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  1. #41
    Elite Member
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    Sep 2003
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    4,144
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    New Brunswick, Canada
    Tractor
    Kubota L5030 HSTC, MF 5455

    Default Re: if i wanted to build a jaw crusher...

    Hi Renze, the babbit as far as I know was just to create a plain bearing surface that could be clearanced correctly and once it failed was easily rebuildable. I would think any bearing material that can be accurately mated and sized to support the load should be ok. What type of lifespan are you trying to obtain?

    I can't help you on the crushing question, I know the loads for brick or concrete are far lower than rock but I also agree the soft material could be a problem letting too much material share the compressive load. Is a wider jaw angle suitable to reduce the size of the crushing zone given there is less risk of stalling the material flow or expelling material with softer material?

    I'm thinking a shop press with a gauge and some ribbed plates might reveal some of the loading. A friend used to have a hydraulic brick cutter for laying paver stones, its cylinder was quite small.

  2. #42
    Elite Member
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    Oct 2003
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    3,288
    Location
    the Steernbos (Holland)
    Tractor
    Zetor 3011, Zetor 5718

    Default Re: if i wanted to build a jaw crusher...

    Quote Originally Posted by slowzuki View Post
    Hi Renze, the babbit as far as I know was just to create a plain bearing surface that could be clearanced correctly and once it failed was easily rebuildable. I would think any bearing material that can be accurately mated and sized to support the load should be ok. What type of lifespan are you trying to obtain?
    I want to pour a Babbitt in the jaw, so the jaw and bearing chamber can distort from welding without requiring machining. For the frame bearings i'm not sure, low grade bearings need to be wide, which increases the span over which the shaft has to carry the bend forces.

    Quote Originally Posted by slowzuki View Post
    I can't help you on the crushing question, I know the loads for brick or concrete are far lower than rock but I also agree the soft material could be a problem letting too much material share the compressive load. Is a wider jaw angle suitable to reduce the size of the crushing zone given there is less risk of stalling the material flow or expelling material with softer material?
    Actually, according to online literature, the narrower the jaw angle the better it works: With a wide jaw angle, rocks get pushed up without the jaws grabbing onto them. A narrow jaw angle is most effective, and concave jaws are best. ITs because a typical single toggle jaw crusher takes a bigger bite at the top, so when the jaw angle is wide at the top and narrow at the bottom, you get a constant downflow of material without stalling in the lower part where the jaw movement is less.

    My idea is to use flat jaw plates from mild steel, with manganese or Hardox ribs welded to them. Then weld two 20x20mm round bars at 40mm spacing, and then a laser cut convex rib which starts and ends with 20mm height but is 50mm in the middle. The opposing jaw plate would be mirrored, so you get a staggered shark bite, concentrating the force on just a few pointloads, even when crushing straight and square concrete instead of round natural rock. That should greatly reduce the peakloads on the crusher. Natural rock is so irregularly shaped that its much easier to pointload it between two flat faced jaws. since we dont have natural rock where i live (just a lot of construction rubble, for which we pay 5 euro per ton to dispose of, and 5 euro per ton to buy back as 40mm minus. Thats when you haul it 10km to the crusher, back and forth.

    Quote Originally Posted by slowzuki View Post
    I'm thinking a shop press with a gauge and some ribbed plates might reveal some of the loading. A friend used to have a hydraulic brick cutter for laying paver stones, its cylinder was quite small.
    I wanted to do this, but forgot about this. But now you mention it, i just happen to have bought a 30t shop press with tonnage gauge 2 weeks ago... It needs some fine tuning of the hand pumps non-return valves because the cylinder moves up when you let the pump handle up again, but once its fixed i have a metering device... I can mock up a crusher die from mild steel for this purpose.

    I have also bought UNP300 C channel, with 10mm thickness of the vertical flanges. It was been used only once, as a temporary machine foundation, and i bought it for 40% of new. Three welded on top of each other will make the sides of my crusher, welded on top of each other i already get the reinforcement ribs on them. Its cheaper than buying sheet steel because square meters of sheet steel have much more uses than 12" C channel and therefor the same material as sheets would be much more expensive
    The material to weld hollow sectioned jaw backings i have taken from when they teared down the old building at work: HE200 B beams, 200x200 H beams with 15mm flanges. Welded against each other with a 10mm sheet of steel between them, would give me a sandwich panel with 15mm faceplates and 10mm internal ribs every 100mm... That should work. This far i have only bought scrap, now i need to flywheels...

    Does anyone have an idea of what to use for flywheels ? Would the flywheel of a big rig engine from the local wreckyard be sufficient ? I cannot get my hands on some train wheels, as they are all sent to Italy for resurfacing when worn. Using the heavy rings of a pig feed pellet press is another idea, but i dont know if those are big and heavy enough. For rotational mass i need both mass, and distance from the shaft center.
    Last edited by Renze; 02-19-2013 at 03:07 PM.

  3. #43
    Platinum Member
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    Apr 2012
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    743
    Location
    pa
    Tractor
    kubota 7040sud

    Default Re: if i wanted to build a jaw crusher...

    the rig fly wheel isnt heavy enough maybe a wheel wieght off a tractor the rear my 70 horse wheel wieghts wiegh 350ibs each

  4. #44
    Veteran Member jimgerken's Avatar
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    Nov 2001
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    Minnesota
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    John Deere 3720

    Default Re: if i wanted to build a jaw crusher...

    Hay balers have real nice flywheels on them.
    I havent been following this discussion all the way, so forgive me if its been said, but when I worked the jaw crusher in the early 80's, we were carefull not to throw in any rocks that were laying around, only the rock that had just been blasted and hauled with the loader. Rocks that lay around above ground get WAY harder in a short time. I don't know why.

  5. #45
    Elite Member
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    Oct 2003
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    the Steernbos (Holland)
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    Zetor 3011, Zetor 5718

    Default Re: if i wanted to build a jaw crusher...

    Quote Originally Posted by jimgerken View Post
    when I worked the jaw crusher in the early 80's, we were carefull not to throw in any rocks that were laying around, only the rock that had just been blasted and hauled with the loader. Rocks that lay around above ground get WAY harder in a short time. I don't know why.
    shear strength calculations do not follow real life, because the shear strength is calculated by mean values of a homogeneous rock. In practice, big rocks break on natural fault lines and weaknesses in the material, so the smaller the rocks get, the more it follows the theoretical shear strength rule, because all natural faults are already used in the first couple of crush events.

    I doubt that the rock get harder laying above ground, because the rock formations are thousands of years old and had enough time to cure... ???

  6. #46
    Veteran Member jimgerken's Avatar
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    Minnesota
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    John Deere 3720

    Default Re: if i wanted to build a jaw crusher...

    Doubt it if you will. I learned it on the job.

  7. #47
    Elite Member
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    Oct 2003
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    the Steernbos (Holland)
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    Zetor 3011, Zetor 5718

    Default Re: if i wanted to build a jaw crusher...

    Quote Originally Posted by jimgerken View Post
    Doubt it if you will. I learned it on the job.
    Natural rock is a valuable landscape product in Holland, we only crush construction rubble. So the question wont become relevant here

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