Rotary Cutter Sharpen or not to Sharpen that is the question

[phiferpharm]

I tried to get the nuts off of my Bush Hog SQ172 and even with my air gun jacked up to the max, then a breaker bar, the nuts just looked back at me and didn't budge. :ashamed: When I got out a light and magnifying glass I would swear the bolt looks like it was flattened after the nut was attached. I was going to pull them, replace them, then grind the originals to a flattened (squared) edge. Guess it will have to wait until I can get a bigger air gun or more air power...

One other thought I had was I believe I read in the other (older) thread that it was important to be sure the blades were balanced.

 

[Soundguy]

I would expect that process if I'm correct) to give extended blade life (3-4 seasons, minimum). If it doesn't, it's a rip off IMHO. I'm leaning toward the "rip off" side.

i'm thinking you are correct. I agree.

soundguy

 

[Gary Fowler]

When I last worked on my blades, they were still pretty good shape as far as sharp edged but due to lots of humps and soft spots, I hit a lot of dirt with my blades and I noticed that rather than have a 45 degree slope upward, the bottoms had worn off so they were more V shaped. I took my welding machine and built up the bottom edge then ground it back flat first. Then I put the bevel back on the top edge so it would give a little lift and cut action rather than slash. I found it easier to just remove the whole assembly from the bush hog. One bolt from center of the stump jumper and the whole thing slides off the shaft. I put some lubrication on the splines when I reinstalled it so it would be easy to get off later also. If you stand the whole frame on its side, it is easy to walk up to it and remove the nut, pull the whole thing, put it on your shop table and do what needs to be done. You dont even have to remove the blades if you dont want to.

 

[smstonypoint]

I'm going to guess the blades are case hardened or built up with a harder alloy weld then ground to a cutting edge.
Sharpening would remove that case hardening (which isn't very deep) or the weld.
I would expect that process if I'm correct) to give extended blade life (3-4 seasons, minimum). If it doesn't, it's a rip off IMHO. I'm leaning toward the "rip off" side.

I believe the blades are produced by Oregon.

"The Fusion process uses electrofusion technology to apply a tungsten carbide coating into the blade in a method that is designed to keep cutting edges sharper longer.

Delivers the same high quality of cut throughout the day without resharpening, available only from OREGON."

Although Bad Boy doesn't recommend sharpening, the Oregon site says that the blades can be sharpened.


http://www.oregonchain.com/OEP/pdfs/OREGON_FusionBlade.pdf

My mower is relatively new, so I can't say anything about how well the blades hold their edge.

Steve

 

[JimRB]

I tried to get the nuts off of my Bush Hog SQ172 and even with my air gun jacked up to the max, then a breaker bar, the nuts just looked back at me and didn't budge. :ashamed: When I got out a light and magnifying glass I would swear the bolt looks like it was flattened after the nut was attached. I was going to pull them, replace them, then grind the originals to a flattened (squared) edge. Guess it will have to wait until I can get a bigger air gun or more air power...

Maybe centerlock nuts which you can buy at a good hardware store in the smaller sizes. Centerlocks I have seen usually have 2 or 3 indentations from the die that squeezed it. Well the indentations is my theory as they have to squeeze it after it has been machined. Distorted thread locknut - Wikipedia, the free encyclopedia

 

[gwdixon]

I tried to get the nuts off of my Bush Hog SQ172 and even with my air gun jacked up to the max, then a breaker bar, the nuts just looked back at me and didn't budge. :ashamed: When I got out a light and magnifying glass I would swear the bolt looks like it was flattened after the nut was attached. I was going to pull them, replace them, then grind the originals to a flattened (squared) edge. Guess it will have to wait until I can get a bigger air gun or more air power...

One other thought I had was I believe I read in the other (older) thread that it was important to be sure the blades were balanced.

If you can get a grinder to the flattened bolt it can be ground down to the top of the nut. That, along with heat, should allow the nut to be removed.

Those big heavy blades are hard to get out of balance unless a major chunk is broken off. Land Pride recommends that the blades be within 1.5 oz. of each other.

Here are the directions from Land Pride:

Both blades should be sharpened at the same angle
as the original cutting edge and must be replaced or
re-ground at the same time to maintain proper
balance. The following precautions should be taken
when sharpening blades:
a. Do not remove more material than necessary.
b. Do not heat and pound out a cutting edge.
c. Do not grind blades to a razor edge. Leave a blunt
cutting edge approximately 1/16 thick.
d. Always grind cutting edge so end of blade
remains square to cutting edge and not rounded.
e. Do not sharpen back side of blade.
f. Both blades should weigh the same after
sharpening with not more than 1 1/2 oz.
difference.​

Like some others, after a couple of seasons I build the blades back to the original shape with 7018 welding rod and then hard face with "soft" hard facing that can be worked with a grinder.

 

[phiferpharm]

I'll check to see if I can get to the nuts through the service hole. Thanks for the info..

 

[the6shooter]

I sharpen my blades every 10 hrs. of service. Some of my customers almost demand it now for the cut. I have good mower blades and some 1/2 worn out blades for thoughs rock infested pastures. Sometimes I go though 2 sets of blades a yr.
The tipical blade only cuts the first 1 inch of the blade just make sure that the end of the blade is kept square and you will really notice the cut.
As for removing the blades from the blade carrier, after you remove the bolts treat them to a good coating of (Copper Coat) this will allow you less effort to remove them the next time. always inspect the condition of the lock washer , and replace as needed.
The (copper coat) keeps you from gualling the threads on the nuts and bolts.
and will keep them in service alot longer.

all the best david

 

[gwdixon]

I'll check to see if I can get to the nuts through the service hole. Thanks for the info..

You may have to remove the pan to get to the nuts. The pan is usually held on by a single nut w/cotter pin on a keyed or tapered spline shaft.

Heat and/or a gear puller may be required to get it all broken down so you can get to the blade nuts.