# Broken cutting edge?



## Groove (Jan 28, 2005)

I've been running an 8' Fisher MM1 for three seasons and noticed it was time to put on a cutting edge. I bought a 5/8"x9"x8' for it with the factory Fisher bolts as I was told not to use grade 8. I was told that you want the bolts to be the weak point. Well my third time out this year and I hit a man hole cover. It sounded like my windshield shattered. I jumped out of the truck after I couldn't see any broken glass. There were broken bolts and nuts everywhere. I broke all 8 bolts all at once! I then searched for my cutting edge. I found it in two pieces! I snapped the thing clear in half.

How often do you guys break edges?

Should I have used grade 8? I feel like if the bolts didn't start to break, the edge wouldn't break and the edge would have (should have tripped.)

Thoughts?


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## JTW (Sep 12, 2005)

WOW....how fast were you going?


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## BayviewLawn (Sep 16, 2005)

Im impressed!Snapping all 8 bolts and the edge..geez..I would think grade 8 should be used and the blade should trip long before sumthin breaks.


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## Groove (Jan 28, 2005)

JTW said:


> WOW....how fast were you going?


You'd think I was plowing a highway but I was just doing a parking lot. I was going 10-15?

Has this happened to anyone?


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## Mick (May 19, 2001)

I've never had that happen, but breaking all eight bolts at the same time and the cutting edge, I have to wonder if the bolts were tight to begin with. I can't hardly see the edge breaking considering the use they commonly get. It should have tripped. I've hit some pretty big rocks that were solidly anchored. It sounded like the whole truck frame was coming apart, but nothing broke. When you said all the bolts broke was really the clue that they might not have been tight enough and allowed the edge to "flop".


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## makplow (Nov 2, 2005)

I agree with Mick. What grade bolts did you use? Even grade #5 Its hard to believe they would all snap. Are you sure your trip is working properly?


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## Rappa (Dec 2, 2003)

Ok you said you have been running this plow for three years. Did you just change the cutting edge after three years? I go through 1 or two a season per blade. Three years seems like along time if the blade gets any use. You must have worn down your trip edge significantly. 

Now you then add to the problem by purchasing a humungous cutting edge. A 9 inch cutting edge is pretty big for a plow, nevermind a blade that has a worn trip edge. You don't have enough "meat" behind the cutting edge where it bolts on to sustain a hit like that without breaking the bolts and/or snapping a cutting edge -wow-... The stress is distributed solely on the cutting edge and nothing on the trip edge. 

In the future, I would buy the regular 6 inch cutting edge for parking lots and driveways. I use an 8 inch on one of my trucks, only because it is plowing the highway and wears extremely fast when you plow the interstate for long hauls each way. The other two have 6 inch edge's. Hope my explanation makes sense.


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## justme- (Dec 28, 2004)

Rappa you can;t assume that. Depending on the amount of plowing an individual does if they use shoes or not, the quality/grade of the cutting edge, and their style will influence significantly the edge wear rate. I have seen commercially used blades last forever, I have seen guys run through 2 edges in a season. The base angle is supposed to be worn down before an edge is put on also.

I have worn only half a inch to 1 inch off my trip edge and cutting edge in 6 years. Previous owner had no real wear to the base angle in 2 years. 

That said- 9 inch edges are too much for a Fisher, especially in 5/8. That's alot of steel. I have to agree I suspect the bolts were not properly tightened- one bolt snapping yeah, maybe 2 bolts, but not all of them. Are you sure you were only going 10 to 15 mph? 
Since I have only seen 9 inch edges available for municipal plows I have to presume it is a hardened edge- made for highway use, which makes them brittle so yeah- a hard solid hit is not unheard of to crack one.
The longer the edge the more severe the angle of attack on the ground- that makes a huge difference in the trip force. I would suggest raising the rear of the moldboard (go to bottom hole) for a new 8 inch edge on a normal blade.


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## Rappa (Dec 2, 2003)

justme- said:


> I have worn only half a inch to 1 inch off my trip edge and cutting edge in 6 years. Previous owner had no real wear to the base angle in 2 years.


You are still on your original cutting edge in 6 years???? Are you serious?


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## Plow Meister (Oct 16, 2001)

Rappa, I am still on my original cutting edge in 10 years and I may have only worn down about 1.5" of edge. I am just now considering replacing it but not until next plowing season.

Granted, a lot has to do with the amount of plowing a plow does, but I do a LOT of plowing when the snow hits. I can't imagine going through even one cutting edge a season. I just don't think that's possible. Maybe in Alaska or other high accumulation areas but certainly not the northeast.


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## Rappa (Dec 2, 2003)

Plowmeister and Justme, all I can say is wow! 6 years and ten years, that's crazy! Maybe myself and everyone that I know are doing something wrong. Maybe they don't make them like they used to? Who knows... I would be curious to hear from others on this subject. I have a friend that plows a highway with his 04 GMC 2500hd and a minute mount 2 that goes through an edge every 2-4 good size storms.

Ten years? Come on now... Does this truck go out on a regular basis?


