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Sharpening Blades

#1

Tiger Small Engine

Tiger Small Engine

My question refers to customer mower blades. Many of the blades I see on customer equipment are really dull and beat up. It is not uncommon that I have to reestablish the angle and depth on cutting edge the blade is so bad. It can take 15-20 minutes per blade to sharpen correctly. I am not asking about how the blades are sharpened. We all have our preference. Are you guys seeing a lot of beat up blades come in? Many of these people are lucky if they sharpen blades once a year. How much do you charge per blade? Also, not uncommon to see bent blades. I can usually straighten them without replacing.


#2

Hammermechanicman

Hammermechanicman

I use an All American sharpener.
www.allamericansharpener.com

All American Lawn Mower Blade Sharpener

We invented what has become THE MOST POPULAR and HIGHLY RATED LAWN MOWER BLADE SHARPENER! Our products are made in the USA and built to last, with a lifetime warranty. We also provide video tutorials about the best way to use our jigs to sharpen your blades.
www.allamericansharpener.com www.allamericansharpener.com
And 36 grit flap wheel. Takes less than a minute for even the worst blades. Blade off the mower $5. I don't straighten blades.


#3

M

MowerNick

I use a neary blade grinder. Takes only a few minutes per blade we charge $8 for one or $15 for a set of two.


#4

M

mcspeed

Hammermechanicman said:
I use an All American sharpener.
www.allamericansharpener.com

All American Lawn Mower Blade Sharpener

We invented what has become THE MOST POPULAR and HIGHLY RATED LAWN MOWER BLADE SHARPENER! Our products are made in the USA and built to last, with a lifetime warranty. We also provide video tutorials about the best way to use our jigs to sharpen your blades.
www.allamericansharpener.com www.allamericansharpener.com
And 36 grit flap wheel. Takes less than a minute for even the worst blades. Blade off the mower $5. I don't straighten blades.
Click to expand...
I watched the video and I’m not seeing an advantage to using their system vs free hand. What am I missing?


#5

R

Rocky J

I had two MTD /Toro economy models that had struck water meter bases and bent the blade and the deck itself. The complaint was a crocked cut. I used a 48 inch straight edge across the spindle pulleys to correct the bend in the cupped area where the spindle bolts onto the deck. I use a truck tire tap down slide hammer to bend it back so the straight edge touches all contact points on the pulleys. Never had much luck straightening blades, they will be better but not perfect . Most of the mowers I work on, the cutting side of the blade looks a lot like the back side . I also use the lapping wheel to shape and sharpen and a nail drove into a nearby post to check for balance . They all needed a oil change three years ago and they did not know it had a oil filter . I have found they just want to roll them off the trailer , go to the front of the line and pick up this afternoon. I found that is a good thing because I do not have to air up all the tires and put it on the charger to load it in two days.


#6

Tiger Small Engine

Tiger Small Engine

mcspeed said:
I watched the video and I’m not seeing an advantage to using their system vs free hand. What am I missing?
Click to expand...
If all I did was sharpen straight blades, then I would not have to use an angle grinder. That is why I use an angle grinder on everything.

When a blade is bent you can get it close with a sledge hammer and a pair of safety glasses while smacking it on concrete. Of course you can’t get it perfect, but close is often good enough.

Many of the blades that come in for sharpening are very dull and have chips on the edge. Have to level out edge and reestablish the entire angle and cutting edge. This takes time to do it correctly.


#7

Hammermechanicman

Hammermechanicman

mcspeed said:
I watched the video and I’m not seeing an advantage to using their system vs free hand. What am I missing?
Click to expand...
Since it holds the angle i can very quickly sharpen the dullest blade to good professional edge in less than a minute. I run a shop and time is money. I have tried a few different sharpeners and the all american is the best bang for the buck for my small shop. A Burr King would be nice but can't justify it.


#8

S

slomo

I still think a hand file is the best way to sharpen. Once you cross over into grinders, one can remove too much material. Course a lot of blades you shop guys see need grinders. Home owners like me, my blades clean up in a few strokes. Too much metal removed gets into heavy balancing tricks.

For me, going over to the dark side, thinking about a 4" angle grinder with a say 220 grit flap wheel. Got 5 mowers to tend to.

For balancing I use one of those precision food grade scales. Weigh each blade end a couple times. Can balance a blade out to 0.0X of a gram per side. My blades run super smooth like a new one. I tried nails and those plastic and metal cone balancer deals. Food scale is in another league.


#9

StarTech

StarTech

You do know new blades are not fully balanced don't you?


