PTO Log Splitter Project

IanM · Mar 9, 2006

MadDog,

I'm curious about the size of the lift cylinder you plan to put on you splitter. After wrestling with 42 inch doug fir rounds split in quarters, I'm planning on building my splitter with a lift! I would think a small cylinder, 1.5" or so by what ever length would be plenty to lift most anything I could roll on it. Have you sized yours yet? I saw on another post where someone used a 3" cylinder for their lift. I assume they just happened to have it.

Was given two 3' x 5' sections of 1/2 inch plate today that I can cut into some of the pieces I'll need. This is going to be slow but fun.

Ian

MadDog · Mar 9, 2006

I haven't sized the lift cylinder yet, but I think you're probably right. A 2" diam dylinder, operating at 2750 psi, can generate abouit 8640# (or over 4 tons) of force.

The calculation isn't very difficult. The greatest force is required when the log lift is in full down position, because that is when the cylinder will be most nearly horizontal. Once you know the angle at which it will be thrusting, andthe length of the arm between the point where the cylinder acts against the lift and the weight of the log, you can calculate the leverage force needed to move the log and the upward vector of the cylinder force and compare them.

What is most important is that the cylinder be mounted in such a way that as the log lift is raised, the distance increases between the point on the log splitter where the cylinder is mounted and the point on the lift arm where the cylinder rod is connected. This is how lift is created as the cylinder rod extends.

jimmysisson · Mar 10, 2006

Mad- here's a pic of the log lifter I made (crude, I know) for my splitter. It's a 2x8 Chief cylinder that lifts on the retract stroke. It has no trouble lifting the biggest thing I've put on it, a 36" sugar maple round about 2' long. It's set up so it pushes the table into the ground slightly when it's down, stabilizing the splitter when you roll the big boy onto the table. When it's raised, it delivers the round almost to the beam, and the outfeed extension of the table catches the off-side split piece for resplitting or throwing onto the trailer or whatever. The pivot points for the table arms are underneath the beam, probably only 3-4" oc apart from the cylinder pin in side view.
In this geometry, the higher the table the faster its motion. If I knew that ahead of time, I might have tried a different geometry. I made a plywood jig (being a carpenter) to test the motion and decide where the mounting pivots would be. The cylinder capacity was well beyond the lift requirements so I just built it the way the parts would fit best with the steel I had.
One choice would be to mount the cylinder under the beam and push the table up. The geometry would be the same, but you'd get more power lifting with an extend motion. I wanted to keep the cylinder away from the underside of the beam, though, as I take this up into the woods and split and dry my cordwood there. Some places it's kind of rough and I wouldn't want pistons or hoses down underneath.
You won't regret the lift table - you get more done in a day if you're not all worn out lifting logs or bending over to run a vertical machine.
Keep us up to date, and thanks.
Jim

MadDog · Mar 10, 2006

Very nice lift, Jimmy, thanks for the pic. I been playing with the geometry of the lift, too. It depends a bit on how high I want the bed of the splitter when I am operating. I'm thinking that about 30" agl would be pretty comfortable. Starting from that, the idea is to:

(1) mount the lift just below the top flange of the H-beam, so that it doesn't interfere with the ram slide but still gets logs up to the splitter bed,

(2) doesn't over-leverage the log but still allows mounting of the cylinder from the base of the H-beam so that the cylinder can raise the lift arm through its full range of travel.

Because the geometry of this isn't at all clear ro me, what I'm planning to do before buying a lift cylinder is to build a simple mock-up, mount it and then take some measurements to determine mounting for the cylinder. At that point, I will know better how much cylinder length and rod extension I need to cover the distance from full up to full down. I'm first going to see if I can make the calculations using graph paper but I expect I'll probably end up using a mock-up.

cp1969 · Mar 10, 2006

You might be able to farm out the design to a local school that has CAD instruction.

MadDog · Mar 10, 2006

cp, I appreciate your suggestion, and I may just do that if I can't figure it out myself.

I have a lot of fun playing around with other people's skills. In a way, that's what I do for a living. /forums/images/graemlins/grin.gif

MadDog · Mar 11, 2006

Finally got started today. Finished grinding and welded the first of the four gussets. I should get at least one more in tomorrow. I'm using 3/8" plate for the gussets and end plates and grinding a V groove to get good penetration in the T joint between the gussets and the flanges of the H beam.

.045" wire at 300ipm and 21 volts produced a nice pool although there's still room for some improvement in my control of the arc. The gussets and end plates go in first and that is good because they are less critical welds than the cylinder anchors and I am hoping that by the time that I have done all of the gussets and end plates my skills will have improved.

BTW, I have also worked out the geometry for the lift arm and cylinder. I don't think that I will need to do a mock-up because graph paper and a ruler and protractor proved sufficient.

