Let's talk about blade sharpening?

[Tiger Small Engine]

I've been clamping my blades and using a side grinder and large file for years. I'll grind or file the cutting edge flat with the bottom of the blade, and grind an approximate angle of cut, close to the original angle.
This general method has allowed me to get a clean, smooth cut every time. IMO the slightly flat edge on the cutting tip allows for force dispersion on the blade allowing the

I sharpen a lot of mower blades, mostly on tune ups for customer mowers. Most of the time, these blades are beat to hell, nicks, very dull, and needed to be sharpened a long time ago. Often an edge needs to be reestablished and they have been sharpened incorrectly, or are bent. It takes a while to get a blade back in shape (just like a chainsaw chain), when it has been neglected. I personally run nothing but Gator G5 blades. I use a 4” angle grinder with a metal abrasive wheel to sharpen. The difference styles of blades dictate being able to effectively freehand and maintain the correct angle with a grinder by hand an eye.

 

[bertsmobile1]

FWIW I sand blast the blades to remove the build up of dirt & clippings
How I sharpen depnds upon the mower that the blades are going onto
Mowers with good overlap just get the edge touched up& nicks removed
Blade with little to no overlap are different as a tiny amount of rounding to the outer edge will leave a mowhalk between the blades
for them it is grind the strait line from he inner edge of the cutting edge to the outer edge of the blade just past where the rounding is
Then restore the edge & angle
I have been trying to justify the cost of an Oregan sharpening tool but in reality I usually replace worn blades .
The ood ones go into a bin and get sent to the local TAFE for students to practice on then go into the "poverty bin" of used but servicable parts used to repair pensioners mowers

 

[bertsmobile1]

I invented and patented a sharpening jig for mower blades in the 1990's.
Your Wife can sit down and sharpen one handed with this device.
Perfect blade every time.
I could not get the price down enough for everybody to afford one. Quit making them
but I have parts and know how if anyone cares to take over
Mini-Miller is what I called it...A Mini Milling Machine.
You want sharp blades...This is it!
Pic is of a yard I mowed with sharp blades and My 1951 Farmall Cub 14hp tractor.
regards gary

Nice idea for strait blades.
Age old story for inventors
Convincing customers it is worth the money and finding the time to make them yourselves.
or
Finding the money to have them made in mass then then marketing them yourself
I have dozens of special tools made for repairing motorcycles that are in this situation .

People never seem to understand that distribution , wholesale & retail profits is at least 75% of the price you pay for anything .

 

[Gord Baker]

I clean off obvious dirt and make 2 or 3 passes against my coarse Grinding Wheel. Same # for other end and blades. It's not the Space Shuttle as Tarryl would say. A gram or 2 out of balance is no big deal.
Tighten carefully after engaging any drive teeth, sharp side Down. Done. Skip OCD.

 

[TobyU]

I clean off obvious dirt and make 2 or 3 passes against my coarse Grinding Wheel. Same # for other end and blades. It's not the Space Shuttle as Tarryl would say. A gram or 2 out of balance is no big deal.
Tighten carefully after engaging any drive teeth, sharp side Down. Done. Skip OCD.

I'm a little confused by your statement sharp side down..
I get a lot of mowers in every year the blades are on upside down and I often tell people that since they usually understand that lawn mower blades are only sharpened on one side, to put the sharpened edge up towards the sky.

 

[aussielawny]

l bought a Magna-matic many years ago when l was starting out, its been gathering dust for 10 yrs or more......l buy Sten blades in bulk & swap em as needed, l'm right on the beach so all of my lawns are sandy and blades wear very quickly

 

[Bange]

Well, let’s summarize here…

End of blades:
So far there is no technical definition for the sharpening limit (apart from cracks, warping or significant material loss), they can be sharpened up to a very subjective evaluation limit.
I would like to see something like this: blades can be sharpen up to the limit of X% of their width and/or Y% of their radius, as they are also insecure or inefficient.

Pre-cleaning:
I think this activity is important, although I agree that dirt occurs equally on both sides of the blade… but in the case of stationary parts where uneven oxidation occurs… does it affect the balance?
I prefer to do the procedure regardless of the case, as I am not a sharpener, I am an enthusiast and time is not an issue for me.
I understand that anyone who works with sharpening should look for a procedure that takes as little time as possible, but without jeopardizing the final result.

Goals:
1 – just lower the height of the lawn (sharpening doesn’t matter)
2 – lower the height of the lawn and leave it healthy and always green (sharpening is important)

Those aiming for #1 can skip this topic, but those aiming for #2 want to know everything about how it's done in the best possible way at their fingertips. Not everyone is going to buy a specific machine to sharpen (for example, me), but knowing how the final result should be, they can do the same (or near) with some expense of time.

Balancing:
I cannot agree with those who ignore balancing, as a piece rotating at more than 3000 RPM, without balancing, contributes to noise and harmful vibrations to the set of pulleys, bearings, increased clearances and previous fatigue.

 

[Bange]

One question...

A = dull blade that needs sharpening.
B = Use of an appropriate power tool for sharpening
C= Another form of sharpening with a specific tool.
Consider B and C after many sharpenings...

What is trend B or C?
View attachment 64064

Attention sharpeners...
No answers!?!?!

 

[woody70]

Saw this post in a daily email and intrigued me. Not a professional sharpener by any means, but I did invest in Magna Matic sharpener and balancer several years ago. If anyone desires to take a deep dive into the scholarly side of blade sharpening, take a look at the video below (be warned its almost an hour long, but very informative). Synopsis of video is keep a 30 degree angle and square end for best cutting.

I mow in rough conditions at industrial sites. Rocks, random pieces of metal that weren't there last time you mowed, and of course fields of bahia grass (which can be difficult to cut with new blades lol). I change blades everyday and keep around 8-10 sets of blades in a rotation for the season. Mow for a day, take them off and replace with newly sharpened set and sharpen the ones I took off. I can attest that keeping a square edge and balanced blade makes a lot of difference. Maybe I've just become in tune with my mower (turf tiger 2 61"), but I can tell by vibration/resonance if a blade is out of whack while I'm cutting. I'll enlist help occasionally when a site is overgrown or I'm running behind and they will ask almost immediately why my mower is cutting faster and better than their is (same mower). I'll look at there blades and they are essentially cutting with butter knives lol. It doesn't show up when they are cutting easy grass like centipede, but when asked to cut fields of bahia/weeds its a different story. Swap blades for them with extras I keep on hand and nothing but smiles lol. Yes, this is kind of an extreme example. Average Joe homeowner with average small/medium lot can probably get away with sharpening/buying new blades once a season depending on conditions. If you do it for a living or side hustle, need to keep those blades at 30 degrees, square end and balanced (your spindles will thank you). You don't have to invest in a expensive system as long as whatever method you use results in 30, square, and balanced.

My setup is below. Ignore the junk around it lol. Once I sharpen a blade, I also blunt it along the cutting edge. Razor sharp blades will dull in about 27 seconds in my opinion. I don't bother cleaning blades unless I can tell they have an uneven buildup on one side. Anyway here is my setup and a short video of me checking balance of a blade. On Magna balancer, once you put blade on horizontally (9/3 o'clock) and let go, if you can count four to eight seconds before it gets to 12/6 o'clock, it's considered balanced. If it barely even moves your really good, because that balancer is VERY sensitive. And no, I normally don't get the blades that balanced lol.

 

[woody70]

Eh, as I rarely post, I have no idea how to upload my own video. So, sorry about not having balancing video in there, but it does show several balancing methods in the original hour long sharpening video.