Using a belt sander to sharpen mower blades - small disaster

[HoosierBuddy]

So...

Today was the annual lawnmower maintenance day. Oil + Filter Change plus sharpen the blades.

Over the years, I've tried various ways to sharpen my blades, but my current procedure sort of goes like this.

Get the mower up in the air and remove the 3 blades. Throw them in the utility sink with a couple of inches of water in it to soak. Drink a cup of coffee.

Use a scraper and a nylon brush to scrape all of the grass crud off the blades.

Use a stationary belt sander to sand the back (flat) side of each blade.

Use a bench grinder on the cutting edge of each blade to recut the "cutting angle".

Go back to the stationary belt sander (150 grit belt) and clean up the edge by cutting at the cutting angle TOWARD the cutting edge.

Put them back on the mower.

Sooo...that's gone pretty well until this morning when I set the belt sander on fire. After I did it it was one of those "how stupid was that?" moments. There are sparks coming off the steel blades and those are getting sucked right into the belt sander's dust collection bag ALONG with a bunch of dry sawdust that was already in the. Do ya think that might be dangerous?

I'm just glad it caught fire while I was standing there and didn't just smoulder for a while and burst into flame after I got done. At least this way the only thing that was hurt was my pride...and the dust bag on the sander. I got it put out before it was completely ruined...but it's definitely "almost ruined".

Phil

 

[96snma]

Pretty lucky on that one.

I've worked at a golf course for a summer job for 7 years. Mechanic there clamps the blades in a vise and uses a flap disc on a 4" angle grinder. Works really well

 

[Steevo]

That's why I don't mix wood and metal work in the same space. Sawdust burns.

 

[darkk]

That's why I don't mix wood and metal work in the same space. Sawdust burns.

Really? When I used to burn wood to heat my house, I had this big *** pile of saw dust. I tried to burn it little at a time in the wood stove. Which by the way had a really good bed of coal and a nice fire going on. Damned saw dust kept putting out the fire. I've never been able to burn saw dust...

 

[andywander]

Metal dust burns too-or explodes!

 

[Jagmandave]

I use my belt sander to sharpen my blades as well, really works well and I can get a good accurate angle on them.

One good thing about what happened, you'll NEVER do that again!

 

[thebeekeeper1]

Once you let the magic smoke out it's just over.

 

[Modifieddriver]

This is why I have a lawn service mow my grass. Usually took me 3-4 hours with a 42" cut Cub Cadet. Could use a new mower. Nice would cost me $4-6K.

Guy comes like clock work every other Friday for $50, or $100/month. Usually 8 months of cutting here. Did the math. Break even is at about 6 years to recover the cost of the mower. Still doesn't include my time, fuel and maintenance costs added to the mower price.

AND ............ I don't start fires sharpening mower blades!!!

 

[24X26]

This is why I have a lawn service mow my grass. Usually took me 3-4 hours with a 42" cut Cub Cadet. Could use a new mower. Nice would cost me $4-6K.

Guy comes like clock work every other Friday for $50, or $100/month. Usually 8 months of cutting here. Did the math. Break even is at about 6 years to recover the cost of the mower. Still doesn't include my time, fuel and maintenance costs added to the mower price.

AND ............ I don't start fires sharpening mower blades!!!

But riding my mower is my zen time. I like it.
My mower has a cup holder for my beer also

 

[Packard V8]

This is why I have a lawn service mow my grass. Usually took me 3-4 hours with a 42" cut Cub Cadet. Could use a new mower. Nice would cost me $4-6K.

Guy comes like clock work every other Friday for $50, or $100/month. Usually 8 months of cutting here. Did the math. Break even is at about 6 years to recover the cost of the mower. Still doesn't include my time, fuel and maintenance costs added to the mower price.

AND ............ I don't start fires sharpening mower blades!!!

I'd love to pay a lawn service, but everyone's math is different. My wife strongly suggests the lawn be mowed at least once a week from April til October - seven months and twenty-eight times. It's an acre and a lawn service wants $100 to do it. That's $2,800 a year. My Cub Cadet 2035 cost me $1100 used. Maintenance parts are usually about $100 a year; this year it will need an electric deck drive clutch, so that may be a bit more.

We had a weed control/fertilizer service for a few years and the lawn looked great. However, they got a new manager and instead of every six weeks, it was every four and sometimes three weeks. Sometimes the guy was in and out in fifteen minutes and the bill was still $75. I decided I could do it myself and by shopping the early sales, the ingredients are $25 every six weeks.

Bottom line, I'm paying myself $50 an hour to fertilize and mow my lawn and maintain the mower. Your results may vary.

jack vines

 

[zkling]

I usually use a flap wheel on an angle grinder. Much easier I think to manipulate the grinder than the blade. The bench grinder is not really suited for lawn mower blades as the wheel puts a hollow ground edge on the blade, which while super sharp is also super fragile. The belt grinder or flap wheel will put a slightly convex edge on the blade which will still be sharp but much more durable.

Don't forget to balance the blade.

To the topic at hand, sawdust is super explosive. So is flour and other finely ground organic materials. A dust cloud of it will catch on fire. Most wood shops heavily ground their dust collection system to prevent static buildup and a possible spark.

 

[Kevin54]

So...

Today was the annual lawnmower maintenance day. Oil + Filter Change plus sharpen the blades.

Over the years, I've tried various ways to sharpen my blades, but my current procedure sort of goes like this.

Get the mower up in the air and remove the 3 blades. Throw them in the utility sink with a couple of inches of water in it to soak. Drink a cup of coffee.

Use a scraper and a nylon brush to scrape all of the grass crud off the blades.

Use a stationary belt sander to sand the back (flat) side of each blade.

Use a bench grinder on the cutting edge of each blade to recut the "cutting angle".

Go back to the stationary belt sander (150 grit belt) and clean up the edge by cutting at the cutting angle TOWARD the cutting edge.

Put them back on the mower.

Sooo...that's gone pretty well until this morning when I set the belt sander on fire. After I did it it was one of those "how stupid was that?" moments. There are sparks coming off the steel blades and those are getting sucked right into the belt sander's dust collection bag ALONG with a bunch of dry sawdust that was already in the. Do ya think that might be dangerous?

I'm just glad it caught fire while I was standing there and didn't just smoulder for a while and burst into flame after I got done. At least this way the only thing that was hurt was my pride...and the dust bag on the sander. I got it put out before it was completely ruined...but it's definitely "almost ruined".

Phil

I'm thinking WTF could go wrong as I just used my belt sander yesterday to sharpen the blades on the JD.

Then I read where you also used the belt sander for wood. I see what you did there. Yep...like Steevo....never mix wood and metal.

 

[Outlawmws]

Really? When I used to burn wood to heat my house, I had this big *** pile of saw dust. I tried to burn it little at a time in the wood stove. Which by the way had a really good bed of coal and a nice fire going on. Damned saw dust kept putting out the fire. I've never been able to burn saw dust...

There is a difference between burning something, and smothering a fire (Which is what you did). ever see someone cover a fire with a blanket and it goes out? sure the blanket may smolder, but if you cut the oxygen supply the fire will go out. Put a pile of sawdust in the cold coal bed, then build a fire on top. it will burn...