ram design question

[mga]

hi...new to the forum.

i just built a new log splitter, using an 8 inch H beam, a 5 x 24 cylinder, 18hp engine and an 11/22 gpm pump.

i am down to designing the ram for this. i have a 1 inch thick,6 x 8 inch push plate, but how should i design the slide for this so that it holds under pressure and move freely?

i came up with several designs, but unsure what will work best.

suggestions or photos? help is appreciated!!!!

 

[woodchop]

Make the bottom slide long enough so it does not " pinch" the pusher on the beam under pressure. Weld your'e name and year fabricated on the face of the pusher with a thick weld to create a rough surface.

 

[CaseyForrest]

Easiest thing to do would be to weld some angle on the underside of the push block base. Crappy thing is you cant run a bead where you really need it doing it that way.

I say, if you have access to some 5/8 or 3/4 drill bits and a press, is to drill 3 or 4 holes along each side and use bolts. You have to make sure your base extends out past either side of the beam to do this, but also puts more material there for stiffness. Youd then need 4 other pices of flat, two JUST Slightly thicker than your top plate. The other two leave about 2" wider than the middle piece to wrap under your top plate.

 

[mga]

Make the bottom slide long enough so it does not " pinch" the pusher on the beam under pressure. Weld your'e name and year fabricated on the face of the pusher with a thick weld to create a rough surface.

WHOA....that's a serious ram design!!

looks like i need to get back to the drawing board and add more steel.

 

[Butch(OH)]

Woodchop has it right, you need a long bearing area for the slide to lessen the amount of push lost from pinching and also breakage. Also looks like Woodchop has been there and done that when it comes to the amount of steel he used in his push block. With a 5" cylinder you are going to have a tremendous amount of push and if your block or wedge is not as heavy as his plan on a short first splitting sesson and a quick trip back to the welding shop.

 

[mga]

steel.....you'd think it would be all over the place. every recycling place i called claim they can no longer sell to the public. what's that all about?

so...i call some steel places.....$#$#$!$@[email protected] think they are now pricing steel the same as they do gold.

this ram is all i have left to do and i already spent 100 bucks on some steel.

so, to make it like the one in the picture...and easy 100 more....not to mention listening to the old lady...who thinks buying new drapes is more important. hard to figure women......

 

[turnkey4099]

steel.....you'd think it would be all over the place. every recycling place i called claim they can no longer sell to the public. what's that all about?

so...i call some steel places.....$#$#$!$@[email protected] think they are now pricing steel the same as they do gold.

this ram is all i have left to do and i already spent 100 bucks on some steel.

so, to make it like the one in the picture...and easy 100 more....not to mention listening to the old lady...who thinks buying new drapes is more important. hard to figure women......

For steel, try any shop that does welding. Been a long time since I bought any but those shops were always happy to sell (and cut to length).

Old engineers saying. It is simple to make one of something alike, the trouble comes when you try to make two of something alike.

Harry K

 

[cord arrow]

...well, you can pour the steel to it, or you can employ standard engineering practices.

...5 to 7 degree open angle on your pusher, 7 to 10 degree closed angle on your wedge.

...this will eliminate all "pinching" forces at the ram end, while maintaining constant straight line pressure on the workpiece.

...i cringe when i see some of the contraptions you fellows have welded up. and bolted up.

 

[mga]

...well, you can pour the steel to it, or you can employ standard engineering practices.

...5 to 7 degree open angle on your pusher, 7 to 10 degree closed angle on your wedge.

...this will eliminate all "pinching" forces at the ram end, while maintaining constant straight line pressure on the workpiece.

...i cringe when i see some of the contraptions you fellows have welded up. and bolted up.

could you elaborate a bit more on that?

any additional information would be greatly appreciated.

 

[Patrick62]

Trial and Error

...well, you can pour the steel to it, or you can employ standard engineering practices.

...5 to 7 degree open angle on your pusher, 7 to 10 degree closed angle on your wedge.

...this will eliminate all "pinching" forces at the ram end, while maintaining constant straight line pressure on the workpiece.

...i cringe when i see some of the contraptions you fellows have welded up. and bolted up.