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## Plow Meister (Oct 16, 2001)

Yup. It is my primary truck. I have 5 other trucks with Westerns that have never had the cutting edge replaced and I have had them going on 7 years now and I bought them all very used.

In a typical storm my truck goes out for about 10 to 14 hours and we get about 10 storms a season. I know the northeast gets a lot more snow than we do but in order for me to have to replace my blade even once a season I would have to plow 100 storms a season according to my numbers.

I don't want to say you are doing anything wrong. Are you buying actual cutting edges or are you just using mild steel?


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## Rappa (Dec 2, 2003)

Yeah as far as I know they are the real deal. And I don't always buy from the same place. I wish I would get that much life out of one! I started another thread in the commercial forum on this topic to see how others weigh in about the subject. I am curious for sure now...


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## PremierLand (Jun 11, 2004)

Maybe what you consider worn down really isnt worn down to other members?


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## Mark Witcher (Feb 21, 2004)

PremierLand said:


> Maybe what you consider worn down really isnt worn down to other members?


I replace mine after about 1 inch to inch & a half of wear. I have seen lots of people run them until its wearing into the moulboard. And if you are running the Pro wings the plow is kinda held up off the ground by the rubber when the cutting edges get too short and then the plow doesnt scrape as well.


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## oarwhat (Nov 29, 2005)

Rappa said:


> Plowmeister and Justme, all I can say is wow! 6 years and ten years, that's crazy! Maybe myself and everyone that I know are doing something wrong. Maybe they don't make them like they used to? Who knows... I would be curious to hear from others on this subject. I have a friend that plows a highway with his 04 GMC 2500hd and a minute mount 2 that goes through an edge every 2-4 good size storms.
> 
> Ten years? Come on now... Does this truck go out on a regular basis?


 I hear ya rappa none of our trucks would make 3 or 4 years let alone 10 wow. My truck goes through 1 to 2 edges a season. I use 1/2" x 6". I didn't catch the 9" blade the first time i read the post. I think you guys correct that blade has to much leverage and weight. My dad and brother got the bright idea to use 5/8" x 8" wing edges we had . The weight ruined springs ,plow pumps, alignments, tires. At first it seems fine but the wear and tear is brutal!!!!


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## Plow Meister (Oct 16, 2001)

Mark,

The rubber on the Pro Wings wears MUCH faster than the steel of the moldboard. Not to mention that the rubber is extremely pliable and bends a lot when needed. There's no way the rubber from the Pro Wings will make the steel cutting edge last any longer.


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## justme- (Dec 28, 2004)

Yeah, primary truck plows regularly. 30 customers on the route on average since I bought the truck.

Couple of things to note- the less snow on the surface the faster the edge will wear. You guys plowing commercial lots that want the snow pushed at one inch have more friction then us who trigger at 3 inches or more. If you plow treated surfaces you also have more friction- no ice layer on the pavement.

Many guys consider the edge worn at 1 inch gone- a 6 inch edge should wear 2 inchs MINIMUM, an 8 inch edge should wear 4 inches MINIMUM. 

Now, I never wore the base angle down before installing the edge- the 1/2 inch edge is flush with the base angle creating almost triple the surface area in contact with the ground versus just an edge. The pressure of the blade on the abrasive is less than 1/3rd- wear rates are less than 1/3rd versus the single edge. Scrapes as good as a brand new Fisher without an edge, but not as good as a brand new cutting edge alone. Good enough for me in most storms and VERY cost effective. 
I tried replacing the edge last season- bought the new one and was ready to unbolt the old when it occured to me the old one was very close in size to the new one- a quick measure confirmed it was only worn about 1/2 inch after 6 years.


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## Groove (Jan 28, 2005)

Rappa said:


> Ok you said you have been running this plow for three years. Did you just change the cutting edge after three years? I go through 1 or two a season per blade. Three years seems like along time if the blade gets any use. You must have worn down your trip edge significantly.


I sub for someone as I have 9-5 job I can't miss. This means I usually only plow half the amount of time the rest of the crew is out. Otherwise I think the factory edge would have lasted me only two seasons.



> Now you then add to the problem by purchasing a humungous cutting edge. A 9 inch cutting edge is pretty big for a plow, nevermind a blade that has a worn trip edge. You don't have enough "meat" behind the cutting edge where it bolts on to sustain a hit like that without breaking the bolts and/or snapping a cutting edge -wow-... The stress is distributed solely on the cutting edge and nothing on the trip edge.
> 
> In the future, I would buy the regular 6 inch cutting edge for parking lots and driveways. I use an 8 inch on one of my trucks, only because it is plowing the highway and wears extremely fast when you plow the interstate for long hauls each way. The other two have 6 inch edge's. Hope my explanation makes sense.


I figured that since the cost wasn't very different between the 6" and 9" and I always hated the drift coming over the top of the plow, a 9" would last longer and allow me to push more without buying a foil. I kind of figured most people would run the 9" but neer looked.


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## Groove (Jan 28, 2005)

makplow said:


> I agree with Mick. What grade bolts did you use? Even grade #5 Its hard to believe they would all snap. Are you sure your trip is working properly?


