Elaboration on how hydraulic log splitter mechanics.
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    Default Elaboration on how hydraulic log splitter mechanics.

    I want to build a hydraulic log splitter. The only requirements I have are it has to have a tonnage of 45,000tons. I want to be able to understand how in other splitters they use only a pump capable of 28gpm and max psi of 3,000psi to create the same force. I've done the math. I don't know if I did it wrong or something else is adding tonnage. Any help?

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    45,000 tons? Are you sure?

    That's quite a log....

    If you really meant 45 tons, (90,000 lbs), then you would need a cylinder with an area of 30 square inches to achieve that force at 3000psi.

    A 6-inch cylinder would get you close.

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    Quote Originally Posted by Stephonoe8569! View Post
    I want to build a hydraulic log splitter. The only requirements I have are it has to have a tonnage of 45,000tons. I want to be able to understand how in other splitters they use only a pump capable of 28gpm and max psi of 3,000psi to create the same force. I've done the math. I don't know if I did it wrong or something else is adding tonnage. Any help?
    You probably are thinking of 45 tons, not 45,000. The latter is 90 million pounds force. The F-1 engine from the Saturn V booster (the most powerful single chamber rocket engine of all time) creates only 1.5 milllion lbs force. You don't, um, need 90 million pounds force to split a log.

    So, 45 tons is (45 x 2000 = ) 90,000 lbs force. You have a compressor that is 3000 psi. That's pounds force per square inch. Force = pressure x area. So area = Force/pressure. That is,

    area = Force/pressure = 90,000 lbs force/(3000lbs force/square inch) = 30 square inches.

    You need a hydraulic cylinder with a ram that is 30 square inches in cross section. Using pi * r squared, that works out to a little more than a 6 inch diameter ram.

    If you truly have 28 gpm at 3000 psi (that's about a 20 horsepower pump), you have 28 gpm * 239 cubic inches/gallon, or 6692 cubic inches/minute. That gives you
    a nominal ram speed of 6692 cubic inches / minute /30 square inches, or 232 inches per minute, or 3.7 inches per second. May be faster than you need.

    But... A 40 ton log splitter with a 25 gpm pump and a 14 hp Kohler engine can be had for 2 grand from Tractor Supply. Used double acting cylinders in that rod diameter range, from Surplus Center, are alone going for more than 2 grand. And you need the frame, suspension, wheels, engine, valves, hosing and fittings, and wedges to boot.

    Is there some magic about 45 tons? Are you splitting 3 foot diameter ebony?

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    Most purchased wood splitters do creative calcutlations on there numbers, most suppliers use a 3600 psi rated cylinder and thats how they can get those ton numbers. But the pressure reliefs are set at 2000 psi so in actualuality it is closer to a 27 tons. A 5” cylinder at 3000 psi will have an 8” ibeam with a 1/2” web flexing and groaning. Trying to figure the math. gallons per minute is speed,psi is how much work it is capable of. then the diameter of the cylinder is figured in to change the psi into tons of push. the formula is radious squared,times pi,times psi.

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    Why do you want to build one? I also assume you mean 45 tons not 45,000 tons??? I gave up a few years ago on rental yard splitters as they could not handle pepper tree, eucalyptus and oak. I have a 60 ton splitter I purchased new for $1800. I could not build one for that as you need a big cylinder, pump and big motor. Does it really make 60 tons, probably not but it leaves the 20 ton rental splitters like at home depot in the dust. Have not found anything yet it could not split.

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    What they call 2 stage pumps eliminates the need for large hp engines.
    When you start pushing 45 tons your fab work will be tested, study the beefy ones.
    good luck
    Gw

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    Quote Originally Posted by awander View Post
    45,000 tons? Are you sure?

    That's quite a log....

    If you really meant 45 tons, (90,000 lbs), then you would need a cylinder with an area of 30 square inches to achieve that force at 3000psi.

    A 6-inch cylinder would get you close.
    What i'de like to do with the splitter will need 45tons, I believe. I was really wanting to make like a 10 split cutter. Having the cylinder press the log against the cutter instead of cutting it itself. I sell wood so the quicker I can split it, the more I make. If you suggest a smaller tonnage, I'm open to suggestions. The reason I'm so hammed on building it is because Ive never done anything like it, and would like the challenge.

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    Quote Originally Posted by Stephonoe8569! View Post
    What i'de like to do with the splitter will need 45tons, I believe. I was really wanting to make like a 10 split cutter. Having the cylinder press the log against the cutter instead of cutting it itself. I sell wood so the quicker I can split it, the more I make. If you suggest a smaller tonnage, I'm open to suggestions. The reason I'm so hammed on building it is because Ive never done anything like it, and would like the challenge.
    At 1.20 / gal. for propane WTF does anyone heat with wood? What is your time worth. Add the cost of gas, chain saws, truck / trailer to haul it, log splitter, Time to do the work, time to stack it, time to carry it in, time to remove the ashes. Wood makes no sense to me at all.

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    Quote Originally Posted by moonlight machine View Post
    At 1.20 / gal. for propane WTF does anyone heat with wood? What is your time worth. Add the cost of gas, chain saws, truck / trailer to haul it, log splitter, Time to do the work, time to stack it, time to carry it in, time to remove the ashes. Wood makes no sense to me at all.
    Until the power goes off and 955 of gas or oil heating appliances need electricity to run, so you sit and shiver? ......no thanks, plus there's nothing to beat a woodstove for a cosy room.

    Just my 2 cents

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    Quote Originally Posted by Limy Sami View Post
    Until the power goes off and 955 of gas or oil heating appliances need electricity to run, so you sit and shiver? ......no thanks, plus there's nothing to beat a woodstove for a cosy room.

