Looking for splitter, might build one

[clr8ter]

I've been looking around for a splitter, and can't find what I really want in a $1 - 1.5K machine. My biggest 2 items are I want the wedge on the outside, and a higher cycle time. Yes, I know, those things don't go together. So I'm contemplating building one, with a higher budget, while still keeping it reasonable. I know little about hydraulic design, but my basic understanding is that starting with the cylinder and working back is the way to go. Pick say, a 4" cylinder with a 30" stroke, 2" rod. Math tells you how fast an X GPM pump will fill that, and the pump says how big the motor has to be. I found a 22gpm HI/7gmp LO pump that requires 12 HP on Surplus center.com. Me desire is for a Honda GX motor, but they don't make an appropriate HP model. Closest is 11.7 HP. Slightly more is probably better, and Predator makes a 15 something HP motor.
Back to the cycle time math, I'm not sure in reality what the splitting cycle time would be. Cycle time; assuming a 30" stroke, 20" log that kicks the pump into HI, but doesn't excessively bog the machine, return to fully retract position.

Any thoughts or opinions on any of this?

 

[Jags]

My first thought would be why a 30-in ram? Depending on what you're feeding most stoves cannot handle anything that long. Come up with your longest usable split and then size the ram accordingly. Excess stroke will only slow the process.
NOTE: A 22 GPM pump should run fine with an 11 hp engine.

 

[blades]

most factory units are running 1/2' lines and 1/2" ports on the cylinder. speed is how fast you can and fill the cylinder, that 1/2" stuff is restrictive which tosses heat generation into the equations. ( on some units I have seen a 1/2" hard line that is only 3/8" bore) ignoring that area for now an 11 gpm can fill a cylinder with 3/4" or 1" ports faster than that 13 gallon pump on 1/2" lines provided that everything after the pump is 3/4" or larger ( most of the pumps have 1/2" outputs that we use for splitters- haven't seen any with 3/4 or larger) lot of the contol valves are 3/4" also. Another area of concern are the fittings 90 deg should be avoided 45 deg better and all shoud be Hi-flow. So the up shot is pump of choice gpm wise , eng of of enough hp ( cheap source for eng are lawnmower tractors with blown hydro trannies- course most of these are vertical shaft units which makes the build bit more difficult) cylinder of choice with min. 3/4" ports and valve and lines at 3/4" as well. if my Habor freight pump and or cylinder ( 20+ years old) ever go south, i will op for a 3/4" port cylinder ( mine is a 24 inch stroke- more than enough unless you have an owb) and the 13-15 gpm pump( current at 11gpm /3gpm?). the unit is plumbed where ever possible with 3/4" and 45deg hi flow fittings ( ya I have one 90 in there, didn't have room for the 45 at that position) the poor original plumbing on the unit would cause so much internal friction in the fluid that after a 1/2 hr. you could not touch the cylinder with out getting burned. The 3/4" plumbing solved most of that and the adition of a 2 nd small expansion tank eliminated air being mixed into the hydro oil due to a very poor location of the return line to tank ( same height as the fill port- bad design as you can't fill the tank any higher than the fill port ( trying to cover the return line port ( should have had a turn down pipe on inside , which it dosen't) then when things expand form heat it boiled over. Which brings another point up 13 gpm pump should have at least a 13 gallon tank -bigger better- gives oil time to cool down a bit. input to pump should be at least on par with the out flow of the tank - pump preferably lower. return line should be a few inches below the hi oil level of the tank and preferably on the opposite end from the pump feed. An internal baffle wood be a plus but not really needed. A filter on the return line to the tank should rated gpm wise at least as much as the pump output. Think I covered all the bases.

 

[clr8ter]

Holy crap, that's a lot of info. Most of that is stuff I didn't know., but which makes sense. So do you consider the 1/2" output on the pump a problem? Just ignore and plumb with 3/4" anyway.

As to the 30" ram; The longest I can shove in my stove is 22". Usually, I aim for 20" wood, the thinking being that some will be cut long, and still fit. So, in all reality, I could easily get away with a 24" cylinder. Fair enough.

