# Blade Sharpening



## Live Oak

It is gettin' to be that time of year and won't be long before the grass will need the first cut. If you did not sharpen your mower blades when you winterized your mowing machine; now is a good time to get it done BEFORE you make the first cut of the season. 

I keep 2 sets of blades and keep one set sharpened up and ready to go in the event I need to swap out due to the old blades getting dull or hitting rocks, etc. 

I have used the grinder and a file and have found that I can sharpen the blades in half the time with the least amount of metal removal and have the best control over maintaining an nice straight & even blade. I use federal bastard single cut file which takes the blade material off real nice and does not over do it with respect to removing blade material. 

Don't forget to static balance the blade after sharpening and use a torque wrench to tighten the blades. Give the blade spindle a few shots of grease too! :thumbsup:


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## MowHoward2210

That's pretty much the way I do it, Chief. 

I hit a softball size rock last fall. Shot out of the deck like a cannonball. I lost about a 1/2" triangle chunk off the end of one of the blades on my 62" MMM. It looks like I can file it down get a good cutting edge. My question is, on a mower that size, is a balanced blade still as critical as it would be on a smaller unit? Evening out the other side would be a lot of work. Got one of my spares on in place of the damaged blade now. Any advice?


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## Live Oak

In my opinion Mow, you ALWAYS want to have a balanced blade. Depending on how far out of balance the blade is; that can be pretty hard on the blade spindles.


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## MowHoward2210

I'd hate to think what the replacement cost of a prematurely worn spindle assembly would be. Thanks, Chief.


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## DeereBob

Chief,
I found a better way to sharpen blades than using a grinder. Use a Rotary Tool equipped with a blade sharpening guide. It maintains the bevel but does not heat up the metal. You need to replace the grinding wheel after 2 or 3 sharpenings but it works like a champ. I've gone through 2 seasons now with my mulching blades so rather than shapening them again I think I will replace them. I also use an electric impact wrench to remove and tighten the blade bolts which does not torque them as much an air tool would. Having a 6 point rather than a 12 point socket also prevents rounding the points of the bolts. Grease my deck spindles everytime I take it to clean and sharpen the blades.


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## leolav

I can one up ya on that one. Try using a 4 1/2" angle grinder with a 80 grit grinding disc. It works quick and the blades cut very well after that. It is also very easy to keep the bevel and at the same time, remove any caked on grass that may be on the blade just by lightly running the grinder over the blade pieces that are affected.


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## Live Oak

I still prefer the file as it does not generate heat like a grinder does. This heat changes the temper of the steel along the cutting edge and I have found that a file sharpened blade lasts me longer. This is particularly so when I sharpen the blades on my 7 Iron 72" MMM blades. Those blades ain't cheap either! Just a matter of what works best for you.


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## leolav

Use a grinding disc with a lubricant that dissipates the heat into the disc. These discs are used extensively in stainless steel applicaitions and does not blue the stainless. It certainly won't distemper a lawnmower blade.


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## Live Oak

I'll have to give it a try and look at that. 

Nice moderator title by the way! hula :tractorsm :lmao:


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## Chipmaker

I like using a 4 1/2" angle grinder as well. I use a #60 reinforced wheel and it only takes a minute to put a cutting edge back on. I really have never been into balancing blades. Never had any premature spindle problems either. No rocks to worry about either. So usually I just need to maintain a decent edge as it gets taken off with all the sand, and as long as both sides are pretty close vibration has never been a problem.

Prior to using a angle grinder I used to use my belt grinder. I still use it whenever the blades are off during the off season when its gone over and checked before storing for winter.


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## DeereBob

This might sound like a dumb question but what advantage is there in using an angle grinder versus a normal bench mounted grinding wheel? Unless I am missing something, neither provides a jig or adjustment mechanism to match the precise bevel angle. This is why I switched from using my bench grinder to the rotary tool since I was changing the angle of the bevel with the former.


