Sharpening Bush Hog

[pennwalk]

I read that it was a good idea to keep the bush hog blades "sharp" to reduce the load on the tractor. When I looked at replacement blades at TSC I was surprised to see that the edge was flat. When I tipped the bush hog up to inspect the blades I found the edge to be round but not much wider than the new blade but the outside corner is rounded off too. I understand from a lawn care friend that the outer end is where the action is. How do I sharpen the blade and when is it time to get a new one?

Chris

 

[Bird]

Chris, a "sharp" blade means you have thin metal on the leading edge. When it hits something hard like a small tree or sapling, that edge can be nicked, notched, or bent. So I believe it's customary for brush hog blades to have an edge that is approximately 1/8" thick. It shatters and tears brush without damage to the blade. Now if you're only mowing grass and weeds (soft material), then I see no reason not to have a sharp edge on the blades; similar to a lawn mower.

<font color=blue>How do I sharpen the blade and when is it time to get a new one?</font color=blue>

I have removed blades and sharpened them on a bench grinder, and I've also sharpened blades without removing them by using a 4" angle grinder. I suppose it could be done with a hand file, but not by this old man./w3tcompact/icons/laugh.gif That would just take too much time and effort. As for replacement, if it's bent, cracked, bolt holes wallowed out - in other words just inspect them for damage and replace them if they are. Otherwise, I don't know how much wear you want before replacing them. I replaced mine when the "sharpened" section of the blade got narrower than the rest of the blade. When you sharpen them, try to take the same amount off each blade so they stay balanced.

 

[Solo]

Chris
I was just reading an article in Progressive farmer about Bush hog blades. The article suggest's that these blades be professionally sharpened, because balance is so important. The vibration unbalanaced blades can cause can be very damaging to the mower.
Solo

 

[pennwalk]

Bird I have admired your posts here on TBN for a while now. I don't know if I am thinking about this too much. After all a bush hog is a pretty crude device which the folks down under aptly name the slasher. But I was wondering. If the outside leading edge does the cutting. On a new blade it is a "sharpened" corner. On my blades the outside corner is somewhat rounded (darned rocks!). Do I just grind away at the round so that the 1/8 inch edge goes around the corner or do I grind away the round so that the whole edge is at a small angle and the square corner is reestablished?

Chris

 

[pennwalk]

I was thinking about just giving in and taking them to the shop but I was thinking that I ought to be able to do it. Its not rocket science. The shop that I am using is pretty slow and sure as shooting on the next sunny day it will come to me like a revelation that I ought to be out bush hogging and sure enough the blades will be in the shop so I will have to slink back down to the basement for a virtual tractor fix but the real think is better.

Chris

 

[Anonymous Poster]

The replacement blades are fairly inexpensive... say from $10 - 20. ea. ... but the removable and re-torquing is actually the time consuming thing...

I would use a brand new blade as a template for your guide... I think you'll be very surprised with the "rounded new edge"... and unless you're putting quite a few hours a year on a brush hog alone...{hundreds...?}, you can probably go a few years before it ever gets to the sharpening stage... /w3tcompact/icons/wink.gif

 

[Thomas]

I have alot of luck sharpening blades w/a small hand grinder..41/2 disc w/stainless steel pad..for you can w/ease get the right angle,and you don't burn nor nick the blade w/a stone disc.
I do sharpen the end of the blade a tad for that might see the first object to be cut,I also lube the heck out of the bolt and housing threads so next time w/ease to remove the blade.

 

[Bird]

<font color=blue>Do I just grind away at the round so that the 1/8 inch edge goes around the corner</font color=blue>

Chris, I'm no expert on this, but I don't grind "around" the corner; just sharpen straight across. And I don't worry about a slighly rounded corner at the end. And as I said, I've sharpened some without removing them, and I've also used the bench grinder, but I prefer removing the blades and putting them in the vise on the workbench and then sharpening them with the angle grinder. Then I weigh them to make sure the weight is the same for each blade in an effort to keep them balanced. And I may very well be over doing it a bit and taking too much time, but I thoroughly clean them on a wire wheel on the bench grinder before sharpening; same as I do with the lawnmower blades.

 

[Anonymous Poster]

Hi Bird,

When I was a kid… after sharpening, my friends’ Dad {God bless his soul} would put the blades on a scale… one on each side {old fashion-looked like the “scales of justice”} to adjust for balance…

Today, with the finish mower blades you re-sharpen them, but with the larger rotary cutter blades {brush hog style}, they recommend replacement versus “re-sharpening”… due to the “tempered” and “hard-surface process” technology in use now…

Evidently using the grinder while sharpening the edge also changes the “temper” of the steel {obviously its heating up the metal} and can make the blade “harder” causing it to become brittle in some instances and… break/shatter… on up to 1” stuff it may not occur but approaching 3-4” or more stuff it can become a deadly/dangerous situation…
__________________

Enough of that… how’s the Tool Truck business been the past week…? Is your brother on vacation? Or do you feel like coming out of retirement…? /w3tcompact/icons/blush.gif

 

[TonyC]

I had an Uncle who used to say "You can cut brush with a school bus if you spin it fast enough". Kinda cute and partially true. As Bird pointed out, if all you are cutting is grass, sharpen 'em up pretty good. If you are truly bush hogging they need not be that sharp and it's better on the blades if they're not.