I never thought about setting the pusher at a angle.... I have set the wedge at a very slight angle... Hmmm

Other than that most of the stuff I have assembled has been with what is laying around. Sometimes it works, sometimes it fails.

My "Critter Splitter" has some good points, and some not-so-great ones.
I am probably going to upgrade my beam to something MUCHO stronger. I am going to incorporate a interchangable wedge design into it. I want to swap from twin/three/four styles of wedge.

-Pat

 

[cord arrow]

i'll try.

an "open" angle on your ram tries to force the workpiece up and away from the beam.

this in turn applies drag pressure to the back-most area of the ram assembly.
now, given that this angle is only a few degrees, as opposed to the acute angle formed if the ram is driven down into the beam, (pinch point), it's relatively easy to see why some folks resort to the "more is better" philosophy to keep this from happening.

now, given that we're essentially trying to lift our workpiece into the air, we'll need something to hold it down.

if we "close" the angle of our wedge, we offset the lifting forces implied by our "open" angle ram.

i've built or have been on the designing end of some monsters, and all have used no more than two bolts each side to secure the ram assembly.

when done correctly, the ram attachment is no more than a guide. just a little something to keep it honest.

in the sake of full disclosure, i did not derive this on my own, i basically stole the idea from ramsplitter. i really could not believe how these splitters did so much with so little.

well, evidently a little engineering can offset a huge amount of steel.......

 

[Butch(OH)]

i'll try.

an "open" angle on your ram tries to force the workpiece up and away from the beam.

this in turn applies drag pressure to the back-most area of the ram assembly.
now, given that this angle is only a few degrees, as opposed to the acute angle formed if the ram is driven down into the beam, (pinch point), it's relatively easy to see why some folks resort to the "more is better" philosophy to keep this from happening.

now, given that we're essentially trying to lift our workpiece into the air, we'll need something to hold it down.

if we "close" the angle of our wedge, we offset the lifting forces implied by our "open" angle ram.

i've built or have been on the designing end of some monsters, and all have used no more than two bolts each side to secure the ram assembly.

when done correctly, the ram attachment is no more than a guide. just a little something to keep it honest.

in the sake of full disclosure, i did not derive this on my own, i basically stole the idea from ramsplitter. i really could not believe how these splitters did so much with so little.

well, evidently a little engineering can offset a huge amount of steel.......

I am glad your copies have worked out but you shouldnt cast rocks when your engineering house is made of glass. You can get by with the attitude with me as long as you are right but your wordy egineering explination sounds more like advertising lore for the uninformed to me. As a matter of fact It defys at least one law of simple machines, you certainly know of simple machines,, right?.

There is no reason to lift the work into the air, as a matter of fact the reason for both angles is to keep the forces close to the beam. The reasons for those angles are quite simple. The beam, pusher and wedge will always be stressed less when the load is closer to the beam . Raise the wood higher, or more accurately the push point on the wood, and you have a longer lever to stress the beam and how does the beam get stressed?? through the guides. Assuming the standard design with the pusher moving a person only needs to split about 5 blocks before he discovers that if the ends are not perfectly square the stresses on the beam and guides are multiplied many times if the long side of the block is towards the top. In that position you have effectively lengthened the lever and the whole push block is rotated backwards imparting a hi force to the guides and beam. A weak beam or block or guides will bend until the push block is flat against the end. A strong design will still impart hi forces to the guides none the less. If the long end is towards the bottom then much less twisting, or rotating force is sent to the beam through the block and guides as the lever is shorter. I kept a weak splitter going for years by paying close attention to how the blocks were rotated on the beam. The simple reason for Ramsplits pusher angle is to ease forces to the beam and the guides by making the bottom get the most push, MOST of the time. Of course a very crooked end will still push on the top but too much angle on the push block to counter act this would create an upward force that could cause the block to pop up out of the splitter, not a good situation. To sum the pusher angle up in simple layman's terms the angle of Ramsplit’s pusher is their best guess (or engineering principle possibly) to keep the push point close to the beam yet not cause the work to pop upward. By keeping the load close they can get by with less meat in the guides. A side note here is that a larger than necessary pusher area also makes for more twist, keep your pushers as small as can be. On to the wedge, it is angled to hold the work down on the beam, simple as that. If that end moves upward while splitting it causes the push point to move up on the push block just like a crooked end does. With the bending that occurs in all splitters under load a wedge welded square to the beam would be angled upwards.

