I think your company wants to give somebody a paycheck to do it wrong. If you want somebody else to get that paycheck then by all means try to prove it to them that they're doing it all wrong. Seriously, you can't win on this.
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Please help, blade sharpness issue
- Thread starter graderhead
- Start date
graderhead
Member
I do have one small hope as the mine manager is actually trying to shake things up and realizes there is a certain "culture" here... but ya, you are probably right.
Nige
Senior Member
Especially in freezing conditions roads will "grow" rocks, the frost pushes them up to the surface. If they are really big a dozer is the only answer, smaller ones can be successfully hooked out with a grader ripper. Remember the 24 has a D6 ripper on it. You can't grade a road well if your moldboard is bouncing off semi-buried rocks all the time.
This blade tip angle thing is interesting.
All the accepted literature says to tip the blade forward somewhat, whether on a grader or dozer or whatever, for better penetration in hard ground. This is obviously knowledge gained from empirical evidence over many years. But this is counter-intuitive. As in Nige's pic ^^^ you would think a more backwards tip to the blade would cut better.
We can compare the cutting edge to a cutting tool on (for example) a lathe. A lathe tool can be negative rake, neutral or positive rake. We are told that a positive rake lathe tool (comparable to tipping the moldboard back) gives easier cutting and requires less horsepower. But then we are told that a more 'neutral rake' moldboard is better for penetration on an earthmover.
One thing a lathe tool has which a cutting edge hasn't is a clearance angle. Even a new cutting edge will quickly wear its clearance angle down to zero.
So why is a more 'neutral rake' recommended for an earthmover? The only reason I can think of is that the more perpendicular the cutting edge is to the ground, the smaller the surface area of the edge of the blade, and the smaller the surface area the less downward pressure needed from the machine in order to penetrate the ground.
If someone could come up with a cutting edge which kept a permanent clearance angle, then lathe tool theory would apply and a tipped back blade would give better penetration. (Possibly ??
)
One thing is for sure. Moving the blade backwards and forwards to give multiple angles to the edge like in graderhead's photos seems counterproductive whichever way you look at it.
Edit:
Maybe the operators are trying to grind a clearance angle on the blade? Run for a time with the moldboard back and then tip forward to use the clearance angle created??
All the accepted literature says to tip the blade forward somewhat, whether on a grader or dozer or whatever, for better penetration in hard ground. This is obviously knowledge gained from empirical evidence over many years. But this is counter-intuitive. As in Nige's pic ^^^ you would think a more backwards tip to the blade would cut better.
We can compare the cutting edge to a cutting tool on (for example) a lathe. A lathe tool can be negative rake, neutral or positive rake. We are told that a positive rake lathe tool (comparable to tipping the moldboard back) gives easier cutting and requires less horsepower. But then we are told that a more 'neutral rake' moldboard is better for penetration on an earthmover.
One thing a lathe tool has which a cutting edge hasn't is a clearance angle. Even a new cutting edge will quickly wear its clearance angle down to zero.
So why is a more 'neutral rake' recommended for an earthmover? The only reason I can think of is that the more perpendicular the cutting edge is to the ground, the smaller the surface area of the edge of the blade, and the smaller the surface area the less downward pressure needed from the machine in order to penetrate the ground.
If someone could come up with a cutting edge which kept a permanent clearance angle, then lathe tool theory would apply and a tipped back blade would give better penetration. (Possibly ??
)One thing is for sure. Moving the blade backwards and forwards to give multiple angles to the edge like in graderhead's photos seems counterproductive whichever way you look at it.
Edit:
Maybe the operators are trying to grind a clearance angle on the blade? Run for a time with the moldboard back and then tip forward to use the clearance angle created??
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biggrader
Well-Known Member
Yup this works good, but just be careful of the grass in the ditches. I've heard of a few guys starting ditch fires from the flying sparks.( I will NEVER admit to starting any ditch fires myself, but have seen it within minutes of me driving by. Must have been the other guy! lol)
As far as better penetration when the blade is pitched forward......I believe it has to do with the width of the steel pushing down into the ground. If you run with the top of the blade approximately 2" ahead of the bottom, you get nice rolling action of the material. Remember, an earth mover has to move the earth, not just cut it. If you run the blade there most of the time, it will grind a nice sharp edge. Then, rolling the blade a head (a little, not all the way), will give you a nice sharp edge to cut with. Once your tough spot is cut, roll it back to your normal operating position.
Rolling the blade all the way forward doesn't serve much purpose with the blade under the machine. This range of motion is mostly provided for highbank and ditch cut positions of the moldboard. In those positions, extra blade tip is often needed to get a decent cut, or to adjust your depth of cut. The skill level of many haul road maintainers mentioned in this thread is pretty low by the sounds of it. They wouldn't know about high bank and what a machine can do in that position. To them, blade pitch must be designed for their squegee use.