#10

Tiger Small Engine

Tiger Small Engine

Hammermechanicman said:
Since it holds the angle i can very quickly sharpen the dullest blade to good professional edge in less than a minute. I run a shop and time is money. I have tried a few different sharpeners and the all american is the best bang for the buck for my small shop. A Burr King would be nice but can't justify it.
Click to expand...
How you can sharpen a blade that is very dull and beat to hell in less than a minute is beyond me. It sometimes takes 10 plus minutes per blade for ones that are really bad. Believe me I do not like spending this much time. Which is why I posted the topic. Surely I can’t be the only shop encountering this issue.


#11

StarTech

StarTech

Here is my shop when I was open most blades were damage to save especially when some blades were only 50% more than my sharpening fee. So why spend time sharpen a completely worn out blade when it take so little time to simply install a new blade.

I remember one walk behind that came in that owner wanted me to sharpen the blade. It was a 21" cut Honda. Well the blade was only 12" long so I didn't do it and owner was too cheap to replace it.


#12

Scrubcadet10

Scrubcadet10

I rarely sharpend blades, except my own, most of the time when I get them in they're worn down to nubs 🤣


#13

M

mcspeed

I bought a cone balancer with a bearing on it….mount in a vice so the blade is perpendicular to normal. The old school cone balancer seemed to be difficult to get the blade centered since the blade hole didn’t match up well to the flange on top of the cone. Have 3 blades on my ZT so like to get a good balance. I keep an extra set of blades sharp and balanced so I’m ready pronto when ready to get some sharp ones installed.

I use an angle grinder and seems to work well. I’m not on the clock so speed isn’t all that important LOL.


#14

S

slomo

StarTech said:
You do know new blades are not fully balanced don't you?
Click to expand...
Mine are. No vibes at all.


#15

T

Telesis

I switched to a 60 grit flap disc from a grinder wheel years ago and haven't looked back. So much easier to deal with the irregular contour on the majority of blades I deal with. Very fast on most blades. I also don't try and make it so I can shave with it!

Just my 2 cents!


#16

Hammermechanicman

Hammermechanicman

Tiger Small Engine said:
How you can sharpen a blade that is very dull and beat to hell in less than a minute is beyond me. It sometimes takes 10 plus minutes per blade for ones that are really bad. Believe me I do not like spending this much time. Which is why I posted the topic. Surely I can’t be the only shop encountering this issue.
Click to expand...
A 36 grit flap wheel takes metal off FAST without overheating.
I have a Bradley S105 grinder that i don't use any more. Really only works on flat blades and takes way longer than the angle grinder and flap wheel. Blades don't need to be perfectly balanced or razor sharp. Mow with razor sharp blades for 15 minutes then see how sharp they are. I have the fancy ball bearing blade balancer and i do balance blades and i sharpen blades to the point you don't want to handle them by the cutting edge. Ever seen how sharp new blades aren't?


#17

ILENGINE

ILENGINE

Tiger Small Engine said:
How you can sharpen a blade that is very dull and beat to hell in less than a minute is beyond me. It sometimes takes 10 plus minutes per blade for ones that are really bad. Believe me I do not like spending this much time. Which is why I posted the topic. Surely I can’t be the only shop encountering this issue.
Click to expand...
Tiger you are having issues with the grinding wheel glazing. Certain blades are notorious for clogging the grinding grit on the wheel, flap, etc. John Deere blades I have found to be the worse. Back when I was using the big Oregon 12 inch blade grinder, I would have to clean the wheel over a dozen times doing a set of JD blades. I haven't had that issue since switching to the Burr King 760 with the 36 grit ceramic belts. Using the Burr King, it isn't hard to sharpen and balance a blade in under a minutes. With the average blade you can do a 3 blade set in just over a minute.


#18

Tiger Small Engine

Tiger Small Engine

ILENGINE said:
Tiger you are having issues with the grinding wheel glazing. Certain blades are notorious for clogging the grinding grit on the wheel, flap, etc. John Deere blades I have found to be the worse. Back when I was using the big Oregon 12 inch blade grinder, I would have to clean the wheel over a dozen times doing a set of JD blades. I haven't had that issue since switching to the Burr King 760 with the 36 grit ceramic belts. Using the Burr King, it isn't hard to sharpen and balance a blade in under a minutes. With the average blade you can do a 3 blade set in just over a minute.
Click to expand...
I have tried a flap wheel and did a horrible job. Would be good for touch ups, not sharpening dull blades.

I switch out grinding wheels frequently. How do you clean a glazed grinding wheel? You may be onto to something here.


