Let's talk about blade sharpening?

[Bange]

What mower is that from

My mower is a Murray 18,5Hp - 42" (2010).

 

[Bange]

Again, I'll go back to how long does it take you from start to finish to remove sharpen a blade and put it back on?
All this soaking, cleaning, wire brushing, scraping, blasting, etc is fine if you are the homeowner and you're only doing your blades once or maybe twice a season but even for someone working on mowers out of their home on the side for just friends and neighbors...this it's just far too much time and effort put into something that makes little difference to the end result or to the result after the next 15 minutes of mowing.
Now for many of us commercial guys who do many mowers a day, this would just be a real waste of time and effort.

There is a happy medium though between using the commercial strong grinders that eat the blades up so much that's unnecessary and doing them with a file. LOL

TobyU, you must agree that a good cleaning facilitates the supervision of cracks in the blade, which may be hidden by dirt or oxidation, even more so if you use a special spray.

 

[TobyU]

Excellent information material... unless the center of mass is different from the center of rotation in some blades (if I understand it that way), because if the compensation is not in the same part (blade), there must be a counterweight connected to it axis to compensate for dynamic balance.
Is there really a blade with a center of rotation different from the center of mass? Which? Can anyone post or tell us what make/model… if it's for a specific type of lawn mower?

I was glad to know about the analysis of the straightness of the blades (24:01), as it is something I didn't even think about and will now move on to the first procedure item, before removing the blades.

The material also answered my question about how to proceed with material removal when sharpening (post # 27), making it clear that option “B” is the most correct.

Another important point was information on the sharpening limit, which is at the beginning of the curvature (22:01)... but what has already been said about the effect of sand, which thins the blade... so, what is the limit of the thickness?

Thank you - I mean no thank you.... for turning it into rocket science or brain surgery when it's just a simple old lawn mower blade spinning on the crankshaft.
Keep it centered on the blade adapter and keep it balanced enough so if you hold it up in the air by the center hole with your pinky neither end drops excessively towards the bottom and all will be fine.

 

[TobyU]

TobyU, you must agree that a good cleaning facilitates the supervision of cracks in the blade, which may be hidden by dirt or oxidation, even more so if you use a special spray.

No, I would not.
This is because the buildup is always from the halfway mark toward the middle of the blade and it's never on the end of the blade that does all the fast spinning.
The cracks and where are always on the rear edge of the outer end opposite from the sharpened edge where the air full sticks up and the little bend that's present on most blades.

In fact, most of these areas are build up, dirt, and even paint free and are polished to a nice shine so any cracks or damage are very apparent by simply looking on both sides.

I understand why some people make this a real hobby and fixate on things when it's their own equipment and if it's a new toy and the only one they're dealing with etc.
I don't understand why people that do this as a larger scale production with lots of volume has a commercial operation worry about it and would try to go above and beyond like some of them do touting their "superior quality" attention to detail, thoroughness, better than the other people or whatever else it is they call it.

Several of those traits are great for your repairs and services but blade sharpening and balancing is just a simple old mundane thing that needs to be done where one is basically as good as the next as long as it's simply done adequately and nobody is going to look at, appreciate, or admire your work.
If they are, I feel they, and you are focusing on the wrong things.

See, I have been doing this professionally for 12 years now with 1000s of customers.
I'm quite opinionated, setting my ways and only do things one way and one way only, have pretty strict requirements for you to be my customer, and can often be quite curt but I am the highest rated mower repair shop in 100 mi radius and I'm currently the second or third shop with the highest number of reviews simply because a few other shops have a lot of text working and do a lot more volume than I do.

