Once you get them moving, it's not so bad, most of the time. Once you have the nut out, generally one hard hit, with a brass drift, and 3 Lb no bounce hammer, and the blades are laying on the ground. Be sure to inspect the pins, as a loose pin will wear the slot out, on the carrier. Pins cost about $10-15, carriers, about $200. Put neversieze on it all, when you re-assemble, and you are good for life!

One blade missing, that would shake like heck, when I removed my blades, by accident, LOL, it left a nice neat pile, blades, bolts, broke of course, found all the washers too.

I will say this, while in highschool, farmer had let our place sit for 6 years, he wanted to use it again, so I had to cut the entire place, 50+ acres tillable, with a 2010 JD narrow front, and a borrowed Bush hog brand cutter, in the top field, I hit a round rock the size of a softball and it went up the back side of me on the seat, up and clear over into the next field, over the hedge row of trees, can you imagine getting hit by that cannon ball ? Never saw anything like it since and I have hit plenty of similar rocks with this poor ole SE-6 that I try like heck to take care of, one thing about it, really are not any guards on it, but it just does not send projectiles out, I think what happened had a lot to do with adjustment, tilted down, hard to see it tossing something toward the operator, but guards are best to have anyway, to be safe. I likely did not have that one adjusted right on the 2010, but I immediately went and found ours which was loaned and used it for the rest of the job, as it had front swinging steel plate guards, man if that had hit me, would have taken my head off, knocked me off or out, and the tractor into the hedgerow, was alone doing this.

Just take the blades off. Sharpen them a little and then I'd either get some hard surface rod or take them to a welder and get some hard surface put on the bottom. It only take a little bit of hard surface, about a 1" wide strip on the bottom side, to work really well. It lets the top wear off and it stays sharp.

I WOULDN'T recommend welding on an already heat treated high carbon steel, especially something spinning with enough force to kill you in the event it fails from being too brittle. Hardfacing on the bottom could lead to it spalling after the top wears too much as well. Just need to look at a hardfacing guide for bucket teeth. Same idea but people aren't usually in any danger should a bucket tooth break.

I don't ever remove them to do routine maint. I'll sharpen them a couple times per year depending on what I've hit.

I use a front end loader and stand the shredder up on end, vertical, Makes access really easy, and no crawling around on the ground.

I typically peel off the nuts with a STRONG impact wrench...my electric Makita won"t do it, but a buddy lends me his Snap On unit. Drive them off with a maul and sharpen away to a reasonable edge, similar to a splitting wedge. I stack blocks up and lower the hog onto them so I don"t rely on hydraulics. I"m skinny, so I can get under there to reinstall...but the blades are HEAVY, and awkward to hold, so I usually have to have someone up top to spin the nuts on a ways. Tap the bolts snug with a hammer and reinstall...AFTER using lots of neverseize. Mine were never off for 20 years (bought it used) and they came off relatively easily. Without flipping it over, I"d never be able to grind on them without removing first...