Bush hog blades not cutting

Indydirtfarmer · Jun 13, 2005

Normally, I don't jump up and down, hold my breath and turn blue, and demand to be paid attention to, but it's coming down to that.

33 years of mowing "professionally". Average 1500 hrs. per year, until 3 years ago when I started adding tractors to the "fleet". Last year it was over 4500 hrs. on the combined crew. This year, we,ve already amassed over 2800 hrs, and summer isn't even officially here yet.

I've ground a few hundred bush hog blades in my day. I've also RE-ground a few because of employees doing sub-standard jobs of sharpening them.

WHAT I'VE FOUND....

Like I said in an earlier post, the degree of bevel is VERY important. Just a tick too abrupt, and they don't cut clean. (Too "flat" and they get nicked up fast and easy) MOST blades are just at the minimum bevel as O.E.M. equipment. I try to add a few degrees of bevel when sharpening. It makes all the difference in the world. I've had mowers to leave a trail of bent-over grass, taken them and touched up the grind just a tad, and they'd cut like a finish mower.

Also, as has been mentioned, when a bush hog blade starts wearing from the underside, getting a touch of "round" to them, instead of the flat surface they were intended to have, you must grind that away also.

I try to get a leading edge with a 1/8th" to 5/32nds" "blunt edge" instead of razor sharp. Depending on WHAT and under what conditions we're cutting, (trash, junk, ect...) sometimes our blades must be touched up on a daily basis to get a clean cut.

I'll try to "measure" the degree I grind my blades at, and pass that along to anyone interested. I do it by "feel" and "sight" now. I've never taken the time to actually measure the angle.

Oh, and by the way, we do teach our operators to run with the RIGHT WHEEL on the previously mowed pass. (Going counter-clockwise) The way a blade is shaped creates lift BEHIND the blade, raising bent grass for the next blade to cut it off. It just works..... Sometimes I just do what works best, and don't question why....

djradz · Jun 13, 2005

Yep, I think the bevel may help with the "uplift" effect that the blades should create. I've always sharpened mine with a little more angle, less blunt, than supplied, or at least try to maintain the OEM angle, in spite of splitting a few rocks. Now, with most of my fields in pretty clean shape, I sharpen the edge to something more like a 1/32" or even less, just a little under "sharp".

PM1 · Jun 13, 2005

Indy,

Do you remove your blades before sharpening each time, or grind them while mounted? I'm asking because removing blades takes me a while, depending on how hard I feel like whacking with a medium sledge to drive the bolt out -- and how cooperative the bolt is feeling on a given day.

Parker

Indydirtfarmer · Jun 13, 2005

I grind 'em in place with a B&D 4-1/2" mini-grinder. Usually have the mower still on the tractor, raised all the way up, with rear wheel resting solid and SAFELY on the deck of my trailer. Still don't get under the mower, (Other than my arms)

Trick is to NOT let them get too out of shape. That takes too much grinding. Frequent "touch-ups" as needed.

Lawnjocky · Jun 13, 2005

Like Indy, I'm in the mowing business and I would like to add my 2 cent's. I agree with every thing Indy said but when it comes to sharpening blades I would include this:
1.For blades that are extremely dull or beatup.
Instead of grinding your blades back into shape you might try to find a blacksmith to sharpen them. A blacksmith will heat the blade , beat it back to sharp and retemper the metal. If you grind you are cutting away steel and run the risk of burning the blade ( loosing the temper ) and increasing the chance of breakage.
I started doing my blades this way years ago because when the shredder get's hooked up it's always bad new's. The stuff I shred there is no way to touch up the blades. Concrete, bricks, rebar, the only way to find it all is when you mow. I kept extra set's and would swap out while the dull ones where getting sharpend.
2. Try to keep the blades balanced. This will reduce wear on your seals, bearings and gears. Also there will be less vibration transmitted to the tractor and operator. This is a minor point to most people, but it does make a difference.

Indydirtfarmer · Jun 13, 2005

There's a thread all unto itself......

What have I hiot while bush hogging....

Car rims/tires, (including a "space-saver spare), concrete blocks, re-bar, propane tank (talk about a thrill) a dead dog, 2 LIVE deer, probably 20 miles of wire, a sawed off telephone pole (left 6" out of the ground), hornets nest(s), my own cell phone, ect., ect., and so on......

I'll go along with the blacksmith idea.... Although, I just replace blades when they get too far from "grindable".

I try NOT to grind excessive amounts at one time. I don't get them hot.

Soundguy · Jun 14, 2005

( I'll go along with the blacksmith idea.... Although, I just replace blades when they get too far from "grindable".
)

Ditto.. byt the time you have to r&r them.. once they start loosing the leading square edge.. they are replace candidates anyway.. vs the cost of re-forgeing them..

Soundguy

have_blue · Jun 14, 2005

( We have been getting so much rain here you can hear the grass growing. )

<shudder!> Ugh! Grass growing is one of the most horrible sounds I can think of. That sound is right behing a saw chain buzzing an ich from my ear and a rod flying through the block of a $3000 engine.

Lawnjocky · Jun 14, 2005

When I had the blacksmith sharpen my blades it cost less than a new set, not by a lot but it was cheaper. He would save up blades from me and others to do when he was slow or had time. That kept the cost down. The real problem with having a blacksmith sharpen blades is finding a blacksmith. Mine quit to take up preaching. I don't shred as much as I used to so loosing him was not a problem. My attitude anymore is if I get out the shredder you're getting out your wallet.

have_blue · Jun 15, 2005

(
33 years of mowing "professionally". Average 1500 hrs. )

IndyFarmer,

Oh yea? I can match that. I mowed yesterday in 103 Deg. heat!. /forums/images/graemlins/smile.gif

All seriousness aside, I agree with your posts. 100% spot on!

It's hard communicating with the group when there are so many different types of tractors, mowers, weeds, and OBJECTIVES.

I can pretty much guess your objective. Getting the best appearance you can reasonably get, make the blades last, and make a profit. Am I close? /forums/images/graemlins/smile.gif

My objective it to make my grass look pretty much like it was cut with a much-envied finishing mower with a bush hog.

I only have 10 acres, mostly flat and smooth except for pond levees. I mow ~2 acres with a lawn mower and ~6 acres with the bush hog.

All my brush, stumps, big weeds, tires, bricks, etc. are long gone except for a small corner of woods. (I don't go there) You can run barefoot in my fields. I probably spent a hundred hours picking up every stick and shard of glass.

I sharpen my bush hog blades REALLY sharp, and do a 5 minute touch up every time I mow. I mow about once every 3-5 weeks (depending on the weather!), when the weeds get knee high and the grass is usually 4-6" high. I run the tractor RPM at 1600-1800 RPM, and the PTO is (I guess) about 450 RPM. The cut is 2", and so smooth it rivals my 42" riding mower.

Here are pics of my pond levee I mowed yesterday. Weather has been over 100 for the last few days, and very dry, so the grass is kind of brown and shriveled.

http://webpages.charter.net/bobad/grass1.jpg

http://webpages.charter.net/bobad/grass2.jpg

I realize this would not work for you, but it works great for me on my "almost lawn" grass, and my puny 6 acre cut. I guess many others here are between our extremes.

Note on blades: My (original equipment)blades must be freak! My previous bush hog blades got very dull fast just from cutting tall grass. My current blades must be 4 or 5 Rockwell "C" points harder, because they *really stay sharp. If they ever wear out, I will take a hardness reading, and try to find some that are of identical hardness.

Stay cool fellows,,,