Thread: New log splitter

splitez makes a decent splitter, all honda engines and the big ones have commercial pumps. This one is the 34 tonner:



11 second cycle time

splitez sure looks like an excellent machine, but 34 ton unit is $4K. way more that I want to spend.

Originally Posted by 046

anyone familiar with current harbor freight offering?

they've got a 30ton with robin motor for $1,100

http://www.harborfreight.com/cpi/cta...emnumber=91840

I'm curious to know how this 30 Ton Harbor Freight unit performs also. In general, Harbor does not have the highest quality stuff, but that Robin engine is good quality and the pump is a name brand as well. Sure would like to hear from someone who has one.

Tom

046: I know nothing specific about the splitter you asked about, but I would get much more in the way of specs and details, if I were you, before I bought it. A 30 ton splitter usually uses a 5" bore cylinder and develops about 30 tons at 3000psi, the max at which most cylinders used in splitters are rated.

I downloaded the manual on the Harborfreight splitter and it uses a 4.5" cylinder. That cylinder can only generate 47,700# of ram force at 3000psi and that is slightly under 24 tons. There is no way that a 4.5" cylinder, operating at usual hydraulic pressures, can generate 30 tons.

Moreover, the 1 3/4" rod is pretty marginal for a cylinder that generates that force. I have a 2 1/2" rod in the 5"bore cylinder that I am using in the splitter that I am building.

Also, a splitter that can generate even 24 tons (not to speak of 30) needs to have a pretty strong structure or it will be subject to twisting (deflection in the beam) at maximum pressures. The spec doesn't say the beam size, but it looks like about a 5 1/2" I beam. H beams are stronger and by way of contrast I am using an 8x8 H beam on the 30 ton splitter that I am building. I'm not saying that this is necessary; I've probably overdesigned mine, but anything less than a 6x6 with reenforcing gussets and endplates may not be adequate.

Finally, the manual specs say that it has a 2.5 gal hydraulic reservoir. That is very thin for a 16gpm pump; the usual rule of thum is 1 gal of reservoir for each gpm of pump capacity. The reason is the need to dissipate the fluid's heat. Excessive heat may build up in the hydraulic fluid, especially under heavy or continuous operation. Heat buildup is increased by smaller diameter hydraulic tubing and the specs do not disclose the size of the tubing/hoses.

Bottom line is that there are lots of ways to save $$ when building a splitter but lots of them affect the quality and durability of the machine in important ways. Generally, you get what you pay for. Were it me, a splitter is not a machine that I would try to cut corners or save $ on. I'm not saying that the HF splitter won't do its job; I haven't inspected or used one and I don't know; but the description of it leaves me with enough doubts so that I wouldn't spend my money on it without a lot more information.

Hope this helps. Good luck.

I didnt know harbor freight sold anything that wasnt a quality import.

I downloaded the manual on the Harborfreight splitter and it uses a 4.5" cylinder. That cylinder can only generate 47,700# of ram force at 3000psi and that is slightly under 24 tons. There is no way that a 4.5" cylinder, operating at usual hydraulic pressures, can generate 30 tons.


You are correct if you are figuring pressure on the surface area of the ram. But you also must then figure out how many square inches the face of your wedge is, the point I mean because thats where all that tonnage is being applied to.

CaseyF, I'm not sure that I'm following you. The total ram force doesn't (I think) get any greater or less, regardless of the area of the area of either the wedge or the push plate. Since the wedge itself is generally sharpened the area of the knife edge is negligable and thus the ram's force is concentrated on a very small area indeed. As for the push plate (on splitters where the wedge is fixed and the cylinder/rod pushes the log into it) I don't think the ram force isn't either increased or decreased by the area of the push plate.

Have I got this wrong? Or am I just misunderstanding your point. I thought that the "tonnage" of a log splitter was the ram force generated by the cylinder and that, I think, is solely a function of the cylinder area multiplied by the pressure (in psi) of the hydraulic fluid.

You're obviously more experienced and knowledgeable about this stuff than I am, so I would appreciate your patience in explaining what I have missed.

thanks... this helps a ton!

ratings can and do get inflated. sure would like to hear from someone who has owned one of these.

Originally Posted by mdlmjohnson

046: I know nothing specific about the splitter you asked about, but I would get much more in the way of specs and details, if I were you, before I bought it. A 30 ton splitter usually uses a 5" bore cylinder and develops about 30 tons at 3000psi, the max at which most cylinders used in splitters are rated.

I downloaded the manual on the Harborfreight splitter and it uses a 4.5" cylinder. That cylinder can only generate 47,700# of ram force at 3000psi and that is slightly under 24 tons. There is no way that a 4.5" cylinder, operating at usual hydraulic pressures, can generate 30 tons.

Moreover, the 1 3/4" rod is pretty marginal for a cylinder that generates that force. I have a 2 1/2" rod in the 5"bore cylinder that I am using in the splitter that I am building.

Also, a splitter that can generate even 24 tons (not to speak of 30) needs to have a pretty strong structure or it will be subject to twisting (deflection in the beam) at maximum pressures. The spec doesn't say the beam size, but it looks like about a 5 1/2" I beam. H beams are stronger and by way of contrast I am using an 8x8 H beam on the 30 ton splitter that I am building. I'm not saying that this is necessary; I've probably overdesigned mine, but anything less than a 6x6 with reenforcing gussets and endplates may not be adequate.