I pride myself on being better and cheaper than everyone else... And often faster but not the customer would have any idea about that because they think everything only takes two or three days and that they are your only customer until a few of them actually call around and find out it's 5 weeks out to get anything looked at.
But I do the little extras for people.
The ones that you can notice and the ones that really matter.
That's certainly not wire brushing or cleaning up a blade to make it look like new.
It's things like tightening up many bolts and nuts on a machine that often loosen up even if the mower isn't in for that or for a general service.
Things like topping off the oil when it severely needs it or even knocking some of the massive chips out of the blade and smacking the massive dirt build up off of an air filter when it's only in to make it start and run and not in for an annual service.
Things like when it's in for an annual service cleaning the whole mower not the best I can or perfectly but cleaning it up a lot nicer and wiping it down with some rust preventative and then buffing it back off so it's not sticky and attracting dust so it looks a lot better than when they dropped it off.
I have at least a big handful of people every single year when I roll them all out to him they will look right at me and go "I don't think that's my mower"
because it's so much cleaner and shinier and brighter than when they dropped it off.
So if I'm going to put extra effort into something to make myself stand out from the competition or just to make myself feel good which is what a lot of this is all about for people... it's not going to be something that's underneath the mower getting coated with wet dirty grass and getting the heck beat out of it by sticks and rocks.
It's going to be me shining them up and making the handles nice and firm even though it wasn't here for that so they realize how much nicer it is when they mow with it after I've seen it, and going back down the stickers that are flipping off and trying to fall off and melting the rubber or gluing the foam back on the tops of the handles where it started to wear off.
It's not just cosmetic.. it's functional creature comforts that make the owner enjoy using their mower more than they did last time more like when it was new.
We all have our hang-ups though. Lol

 

[bodean]

All but one of my mower blades are heavy thick steel. Using a file is not an option and replacing with new blades is cost prohibitive. If I do find affordable blades, they are cheap junk that won’t hold an edge or bends with the slightest impact. After a good cleaning using a brass wire wheel in a smaller bench grinder, I clamp a piece of 2” angle iron with the point facing up to the tool rest of my 8” stand grinder that has both course and medium grit wheels. I make several light passes while allowing the air from the spinning wheel to help keep the blade cool in between passes until desired sharpness is achieved. I always back grind the freshly sharpened edge slightly using the finer grit wheel. I have found that this prevents the blade from completely gouging into a tree root until it suddenly locks the engine down. Since all my blades have round bolt holes in the center, I have never experienced an imbalance just using an old worn out #1 Phillips screwdriver shank to balance the blade. The only blades that I don’t sharpen this way are the 1/2” blades on my 3 point (Bush-hog type) rotary mower. Right or wrong …this works for me.

 

[JD14SB]

I sharpen my Blades with a 1" Belt Sander. I have to hold the Blade at the correct angle by hand. I used to sharpen my Blades to a razor edge but one Lawn Mowing, the Blade has lots of dings. So I file a flat edge like was recommended. I have an Oregon Blade Balancer that is imported. It was over $100.

 

[bodean]

I sharpen my Blades with a 1" Belt Sander. I have to hold the Blade at the correct angle by hand. I used to sharpen my Blades to a razor edge but one Lawn Mowing, the Blade has lots of dings. So I file a flat edge like was recommended. I have an Oregon Blade Balancer that is imported. It was over $100.

My dad has always sharpened his mower blades with his belt sander. It runs slower than a grinder so there’s less heat buildup and better control.

 

[Bange]

No, I would not.
This is because the buildup is always from the halfway mark toward the middle of the blade and it's never on the end of the blade that does all the fast spinning.
The cracks and where are always on the rear edge of the outer end opposite from the sharpened edge where the air full sticks up and the little bend that's present on most blades.

In fact, most of these areas are build up, dirt, and even paint free and are polished to a nice shine so any cracks or damage are very apparent by simply looking on both sides.

I understand why some people make this a real hobby and fixate on things when it's their own equipment and if it's a new toy and the only one they're dealing with etc.
I don't understand why people that do this as a larger scale production with lots of volume has a commercial operation worry about it and would try to go above and beyond like some of them do touting their "superior quality" attention to detail, thoroughness, better than the other people or whatever else it is they call it.

Several of those traits are great for your repairs and services but blade sharpening and balancing is just a simple old mundane thing that needs to be done where one is basically as good as the next as long as it's simply done adequately and nobody is going to look at, appreciate, or admire your work.
If they are, I feel they, and you are focusing on the wrong things.

