Lawn mower blade sharpening

turbodog

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Mine is a 30 inch Honda ride on. It has right hand threading. I used a 1/2 inch drive breaker bar and a good amount of muscle to break it free. I tried it last year, with enough force to make me consider that it might be a left hand thread.

So, blade in hand, with some light cleaning up against a fine grit grind wheel. It cuts, once again, like it should.

Put a couple drops of oil on the bolt threads before reinstalling.
 

turbodog

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... custom lowered my blade.
In doing so, I can have the deck higher & not 'plow' the grass as much.
...

You can also affect airflow and 'thrown object containment'. Doesn't sound like a good idea.

That thing throws a rock and hits a neighbor... and you're going to regret your modification a.k.a. exhibit 'a'.
 

turbodog

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Thanks. I gave it a shot of PBblaster before putting it back on.

Penetrating oils are thin and volatile... doubt it will hang around long. Actual oil is my go-to as blade bolts self tighten as the blade hits items (dirt, ant beds, rocks, sticks, heavy grass, etc).
 

Poppy

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@bykfixer , that was an interesting read.

Years ago another friend explained to me that a nut and bolt threads actually have a "spring tension" and that using a lubricant can reduce the torque needed to bring the bolt to its designated spring tension. Reading your attached article, demonstrates, that the use of the "proper" anti-seize lubricant, one can obtain a more uniform spring tension.

I believe that if a bolt is over-tightened it can fatigue, and lose its spring tension. Some bolts on cars are supposed to be replaced with a new one, when a part is re-installed.

I considered using anti-seize on my mower, but decided against it. I didn't know if that was a good idea. So, I just used what I had at hand.
 

kerneldrop

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There's wet and dry torque specs. Threads do stretch. Some high-level benchrest shooters believe a barrel tightened to 150ft lbs shoots better than 50ftlbs. I use 50ftlbs because I saw no difference. Lug nuts prove that bolts can be over tightened and still work just fine.

It's unlikely $20 lawnmower blades are properly heat treated. Also, you need high quality uniform steel for a proper heat treat. USA steel is vastly superior to most overseas steels. I don't know if lawnmower blades are USA steel. Regardless, the blades at the manufacturer are sharpened after heat treat and on a high speed belt sander. So the heat treat if one is already altered. I've never sharpened them but if I did I'd use my angle grinder.

I keep a bucket of water next to my belt sander when I sharpen knives at 1800 SFPM. An angle grinder is probably 3600 so def can get hot if you let it.

Everyone needs a 1/2" high-torque impact driver. Y'all can use lawnmower blades as the reason you just have one.
 
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bykfixer

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@bykfixer , that was an interesting read.

Years ago another friend explained to me that a nut and bolt threads actually have a "spring tension" and that using a lubricant can reduce the torque needed to bring the bolt to its designated spring tension. Reading your attached article, demonstrates, that the use of the "proper" anti-seize lubricant, one can obtain a more uniform spring tension.

I believe that if a bolt is over-tightened it can fatigue, and lose its spring tension. Some bolts on cars are supposed to be replaced with a new one, when a part is re-installed.

I considered using anti-seize on my mower, but decided against it. I didn't know if that was a good idea. So, I just used what I had at hand.
For a lawnmower blade I dip the bolt in the used engine oil for a lube and bond breaker. See, I sharpen the blade after changing the engine oil.

Most walk behind torque spec is 35-50 pounds and riders 70-90. For my walk behind blade I just use what I call 4 finger pull to tighten then check with a beam torque wrench. Four finger pull means gripping the 1/2 drive ratchet handle with four fingers (no thumb) and when it's tight enough to pull all four fingers straight it's close to torque spec. Your results may vary depending on finger strength.

For anything over 75 pounds I use a breaker bar. After I broke a ratchet one day tugging on a stuck exhaust manifold bolt and dealt with a sore wrist for days after that I just decided a breaker bar is the way to go. I had the bright idea of sliding a 12" long bicycle seat post over the ratchet handle for leverage that day. When the tool broke it had broken an extension, the socket and the ratchet head all at the same time. Trouble was the next day two expert engine builders were schedule to arrive at my home to assist my son and I assembling an engine for his car. When they saw what I done to that tool they took pity on me and fastened the tough stuff. Stuff like the 180 pound crank pulley bolt.