Finally, the manual specs say that it has a 2.5 gal hydraulic reservoir. That is very thin for a 16gpm pump; the usual rule of thum is 1 gal of reservoir for each gpm of pump capacity. The reason is the need to dissipate the fluid's heat. Excessive heat may build up in the hydraulic fluid, especially under heavy or continuous operation. Heat buildup is increased by smaller diameter hydraulic tubing and the specs do not disclose the size of the tubing/hoses.

Bottom line is that there are lots of ways to save $$ when building a splitter but lots of them affect the quality and durability of the machine in important ways. Generally, you get what you pay for. Were it me, a splitter is not a machine that I would try to cut corners or save $ on. I'm not saying that the HF splitter won't do its job; I haven't inspected or used one and I don't know; but the description of it leaves me with enough doubts so that I wouldn't spend my money on it without a lot more information.

Hope this helps. Good luck.

Originally Posted by mdlmjohnson

CaseyF, I'm not sure that I'm following you. The total ram force doesn't (I think) get any greater or less, regardless of the area of the area of either the wedge or the push plate. Since the wedge itself is generally sharpened the area of the knife edge is negligable and thus the ram's force is concentrated on a very small area indeed. As for the push plate (on splitters where the wedge is fixed and the cylinder/rod pushes the log into it) I don't think the ram force isn't either increased or decreased by the area of the push plate.

Have I got this wrong? Or am I just misunderstanding your point. I thought that the "tonnage" of a log splitter was the ram force generated by the cylinder and that, I think, is solely a function of the cylinder area multiplied by the pressure (in psi) of the hydraulic fluid.

You're obviously more experienced and knowledgeable about this stuff than I am, so I would appreciate your patience in explaining what I have missed.

Allright, if you have a 4 in cylinder, the surface area of the ram inside the cylinder is 12.56 sq in. If you are running 2500psi you have a 31,400 pounds of splitting force.....On the cylinder. Now, the surface area of the knife edge on your wedge is not 12.56 sq in, its WAY les than that, so the tonnage on your cylinder gets mutiplied slightly. Lets say that the area of the knife edge is 1.4 sq i, then you multiply your 31,400 by the 1.4 and you get your tonnage at the wedge....which comes to just under 44,000, which equates to 22 ton. 22 ton is normal for a 4" splitter.

Pounds of splitting force equals= (hydraulic pressure in psi) X (piston surface area in sq. in.). I have never heard of the size, shape or color of the wedge entering into the calculations but it may be how HF does their calculations.

Originally Posted by TreeCo

Pounds of splitting force equals= (hydraulic pressure in psi) X (piston surface area in sq. in.). I have never heard of the size, shape or color of the wedge entering into the calculations but it may be how HF does their calculations.

I agree with TC. Splitting force is spec'd in force (pounds) not in force per unit area (pounds/sq. In). Therefor bringing the area of the splitting wedge back into the equation means absolutely nothing in determining the total force that the ram is capable of generating. I'm not sure how the HF guys get away with claiming that their unit is 30 tons unless they are running abnormally high pressures which is not likely.

I did a litte more research myself on the HF splitters. For me, I just plan to split 4 to 6 cords per year so I'm not looking for a production machine. Someone said that the oil resevior should have 1 gal of oil per each GPM flow rate to allow for heat disipation. This may be true for a production machine that is running many hours at a clip. I see myself splitting maybe an hour at a time or so and don't really worry too much about overheating the oil. Maybe you need to keep an eye on that.

Here is a thought I had about how the HF splitter is spec'd. To generate 30 tons of force ie. 60,000 lbs with a 4.5" cylinder, you need oil pressure of 3774 PSI. This may not be unrealistic. I visited the Haldex web site, they use these pumps on the HF splitters, and found that there are 2 stage pumps that max out a 4000 PSI. The problem I have is that I don't know what model pump the HF splitter uses. Another interesting thing I noticed is the 24 ton HF splitter (91839) has an 11 GPM pump and the total unit weight of 498 lbs. The 30 ton unit uses the same 9 hp motor and what appears to be the same 4.5 inch cylinder but it has a 16 GPM pump; this unit weighs in at 663 lbs. Obviously they beefed up something to allow for the higher splitting force, my guess is the I beam is heavier. Maybe it is running at the higher pressures after all.

Ok. Here is one of the design flaws I see with this splitter after doing more research. When the splitter is in the horizontal position, the split wood coming off the rail will be falling right on the top of the pump where the hose exits. If you look at many of the other splitter designs out there, the pump is on the opposite side of the unit. Say for example you load on a hunker of a log and it accidentally rolls off on pump side of the splitter, it may potentially land on the top of the pump assembly that is cantilevered off the motor. Over time I'm sure the split logs catching the output hose at the pump will not be good either. This is a bad design in my opinion.

Yep v8titan I agree that's a terrible design. The engine should be transverse, perpendicular to the bar, and the pump should be under the beam.

(Hey v8 where abouts in NJ are you?)

Originally Posted by DeanBrown3D

Yep v8titan I agree that's a terrible design. The engine should be transverse, perpendicular to the bar, and the pump should be under the beam.

(Hey v8 where abouts in NJ are you?)

I'm up here in Watchung. That's Near Summit/Berkeley Heights area.