    Just my 2 cents
    Allot of people around my area have "Hybrid" systems.
    A woodstove and a furnace/boiler (Natural gas, propane, oil, electric, etc.)

    So they fire the wood stove to knock a bit off the bill, and get that
    cozy concentrated heat in one room. Plus that emergency backup
    feature.

    When their too tired to haul wood, they just turn up the thermostat.

    Note the OP is wanting to split wood for sale to others.

    As long as they pay for it, who cares what they do with it....

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    Quote Originally Posted by moonlight machine View Post
    At 1.20 / gal. for propane WTF does anyone heat with wood? What is your time worth. Add the cost of gas, chain saws, truck / trailer to haul it, log splitter, Time to do the work, time to stack it, time to carry it in, time to remove the ashes. Wood makes no sense to me at all.
    I live in a rural small town. Many of the homes here have been for 60 years or more, and have two stories. A lot of them are dual firplace wood heated households. The cost of putting ventilation in is more expensive than cutting up a tree.

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    Quote Originally Posted by Limy Sami View Post
    Until the power goes off and 955 of gas or oil heating appliances need electricity to run, so you sit and shiver? ......no thanks, plus there's nothing to beat a woodstove for a cosy room.

    Just my 2 cents


    That is what the auto start / auto changeover propane generator is for. No there is nothing to beat my favorite chair and a room that stays at 70 degrees with no effort on my part! just my 2 cents

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    I have been involved with building a couple of them the last one was 24 horse briggs style motor out of a generator that had gone bad. it had a taper shaft so we bought it cheap. We used the 16 gallon per minute 2 stage pump and built the adapter. We started with a 3.5” cylinder because thats what we had. It would keep 3 guys hopping on rounds 2’ and smaller the splitter was a greedy whore when to came to keeping it fed. Upsized the cylinder to a 5” from the salvage yard that was a tierod cylinder, ended up blowing the cyclinder seals because of the flexing on larger tougher rounds. So now its waiting on proper 5” welded cylinder with a 3” shaft. with used parts we were about 1800 just in parts and seals and need another 600 for a cylinder. If I built another it would be a boxed beam style rather than I beam even for a 5” cylinder

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    Quote Originally Posted by Stephonoe8569! View Post
    What i'de like to do with the splitter will need 45tons, I believe. I was really wanting to make like a 10 split cutter. Having the cylinder press the log against the cutter instead of cutting it itself. I sell wood so the quicker I can split it, the more I make.
    Ok, this makes economic sense. The 28gpm pump, driven by a 20hp motor, and driving a 6 inch diameter ram that pushes the wood into a 10 split cutter. I get it.

    You'll need some way of centering the log - I think you want the center of the log at the center of the cutter, and a two foot diameter log and a 3 foot diameter will center out if you you have a static workpiece support.

    Quote Originally Posted by Stephonoe8569! View Post
    If you suggest a smaller tonnage, I'm open to suggestions. The reason I'm so hammed on building it is because Ive never done anything like it, and would like the challenge.
    I understand this. As do many others. I'd suggest going overboard with the frame i-beam or boxbeam, as idacal seems to suggest. You may find a surplus cylinder at Surplus Center. Good luck.

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    At these levels of expense for the machinery (purchasing & operating), I'm thinking "Chipper" and "Extruder" might be easier.

    Plus, you can start bringing in "already chipped", from other suppliers.

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    Thanks you my questions have been answered even better than I was hoping for!

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    Quote Originally Posted by Limy Sami View Post
    Until the power goes off and 955 of gas or oil heating appliances need electricity to run, so you sit and shiver? ......no thanks, plus there's nothing to beat a woodstove for a cosy room.

    Just my 2 cents
    Quote Originally Posted by Stephonoe8569! View Post
    I live in a rural small town. Many of the homes here have been for 60 years or more, and have two stories. A lot of them are dual firplace wood heated households. The cost of putting ventilation in is more expensive than cutting up a tree.
    Y'all stop bringing logic and reason into a perfectly good "trash people that don't do things like I would choose to do" argument.


    Believe it or not, some people, myself included, burn wood for more than simply cost reasons. At my old place, to burn LP I would have had to install an LP furnace and then still have to pay for the gas. Plus, what about the tough winters when LP is over $4/gallon? Not so economical then... that wood-stack doesn't change value, once it's on your property, it's value is secured unless you fail to keep it dry or keep it from decaying.

    For me, I have geothermal heat now, it's nice, but it can't keep up when the temp drops below the teens. The vast majority of geo systems are installed with simple electric backup, which is $$$$ to run. We also have an in-ground pool. I will be installing a small boiler to serve 3 functions at my place; secondary (or primary) heating in the winter, heating the pool up in the spring, and domestic hot-water heating any time the boiler is running. I have no shortage of wood at my place. Dead-standing ash trees are abundant and will require minimal splitting.

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    Quote Originally Posted by moonlight machine View Post
    At 1.20 / gal. for propane WTF does anyone heat with wood? What is your time worth. Add the cost of gas, chain saws, truck / trailer to haul it, log splitter, Time to do the work, time to stack it, time to carry it in, time to remove the ashes. Wood makes no sense to me at all.
    $1.2 per gallon for propane? Where? My delivery just was about $3.50/gal.

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    Quote Originally Posted by bosleyjr View Post

    If you truly have 28 gpm at 3000 psi (that's about a 20 horsepower pump)
    You might want to recheck your references. One horsepower of hydraulic is about 1gpm at 1725psi.

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    Re: $4.00 gallon propane.

    Buy (don't rent) (2) tanks, or whatever you need to get thru
    the winter.

    Fill up in the summer, when prices are much better.


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