want to build a log splitter, need advice

[chad fitz]

Hello, Im new here, it looks like there is alot of knowledge on this forum. Have some questions. Im going to build myown log splitter for next year and have several questions. As of now I think i want to copy or come close to the iron oak splitter with adjustable weadge and log lift. Like i said i will have alot of questions but will ask only a few at a time to help keep things organized.
Question. cylinder size, motor hp, pump = tonage and cylcle time, i know one equals the other but dont understand the calculations which means i dont know if i change A, this will happen.
Currently condidering the following
4" x 24" cylinder with 1 3/4" or 2" rod. Iron and oak uses 3" rod, what difference does the rod make? If i end up with a 4 1/2 or 5" cylinder, whqat happens? slower cycle, more tonage? How much slower? how much more tonage?
2 stage 22 gpm pump, is there a "right" size hydrualic tank?? they use 14 gallon. Is there a rule of thumb for gpm = oil capacity?
11hp motor, they use honda, i will likely not be able to affford honda, so will any 11hp motor work the same. If i end up with a higher hp motor what will happen? speed, tonage, go up. will i need different pump etc??

Thanks for any and all help, i have the fabrication ability but not the knowledge to know what parts to get. My plan is to gather all the parts over the next few months in the hope of saving money.
chad

 

[hr3]

Not sure if you know it or not but there is a search function at the top of the page.. You might try it here and in hydrualic section too.. Good luck with your project..

 

[bullbreaker]

Welcome to TBN ! Might also want to do a TBN search under home made LS tons of info on here from members who have built them.
Good pic's too !

Boone

 

[muddstopper]

Here are enough calculators to get you started. Surplus Center - Tech Help

 

[chad fitz]

thanks for the links, i will take a look at them and then likely have more questions down the road.
thanks again chad

 

[motoman3b]

Chad, you'll be fine with a 4" cylinder the bigger you go the more tonnage but slower cycle times. I rebuilt a splitter and with a 4" cylinder running 3000psi I havent found a log it wouldnt split. The bigger the rod the better for cycle time and strength, match the motor to the pump bigger is only going to suck more gas the pump will only pump what it can. As far as oil capacity they recommend 1 gallon of fluid for every gpm so 22 gals for that pump. Good luck with the build you'll learn alot!

 

[LD1]

Motor gets sized to the pump. Going with a bigger motor only burns more gas, but dont increase speed or power, cause those are determined by the pump. You only need a motor big enough to run the pump up to is max pressure, anything above that is a waste.

I have heard two rules of thumb on sizing tanks for a 2-stage pump.
1. 2.5-3x's the high pressure flow. On a 22gpm, the high pressure is like 6gpm. So that makes you need a 15-18gallon tank.
2. Half of the low pressure flow. Which is 22gpm on a 22gpm pump. That would call out for 11. Iron an oak is tried and true, if they use 14 gallons with a 22gpm pump, stick with that. But is their resivoir actually 14gallon???or is that total system capacity???

Either way, on the tank, you are splitting hairs. If it were mine, I'd probabally just make it an even 15 gallons That way, 3 buckes of oil works out perfectally.

Cylinder size:
As cylinder size goes up, speed goes down and force goes up. At 3000psi, the following:
Cylinder.............extend time...................tonnage
4x24..................3.6 sec..........................18.84
4.5x24................4.5sec..........................23.85
5x24..................5.6 sec...........................29.5

A 4" cylinder will slit mostly EVERYTHING with a single wedge. But with you wanting a 4 or 6 way, you may find some things it wont go through. I'd opt for the 4.5" if it were mine. Thats a good balance of speed and power.

As to the larger rod, yes it makes it stronger, but a 2" rod on a 4 or 4.5" cylinder is pleanty strong so I doubt thats why they did it. Rather it makes the return cycle alot quicker since the rod occupies space in that side of the cylinder, the bigger it is, the less fluid it takes to fill up and fully retract.

with a 4.5" cylinder, going from a 2" rod to a 3" rod shaves a full second off the cycle time. (3.6 sec vs 2.5 sec). A full second when splitting wood for production is huge.

And any 11HP motor should work just fine. It dont matter wether is honda, briggs, kohler, or anything else, 11hp is 11hp. Just be sure to use a lovejoy coupling and not a ridgid shaft to shaft coupler

And as others have mentioned, do a search on this site. These questions have been answered numerous times in the past, and you can see the end result of several here who have done what you are wanting.

