How often do you sharpen/replace blades on you rotary cutter?

[DKCDKC]

I've found a slight edge makes the cutter do better on patches of grass. It always cuts brush well. I stand the cutter up, brace it and touch it up every spring with a grinder. I took the blades off once in 12 years just to check balance.

Biggest problem I've observed some folks having with the cut is not keeping the PTO rpm at the proper level. A slower blade cuts poorly, if at all.

 

[vabiker23518]

I feel better after reading these posts...I purchased a used Land Pride 15-48 several years ago and use it to cut grass around the cabin and keep trails open. Cuts well, and never have sharpened the blades. I think I'll check them out at seasons end with thought of dressing or replacing the blades. Will be a bear to get them off after all these years!

 

[Lawnjocky]

I try to keep my blades sharpened. Not like a lawn mower blade but with the 1/16 - 1/8 blunt edge as mentioned by others. My reason's are simple (just like me). A dressed edge will cut faster, neater, use less fuel and produce less strain on the machine.

Side note.
Several years ago there was a guy who did blacksmithing as a hobby. He would heat them up and beat an edge back on the blades. A grinder was only used to lightly dress them. That worked great. Those blades stayed sharp a lot longer plus he wasn't taking away as much steel as compared to grinding. Not to mention it was pretty cool watching him work that steel.

 

[SARG]

I sharpen mine often with a 4 1/2 inch hand grinder. Just raise the deck and sharpen them from behind. Takes maybe five minutes and it does improve the performance.

 

[pacerron]

I've found a slight edge makes the cutter do better on patches of grass. It always cuts brush well. I stand the cutter up, brace it and touch it up every spring with a grinder. I took the blades off once in 12 years just to check balance.

Biggest problem I've observed some folks having with the cut is not keeping the PTO rpm at the proper level. A slower blade cuts poorly, if at all.

RPM is a factor in the cut.
The gearboxes are basically only transferring horizontal rotation to vertical in either a single spindle ( bush hog type) rotary cutter or a multi spindle finish cutter. If we are running 540 RPM PTO speed on a bush hog type the blade spindle is running at 540 RPM and the one 6 foot blade has a tip speed of about 10,000 fpm. On my Woods finish mower, as an example, and I imagine most finish mowers, the belt pulley under the gear box is considerably bigger than the 3 spindle pulleys for the blades. At 540 PTO on my finish mower the blade spindle speed is 1,939 RPM according to the book or basically 4X the PTO speed. The blade speed is 16,360 fpm for each cutting width of 30" x3 spindles. Therefore, if we use 2 spindle blade widths which equals about the cutting width of the 6 foot bush hog, since you must allow for overlap after
the first pass, I could argue that the same width of grass cut by the single blade bush hog at 10k fpm is being cut at the rate of 32.6k fpm by the finish mower at the same forward ground speed for both mowers.

So yes, sharpening of bush hog type blades ( sharp like a mower, as some indicate) could improve the cut of pasture grass versus slapping it off with normal profile blades but at the expense of blade life, particularly if used for brush cutting after making a mower sharp profile, but you still don't have the RPM.
I look at it like, when your little yard trim push mower blades get dull and shred the grass if you run the engine at idle, turning it brown, versus a clean cut with sharp blades with the throttle set to proper running speed.
So, if you buy all that, would you like to buy the Brooklyn Bridge at a fantastic price but only if you call in the next 10 minutes?

 

[Soundguy]

I feel better after reading these posts...I purchased a used Land Pride 15-48 several years ago and use it to cut grass around the cabin and keep trails open. Cuts well, and never have sharpened the blades. I think I'll check them out at seasons end with thought of dressing or replacing the blades. Will be a bear to get them off after all these years!

i got an old servis (think rhino ) heavy duty 6' mower.. early 70's era.. got it free.. it was a beater.. needed a lower seal, lots of welding and paint.

when I looked at the blades.. they were as round /dull as my finger..

 

[Stihlrunner]

I hit mine with a grinder while still on the machine. It takes about 5 min per blade. I do it about every 25 hours of mowing. Spend more time on the end. That is where most of the cutting takes place. Dull blades may work better in rough stuff. It makes tree stumps less likely to become spears(tough on tires).

Same with me, when I am mowing tall grass I will dress the edge while they are still on the mower, otherwise it's saplings and such and I leave them dull.

 

[rasimmo]

My FIL has 2 sets of blades for his. After about 10 hrs of use, he swaps blades. He takes the "dull" ones to the blacksmith shop and has them heated and hammerred out to a good edge. I think he's crazy and just laugh at him.

Wow, as I was typing that I realized why my wife is nuts. Thanks for helping with that realization.

 

[Soundguy]

oh my.. swaps every 10 hrs and has them worked? I'd shoot myself if I had to swap mower blades every 10 hours.

I'd never have time to do any other chores! oh well.. I guess some people wash their hands alot.. or only vacume their carpet in one direction too..

 

[wirenut]

I found a sure way to find rocks or chunks of concrete, is to sharpen my blades on the BH or lawn mower. Anyone else notice this?:confused2: