Please help, blade sharpness issue

[graderhead]

I have an issue that seems to be a can of worms i never intended to open...... Most ppl in the industry talk about mouldboard position when discussing cutting, I would like to know your opinions on the actual cutting edge shape.

I operate cat 16(g+m) graders as well as cat 24(g+m) graders on a mine site in Canada and most of the time the cutting edge looks just like a "U" from operators rolling the MB back and forth "working the edges" (is the back edge really meant to cut??... does everybody chase their edges around like this?) It would seem to me that the edge was meant to be sharp, and would cut from the front, and maintaining sharpness is part of the skill.

What do you call sharp? can and do you work with a cutting edge that is +/- 90%...... seems to make more sense to me if the blade looks more like a triangle than a square.

any help is welcome, if you need more details just ask

 

[Nige]

I would agree with you. As far as I'm concerned the profile of the bottom surface of the cutting edge (circled in the sketch below) should be a straight line from the front to the rear. I had to take an illustration and rotate it a bit to illustrate the point, so don't read too much into the angle of the cutting edge in the drawing. I wouldn't normally expect to see the moldboard on a mine haulroad maintenance grader to be rolled back as far as that sketch indicates. What's meant to cut IMHO is the front bottom corner of the edge. In a way it's almost self-sharpening as it wears. The profile as shown in that sketch (albeit with a different angle) is what I'd expect to see on any grader coming to the shop for a cutting edge change.

 

[Oxbow]

I agree with Nige. I have heard of operators (some, not all) in mine-haul road applications rolling the blade all the way forward and even putting the controls in float, due to lack of ambition and the desire to learn in my opinion. This is possible only when the edge is rounded over.

I prefer to do most of the work with the blade about 90% back which will tend to sharpen the cutting edge somewhat to look like the illustration in Nige's post. The blade will carry more material in this position. I roll the blade forward to aid in cutting hard material (assuming the edge is sharp), and to make finish passes where one can see the cutting edge better.

I am not a full time blade operator though, so folks with more experience may correct me.

 

[Nige]

The one thing I see on grading mine haul roads that can be as hard as concrete is the apparent reluctance of grader operators to first drop the ripper/scarifier into the road surface to loosen the top 3-6" so that the material can be "worked up" so as to produce a properly-graded surface. Really the moldboard/cutting edge "angle of attack" relative to the ground is dependent on how the material rolls up and off the moldboard. The easier the material rolls the less energy is needed to cut. Therefore it would be logical to assume that an AOA that works perfectly on one type of material would not necessarily work so well on another. That's whay all grader operating manuals give a prewferred angle to start off with (the top front corner of the moldboard about 2" ahead of the cutting edge IIRC) and then roll the moldboard slightly forward or backward from that position to get optimum cutting perfromance and material "roll".

Agree with Oxbow that rolling the moldboard over forwards when doing road maintenance work (as opposed to road construction finishing operations) as far as it will go is simply because the operator lacks ambition.

 

[graderhead]

Thank you so much for your help folks, your info was very helpful. over the years it seems our mine team has developed a misconception about how a grader works.

from the comments, it appears that someone down the road was a lazy operator and everyone has forgotten how to keep a sharp blade due to poor training,(by same operator) and after 40 years we are now basically large metal squeegees.

i have tried to bring this up several ways to our team, to no avail.... they are convinced that this fella knows what he is doing, and cannot figure out why we are destroying graders.(picture a grader, MB fully rolled forward, front wheels barely touching the dirt due to the downpressure needed to cut with a rounded edge)

any suggestions on how to educate the ppl who run the mine about this? any time i bring it up, it turns into a bs session about MB position and I am outranked and out-numbered.

thanks again everyone, you have really put my mind at ease.

 

[bigshow]

Hahaha, large metal squeegees, I love it. The only way to get through to closed minded, ignorant people is to write what you want to say on a 20lb. hammer and then hit them in the head with it.