Rolling the blade all the way to the rear serves a few purposes. Rolling the blade back is best for carrying material, or sorting out rocks. This position lifts material off the ground, and if left 1-2" off the ground can let small material pass under the blade while moving larger rocks off to the side. This is often used on haul roads when spillage clean up is needed without cutting into the road surface.
Rolling the blade all the way forward doesn't serve much purpose with the blade under the machine. This range of motion is mostly provided for highbank and ditch cut positions of the moldboard. In those positions, extra blade tip is often needed to get a decent cut, or to adjust your depth of cut. The skill level of many haul road maintainers mentioned in this thread is pretty low by the sounds of it. They wouldn't know about high bank and what a machine can do in that position. To them, blade pitch must be designed for their squegee use.
Rolling the blade all the way to the rear serves a few purposes. Rolling the blade back is best for carrying material, or sorting out rocks. This position lifts material off the ground, and if left 1-2" off the ground can let small material pass under the blade while moving larger rocks off to the side. This is often used on haul roads when spillage clean up is needed without cutting into the road surface.
Nige
Senior Member
Maybe this diagram might help. It's basically the same as the one I posted before and expanding on posts that various contributors have made to date. Consider the "sharpen, cut, & roll the material" to be a 3-step process that goes something like this. That's what the 3 parts of the diagram are intended to show if you read them left to right. The thick black line represent the road surface.
Step 1 - Roll the moldboard back and use the road surface to "sharpen" the bottom of the cutting edge if it's not already sharp. Note how the edge is parallel to the road surface. Think of the road surface as a sharpening stone if you like.
Step 2 - Once you have your cutting edge to the desired "sharpness", roll it over forwards so that only the front corner (toe) is touching and the heel is well up above the road. Think of it as a chisel if you like. This is going to give you the most downwards cutting pressure on the road surface that the deadweight of the grader will support. Any more than that and you'll simply lift the front wheels in the air.
Step 3 - As soon as you have penetration and the material is "rolling" up the blade nicely then the moldboard is rolled back slightly to decrease the angle of attack of the toe (and so prevent the cutting edge trying to continually dig itself into the road) but at the same time not so far as to allow the heel to touch the surface and thus lower the downwards pressure on the moldboard. The happy medium is somewhere in between. However while you are grading if you can actually roll the moldboard well back you will in actual fact be sharpening it ready for the next cut.
Note: Whether you use either straight or curved cutting edges a brand new set are going to have a certain amount of "inherent sharpness" because of the way the edges bolt to the moldboard and the angle at which they present themselves to the road. The trick is maintaining that sharpness right from new to worn out.
P.S. For obvious reasons the thicker the cutting edges the more difficult they will be to sharpen.
Step 1 - Roll the moldboard back and use the road surface to "sharpen" the bottom of the cutting edge if it's not already sharp. Note how the edge is parallel to the road surface. Think of the road surface as a sharpening stone if you like.
Step 2 - Once you have your cutting edge to the desired "sharpness", roll it over forwards so that only the front corner (toe) is touching and the heel is well up above the road. Think of it as a chisel if you like. This is going to give you the most downwards cutting pressure on the road surface that the deadweight of the grader will support. Any more than that and you'll simply lift the front wheels in the air.
Step 3 - As soon as you have penetration and the material is "rolling" up the blade nicely then the moldboard is rolled back slightly to decrease the angle of attack of the toe (and so prevent the cutting edge trying to continually dig itself into the road) but at the same time not so far as to allow the heel to touch the surface and thus lower the downwards pressure on the moldboard. The happy medium is somewhere in between. However while you are grading if you can actually roll the moldboard well back you will in actual fact be sharpening it ready for the next cut.
Note: Whether you use either straight or curved cutting edges a brand new set are going to have a certain amount of "inherent sharpness" because of the way the edges bolt to the moldboard and the angle at which they present themselves to the road. The trick is maintaining that sharpness right from new to worn out.
P.S. For obvious reasons the thicker the cutting edges the more difficult they will be to sharpen.
Grader4me
Senior Member
lol..been there but no grass fires....I don't think..
Keerym and Nige...good information and the diagram is perfect.
biggrader
Well-Known Member
Nige, you are the man!!!!. was going to try and explain the same thing but you did it much better than I could have ever hoped. Right On!!