And my dad was one of those more is better when fastening a barrel. But he would not exceed the manufacturers reccomdation.
 

orbital

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You can also affect airflow and 'thrown object containment'. Doesn't sound like a good idea.

That thing throws a rock and hits a neighbor... and you're going to regret your modification a.k.a. exhibit 'a'.
+

It's still within the underside of deck.
From factory, the blade was just too far up inside deck.

I'm good with it.
 

orbital

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+

*** PUBLIC SERVICE ANNOUNCEMENT ***

Please don't be that guy who cuts his lawn overly short, then runs the sprinkler to make it grow.
It's far healthier for your lawn to keep the grass taller,, also not absolutely wasting water.
 

knucklegary

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"Never Seize" is an anti seize compound used on threads when you want to easily remove rusty lawnmower blade nuts, etc..
Also use for exhaust manifold gaskets, bolts, exhaust pipe clamps bolts/nuts. Parts that don't get removed often, anti seize paste makes it a breeze when you take it back apart.
You can find the stuff at any auto parts store.

Oil is better than nothing👍
 

Poppy

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"Never Seize" is an anti seize compound used on threads when you want to easily remove rusty lawnmower blade nuts, etc..
Also use for exhaust manifold gaskets, bolts, exhaust pipe clamps bolts/nuts. Parts that don't get removed often, anti seize paste makes it a breeze when you take it back apart.
You can find the stuff at any auto parts store.

Oil is better than nothing👍
Yeah, it works really well, but...
You don't want to put any anti-seize compound on ball joint studs when you are installing them.

I did the ball joints on my full sized Bronco, when it was about 20 years old. Doing them in the driveway, I was challenged in getting a full swing on a Big F...ing Hammer, to get them loose. So when I installed them I put some anti seize on the studs.

The problem was that when I tried to torque them down IIRC about 120 ft pounds, they started spinning at about 30 ft pounds. I called my friend who owns a front end shop, and he told me that I needed to put my floor jack under the spindle to put pressure on the ball joint and then torque it.

Well, I was only able to get it to about 60 ft pounds. I decided to put the rotors and calipers, and tires back on, and take it to him. He was going to do the alignment anyway.

When I called him, he laughed when I told him I put anti-seize on the studs. He said that I needed to take it all apart and wipe that stuff off!

Lessons learned.
 

knucklegary

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Agreed, tapers need to fit together clean metal to metal. That's why they make pullers for tie rods, and ball joints (-;
Poppy, you can help me work on my stuff any day!
 

Poppy

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Agreed, tapers need to fit together clean metal to metal. That's why they make pullers for tie rods, and ball joints (-;
Poppy, you can help me work on my stuff any day!
Sure KG, I'd love to :)
IIRC, I used a pickle fork. Hence the banging in a confined space.

1684784541862.png
 
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bykfixer

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Yeah, it works really well, but...
You don't want to put any anti-seize compound on ball joint studs when you are installing them.

I did the ball joints on my full sized Bronco, when it was about 20 years old. Doing them in the driveway, I was challenged in getting a full swing on a Big F...ing Hammer, to get them loose. So when I installed them I put some anti seize on the studs.

The problem was that when I tried to torque them down IIRC about 120 ft pounds, they started spinning at about 30 ft pounds. I called my friend who owns a front end shop, and he told me that I needed to put my floor jack under the spindle to put pressure on the ball joint and then torque it.

Well, I was only able to get it to about 60 ft pounds. I decided to put the rotors and calipers, and tires back on, and take it to him. He was going to do the alignment anyway.

When I called him, he laughed when I told him I put anti-seize on the studs. He said that I needed to take it all apart and wipe that stuff off!

Lessons learned.
When I worked for the gubment a mechanic there would say "you should give away your tools" when I'd tell him stuff like that.
 

Sjvalleydave

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As an earlier poster said, after time and re use of bolts, threads will start to deform. Hi end rod manufacturer's suggest using recommended stretch numbers. Most familiar to me is the CAR S7 bolt. 7/16"...recommended stretch is .005"-.007". TQ is 95ft lbs using light assembly oil...
 
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