Bush hog blades not cutting

[Indydirtfarmer]

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]

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]

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]

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]

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]

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]

</font><font color="blue" class="small">( I'll go along with the blacksmith idea.... Although, I just replace blades when they get too far from "grindable".
)</font>

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]

</font><font color="blue" class="small">( We have been getting so much rain here you can hear the grass growing. )</font>

<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]

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]

</font><font color="blue" class="small">(
33 years of mowing "professionally". Average 1500 hrs. )</font>

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,,,

 

[gsganzer]

I'm with you Bird. I have a Rhino SE4 and find that it cuts better going clockwise. It actually seems to discharge the cuttings to the left side beneath the deck, leaving a row of cut grass clumps to the left side of the cut swath. If I go CCW, then I'm trying to re-cut the discharged clumps when I overlap my swath. Anyone else find this?

 

[Freds]

All this talk about cutting direction.....

I don't think I have a predetermined cutting direction. If I'm cutting a section of field, I make about three loops around the outside (clock or counter determined by the direction I entered the field), then I start bisecting the field using this outside path to turn the tractor and head back the other way. I'll make a couple row cuts and start widening them, sometimes having the cut path on the right and sometimes on the left. Eventually I'll start a fresh path and keep working the field from one side to the other.

I'm still thinking it's the extra weight of the tractor and the lousy touchup on the blades I'm sure I gave it. There just didn't seem any easy and safe way to brace those blades and stop them from turning, so I one handed the 4-1/2" grinder the best I could and even with one end of the brush hog held up with a couple chains on the FEL and some 4x4s as a couple deadmans.... I wasn't going to crawl under it /forums/images/graemlins/shocked.gif

 

[have_blue]

Hey Freds, The driveway leading inside my tractor shed is on an incline, and I use it to help get my bush hog higher up in the air when I sharpen my blades. I back the tractor outside, turn it around, then back it part way back inside the shed. When the rear tires are just up on the slab, I set the parking brake and raise the bush hog up. It's amazing how high it goes with the tractor's front wheels a foot or so lower than the rear wheels. A pair of 4x4's with notches chain sawed in the ends make excellent braces. I sit on an old lawn chair and grind the blades, but it's tight. I need a milking stool! /forums/images/graemlins/smile.gif

I'm going to build a 3' high dirt ramp out back of my shed to make it even easier. I will back the tractor up, wheels on top of the ramp. Bush hog raised up and braced. I am thinking I can sharpen the blades and clean the deck in relative safety, WHILE STANDING. My back will throw a party!

 

[Bird]

And if you have the hydraulic top link, you can really tilt it up high.

 

[Slippy]

I finished mowing last year with my 10' pull behind rotary cutter last year and it did fine. This year I started cutting and I thought there was something wrong with the cutter. Every pass I would leave a stream of pushed over grass that did not get cut. I tried every direction, every speed, and nothing helped. I looked at my blades and they looked good, and deck was very clean. Because of the 10' cut, every pass all four tires are in uncut grass. So as I paid closer attention, I observed that the tires were pushing the grass down, and it was not springing back up. Because there is absolutely no difference in my equipment since last fall when I was cutting to this spring, I came to the conclusion it must be the conditions. In thinking about last year, we got a lot of rain and I usually cut grass when it was a little wet or damp. This year it is bone dry. Even water holes, low places are dry this year that I have never seen dry before. So, I concluded it was the dryness of the grass. To test my theory, I am going to cut the next chance I get when the grass is damp and see if this makes a difference. It is very frustrating because it turns my 10' cutter into a 5' cutter becasue I have to overlap next time around. With 250 acres to mow (if I don't cut any hay) thats not good.