Additional thought; On cylinder bore size and rod diameter, how much is enough? Not looking to make a 40 ton monster, something in the range of 25 to 32 ton is fine. I believe that pump pressure and ram bore will tell you the tonnage it's capable of. Not sure how the rod diameter comes into play.

EDIT; a quick search tells me that most cylinders come with 1/2" ports, or SAE8, same thing. I had to go all the way to a 5" bore to find one with 3/4" ports, and then they get expensive. Even $600+ cylinders have 1/2" ports.

 

[ericm979]

A large rod makes the ram retract faster, because the effective piston area on the rod side is smaller (more rod == less piston). The force you need depends on the wood you're splitting.

There are calculators on line to get the force at the wedge. Keep in mind that a lot of splitters get their high force numbers by running a high relief valve pressure (and also a lot of manufacturers inflate their numbers). The cycle time is

cylinder swept volume in gallons/(GPM/60) + swept volume - rod volume/(GPM/60)

where swept volume is the volume of the stroke length you're using, which may be the total stroke or something shorter.



One option is to buy a H/V splitter and convert it to stationary wedge. You might need a retractable support leg if you add an outfeed table.

 

[crstrode]

Holy crap, that's a lot of info. Most of that is stuff I didn't know., but which makes sense. So do you consider the 1/2" output on the pump a problem? Just ignore and plumb with 3/4" anyway.

As to the 30" ram; The longest I can shove in my stove is 22". Usually, I aim for 20" wood, the thinking being that some will be cut long, and still fit. So, in all reality, I could easily get away with a 24" cylinder. Fair enough.

Additional thought; On cylinder bore size and rod diameter, how much is enough? Not looking to make a 40 ton monster, something in the range of 25 to 32 ton is fine. I believe that pump pressure and ram bore will tell you the tonnage it's capable of. Not sure how the rod diameter comes into play.

EDIT; a quick search tells me that most cylinders come with 1/2" ports, or SAE8, same thing. I had to go all the way to a 5" bore to find one with 3/4" ports, and then they get expensive. Even $600+ cylinders have 1/2" ports.

It is not the size of the fittings (ports) that mater, it is the inside diameter and length of the line where most unrecoverable loss occurs. Keep the lines short and straight with the minimum number of fittings and you'll be good.

You can refer to "Crane technical paper #410; Flow of Fluids", or take my word on it as a retired Nuclear Control Systems Engineer . . . just sayin'

 

[clr8ter]

It is not the size of the fittings (ports) that mater, it is the inside diameter and length of the line where most unrecoverable loss occurs. Keep the lines short and straight with the minimum number of fittings and you'll be good.

You can refer to "Crane technical paper #410; Flow of Fluids", or take my word on it as a retired Nuclear Control Systems Engineer . . . just sayin'

Yeah, I can probably take your word for it. So, 1/2 ports on the pump, cylinder, and maybe valve, but use 3/4" ID hose and keep straight and short if possible...

 

[qwee]

If I was you I would consider a kinetic splitter from SuperSplit - they are in your neighborhood. They are just better than hydraulic splitters. You pay a bit more but you work a lot less. I unfortunately used a kinetic for a while. If I had only remained in the hydraulic slow zone I wouldn't know the difference. But if you aren't doing that much wood a hydraulic splitter is fine.

 

[clr8ter]

I've actually used one of those. I liked it, but it's not the greatest at big, gnarly pieces. Plus, the expense.

 

[Jags]

With 1/2 inch ports on pump and cylinder the relatively short hose runs on a splitter will barely notice the upsizing to larger hoses.

 

[blades]

the output of the pump is fine . 3/4" valves are priced about the same as the 1/2"- larger bore less restrictions. 3/4" ports on cylinders can be had at about the same price as 1/2" just got to talk directly to MFG, not everything is in those listings. 3/4" line will cost a bit more than 1/2". Again restriction in the fluid flow causes friction = heat . Heat is the bane of hydraulics- should not run much more than apx 120 deg F. 2" ram is pretty common in both 3"and 4" cylinders. The ram is what is transmitting the force. Don't want that deflecting . If you are building it might as well get right the first time, only cry once that way wallet wise.

