Bush Hog Blade Question

cperky · Aug 19, 2004

Anyone ever tried using a bench grinder to sharpen your blades? (after removing them of course) I have a RFM and a rotary cutter. Neighbor has a bench grinder. Just wandering if it would be easier to do. I plan on using my impact wrench to remove and reinstall the bolts.

soarkrebel · Aug 19, 2004

Soundguy i don't think your going to feel the vibrations that could cause damage on a tractor with all the other vibrations going on. but the bearings in the drive line will.
In my woods manual under sharpening the blades it has a highlighted section with the word important in bold.
it states when sharpening the blades ,grind the same amount on each blade to maintain balance. replace blades in pairs. unbalanced blades will cause excessive vibration which can damage gearbox bearings. vibration may also cause structural cracks to cutter.

now a section before this is titled servicing blades. it gives instruction on how to remove them for servicing . but what catches the eye again is another important section. in it an explanation of of how extreme force will be needed to remove a siezed blade bolt to prevent damage to the gearbox.

Now i see it as by removing the blade i get three benefits. one i can clean the bolt and coat it with anti sieze . another is to inspect the bolt for wear. and i can get a better edge and try to keep them within balance of some sort.

Now i use a beam that i made that is balanced hanging on a hook freely. i don't get picky but if the beam remains pretty level i assume that the blades are pretty close to balanced.

now i don't get an ACES vibration analyzer and balance them but my homemade methods works.

I have alot of rocks on my property and my blades take a beating sometimes. if i have chunks out of the tips that i can't work out without getting my blades real narrow and maintain some kind of balance i just buy new ones. at $45 bucks thats not that bad.

Anyway thats my method and reasoning behind my way.

Soundguy · Aug 19, 2004

( Anyway thats my method and reasoning behind my way )

Like I said.. everyone has their own technique. It is up to the individual to do whatever their wallet is comfortable with.

Me , personally, try to do a decent job, and then let her rip.

As for the siezed bolt issue.. I believe that is more of an issue of whether or not the balde can rotate on the bolt to clear an obstacle.. and yes.. I hit mine with PB at the beginning and end of every season, and ensure that they will swing before powering it up.

That manual is made to shield liability of their company.. not specifically to benefit the end user.... that 'benefit' to the user is merely a welcome coincidence... thank the lawyers for that kind of thinking.

While I have seen catastrophic damage to a gearbox from shock loads and shear pins that don't snap.. I don't think I have ever seen a gearbox bearing go out.. seals yes.. bearings no.

The GC I work for has about3 old hogs stacked up in the back.. dating back to the early 80's.. all of them have a gearbox that is otherwise in working condition... mainly the decks gave out, or were otherwise so 'rpaired as to need replacing. One unit has had the box converted to grease due to a bad seal.. but that mower had been running before I even came to work here in 92'.. and according to the mechanic, ran at least 5 years on grease...

I'm not saying it can't happen.. as we have seen bearing failures here... But.. I'm not going to 'spend' a good portion of time each season to remove and replace blades.... time is money.. And according to my 'books' and cost averaging.. it is easier for me to buy an economy hog.. use the heck out of it.. perform light maintenance on it.. and then replace it when it is used up, vs. putting many 'non-mowing hours and replacement parts on it during its lifetime. That's how our company operates as well... we simply found we had a better return on our dollar with cheaper mowers.. on average, they lasted almost as long as hi-dollar units.. could be replaced twice as often if needed, and still be less than the cost of the new unit, and given that.. replacement schedule.. we actually had a higher average # of years with a 'new' mower. It was also painfully evident that a buried manhole completely destroys a mower, whether it is 500$ or 1200$... The manhole doesn't discriminate... again.. let your wallet make the decision.. me? I don't have the time available.. maintenance by replacement is simply cheaper for a guy that works 6 days a week..

Soundguy

cisco · Aug 19, 2004

I've a 72 inch wide Woods, and can't say that removing the blades is a snap (even with access door on top of deck), but it can be done in 10-15 minutes, without power tools, for both blades. My dealer recommends changing out the bolt that holds the blade when I switch out blades, as it seems the bolt can, after heavy and long use, shear off. Anyhow, an extra set of blades and bolts cost me $35. So, when I remove a blade, I immediately replace it with a sharpened one, switch out the bolt (? $1), and that's it. As far as sharpening - a bench grinder and a light hand seem to work (one does NOT need a real sharp edge).
As far as other methods, I tried lying under a raised (and blocked) cutter - once - was not satisified with the uniformity of the grinding, and wasn't too happy about the prospect of being squashed.

OkieG · Aug 20, 2004

Looks like everyone here is using loaders or boom poles to stand their hogs up. 

I don't think everyone here is. Altough I like the "lean it up" alternative (for me) better than crawling under the cutter for sharpening. That 45hp brutus of mine is no palm grinder. It's torquey and gets heavy quick. The threat of self-inflicted injury aside, I, like cisco and SoArk, just feel better with the blade off the machine and in a vice.

 Everyone's setup is different. 

I agree...or, even if our setups aren't so different, at least we can have different preferences, skills and comfort levels. It's often easy to believe MY way is the BEST way. But, I'm not really trying to convince anyone of that. Just like you, the technique I describe expresses where my preference and comfort level lie...and why. It is offered, as always, for consideration and comment.

Responses (like yours) are a great way for me to look at a task from a different perspective. That's one way I learn, and one reason why I like TBN. And your approach certainly is valid. I appreciate your explanation.

OkieG

OkieG · Aug 20, 2004

Anyone ever tried using a bench grinder to sharpen your blades? 