 

[MFWD]

Hey Chad,
I don't know your age or skill level, but making a splitter is a fun and rewarding project! Every time that you use it you will be rewarded with the feeling of accomplishment !!! I built one about 25 years ago and am still using it today !!! I was a Technical Education high school teacher and I built it over several months after school hours. Got to take the perks when you can get them...LOL !!!! I had complete use of the metal shop and that was VERY helpful. One of the best machines that was of great help was the vertical milling machine........not everyone has one of those to use....maybe you do !!!! It was great for squaring up metal, leaving a straight true edge and also for milling the point on the splitting wedge. To this day, 25 years later, you can still almost cut yourself on the edge !!!! Also, you have to remember that you won't save much money buy building it yourself, with the cost of all the items needed, this is an expensive venture. Steel prices are very high right now also. This forum will probably be of some help, but you should go to ArboristSite.com and pose this question there. That site is made up of people who just love cutting and burning wood. Many people on that site have built their own splitters and they are a wealth of knowledge !!!! Good luck with the splitter and please keep us updated with pictures !!!!!

MFWD

 

[Scooby074]

My Build http://www.tractorbynet.com/forums/build-yourself/219145-woodsplitter-build-timberwolf-clone.html

There are many others too. I have a hyd 4way and lift on mine FYI.

I use a 5" cyl with a 22gpm pump and you cant keep up with it as one guy. 2 guys are working. My pump never really has to shift to low flow (high press) so it basically sees 22gmp all the time. Typically when working by myself, I only run the engine at 3/4 throttle to save fuel, and even then its plenty quick.

My advise, if you go with a 22gpm, step up in motor size. I have a 14hp robin on mine, and if i turn the pressure up above 2200psi, the engine will stall. The manual says 14 should work fine, but in practice I'd say 16hp minimum, maybe 18!!

 

[LD1]

My advise, if you go with a 22gpm, step up in motor size. I have a 14hp robin on mine, and if i turn the pressure up above 2200psi, the engine will stall. The manual says 14 should work fine, but in practice I'd say 16hp minimum, maybe 18!!

Thats odd. Does it only want to stall when you are only running 3/4 throttle??

2200psi on the HP side of only 6.5gpm and factoring only 85%eff should only require 9.8hp to do that. Odd that you are stalling a 14hp motor??

Looking at the specs, it is also odd that the iron and oak is only using an 11hp motor. cause the calculations 3000psi call for a tad over 13hp. Maybe they are only running 2500psi, or maybe the 11hp is with a 16gpm??? but even 2500psi calls for a tick over 11hp.

At any rate, something between 14hp and 18hp should be fine and should be little efficiency difference in them. But you dont need to go overboard and get a 25hp or bigger motor to drive it. Our splitter has an 11gpm pump which is 2.9gpm at max 3000psi. At 85% that calls for 6hp. We have a 6.5hp briggs and it has never even thought about stalling.

 

[Scooby074]

Yeah the calculations dont work, at least in my experience. It does this at wot and 3/4.

Perhaps the motor isnt a true 14hp. I looked at its power graphs and its "supposed" to be. Its a Robin/Subaru. Not a "Bad" name in motors.

I have the pump chart somewhere for that Barnes 22gpm unit somewheres. I think it specs out that 14 hp is required.. Ill have to try and find it.

 

[LD1]

Thats odd your 14 hp does that. Maybe you are right that it isnt a true 14hp, or it is getting tired.

14hp does make sense for them to "spec", since the numbers (3000psi x (6.5gpm) / (1714 x 85%eff) and you get 13.38hp required.

Its just odd that yours does it at such a low pressure where eve less HP is required.

I dont know how I & O get away with the 11HP honda unless it is a 16gpm pump or a 22gpm turned way down

Either way, like I said, anything between 14 and 18hp and you arent going to notice much difference in efficiency. Just keep it within reason. No need for a 27hp kohler to drive a 22gpm pump.

 

[Camdigger]

Yeah the calculations dont work, at least in my experience. It does this at wot and 3/4.

Perhaps the motor isnt a true 14hp. I looked at its power graphs and its "supposed" to be. Its a Robin/Subaru. Not a "Bad" name in motors.

I have the pump chart somewhere for that Barnes 22gpm unit somewheres. I think it specs out that 14 hp is required.. Ill have to try and find it.

It is baffling to me your engine isn't capable of running the pump. Log splitter pumps are usually Hi volume/low pressure combined with a lower volume/high pressure side for the extra oomph for the split. it almost sounds as if your pump isn't making the functional switch between the low pressure-hi volume side and the high perssure-low volume function.

BTW, what is the gpm output of the low volume setting? You have only given an output of 22 gpm, which I presume is the low pressure output. There should be two output rates for a typical splitter pump.
Are you running a pressure gage?

 

[Scooby074]

22GPM Barnes. P/N 1300488. Notice high flow @750psi peaks at over 14 HP (red line is approx 14hp).