 

[clr8ter]

Agreed there. Might as well spend the $ and not wish for more. I did end up finding cylinders with 3/4 ports on rugged made. NOT cheap, but looks good.

 

[blades]

just looked up those cylinders 4"x24" stroke", 2.25" ram, $239 that's a decent price for brand new. for my rig that is a drop in. their valve prices are nice also. if you get the one with power beyond you could add a lift later on or right away (hint ya got to cut the flow rate down for a lift, easy to make your own flow control by welding a fitting closed and drilling a 1/8" hole through weld course ya got to do that with out mucking up the theads)

 

[clr8ter]

I just looked at the power beyond valves, they don't have an auto return. It also says it's not an auto return valve. Not sure what that means. I think I'd rather have an auto return over a lift. If I did go with a lift, making my own as you say would be easy. I work at a metal fab shop, and welding is part of my job, so no issue there...

 

[xman23]

I've seen a few slick home built's. Quite a project I don't think your saving any money, unless you have access to free parts.

 

[clr8ter]

Nope, spending more money at the point. And yeah, I would design it to be slick, and very professionally done, to include powder coating. I work at a metal fab shop, and half or more of the steel I'd need is just hanging around. All mechanical parts would be new.

 

[duramaxman05]

You could build a 2 way splitter. No wasted return. Ours is a 2 way that used to run off the pto on a tractor spinning a 20gpm single stage pump. I put a 10hp briggs vanguard on it and it works pretty good. The single stage will kill the engine if the knife stops. If the wood gets too rough and knotty, I just cut it up with the chainsaw. You can split a lot of wood with a 2 way.

 

[clr8ter]

I don't think it'd save time for me. With auto return, I fiddle the next piece of wood while it's doing that. A bigger time savings for me would be sizing it just slightly longer that what I have to split, so it can return all the way without having to do too much non-splitting ram travel. To that end, a high GPM pump is in order. I see that it's easy to get a high GPM in low pressure, but harder to find one that will do it in high pressure. About the best I've found is 7 GPM in high.

 

[duramaxman05]

On benefit to the splitter we have is when you split a good size round, you can put both halves on one side of the table and move them towards you when ready to split. We usually have the conveyor set up behind you on the right side to set the wood on.

 

[ericm979]

I don't think it'd save time for me. With auto return, I fiddle the next piece of wood while it's doing that. A bigger time savings for me would be sizing it just slightly longer that what I have to split, so it can return all the way without having to do too much non-splitting ram travel. To that end, a high GPM pump is in order. I see that it's easy to get a high GPM in low pressure, but harder to find one that will do it in high pressure. About the best I've found is 7 GPM in high.

My splitter goes into low speed (high pressure) so rarely that I don't really care how fast low speed is. It's a 4.5" cylinder and I have some wood species that are quite difficult to split- live oak, eucalyptus (blue gum) and bay. There's times when the wedge is more like cutting the wood than splitting it. It's convenient for me to be able to keep going when that happens and not have to toss the wood aside and come back later with a saw. Of course other folks have different work patterns where that might not be an issue. I tend to either cut or split but not both in the same session.

I recommend making it so the pusher goes within a half inch of the wedge. On my splitter it's more like 1.5" and with the stringy wood that's not close enough. Bay is the worst. If all your wood is like fir and splits with just a few inches of wedge in it, disregard this idea.

My splitter has a detent return where I move the lever and the cylinder retracts all the way. I think that's typical. Is auto return more automatic than that?

 

[clr8ter]

Yes, auto return is hands off ram retraction. There's a detent to keep the lever in the retract position. I wouldn't build a splitter without this feature, no matter the cost. As far as having the ram get closer to the wedge; YES! I have often wondered why they stop 2" short. Stupid IMO, considering the ram extension is fixed. It's not like you could keep going and run it into the wedge... I was definitely planning on making the ram go to within 1/2" or less. Come to think of it, I could build the ram with a groove to "over travel" it, without hitting it...