I think they were in a Fisher bag. I'll go back to the store and look later. The guy at the store told me not to use grade 8 and to use the carrage bolts they stocked for it.


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## Groove (Jan 28, 2005)

justme- said:


> That said- 9 inch edges are too much for a Fisher, especially in 5/8. That's alot of steel. I have to agree I suspect the bolts were not properly tightened- one bolt snapping yeah, maybe 2 bolts, but not all of them. Are you sure you were only going 10 to 15 mph?
> Since I have only seen 9 inch edges available for municipal plows I have to presume it is a hardened edge- made for highway use, which makes them brittle so yeah- a hard solid hit is not unheard of to crack one.
> The longer the edge the more severe the angle of attack on the ground- that makes a huge difference in the trip force. I would suggest raising the rear of the moldboard (go to bottom hole) for a new 8 inch edge on a normal blade.


I wasn't looking at the speedo but don't drive that fast. It's my truck and I get paid by the hour, not the job.

I did move the mount to the bottom hole to level the plow. I had the same concern after I put it on. There must be a trick to move that mount but I didn't find it. I was out with prybars straps and a whole lot of kicking and swearing to get it in the bottom mount holes!


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## justme- (Dec 28, 2004)

That's how I moved mine too. I suppose if you unbolted the tension spring in the center... but the condition of mine I decided better to leave it alone.


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## MickiRig1 (Dec 5, 2003)

I broke a 1/2 " cutting edge vertically right in the middle on a half paved street hitting a water shut off flange. Didn't break a bolt. I have never broke one on a Meyer plow.


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## Groove (Jan 28, 2005)

I went back to the store where I bought the edge and bolts. The bolts they supplied were not Fisher brand and neither was the cutting edge. The bolts were a three letter name starting with I. I think they were irc carriage bolts. Anywaym they were marked as grade 5 bolts.


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## paponte (Oct 28, 2003)

I salute you! :salute: 

I have cracked my edge in half, but have never actually broken and carriage bolts. I hit a manhole cover doing about 25, flipped the sucker like a coin and watched my plow pop over the hood of my truck and blow out a headlight. Still didnt break the bolts off. :salute:


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## DESTEFANO3782 (Aug 8, 2005)

Jesus Thank God You Stil Have A Plow. If You Racked Up 8 Bolts And Snapped An Edge You Had To Hit That Think At Some Strange Angle, Un Heard Of By Me. I Go Through About 2 Edges A Season And Never Had Anything Like That Happen.


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## oarwhat (Nov 29, 2005)

Groove said:


> I went back to the store where I bought the edge and bolts. The bolts they supplied were not Fisher brand and neither was the cutting edge. The bolts were a three letter name starting with I. I think they were irc carriage bolts. Anywaym they were marked as grade 5 bolts.


 I'd get bolts someplace else. Grade five bolts have 3 small lines on the head, grade eight have 5 lines, bolts with just letters or a name on them are grade 2 or less. I forgot that one time we bought a replacement edge for a western and the bolts were breaking with normal use. I never noticed they weren't hardened when we put the blade on.


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## bank32 (Dec 16, 2005)

oarwhat said:


> I'd get bolts someplace else. Grade five bolts have 3 small lines on the head, grade eight have 5 lines, bolts with just letters or a name on them are grade 2 or less. I forgot that one time we bought a replacement edge for a western and the bolts were breaking with normal use. I never noticed they weren't hardened when we put the blade on.[/QUOTE
> 
> I all ways thought it was grade 5 or better on the bolts. Also I get about 3 seasons out of my edges.


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## bank32 (Dec 16, 2005)

I also hit a concrete light base bent the sh!t out of the edge & the board but did not break a bolt or the edge.


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## MickiRig1 (Dec 5, 2003)

When I broke my cutting edge I loosened up the bolts and put it down on the cement floor to get the edges level again. I tacked it, then raised it up and cranked the amps up and used the biggest rod I had. It's still pushing snow if we had any snow that is.


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## timberjack (Dec 21, 2000)

I just broke my cutting edge yesterday, at about the halfway point of the blade. The plow has about 5 hours on it since being installed. I don't even remember hitting anything hard, and i definately don't get over 10 mph while plowing. I just happened to have a look as i walked by when i was done, and noticed the crack. I'm going to buy a new one, but i think i'm going to weld this one up, and keep it handy in case i need it some stormy night.

I have noticed the new blade and/or cutting edge has been very "grabby" at full angle. I have to wonder if the extra torque on the edges was what did the breakage. I'm going to take the grinder to each corner and chamfer them a bit, and see if it helps the new one, maybe even run the grinder down the whole length a bit too. For my plowing i don't think an extremely sharp edge is beneficial. If i was doing parking lots, or long flat pushes, maybe, but not the irregular roads and terrain i plow.

FWIW, the plow i replaced this one with, a Western 9' Pro Plow, had the original cutting edge on it over 9 full seasons, with plenty left to wear too. But, i don't do any commercial plowing, just my yard, and sweeping up my logging roads after i do the worst with a grader. I would estimate probably 20-30 hours a year of plowing. 

Just poor luck that the new one broke this quickly i suppose. 
Ken


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