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## Chipmaker

An angle grinder with a little practice and use and you can feel when your on the original edge. Enough use with one and you can really do some intricate grinding, and you do not need a guide. Its all in the feel and watching your pattern on the item yur grinding and knowing where your contact point of the wheel is working. You can grind flat or concave work easily. On a bench grinder your stuck with using the face of the wheels unless you like chancing it and grinding on the sides. The basic grinder that is bench mounted is IMHO a pityfull way to remove metal of any kind. Its hard to grind and obtain a flat finish due to the nature of the wheel and where you grind. You can easily make an attachment to hold an angle that will fit a bench grinder. I have two of the bench grinders andits been a very very long time since I used either of them. I prefer a belt grinder. Grit sizes are easy to change out, they cut faster, and if I use a stick lube for abrasive belts I can get fdast cuts and a mirrow surface. Belt grinders are just more suitable to stock removal than a wheel type is. I know you can get different types of wheels, but I can change my belts out on a belt grinder and have it back in use before a wheel type coasts to a stop. The average stones (grey) incolor that comes with most bench grinders are suited for just mediocre tasks. To buy good stones in various types and grits would cost a small outlay of $$ as compared to a good and larger selection of belts on a belt grinder. 

I know you asked about wheel vrs angle. An angle grinder is suited for grinding on a section of its wheel that will impart a flat finish. You can get various wheels for these angle grinders so you can utilize the edge, full flat or a 30 deg angle from flat. I can block up my bush hog or raise my deck and touch up my blades quick and easy without having to take them off, by using my angle grinder. The rotary type grinders as sold for use in electric drills etc with a angle built into them may work, but they are extremely slow compared to a angle grinder or belt grinder.

When you grind a lawn mower blade on the face of a bench grinder wheel it is sort of hollow ground, this may e ever so slight, but its still a hollow ground edge. Hollow ground edges are not substantial for impact or long wear. You also have to remove more material with a bench grinder each time you use it as compared to a grinder that will grind flat.

Wheels are harder to change so most folks will keep on using whatever wheel is on the grinder to do what grinding they need to do even if its not the right wheel for the job. Changing a wheel on a angle grinder is a snap. Bench grinder wheels have to be dressed periodically to keep them true and cutting good and restore the correct profile. Not necessary with an anle grinder or belt grinder.


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## Chipmaker

> _Originally posted by leolav _
> *Use a grinding disc with a lubricant that dissipates the heat into the disc. These discs are used extensively in stainless steel applicaitions and does not blue the stainless. It certainly won't distemper a lawnmower blade. *


Leolav
Awhie back I posted a question in another thread that had to do with abrasives, but I never got back in time to the forum and lost track of the thread. Are you in a business that deals with grinding and abrasives etc?

What brand or type of stick lube do you use. I use a product called Formax F-26 Its a heavy based grease stick, and it imparts a finish that is beautiful. You can take a 80 grit disk or belt and grind something dry, and then add the grease to the 80 grit disk and it gives a finish like you would have used 120 or 150 grit on but it cuts at the rate of the 80 grit, and it keeps disks and belts from clogging up and overheating. I assume you know its usually when a belt or disk gets clogged with the material its grinding that makes it buildup heat, moreso than the general abrasive action. I live by Formax F-26 and in general the entire lineup of Formax products. Yes its a lot more messy than dry grinding, but its a small price to pay for the end results. I grind everything in my shop no matter what it is with a stick lube of some kind, as I don't like abrasive particals getting into and on my machine tools. I have a small shop so dust and abrasive particals are a problem if I grind dry.


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## Ingersoll444

My problem with a bench grinder has always been that something always gets in the way. Seems that however I twist, or turn the blade, it is eather hitting the gide/motor, or just not a nice level cut. Always fighting it. Got one of those drill stones with the angle on it, and its useless. Drill just turns to slow. My dremil? Always hard to get a flat serfice. Always digging rutts in it.

Got my first ever angle grinder last fall. I will try that this year. Well, if I can stop mowing rocks, and bending the blades anyway.


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## DeereBob

Chipmaker,
Thanks for the explanation and obviously skill is a factor in it's use which since I don't have one, have not developed. Your points about the bench grinder are exactly what I found. The rotary tool is definitely much slower but still produces a nice result. But for the price of a good angle grinder I could buy 4 or 5 sets of new blades which is why I am unlikely to buy one even though I could easily afford it. If I wanted to sharpen or touch up blades on the deck without having to remove them, like you do, then this is the best tool for the job.


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