 

[Oxbow]

I do not have one available, but I believe that this is addressed in the Cat operators manual. Perhaps you could find that page, copy it, and post it somewhere conspicuosly without taking credit yourself for posting it. Then maybe one of the higher ups will read it and take credit for the "new way of operating", and implement the technique.

My Dad used to tell me, "if you have a really great idea and want to see it come to fruition, whisper it to someone else and let them take credit for it".

One of the past forum contributors, a gentleman by the name of Randy Krieg I think, had worked for Cat in the development of graders and I believe he co-authored the current operators manual. I have not seen him on here for awhile, but he has contributed extensively to a thread in this forum entitled "Operting Techniques" or something like that, in the motor grading section.

I believe that you can still find it, and it is well worth reading if you have the time. I came across it one night about 9:00, and before I knew it it was 4:00 in the morning and I had read the entire thread, which is quite lengthy. Some very bright and creative people contributed to that thread over the years, and in my opinion it was a treasure to find.

The problem you face is that if someone on another shift runs with the moldboard rolled forward all the time you do not get the opportunity to run with it sharp when it is your turn, unless the cutting edges have just been replaced.

Good luck enlightening the powers that be!

 

[Oxbow]

I found the thread that I mentioned above, and here it is:

https://www.heavyequipmentforums.co...Techniques&highlight=motor+grading+techniques

 

[graderhead]

I like the hammer idea, might keep it for later though.

I have pointed out the manual to the training dept and only got blank looks and more MB rolling bs, these guys do not like change, too much work maybe? ah well

looks like Oxbow's dad had the right track and I intend to find a way to try just that. could be they are resisting the idea due to years of being the go-to guy and can't allow someone to have better ideas as it would threaten their percieved "position". besides, who likes to admit they are wrong? I know l don't.

thx for the link Oxbow, every little bit helps

 

[Oxbow]

You bet graderhead, enjoy the reading!

 

[Cmark]

This is the paragraph from Cat's "Motor grader application guide" on moldboard tip.



7. Moldboard tip. This is a very important feature:
its proper use will increase machine productivity,
increase cutting edge life and could prevent
machine damage.
The top of moldboard can be tipped ahead of
or behind the cutting edge. This helps position
the cutting edge at its proper angle to obtain
the desired material cutting and rolling action.
Maintaining a rolling action on the material while
working will reduce horsepower required and
provide maximum productivity.
Normally start with the moldboard top positioned
approximately 2 inches (5 centimeters) ahead
of the cutting edge. From this position, tip the
moldboard forward or back to obtain and maintain
the desired cutting-rolling action. Tipping the
moldboard forward will increase moldboard
throat clearance (distance between the top of
the moldboard and the bottom of the circle).
Generally, a wider throat opening allows better
material flow along the moldboard in all soil
types. Material buildup into the circle area may
increase circle wear. It can also stop material
rolling action and cause it to be bulldozed.
Bulldozing material requires more horsepower,
more traction, and reduces motor grader
productivity.
To cut hard material or for finishing work, tip the
moldboard further forward than the start position.
When finishing, tip the moldboard top 4 to 5 inches
(10.2 to 12.7 centimeters) ahead of the cutting
edge so the cutting edge is approximately 90 degrees
to the cut surface. This moldboard tip position
will generally position the drawbar parallel to the
finished grade. When the drawbar is parallel to the
finished grade, circling the moldboard will have little
effect on the cross slope being cut. The amount of
tip required will change slightly depending on the
machine, tire size, cutting edge size (6 or 8 inch
[15.2 or 20.3 centimeters]) and if cutting edges are
new or worn.
Tipping the moldboard forward or back will
change cut depth or blade height off the ground
across the entire moldboard length. The tip
control, for example, can be used to raise both
ends of the moldboard for feathering material
at the end of a cutting pass or for increasing cut
depth over the entire moldboard length by use of
a single control.
Cutting high bank slopes or deep ditches requires
more forward tip on the moldboard to obtain
the proper cutting-edge-to-material contact.
Attempting to cut with the moldboard in the
full rear position in these applications, or with
worn cutting edges, could result in difficulty
penetrating and cutting the material.
N O T E
Use caution when working with the moldboard at
full back tilt. Damage can occur to the moldboard
tip pivots, cutting edge attachment bolts and
support area for the cutting edge. This may
cause a reduction in cutting edge support.
For maximum cutting edge life in road
maintenance work, maintain a near constant tip
angle. Frequent changes to tip position in this
application result in accelerated cutting edge wear.
In general, tip the moldboard rearward for heavy
clays and cutting packed snow or thick ice, after
first penetrating the material with the moldboard
tipped forward.
In snow removal work, tip the moldboard so the
cutting edges are approximately 90 degrees to the
work surface. This allows the moldboard to slide
over the road surface with less damage TO THE
ROAD and over many obstructions without
damage to the machine.

