Log splitter build

Discussion in 'Hobby Engineering' started by maldotcom2, Jun 22, 2014.

  1. maldotcom2

    maldotcom2 Member

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    I'm looking at building a log splitter. The two stage hydraulic pump i'm looking at using has the potential for 3000 PSI output, however the ram which it will feed is only rated to 2200 PSI.

    I skipped out on fluid dynamics at TAFE so I just need to know if there's a simple way to limit the fluid pressure to the ram. I *really* don't want that cylinder to let go at those pressures. :Paranoid:

    In return for any advice, i'll post up a thread to show my creation at a later date. :cool:
     
    Last edited: Jun 24, 2014
  2. powella

    powella Member

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    You need a pressure release valve... And a pressure gauge to see what is going on...
    Be careful playing with hydraulics at high pressure...

    Cheers,
    AP
     
  3. mils1

    mils1 Member

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    The pump should have a pressure compensator, if not a pressure control valve is needed. Hydraulic pressure is safe as you can't compress a liquid but air can be dangerous.
     
  4. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Thanks, I am proceeding with caution. So basically that's a valve with an adjustable bypass which feeds back to the tank? Makes sense.


    I don't think it has any form of adjustable pressure control.
     
  5. kbekus

    kbekus Member

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    A build-it thread would be awesome please.
     
  6. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Will do.

    My first decision will be the hydraulic ram. I need to ensure it can provide enough force to split aussie hard wood, which has got to be the toughest in the world.
     
  7. disco frank

    disco frank Member

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  8. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Impressive. It bucks the log AND does an 8-way split.

    That ram has to be making in the vicinity of 50 tonnes of force. :leet:
     
  9. oculi

    oculi Member

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    just make one of these



    for the proper way you want to do it you will want some kind of pressure reliefvalve, or just put a gauge on and don't go above 2000 PSI or whatever the working pressure of the ram is.

    simpler way to do it would be to use a ram that is rated higher than the pump.
     
  10. OP
    OP
    maldotcom2

    maldotcom2 Member

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    That's so red-neck. Nek minit the axe head comes off and hits him in the forehead.

    I think i'll change rams and use a bigger one with a 4 inch bore. I'm confused though because the specs of the ram state 2500 psi "rated pressure" and 3850 psi "max pressure". I'm no expert but those two terms seem synonymous to me.

    So can I run it at 3000 or not??
     
  11. mtma

    mtma Member

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    To me the fact that they've provided two ratings to you suggests that the cylinder is designed around 1.75x safety factor; and that at 3,850 psi is the design value where the cylinder can be expected to fail irreversibly. This sort of rating is smack bang inside 'agricultural' range. Even the very cost conscious ag cylinders made by PTE are around 2:1 on buckling - and more likely around 3:1 hydraulically.

    P.S: You've mentioned the ram is rated to 2,200 psi in the OP but now you say 2,500 psi. If it's 2,500 psi the safety factor is around 1.5 which is even more marginal. To be honest I'd probably be rethinking this supplier unless it's one designing lightweight cylinders for racing boats or something. Does it really matter on your log splitter? Maybe not - but my philosophy is always 'Do it right or do it twice'.

    As for limiting the pressure you can get the result you want with either a pressure relieving valve or a pressure reducing valve.

    Both will control the output pressure to the cylinder however they work differently. The relief valve will probably be the most simple and suitable in this instance, as the reducing valve relies on the upstream system to have its own inbuilt pressure control (e.g. a pressure relief) to function properly.

    Most 'power pack's will be inbuilt with a pressure control of some sort, but if you're piecing something together you may need to add your own.

    Draw a schematic no matter how basic and make sure you're understanding what you're putting together before doing so. It will save headaches later.

    That's far from a sufficient qualifier to classify hydraulic pressure as safe. Most of the equipment hydraulics gets used on has more than enough potential to cause grievous injury from unplanned movement, the pump alone is usually enough to cause oil injections from pinholes and injuries related to hose blows - on top of that some systems do store energy by design.

    'Safe' should never be something that anybody should assume.
     
    Last edited: Jun 23, 2014
  12. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Thanks for the info.

    I was talking about two different rams from different suppliers. So far my searching has only been from online suppliers from the states. I will ask local hydraulics suppliers for a quote but I am expecting unreasonably high prices. Really i'd like a 4" double acting cylinder rated to 3000 PSI with at least 16" extension.
     
  13. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Ok. For those interested, i'll just make this the build thread.

    In my hunt for a hydraulic ram I rang my local hydraulics shop for quote on a new ram. They wanted $700 for something barely big enough *cringe*. I told them about my project, and they said they were cleaning up the shop and had some used rams for sale for $50 each. No receipt, no assurances, they have been sitting around for years. I said i'll take two!


    Click to view full size!


    These things are monsters. I know next to nothing about them, except they are *extremely* heavy and solid. The red one is a 4" and the yellow is a 3.5". Both are almost the same length, at 40 inches. If they work, beautiful. If not, a DIY hydraulic rebuild will be included in this thread. Oooo exciting. :Paranoid:

    In other news, i've ordered a high quality 2 stage 11 GPM hydraulic pump from the states. Should be here next week. Also ordered a rip-off Honda 6.5 HP 4 stroke motor to drive the pump. Once they arrive I can begin drawing everything up in CAD.

    My next dilemma is how to go about coupling the horizontally opposed shaft of the motor to the pump. There is a commercial solution called a Lovejoy disc coupling, however if I can DIY something that would be better...
     
    Last edited: Jun 24, 2014
  14. Meth

    Meth Member

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    or... calculate the poundage (I'm Old - cant use Nm or KW....), use mechanical "disadvantage"
     
  15. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Well i'm young and I quite often find myself working in pounds and inches. PSI is much more widely understood than kPa. Not sure exactly what you're referring to, but if you're talking about Pascal's Law, then this unit should, in theory, make around 17T of force.

    Here's a drawing of the CAD assembly, consisting of the beam, stop, wedge and cylinder.


    Click to view full size!


    I may also add a support under the front end of the cylinder to alleviate any stress caused from the full weight from the cylinder acting on the slide mechanism.

    The 6.5 HP motor, hydraulic pump and valve have all arrived now. :leet:

    I decided to go with the commercial Lovejoy jaw type coupling to join the motor output shaft to the pump's input shaft. For $40 it wasn't worth the time to engineer the same thing from scratch. Here's a mock-up of the bell-housing with coupling. Pump and motor are not fully drawn (shafts only), so imagine motor is on the left and pump is on the right. 19mm and 1/2" shafts respectively.


    Click to view full size!


    Fabrication of the Bell housing started on the weekend.


    Click to view full size!



    Click to view full size!


    And here is some of the steel I have so far. 200*100*6 RSJ, 10mm plate, and salvaged safety rails (6mm plate and tubing). I also have some 8mm plate and 1/2" plate.


    Click to view full size!
     
    Last edited: Jul 7, 2014
  16. mad_mic3

    mad_mic3 Member

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    How's the progress with this going
     
  17. OP
    OP
    maldotcom2

    maldotcom2 Member

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    Sorry for super late reply. I didn't sense much interest in this so I didn't bother to post updates. After a whole heap of procrastination (read: 6 months) It's almost finished, just gotta pull my finger out and get the lines made. I'll post some fresh pics soon. :thumbup:
     
  18. Mickatroid

    Mickatroid Member

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    Cool looking forward to it. How about a youtube link too :)
     
  19. ShadowBurger

    ShadowBurger Member

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    yeah give us a few piccies :)
     
  20. Frostex

    Frostex Member

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    also interested. this is cool as!
     

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