#19

M

mcspeed

How does a flap disc remove material faster than an angle or bench grinder? Perhaps I misunderstood what was previously posted……


#20

Hammermechanicman

Hammermechanicman

mcspeed said:
How does a flap disc remove material faster than an angle or bench grinder? Perhaps I misunderstood what was previously posted……
Click to expand...
Have you compared a 36 grit flap disk to a grinding wheel?

www.ustooldepot.com

Burr King Model 760 2 X 60 Three Wheel Belt Grinder 75100 Fixed Speed

Burr King Model 760 2 X 60 Three Wheel Belt Grinder
www.ustooldepot.com www.ustooldepot.com

A 36 grit flap wheel is nowhere as nice as a Burr King but it gets the job done at the same speed.


#21

Hammermechanicman

Hammermechanicman

Tiger Small Engine said:
I have tried a flap wheel and did a horrible job. Would be good for touch ups, not sharpening dull blades.

I switch out grinding wheels frequently. How do you clean a glazed grinding wheel? You may be onto to something here.
Click to expand...
What was horrible about it?


#22

S

slomo

Tiger Small Engine said:
How do you clean a glazed grinding wheel?
Click to expand...
You take a diamond or similar hard device and grind off a layer of your wheel. Starts fresh with new grinding material.

Bad thing about wheels is they grind in one spot only. Blade bevels are flat not rounded.

Most people see shiny metal and call it sharpened. :eek:


#23

S

slomo

mcspeed said:
I bought a cone balancer with a bearing on it….mount in a vice so the blade is perpendicular to normal. The old school cone balancer seemed to be difficult to get the blade centered since the blade hole didn’t match up well to the flange on top of the cone.
Click to expand...
I used to do the same. Then I got a precision food scale. Weighed each side of the blade. Noticed how far the blade was still out of balance.


#24

M

mcspeed

Hammermechanicman said:
Have you compared a 36 grit flap disk to a grinding wheel?

www.ustooldepot.com

Burr King Model 760 2 X 60 Three Wheel Belt Grinder 75100 Fixed Speed

Burr King Model 760 2 X 60 Three Wheel Belt Grinder
www.ustooldepot.com www.ustooldepot.com

A 36 grit flap wheel is nowhere as nice as a Burr King but it gets the job done at the same speed.
Click to expand...


I guess I haven’t. 50 is what I have. Will have to get one and give it a shot.


#25

ILENGINE

ILENGINE

Tiger Small Engine said:
I have tried a flap wheel and did a horrible job. Would be good for touch ups, not sharpening dull blades.

I switch out grinding wheels frequently. How do you clean a glazed grinding wheel? You may be onto to something here.
Click to expand...
Cinder blocks \concrete building blocks make a good cleaner for grinding disc.


#26

StarTech

StarTech

Strange in 20 yrs I never had stones to clog doing blades. Now doing aluminum is different but that is because I was using the wrong stones. Usually I wear down stones to around 4" (from 6") then have to replace them due to the grinder body inferring with the blades.


#27

Tiger Small Engine

Tiger Small Engine

ILENGINE said:
Cinder blocks \concrete building blocks make a good cleaner for grinding disc.
Click to expand...
The flap wheels would have taken all day on blades that are very dull. I tried them and they didn’t work.

I have been reading up on grinding wheels getting glazed. The harder the wheel, the easier it is to glaze up. These are cheap wheels I am buying in bulk from online. I will try dressing them on a concrete block and see if that helps.My wheels are glazing up and becoming ineffective fairly quickly. When I put a fresh wheel on, at first it grinds really well and will dig in if you aren’t careful.


#28

S

slomo

Tiger Small Engine said:
The flap wheels would have taken all day on blades that are very dull. I tried them and they didn’t work.

I have been reading up on grinding wheels getting glazed. The harder the wheel, the easier it is to glaze up. These are cheap wheels I am buying in bulk from online. I will try dressing them on a concrete block and see if that helps.My wheels are glazing up and becoming ineffective fairly quickly. When I put a fresh wheel on, at first it grinds really well and will dig in if you aren’t careful.
Click to expand...
You can't clean a wheel with concrete. You have to remove wheel material. With that comes what clogged the wheel up. Concrete is softer than the grinding wheel. All you will do is gum it up again. You need a piece of carbide steel or a wheel dressing stone.


#29

StarTech

StarTech

Tiger Small Engine said:
The flap wheels would have taken all day on blades that are very dull. I tried them and they didn’t work.

