Brush hog blades

[HillbillyFarmer]

I've never sharpened the blades on my JD MX-6 and they seem to work finie on brush and heavy material, but yesterday I mowed part of a hay field that hadn't been mowed since June and it hacked and tore the grass.
Question: How sharp should the blades be to cut grass and how sharp are they out of the showroom?
My blades are REALLY dull after mowing many many acres of heavy brush and small trees over the past year and a half.

 

[bamatoolmaker]

I have been wondering the same thing.It seems the people that I have asked have different opinions.Some say grind edge square and some say taper top side to a knife edge.I am sure these good people will tell us the best way for the different uses.

 

[Gizmo36]

Don't sharpen both sides only the top .I only take the bad spots out the bottom is curved up

 

[MrJimi]

I would think a trip to the store to look at new ones would be good.
Jim

 

[schmism]

they only need to be shapened on the top side, single bevel down to were you leave about 1/8 flat on the face. (ie not all the way to a sharp point)

others like to fill the larger kinicks with weld first so they dont have to grind them all the way out thus maintaing the full weight of the blade. (and ballance)

 

[HillbillyFarmer]

I would think a trip to the store to look at new ones would be good.
Jim

Yea, a trip to the store would be nice, but it's over 30 miles one way. We don't all live in suburbia and use our tractors for mowing the lawn.

 

[vallyfarm]

pull them off if you can, and put theold angle grinder to them As stated, only grind the top surface. Take your time to avoid too much heat build-up and grind them to about 45* angle. I get 2-3 years off a set of blade before too many rocks destroy them. 45* is sharp enough to cut the heavy grasses, but blunt enough to shatter the woody material. ALWAYS use something to lube the pivit bolts when you re-install them. This is a major stress point that can wear or weaken whit long hours on the blades. Mike

 

[shaley]

I notice Agrisupply has them for about $15 ea.
BLADES, ROTARY CUTTER Available at Agri Supply® where we have something for everyone

 

[Soundguy]

Yep.. lube the pivot.. and only sharpen to 1/8 or 1/16 flat if also cutting grass.

Soundguy

 

[RalphVa]

On my Gravely, I always sharpened its blades like a regular lawn mower blade. I had both a single heavy blade and dual/crossed lighter blades. The heavy was better for brush hogging; while the crossed dual blades did grass a little better.

On my LX4, I sharpen on the bevel of the blade and don't make it "lawn mower" sharp. The edge is sorta gently rounded. It does okay on grass. I keep hiking trails mowed with it and some fields of grass.

Ralph

 

[sandman2234]

I never take the blades off to sharpen them. I just raise the bush hog (or load it on the truck in the case of my little one) so that I can sit behind it and sharpen the blade from the rear. Spin it around and do the other one and your done. Safety glasses are a requirement, a clear faceshield advisable. A good 4" right angle grinder helps, instead of those cheapo's with no horsepower.
Maybe this is why I never can get the blades off when I really need too, because I don't take them off often enough.
David from jax

 

[cisco]

Hmm, there's many many prior threads on this. In brief, one shouldn't sharpen brush cutter blades like those of a lawnmower. Brush cutter blades are meant to be dull, and advice re. sharpening to the 1/8" range is about right. One can usually do that with an angle grinder (eye protection, chocks under the brush cutter so it can't crush you if the hydraulics in the 3ph fail) periodically. Me, I change out blades (they weigh about 15 pounds each on my Woods) once a year ($48), and sharpen them after sessions in the heavy brush, before I tackle the grass. It doesn't do as well as my Hustler mower, but the cut is decent.
Note that I leave the "old" blades on over the winter, so use them for the first cut on the property in the Spring - when there's debris. Then I do the yearly blade change.
Changing blades can be a chore (takes me about 1/2 hour), as I need a 3/4" impact wrench (took me a while to figure out my 1/2" wouldn't work), and be sure to lubricate with lithium grease or similar the area of blade rotation on the shafts.
The above said, I've a close friend, and hunting buddy, who's never changed out the very heavy blades on his brush cutter. Still works great for heavy brush and saplings, but his wife is getting a tad dissatisfied about the quality of the grass cut on the lawn in front of their house.

 

[Bob_Young]

I like 'em sharp and keep 'em sharp. Most of my cutting is orchard grass, weeds, and multiflora rose and with sharp blades the load on the tractor is noticeably reduced and the cut is cleaner.

My 30 yr. old 5' Woods Dixie Cutter was treated to a new set of blades a couple of years ago. The old ones bore only passing resemblance to the new ones and, because of over 25 years of sharpening, were a lot lighter. They done good. Bounced off a lot of rocks and iron fence posts over the years. If sharp blades lead to bad things, I can't prove it.

Both the old Dixie Cutter and my new Woods BB720 have the same blade bolt retention system...a keyhole retainer plate held in position by a 1/2" (?) cap bolt. Remove the bolt through the hole in the deck, tap the plate outward until the blade bolt reaches the large part of the keyhole and then bolt and blade fall away. R&R is about 15 minutes each way. I usually remove them for sharpening and bolt lubing every 10 to 15 hours of operation or whenever the cut looks ragged. They get sharpened on a bench grinder.

Today I sharpened the blades on my new 48" King Kutter XB cutter. Because they cannot be easily removed, I sharpened them on the cutter with an angle grinder. They were 'eighth inch dull' and it took some time to get an edge on them. I really prefer to remove the blade for inspection and blade bolt lubing but this thing has blade bolts that are held in place with castellated nuts and cotter pins; plus there's no access hole in the deck to get at the nuts. Gotta remove the entire stumpjumper to remove the blade bolts. I doubt those bolts will see grease until the blades are replaced. The Woods system is better, by far, but a 48" Woods would've been half again what I paid for the KK. You get what you pay for but, for all that, KK seems like a sturdy little beast.
FWIW
Bob