I might have to adjust the shift point lower ... Not sure if i want to screw with it though. It splits everything as is

 

[Camdigger]

22GPM Barnes. P/N 1300488. Notice high flow @750psi peaks at over 14 HP (red line is approx 14hp).

I might have to adjust the shift point lower ... Not sure if i want to screw with it though. It splits everything as is

The source i came up with quoted 650 psi as the factory set point for max high volume output. Hmmm the plot thickens...

 

[LD1]

22GPM Barnes. P/N 1300488. Notice high flow @750psi peaks at over 14 HP (red line is approx 14hp).

I might have to adjust the shift point lower ... Not sure if i want to screw with it though. It splits everything as is

Are you saying that it is stalling on the HF-LP side?? I thought you said it was stalling above 2000psi which could care-less where the HF-LP side is set at.

And if you have enough power for it to shift with it set at 750psi, you certainly shouldnt be stalling at a tad over 2k on the LF-HP side

 

[Scooby074]

It was around 2500 on the high when i was getting it to stall. Earlier I indicated "over 2200" I wasnt really clear but,thats where I set the old pump to keep it from stalling out. Perhaps I could have tweeked it a bit more and got a few hundred PSI, but I had a problem with system pressures jumping all over the place and my autocycle valve was giving me fits.

I dont know where exactly I'm shifting right now.. Could be 650 as mentioned above? I dont think I ever had an issue with stalling on the LP side in operation, I did cause it to stall on lp when playing with the settings. My current pump is a new, warranty replacement pump and I havent begun to screw with it. So it's whereever the factory set it.

Northern says its rated 22GPM@650psi and 6.5GPM@2500. If its shifting at 650, that puts me at around 11 HP required. 11HP should only capable of pushing 2000 PSI with that pump.

Heres the same curve with ~11hp, 650PSI (LP) and 2000 Max press.shown in blue. 3000PSI is in Yellow. In order to hit 3000, you need minimum 16HP by that curve. The calculations say that shouldnt be the case though. It should be OK with less. Thats why I suggested going bigger than 14 and certainly bigger than 10 or 11 as Northern suggests. In practice the pump uses more HP than it should

 

[Camdigger]

If your pump is shifting and is stalling your 14 hp engine at 2500 psi, that is exactly what the red line in your diagram tells me it should, within 10 - 15%. That's about as close as I would expect under the conditions I would expect on a splitter. Oil viscosity and filter condition (if so equipped) as well as ambient (outside) temperature will all affect oil properties and back pressure.

 

[chad fitz]

Wow, al the info is great. mY background is custom woodworking and laser engraving. My neighbor will be doing all the fabrication in his steel shop. My job is the design and grociery shopping, and making sure this thing make splitting wood as comfortable and enjoyable as possible. Nothing worse thean using a splitter that has a tire right where you want to stand etc..... I split most of my wood alone, thereforethe splitter will have the capabilities of the second person that never shows. Again, thanks for the info, this is all helping very much.

 

[Scooby074]

If your pump is shifting and is stalling your 14 hp engine at 2500 psi, that is exactly what the red line in your diagram tells me it should, within 10 - 15%. That's about as close as I would expect under the conditions I would expect on a splitter. Oil viscosity and filter condition (if so equipped) as well as ambient (outside) temperature will all affect oil properties and back pressure.

I agree..
The whole point I was trying to get at was that Northern and Hyd Sirplus are saying that 10-11 hp is OK to use. You'll never see its rated output using that (aside from what IO and TW seem to be getting away with)

Curve calls for ~14 ish HP, but i could never get it reliable with MY 14Hp engine at 2500. I agree there can be outside factors as listed in your post.

Calculation says you can get by with 11.15 Hp@2500 & 6.5 GPM. (2500*6.5)/(1714*0.85) = 11.15 HP

Basically all im saying is follow the curve as the bare minimum and not the calculation when using these pumps, or you'll end up short on HP, doubly so when you start figuring in real world conditions like thick oil and other loads.

This is what burned me. I calculated (and read) ~12Hp to run the pump @2500 reliably. I stepped up a bit and went with a 14Hp engine. I still cant hit 2500 reliably. I really need 18 maybe 20 , in real world conditions.

I did not have the pump performance curve when I bought the pump for my machine. At the time, Barnes Haldex was sold (?) and changed names to Concentric, and all the old links to their manuals were invalid... And search engines hadn't updated to point to the proper place. If I had of seen the chart for the pump prior to purchase I'd never have went with 14 Hp. Probably 18 minimum. The upgrade cost at time of purchase isnt that bad.

Im trying to prevent others from the same issue.