I have been reading up on grinding wheels getting glazed. The harder the wheel, the easier it is to glaze up. These are cheap wheels I am buying in bulk from online. I will try dressing them on a concrete block and see if that helps.My wheels are glazing up and becoming ineffective fairly quickly. When I put a fresh wheel on, at first it grinds really well and will dig in if you aren’t careful.
Click to expand...
Cheap doesnt means good quality or the right materials. So what are the ones you are buying?

I buy heavy duty Aluminum Oxide bonded with Vitrified Clay and I usually 2-3 years out of them before they shed down to small to use.


#30

A

Auto Doc's

Way too much sand in my area, I seldom sharpen blades. Most have the lift area sandblasted badly or they are starting to crack. Even if they could be sharpened, they would not be safe enough to keep using them.

Ebay to the rescue for most of my blade needs unless the customer wants to pay big bucks at the local hardware store.


#31

ILENGINE

ILENGINE

Auto Doc's said:
Way too much sand in my area, I seldom sharpen blades. Most have the lift area sandblasted badly or they are starting to crack. Even if they could be sharpened, they would not be safe enough to keep using them.

Ebay to the rescue for most of my blade needs unless the customer wants to pay big bucks at the local hardware store.
Click to expand...
I have been seeing a surge in that exact air lift cracking. sandblasted groove cut into the air lft the past few years. Seems a lot more common than years past. I don't know what has changed.


#32

StarTech

StarTech

Metal quality is down. They are using cheaper metals to keep the sale price down and actually end sell more because of it.

You tell it by how easily the blades are sharpen now. High quality steel takes longer to reshape.


#33

S

sixbales

Tiger Small Engine said:
My question refers to customer mower blades. Many of the blades I see on customer equipment are really dull and beat up. It is not uncommon that I have to reestablish the angle and depth on cutting edge the blade is so bad. It can take 15-20 minutes per blade to sharpen correctly. I am not asking about how the blades are sharpened. We all have our preference. Are you guys seeing a lot of beat up blades come in? Many of these people are lucky if they sharpen blades once a year. How much do you charge per blade? Also, not uncommon to see bent blades. I can usually straighten them without replacing.
Click to expand...


#34

B

BTBO

slomo said:
I still think a hand file is the best way to sharpen. Once you cross over into grinders, one can remove too much material. Course a lot of blades you shop guys see need grinders. Home owners like me, my blades clean up in a few strokes. Too much metal removed gets into heavy balancing tricks.

For me, going over to the dark side, thinking about a 4" angle grinder with a say 220 grit flap wheel. Got 5 mowers to tend to.

For balancing I use one of those precision food grade scales. Weigh each blade end a couple times. Can balance a blade out to 0.0X of a gram per side. My blades run super smooth like a new one. I tried nails and those plastic and metal cone balancer deals. Food scale is in another league.
Click to expand...
A 220 grit flap disc is not aggressive enough, unless you have time to spare. I use a 60 grit with a moderate amount of pressure.


#35

J

J.D. Dave

Slomo, I don't understand how you are using the scale would you explain that a little better. I have lots of time on my hands and would love to try this.


#36

C

*CPB*

Mowing the lawn is a chore to most people; so is mower maintenance. The thought of an oil change, scraping the deck, and the "health" of a mower blade is the last thing such a person thinks about.

To those of you who own shops.... how many blades are you sharpening each year? If it's several hundred then why not invest in a dedicated blade sharpener? It'll pay for itself the first year.

I don't own a shop, but I sharpen blades on the side and charge $10/blade for a single blade. I offer discounts for multiple blades, but the first time I see any blade it's $10 just because it's going to need more work to get back into shape. A typical homeowner OEM Toro Recycler blade is $20+, so they're saving over $10 or 50%. A 3 blade set of commercial blades can be close to $100. I picked up a commercial customer last year who hates sharpening blades. He drops off 2 sets of blades every other week and is happy to pay me vs. buying new blades.

A few other things....

All bets are off if a blade is being used in sandy soil. I've seen pictures of blades that have been sandblasted to death and have basically disintegrated.

If a blade is visibly bent, don't try to straighten it. It's been compromised; just sell them a new blade.

I don't understand using a scale to balance a blade? Weighing one side at a time.... but where is the rest of the blade at when one side is on the scale?