I want to run the splitter with the top of the beam at about 30". A 38" lift arm will touch down nicely from that height and I'll weld an 18" long log platform to it, which should be flat on the ground at an angle of about 40deg.

With that laid out on graph paper I then started to experiment with cylinder distances using the inside of the bottom flange for mounting the cylinder and mounting the lift arm under and a couple of inches in from the edge of the top flange. The configuration that appears to work best is mounting the cylinder rod about 32" down the lift arm. When the lift arm is all the way down, the rod will be completely retracted and the cylinder/rod distance to the lift arm will be 26 1/4" As the rod extends it will push the arm and log platform upwards as it rotates on the pins by which it is attached to the under plane of the upper flange. By the time the the lift arm is level with the splitter bed (and horizontal) the rod will have extended about 5" (total cylinder/rod length a bit more than 31"). When the lift arm is in the full up position for storage the rod will be extended about 12-13" (total cylinder/rod length 38-39").

I can get a 3000# 2" bore cylinder from Baileys with retracted length of 26 1/4" and 16" stroke for $74 and that should work. I'm going to wait to order it until figure out the details on the wedge adjustment cylinder.

It's going to be a while before I'm ready to build and install the lift. For the next month or so, my weekends will be fully occupied setting up the cylinder, anchor, ram slide, wedges and platform above for the hydraulic tank, pump and valves.

Lots to do, but at last its underway.

jimmysisson · Mar 12, 2006

Mad, here's another thought. This weekend I got my old splitter out, rebuilt the carb and used it about 3 hours. I now remember a quirk. You roll a round onto the lift, pull the lever to start the table up. Let's say you then let go of the lift lever to rearrange the log so it aligns better with the ram. This happens most times, as the log shifts on the platform. Then, when you start back up, the table drops before lifting again. I guess a piloted check-valve cylinder like is used on hydraulic top links would prevent the sag-then-lift scenario, though it's expensive.
It's nice if the splitter somehow incorporates a kind of outfeed table, so the chunk split off first does not fall to the ground. On a big log, that first offsplit may be heavier than you might want to lift by hand. On mine the lift table extends out so the split piece stays on it, that works pretty well. Your lift geometry should try to put the table near the beam at as many points in its lift range as possible, to keep that area clear of debris and small splits.
I also advise your design gives you some room near the control valve to get away from the piece being split. I've been clearing some diseased beech trees; they burn great but have quite contorted grain. They tend to split hard, then burst apart when the splitter overcomes the inherent tension in the grain. You don't want to be stuck standing right next to the piece when it's breaking apart. My tires are right there, but with enough room to stand away a little.
Sometimes I wish I had a leg on the rear of the beam, since the trailer is balanced well until a real heavy log is pushed through the wedge. That brings the front up, so any slop in the hitch (mine is a pintle) translates into the back dipping down some. An adjustable leg would stabilize the rig.
We're interested in your progress.
Jim

bobodu · Mar 12, 2006

Sure wish I had a lifting device now...

That log is about 22 inches in diameter...weighs much more than I do!! /forums/images/graemlins/blush.gif

Think I'm gonna go with a simple knuckle boom and tongs though.Then I can easily move the splitter to the pile and pick the log up...don't have to roll it to the splitter like I would with a cynlider lift thingie. /forums/images/graemlins/grin.gif

MadDog · Mar 12, 2006

Jim: Thanks for the very helpful ideas, particularly extending the lift to serve as an outfeed table on the lift side. I am also planning an outfeed table on the other side.

I am going to attach the pto mountings to the middle of the beam so that the splitter mounts like most ground-engaging attachments, rather than going front to back. The H beam alone weights almost 350# and, with cylinders (ram, lift and wedge), hydraulic reservoir, valves, wedge, etc. the whole machine is going to weigh about 1050# (30 gals of hydraulic fluid will weigh about 250# or more). That's an awful lot of weight to be leveraging out about 8' behind the 3ph if you mount front to back. This way, the whole thing won't go much more than 4' back.

I am also planning to put drop-down legs on the ends to take the weight of the machine off the 3ph when it is running. I have this arrangement on my chipper/shredder and it works very well. It is easy to make telescoping legs; you just weld a short length of tubular steel (with a set of holes for pins to hold the legs) to the H beam and then make the legs from the next smaller size tubular that will fit inside the first, with a series of holes so that you can pull the legs up while moving, and adjust them for uneven terrain when deployed. You then weld 3x3 plates to the bottom of the legs so they don't sink into the ground.

BTW, installed the second gusset and ground #s 3 and 4 ready for welding when I get home from work tomorrow.
I also built the dolly frame. Once I attach the wheels, I am going to transfer the beam from the blocks on which it is now resting to the dolly, so that I can maneuver it more easily while installing the ram, etc. That will also get it up a bit higher where it is easier to work on.

When I've made enough progress so that I'm not totally embarrassed, I'll post some pics.