I believe I've read of some folks using their bench grinder. The problem I run into with any long surface needing grinding and the bench grinder is that the grinder motor gets in the way. Though, I think a satisfactory job could be done.

OkieG

have_blue · Aug 20, 2004

Hi PR,

No time to read all the replies, sorry if I give you repeats.

Removing those Jesus nuts looks like a real chore, so here's what I do.

I park the tractor at the top of a slope with the RC hanging over the slope to get more room underneath. I raise the RC up high, and block it up with a pair of notched 2x6's for safety. I use a little angle grinder to sharpen the blade. Takes about 15 minutes total. I sharpen often, because long grinding sessions cramp up my hands and wrists.

You mentioned shredding. I try to avoid shredding. Shredding indicates either a dull blade, or the front of the deck is not a little lower then the rear. This robs horsepower, big time. I also find that cleanly cut grass stalks lay down against the ground and look better and rot quicker than fluffy shredded grass. I do not like to hear my deck sounding like "#$%^&*(%$^&*^#$%&*^", but rather like "ZZZZssssshhhhh..." That lets me know the blades are sharp and the deck angle is about right. I like to look back and see the cut grass stalks mostly full length and laying flat on the ground rather than in shredded windrows.

SteveBenson · Aug 20, 2004

I do it the same way. I crack the bolts loose on the ground attached to the 3 pt hitch with a 3/4" breaker bar and a 4' pipe. Then I just use the 3 pt lift to raise it with a couple cinder blocks under the deck for safty.

Plus, after a few years you will need to replace the blades. I just bought a new set for my 6' bush hog and was surprised to find they were only $19 a piece. Why did I wait so long?

I just used the cheater bar to get the bolts real tight again. My deck has two bolt holes in the top for access. It might be a good idea to inspect them before every use. I've never had a problem in that department.

soarkrebel · Aug 21, 2004

( Me , personally, try to do a decent job, and then let her rip.
)

I don't try to do just a decent job i do a correct job so she doesnt RIP!

( As for the siezed bolt issue.. I believe that is more of an issue of whether or not the balde can rotate on the bolt to clear an obstacle.. and yes.. I hit mine with PB at the beginning and end of every season, and ensure that they will swing before powering it up.
)

The siezed bolt issue is in reference to getting the bolts out of the crossbar. if they get seized alot of folks are going to try and force them out by driving them out. this in turn puts severe stress on the output shaft mainly the bearings that support it. by driving the seized bolts out you may cause flat spots on bearings and cause premature wear. it does say that if this occurs to support the crossbar from underneath to prevent this from occuring.

me i don't have that problem cause i do remove my blades to sharpen and make sure i coat them with never sieze or sometimes i use moly 50.

( That manual is made to shield liability of their company.. not specifically to benefit the end user.... that 'benefit' to the user is merely a welcome coincidence... thank the lawyers for that kind of thinking.
)

That statement is only partially true IMO. yes they want to shield themselves any manufacturer wants to do that.
But if they didnt want to aid you the user and truely protect themselves they wouldnt give any information on how to perform this and other service on your machine. they would just say let your dealer perform this service. and if you did this service and something happens they can say you were not qualified.
I am sure bushog, woods,rhino and even agrafab do research and testing on their products and try to provide the best methods of maintenance to the customer . this protects them and you . if you follow the method then you are more than likely to get many more years use and possibly many more years on this earth in reference to rotary cutters.
I guess my occupation as a aircraft technician makes me a little more into following manufacturers data. first if i don't i may find myself in trouble with the FAA and worse i may have peoples deaths on my hands.

yeah rotary cutters and airplanes are different but i try and apply my ethics to my own stuff as i do the 22 million dollar airplanes i work on. yeah my tractor only goes max 18mph and the planes go 500 + mph but i stick to doing my best to keep both right.
but i go back to my 8 years working on helicopters and how vibration does so much damage. ever rode in a helicopter? they are they the ultimate in vibration.

( While I have seen catastrophic damage to a gearbox from shock loads and shear pins that don't snap.. I don't think I have ever seen a gearbox bearing go out.. seals yes.. bearings no. )

The shear pins that don't snap is probably another prime example of someone just sticking a bolt in there and not finding out what it needs. again woods has that old important (lawyer approved) statement in reference to that . states use a grade 2 bolt. how many throw a grade 5 or worse a grade 8 in there . that lawyer approved liability shield would have probably helped that end user if they had used it.
seals are going to wear out .dry rot ,heat damage or torn they will need replacement in time thats just machinery common sense.

( The GC I work for has about3 old hogs stacked up in the back.. dating back to the early 80's.. all of them have a gearbox that is otherwise in working condition... mainly the decks gave out, or were otherwise so 'rpaired as to need replacing. One unit has had the box converted to grease due to a bad seal.. but that mower had been running before I even came to work here in 92'.. and according to the mechanic, ran at least 5 years on grease... )

You know paint will go a long way to keeping the housings structurally sound . not dent free but corrosion controlled.
and yep my grandfather had an old sidewinder that had grease in the gear box until the old upper deck was taken over by rust and feel apart. a little time and metal and it would probably still work.

I work to much also but i find time to keep up my stuff. and i do follow data. I get creative when i am building something .and lastly i would like to state that i am not meaning to offend you or your opinion just making a rebuttal of my opinion. /forums/images/graemlins/grin.gif

soarkrebel · Aug 21, 2004

In my opinion the blades aren't expensive . just compare them to what they want for lawn mower blades /forums/images/graemlins/shocked.gif.

I don't have a torque wrench that goes to 450 ft lbs i do fudge there. i have thought about drilling and cotter pinning the nuts and bolt. that is a little extreme huh? /forums/images/graemlins/smirk.gif