Logsplitter 2.0

[rswyan]

Not really true.

Actually, it is true ...

Let's say it takes 15 tons of force to split a particular piece of wood.

Using my rig with the 4" cylinder, it would take 2387 psi to generate that much force ... and about 4.9 hp to generate that 2387 psi @ 3 gpm.

Using jimmy's rig with the 5" cylinder (but with the same pump), it would only take 1500 psi to generate that much force ... and only about 3.0 hp to generate to the 1500 psi @ 3 gpm.

Diameter of the cylinder, and tonnage it generates, has little to do with the load the motor sees.

Actually, I'd say it has a lot to do with it ... but I'm assuming a scenario in which one isn't seeing maximum pressure.

You size the motor to the pump.

No argument there ...

The motor dont care what size cylinder there is, or how much force the cylinder can generate.

Of course not ... it's an inanimate object ... it's incapable of feeling or thought ...

What puts load on the motor is PSI.

Yup ... that exactly true ... but when it takes less psi to generate the same splitting force, there is less load on the motor.

If you have both a 4" cylinder and a 5" cylinder.....and pump set at 2500 psi, the motor is gonna see the exact same load when generating max pressure.....no more.

That's also true ... but the part highlighted in bold is your qualification.

I didn't qualify my original statement in that manner ... which is why it is potentially true ... but not always true in every case (ie. max pressure)

The difference is .....for that same 2500 PSI, the 5" cylinder can generate more power....but is proportionally slower as well.

Yup ... and generating the same force at less pressure = less load on the motor.

Looking forward to seeing how the revisions to the lift and wedge work out. Keep us posted

Will do ...

 

[rswyan]

Don't feel too bad over it. Most of the HF coupons exclude Predator anyway.

Apparently, rumor has it, that they will accept the coupons on Predator gas engines ...

 

[rswyan]

One thing about the Predator engines is...most high performance Honda parts will fit them...
By just changing the carb. jets and the muffler (header) you can increase the HP...other mods will increase it even more...some guys have dyno tested the hemi-6.5 model at twice and three time the stated 6.5 HP...after the modifications...

FWIW...some good info on mods of all types for the Predators can be found here:

Honda / Clone / Predator

Good info to know ... :thumbsup:

 

[LD1]

Typically you see a max load on the motor scenario, momentarily, #1 when retracting the cylinder and building enough pressure to kick out the detent, and #2, when shifting the pump from high flow to low flow.

Those are the biggest "load" on the motor as they are nearing in on max HP requirements.

So in that asspect.....those two functions being pressure based, there would be no difference.

The point you make is valid, but overall....it is unlikely you would notice a difference in the two splitters in terms of how "hard" the motor is working. And besides, you have a 4" cylinder with 4-way wedge. IF you had a 5" cylinder you would probably have a 6-way or 8-way wedge....so you would just load it up more and the load on the motor would still be the same

 

[rswyan]

Typically you see a max load on the motor scenario, momentarily, #1 when retracting the cylinder and building enough pressure to kick out the detent, ...

I have a 1A and 1B on this one ... since I have detent on both retract and extend.

Also, the max pressure to kick out the detent is only 2000 psi ... which is 20% below max system pressure. Might be able to get more if the detent could be shimmed ... but I don't know how advisable that would be.

The valve will operate above 2000 psi of course, but you have to hold it.

and #2, when shifting the pump from high flow to low flow.

... assuming that one has the unloader on the pump adjusted so that it's maxing out the engine in high flow/low pressure mode ... which, from an efficiency standpoint, one should.

I'm not there yet ... as I backed the unloader adjustment out pretty far, as part of trying to figure out what was going on with that old engine. I can probably squeeze a little more out of the current setup as far as the shift point goes, without stalling the motor.

Those are the biggest "load" on the motor as they are nearing in on max HP requirements.

Except if I hold the valve in, after the detent releases, to generate maximum force on extend.

So in that aspect.....those two functions being pressure based, there would be no difference.

True.

The point you make is valid, but overall....it is unlikely you would notice a difference in the two splitters in terms of how "hard" the motor is working.

And besides, you have a 4" cylinder with 4-way wedge. IF you had a 5" cylinder you would probably have a 6-way or 8-way wedge....so you would just load it up more and the load on the motor would still be the same

Quite likely ...

 

[rswyan]

Thought I had the pin locations for the log lift sorted out ... but it turns out not.

So rather than taking one step forward only to have to take two steps back, I got all the dimensions and modeled the parts in my CAD program yesterday and spent a few hours trying to figure it out.

This thing is giving me fits ... could be it's a "you-can't-get-there-from-here" sorta deal ...

I think it's a combination of factors:

1. location chosen for the log lift hinge (arbitrary decision, and not easy to change at this point)

2. stroke length of cylinder being used (arbitrary decision, and not easy to change at this point)

3. log lift being three sections with two angles, rather than two sections with one angle (arbitrary decision, and not easy to change at this point)

The second (top) angle is creating a clearance problem with the cylinder, which prevents getting a decent initial starting angle.

Gonna spend some more time on it here in a bit and see if I can't come up with a solution.

 

[LD1]

Do you have the table back on the splitter? and the new cylinder base mount tacked on?

Perhaps post a good side shot of what you are into, maybe we can offer some advise.

 

[rswyan]

Do you have the table back on the splitter?

The output/catch table and the log lift are both back on the splitter currently.

... and the new cylinder base mount tacked on?

Nope ... decided no more tacking - or cutting metal for that matter - until I really have it figured out.

Base mount might be hanging up there with a magnet, hafta go check.

Perhaps post a good side shot of what you are into, maybe we can offer some advise.

I think I've come up with a workable solution ... at least in terms of clearances ... dunno about initial force.

A little more involved than I would have preferred, but probably the least amount of T and E in light of the various options.

I'm going to redo it as AJ suggested - cut the lift where the vertical section meets the section that is at 45 degrees ... and roll the vertical section back so it's laying at 45 degrees.

I'll have to extend the (new) 45 degree section a little ... to get it to meet the hinges. Hafta see what I have available in the way of steel to accomplish that.

Picture below shows the new design, both lowered and raised ... circles show the retracted and extended lengths of the cylinder, has about 55 degrees of swing in it's current incarnation:

The drawing is scale, major grid = 1', minor grid =1/2"

 

[rswyan]

LD,

Here's the new dimensions ... if you wouldn't mind running the numbers :

AB = 8.75"

BC = 18.25"

AC = 22.312"

AD = 46.812"

I make the initial angle to be 22.1427 degrees ... which should yield 6661 lbs of force @ 2500 psi.

Taking into consideration the leverage, or lack thereof, I get 47.66% (22.312 / 46.812) ... which means I should be to lift around 3130 lbs ...

That sound about right ?

 

[rswyan]

Just checked the odds and ends up in the shop ... should have enough 1 1/2 square tube to extend the lift out on a 45 degree angle and meet the hinge pins.

The piece of 1 x 3 bar stock that I cut and drilled for the base end attachment will work perfect with the current placement ... should still have 1/8" of retraction left after the lift hits the ground.

In comparison to the last drawing I posted, I'll be shortening the ends of the 1 1/2" tubes (that are on a 45 degree angle) at the top ... so that the log lift can be left in the "up" position as the push block travels down the beam. Should have plenty of clearance ... although there will be about a 3" gap between the lift and the beam.

Couple of new dimensions, after a little tweaking:

AB = 9"

BC = 18.125"

Initial angle: 22.8495 degrees ... ?

Cylinder force @ initial angle: 6862 lbs ... ?

Lift, taking leverage into account: 3270 lbs ... ?