See, I have been doing this professionally for 12 years now with 1000s of customers.
I'm quite opinionated, setting my ways and only do things one way and one way only, have pretty strict requirements for you to be my customer, and can often be quite curt but I am the highest rated mower repair shop in 100 mi radius and I'm currently the second or third shop with the highest number of reviews simply because a few other shops have a lot of text working and do a lot more volume than I do.

I pride myself on being better and cheaper than everyone else... And often faster but not the customer would have any idea about that because they think everything only takes two or three days and that they are your only customer until a few of them actually call around and find out it's 5 weeks out to get anything looked at.
But I do the little extras for people.
The ones that you can notice and the ones that really matter.
That's certainly not wire brushing or cleaning up a blade to make it look like new.
It's things like tightening up many bolts and nuts on a machine that often loosen up even if the mower isn't in for that or for a general service.
Things like topping off the oil when it severely needs it or even knocking some of the massive chips out of the blade and smacking the massive dirt build up off of an air filter when it's only in to make it start and run and not in for an annual service.
Things like when it's in for an annual service cleaning the whole mower not the best I can or perfectly but cleaning it up a lot nicer and wiping it down with some rust preventative and then buffing it back off so it's not sticky and attracting dust so it looks a lot better than when they dropped it off.
I have at least a big handful of people every single year when I roll them all out to him they will look right at me and go "I don't think that's my mower"
because it's so much cleaner and shinier and brighter than when they dropped it off.
So if I'm going to put extra effort into something to make myself stand out from the competition or just to make myself feel good which is what a lot of this is all about for people... it's not going to be something that's underneath the mower getting coated with wet dirty grass and getting the heck beat out of it by sticks and rocks.
It's going to be me shining them up and making the handles nice and firm even though it wasn't here for that so they realize how much nicer it is when they mow with it after I've seen it, and going back down the stickers that are flipping off and trying to fall off and melting the rubber or gluing the foam back on the tops of the handles where it started to wear off.
It's not just cosmetic.. it's functional creature comforts that make the owner enjoy using their mower more than they did last time more like when it was new.
We all have our hang-ups though. Lol

Here's how things are... your customer gave you the machine for a repair, not to clean or wash... but you cleaned and washed... was it necessary to carry out the repair? Almost certainly not, you do it to add a differential to your work, but you spent time and at least water… congratulations, nothing against that.
But in the time spent for this “plus”, you could have sharpened a set or two of blades…
Yes, each one has its “hang-ups”…
I don't have your experience in sharpening to ensure that cracks only occur on the polished points in normal use... just like an automotive grinder shop, I prefer to use a chemical crack developer, as it doesn't hurt, it covers my lack of experience in the matter , in addition to my poor vision due to age.

 

[Bange]

If you live in an area where the soil is sandy then to me that's a whole 'nother animal. Over the years I've seen pics of the effects sand has on blades and it's just crazy the way the metal gets eaten away. If that's your situation then I would just sharpen regularly and then recycle them long before they look anything like the ones in these pics....

View attachment 64171View attachment 64172

If you don't have sandy soil and are only cutting grass and not hitting a bunch of foreign objects then your blades should last years with regular sharpening, IMO. I have blades I've sharpened dozens of times and there's still plenty of life left in them. The pic below is taken from the Magna-Matic sharpener manual, and shows their opinion on the right and wrong way to sharpen a blade over the course of its life. I sharpened a blade last year that was getting close to looking like the bottom one. I showed the guy the picture and told him to get another set of blades. Although they don't explicitly say it, I believe Magna-Matic believes that you can sharpen the edge of a blade almost back to where the sail of the blade starts to curve upward. You can see that in the pic below as well. That seems to make sense to me.

View attachment 64176

It's not my case, but I understand perfectly what small grains in speed cause in metal...
The photos show the final result, but well before that the blades should be retired... horrible and dangerous thing.
Yes, the wood70 video, also based on the same source, showed the most correct sharpening evolution... "B" in my question.

 

[Hammermechanicman]

Are all the mower shop guys enjoying this thread?

Must be the new oil thread.