R.D.G013
Senior Member
- Joined
- Apr 6, 2013
- Messages
- 257
- Location
- sunshine coast qld australia
- Occupation
- Heavy equipment operator/foreman for about 48yrs o
Having done a fair bit on graders I usually keep the blade fairly well back as this keeps the material alive so to speak and is easier to push a bigger load as u r carrying it rather than sledging it along, also moves across the blade quicker. Doing final trim work for asphalt laying I have it rolled forward as this lets u see the edge better and forces the material down on to the ground so u r sorta riding on a wedge of gravel in front of the blade. Moving a windrow across a road, usually have it fairly well back as it rolls a lot better, any large objects are lifted up and rolled out to the side of the blade rather than forced into the ground and eventually under the edge.Never tried the sharpening on the asphalt thingy, don't think the local councils would look at it to kindly if u did that to their roads. We put new edges on to do a final trim and throw the old ones back on to do the rough stuff.
graderhead
Member
this is the best explaination I could hope for, do you mind if I print it to hand out to guys at work?
ben46a
Senior Member
When I was at albian I changed the cutting edge on one 24 twice in a 12 hour shift. Others said they had done the same. It boggeled my mind as here at home a cutting edge on a 140 will last a month.
cuttin edge
Senior Member
Our company had a road job one year, and our second grader man who mostly did private work was off with an injury. They hired an older man that had worked doing woods roads all his life. At the time we had a 1989 730 Champion. For the job, they rented a 972D. I stayed local as I had experience with our Puckett, and Alitec mini graders. After A month or so' I was sent over to the road contract to help prepare the subgrade. The forman, and the government engineer didn't see eye to eye, and the engineer was making us string line the subgrade. There was a long section that was between 5 and 8 inches high. I sugested that the 2 graders work together. I took the lead with the old Champion, and the 972 came behind. After the first pass I could tell that I was cutting, and the JD was only moving my windrow. I cut the strip he had just done again, and again he just moved my windrow. So I walked back to clairify that he knew that we had to cut a fair bit off the road. He said ok, and we continued on. I looked back, and he was spinning and not moving a thing. Does your 6 wheel drive work....yep got her on. Are you rolling your moldboard ahead and back.....What do you mean.... I was moving twice the hard packed material with a worn out underpowered old champion, with a 14 foot moldboard, and no 6 wheel drive, and winter tires than a brand new 972 6 wheel drive new tires. I tried the JD, and it worked like a top, and made the old Champion look sick. In my opinion, one of the greatest features of a modern grader is the ability to roll your moldboard. I start the cut with the blade ahead, and roll back until I find the sweet spot. If I feel her start to break traction, just roll the blade back a bit to take the pressure off. I would like to try one of those black cat cutting edges with the rotating teeth that the government graders use. They say they they are great on the hard pack.
rsherril
Senior Member
- Joined
- May 2, 2009
- Messages
- 264
- Location
- Far West Colorado
- Occupation
- Geologist, Retired from teaching sciences
Does anyone swap sides with the cutting edges to even out the wear across the bottom edges and extend their life? I suspect that in a production setting this may not be economical. I watch for wear in the center, then swap sides when there is about an inch difference with the outside ends. Will do this once or twice in the life of a cutting edge, especially if the emphasis is on snow plowing. I generally wear out a set of edges in a year or so.
cuttin edge
Senior Member
Once the blades wear up in the center, we just use the cutting torch to square them up. I have heard the argument that this ruins the hardness of the steel, but I have been doing it for 20 years without problems. As far as snowplowing, we just let them wear to the shape of the road. I mostly do asphalt prep, and not a lot of road maintainance, and it surprises me how fast a cutting edge can wear out on a hard packed road. I have always wanted to try http://www.blackcatblades.com/xContent/products/img/scarifierbits.jpg
pedrocar
Well-Known Member
If you have to cut a haulroad that hard you will damage your edge the lower the edge gets the thicker it gets it gets hotter wears more , harder to push . if a roads that bad it needs more than just trying to
grade a hard surface ,rip and remix and lay out material you can work with this is time comsuming and very expensive not to add incovience to work routines,Have extra material on your shoulders and a water cart do maintaince .helps to do more often makes the job easier better finnish ,less wear and tear and edges,Edges last longer without scolloping and the need to change end for end to get the wear from them ,edges on bigger machines cost **** loads stuff em and you have a probelm for a long time .making your job and everone elses job hell . Big gear destroys road surfaces , and destroys tyres so more grading actuallys costs less and becomes easier ...
grade a hard surface ,rip and remix and lay out material you can work with this is time comsuming and very expensive not to add incovience to work routines,Have extra material on your shoulders and a water cart do maintaince .helps to do more often makes the job easier better finnish ,less wear and tear and edges,Edges last longer without scolloping and the need to change end for end to get the wear from them ,edges on bigger machines cost **** loads stuff em and you have a probelm for a long time .making your job and everone elses job hell . Big gear destroys road surfaces , and destroys tyres so more grading actuallys costs less and becomes easier ...
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Willie B
Senior Member
I should but out, as I know nothing of the subject. When I put hard surface on the underside of the cutting edge on a loader bucket it rubs on hard road surface protecting the edge from wear. The upper face wears slightly from material passing over it & remains sharp. Might there be a very hard material for the lower face of grader cutting edge? Certainly most towns here in VT use the carbide replaceable studs on cutting edges.