#37

R

RevB

Tiger Small Engine said:
My question refers to customer mower blades. Many of the blades I see on customer equipment are really dull and beat up. It is not uncommon that I have to reestablish the angle and depth on cutting edge the blade is so bad. It can take 15-20 minutes per blade to sharpen correctly. I am not asking about how the blades are sharpened. We all have our preference. Are you guys seeing a lot of beat up blades come in? Many of these people are lucky if they sharpen blades once a year. How much do you charge per blade? Also, not uncommon to see bent blades. I can usually straighten them without replacing.
Click to expand...
I think you got a lot of advice about how to sharpen so I'll take the root cause question you asked. The Brinnell hardness of the steel used these days is far lower than the blades from years ago primarily because of some mistaken belief that a 19000 ft per minute tip speed, softer blade, won't inflict as much damage to human limbs and will "give" rather than cut. Yeah. Right. Same goes for limiting damage to the drive train. If it hits a T post stub there won't be much give. Mass and velocity rule the day.....hit that T stub with an 8ft brush hog and you'll never even feel it slice through....unless it takes the more direct route and just yanks what's left out of the ground. But then it just gets really noisy for a bit til it spits it out.

If you want the blades to really last you'd have a couple of beads of high tensile, low hydrogen steel welded to the cutting edge and then establish the angle and edge....but that also brings liability issues should someone be injured. So most don't. They just throw away blades regularly and replace.
Tiger Small Engine said:
My question refers to customer mower blades. Many of the blades I see on customer equipment are really dull and beat up. It is not uncommon that I have to reestablish the angle and depth on cutting edge the blade is so bad. It can take 15-20 minutes per blade to sharpen correctly. I am not asking about how the blades are sharpened. We all have our preference. Are you guys seeing a lot of beat up blades come in? Many of these people are lucky if they sharpen blades once a year. How much do you charge per blade? Also, not uncommon to see bent blades. I can usually straighten them without replacing.
Click to expand...


#38

B

Brucewayne

Rather than sharpening I just order new blades.


#39

P

Peva

Nice thread! A lot of good info. I have a little tear in my eye from the camaraderie. 👍

Most blade sharpening instructions I have seen specifically mention rounding the sharpened edge somewhere between (IIRC) 1/32 and 1/16 radius. I'm thinking that an advantage to that is less inadvertent nicking. Also less total removed metal (and time) to maintain the proper wedge angle with slightly rounded but "perfect" edge (i.e., all nicks and other imperfections removed).

So, I'm thinking longer blade life, maybe quicker sharpening job - and, as others mentioned, it's going to quickly more or less wear close to that in a matter of less than an hour of cutting time.

Also - by educating the the public to accept slightly rounded new edges, blade manufacturers see a plus of less risk (liability) of some customer or their kid getting a deep cut from intentionally or inadvertently dragging a finger tip or other body part along an exposed edge in the store or otherwise before installation.


#40

MyGrassHasCrabs

MyGrassHasCrabs

I know this isn't going to go over worth a crap, but I use a bench grinder. I do about the same amount on each side, and my blades have that bend in them to increase the lift. It takes maybe a minute for each side or less and I've never balanced them once I'm done. Been doing it that way for 25 years and it works ok for me, but maybe I'll try some of these other methods folks have mentioned here. Angle grinder sounds interesting. Cheers and don't forget eye protection!


#41

D

Davenj4f

slomo said:
I still think a hand file is the best way to sharpen. Once you cross over into grinders, one can remove too much material. Course a lot of blades you shop guys see need grinders. Home owners like me, my blades clean up in a few strokes. Too much metal removed gets into heavy balancing tricks.

For me, going over to the dark side, thinking about a 4" angle grinder with a say 220 grit flap wheel. Got 5 mowers to tend to.

For balancing I use one of those precision food grade scales. Weigh each blade end a couple times. Can balance a blade out to 0.0X of a gram per side. My blades run super smooth like a new one. I tried nails and those plastic and metal cone balancer deals. Food scale is in another league.
Click to expand...
I use a 40 grit flapper disc on a Dewalt angle grinder. Makes for a very shiny look. I would think a 220 grit would take all day. Yes, very fast, but often I have to dress up the tip on a grinding wheel. Got to have the tip as close to a square angle as you can get it. The more rounded the tip is, the worse job of cutting occurs. I use a Magna Matic balancer. Love it, does an excellent job. I have used my shop press to straighten blades, but it's time consuming unless I'm doing it for myself. Only encountered that with the 21" blades, never on the 18" blades. When I was mowing more full time, I changed my blades every day, that way they dressed up very fast. I use two hoists in my shop to lift the whole mower, can change the blades out with a 3/8" impact wrench in less than 2 minutes.


#42

B

borisdmower

Sharpen!!! My blades wear from the back. (Sandblasted) I’m lucky if I need to sharpen them once before they are flogged out, I reckon they last about 15 hours. Mower shop said that is normal for where I live.


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