 

[MKTEF]

Don't tell anybody, but you can sharpen your edge on a length of asphalt road. Just lay your edge down carefully, and sharpen it over a distance.
Some sparks will flow as u go, but the edge will then be good to go.
I see the problem doing this with the 24 though...

 

[Desertwheeler]

We have problems at the mine I work at with operators err um more drivers one sideing the blade and haveing 6 inches on left and 2 on the right. Also they all have different pitch ideas on the moldboard and rarely sharp. We also run the edges with the sandpaper looking stuff that I can't remember what they call.

 

[Nige]

graderhead. If you want a complete copy in pdf form of the Cat Motor Grader Application Guide referred above please PM me with your e-mail address and I will fire it off to you.

Also - please post a photo of the grader being used as a "squeegee", asking for help to improve. I suggest starting a new thread for the photo for reasons that will become obvious. After a number of the more shall I say erudite contributors from on here (that's you CMark ......!!) have done, to quote the famous Chinaman, their best Raff out Roud impression and hauled themselves up off the floor (give it time, I'm sure it will be worth it, even for the humour value) show the thread to the naysayers at your place of work. You could come back later and tell us how it went .........

 

[graderhead]

I have a copy of the guide, and l have had ppl quote it when argue-ing the issue. one thing l do notice is the size of the cutting edges we use. they are about 2.5 inches thick and about 20 inches tall as well as perfectly straight. when l look at pictures of other graders, the edges are never that tall. l believe that they are not compensating for the edge height when following the recommended operations, leading to the MB being way too far forward from the onset, also there is no edge coming out of the shop, both sides of the blades are shaped the same, bolt holes and all.

we are not allowed to bring cameras onto the site, but l will see what i can do about a photo.

BTW some guys here even brag about how fast they can burn through it (4 hours??? really?) just to sit in the coffee room while new blades are installed.

 

[Nige]

Intrigued about the cutting edge design. On our 16M we use 10" deep 1" thick straight (not curved) cutting edges. Reason is more wear material.

I realise it may be difficult but any chance of a photo of the edges as a kickoff.....?

On really abrasive material I've seen graders take a set of edges in 8 hours. Not terribly unusual then.

 

[Grader4me]

I just got finished on a job in Fort Mac Alberta. To get to where I was working we had to travel on the haul roads for the mine site. I noticed the Cat 24 "m" that was blading the road had his blade rolled all the way ahead. He had serrated blades on. The cutting edges were obviously dull and by applying more pressure to make the cut all he was doing was making a mess. The blade was nose diving on the weaker spots of the road and jumping back up on the hard ice. The road was very hard to drive on. Good information in this thread about proper blade angle.

 

[Nige]

In view of the post above I'd repeat the comment about loosening the top surface with the ripper before starting to grade. Roads travelled by heavy mining trucks can get compacted to resemble something like concrete.

 

[Grader4me]

In any other season yes I agree to rip them first, but these are winter haul roads (ice) and they just keep them scratched up for a smooth driving surface and traction. By using the correct blade angle you can always keep the blades sharp and do a good job scarifying ice roads.

 

[graderhead]

we are not allowed to rip the haul road during winter here, the reason being that there are large rocks buried in the road and if you catch a ripper tooth on one of them it will damage the grader. this winter one of our rentals caught a big one and tore the whole ripper off of the assembly.

blade photos on the way