thatguy said:
I did a quick search and didnt fully get my question answered about sharpening lawn mower and bush hog blades..
I have seen 'grinding' and 'cutting' wheels at different stores and also the 'flap discs' ...
Would i be better of using the grinding wheel or flap disc to sharpen the blades?
Are there different hardness of grinding wheels?
Would the flap disc not get the blade as hot?
What grit would you recommend for the flap discs? 36, 60, 100, 120??
I am just worried about taking too much metal off with my inexperience, so I am leaning toward the flap disc if that works OK..
thanks
Brian
I will take a run at it, and tell you how I see it.
Normally the difference between Cutting and grinding wheels is their thickness. In a standard 4.5" wheel, a grinding wheel is usually about 1/4" thick, and a cutting wheel, made to go in edge wise and cut is usually 1/8" or so thick. There are several different grits available as well.
For me, being the impatient person that I am, I use grinding wheels to sharpen both my mower blades and when they come up Bushog blades.
As for useing a flap wheel, they do not remove material as agressively as a grinding wheel, so I tend not to use them except for very fine and smoothing type work, which I do not see the need for on mower or bush hog blades.
How I sharpen mower blades.
For background, My wife runs a lawncare business, we usually have two 60" ZTR mowers running. I usually sharpen commercial 1/4" blades, at least 6 and usually 12 at a time.
Wipe, or clean in some form excess grass from the blades prior to starting
For mower blades, I put them in a vise, holding near the ground part (cutting edge) of the blade, area to be sharpened pointed up.
I then take a standard 4.5" grinder, running a standard grinder wheel (I prefer the US made ones, slightly more expensive but worth it too me) My first cut is made flat, and I level and even out the leading edge of the blade. After the leading edge is flat and straight, I then turn the grinder on edge and cut the profile into the blade, I tend to start at the root, and work backwards too the tip. It will be easy to overheat the tip if you are not carefull. After doing a couple of blades you will develop the feel for how much pressure to apply and how quickly you need to move. I usually just continue copying the original manufacturers angle. You can play with increasing the angle to make them sharper, or decreasing the angle to make them hold the edge longer, but it will be a duller edge.
When I get close, I will make a quick "swipe" type pass on what is the bottom of the blade, to remove any burr and then I do my smooth finishing pass on the ground surface of the blades.
On mower blades, I bring them to a sharp cutting edge, but do not need it too be as fine as I would acheive with a flap wheel. IE I need it to be as sharp as a decent ax, not a razor blade.
On my mower blades, I balance them with a simple pyramid looking balancer. I have looked at going with the magna matic etc, but again, it is kind of the razor thing too me. After our blades spin about 3 minutes, that balance would show off again, so I just do not see the need to go that fine.
As to sharpening bush hog blades.
I have done a couple sets, but certainly do not consider myself an expert. My experience has been that by the time a bush hog comes to me to be worked on, they are just beat to death. Usually I have been taking off blades, welding stump jumpers, cutting out bolts etc, and prior to reassembly I will sharpen the blades.
I use my 9" grinder with a 7" wheel and leave the front 1-8" or so flat. My belief and understanding that those mowers tend to beat the plants into submission more then cutting them off smoothly like a finish mower. On the ones I have done, I weighed both blades and got them close, as I removed substantial material to remove dings, missing chunks etc. I use the same basic order to sharpen as I do the mower blades, but that is probably more from habit then from experience.
If I was doing my bush hog, I would probably just try and get under there with my 4.5 grinder and try and dress them without removing them. Then again, I am not worried about how sharp they are, I want them busting up the stumps etc that they hit.
Have fun, hope my description was clear enough.