Now away from my angry reply to the above. For all of you who are reading this wondering if your splitter is about to implode.
A longer guide will make for less force to the guide and beam in all situations and hurts not a thing for the backyard splitter builder who need not to be concerned with saving $10 per unit in material costs. I will stick with my first post, more is better, better than breaking, better than fixing, better than getting an MIT grad to draw it.

If all alse fails go copy one that works, good advise from Mr Cord Arrow

 

[SmokinDodge]

i've built or have been on the designing end of some monsters, and all have used no more than two bolts each side to secure the ram assembly.

Can we see some pics of them? How many cord have they split since they were built? Any modification to the original design?

 

[turnkey4099]

Nothing but shade tree mechaniking here but...

As I see it, adding angle to the wedge will only do one thing. Aid in -starting- the split. The split will then be starting on a point vice the full face of the wedge.

Once the split starts it isn't going to matter what the wedge angle is in practical terms as the split runs well ahead of the wedge. Well, it does except when shearing through knots.

I don't see that adding a few degrees of angle is going to accomplish anything other than at the start of the split.

One item that I don't see used is a strap holding down the front of the cylinder (no, mine doesn't have it either). In the shop I used to work (Ag implement manufacture) I saw a cylinder rod bent 30 degrees because the front of the cylinder was free to rise. Mine probably would never do it as it is not very powerful but some of the ones being built should add the strap. It is just a "U" folded over the cylinder and welded down to the armiture, the cylinder just 'floats' in the U.

Harry K

 

[mga]

interesting that you mention a front strap. i just threw out a 5 inch cylinder because the rod bent because the front of the cylinder raised so much under force. it was an old cylinder any ways and was experimental. but, to see an 1 3/4 inch rod bend like that was amazing.

however, this made me wonder about the ram/slide and how important it would be to build one right. my "new" splitter will definately have a front "hold-down" just "in case". better to be safe than buying a new piston rod.

back to the slide: didn't mean to start any controversy about this, but as i contemplated ram designs, i tried considering all the forces involved. what i have been doing is using 3/4" thick pine boards to build prototypes on the beam....so that i wont be wasting money on steel. i realize wood isn't going to give me the same "effect" as steel would, but i really don't want to be repairing this later or going out to buy a new cylinder down the road. (hey...don't laugh...they build cars out of clay before they build them out of steel)

i decided that keeping the piston rod low to the beam and the push plate as small as possible is my best option to reduce other forces. i thought i was getting close to a good design until the "5-7 degree angle" came into the conversation......now i have to rethink what i have.

so.......if i were to slightly tilt the ram push plate backwards about 5 degrees this would be better? seems like i will have to be sure it has some good support plates behind it because this would be putting pressure on the top slide...correct?

now, the wedge....they are usually just straight pieces welded to the beam. i never gave that much thought. that should be on an angle as well? or did i misunderstand that?


___________\_______\____ would this be basically what i'd be looking at? the first ( \ ) is the ram plate the second ( \ ) is the wedge. simple drawing...i know.

 

[turnkey4099]

interesting that you mention a front strap. i just threw out a 5 inch cylinder because the rod bent because the front of the cylinder raised so much under force. it was an old cylinder any ways and was experimental. but, to see an 1 3/4 inch rod bend like that was amazing.

however, this made me wonder about the ram/slide and how important it would be to build one right. my "new" splitter will definately have a front "hold-down" just "in case". better to be safe than buying a new piston rod.

back to the slide: didn't mean to start any controversy about this, but as i contemplated ram designs, i tried considering all the forces involved. what i have been doing is using 3/4" thick pine boards to build prototypes on the beam....so that i wont be wasting money on steel. i realize wood isn't going to give me the same "effect" as steel would, but i really don't want to be repairing this later or going out to buy a new cylinder down the road. (hey...don't laugh...they build cars out of clay before they build them out of steel)

i decided that keeping the piston rod low to the beam and the push plate as small as possible is my best option to reduce other forces. i thought i was getting close to a good design until the "5-7 degree angle" came into the conversation......now i have to rethink what i have.

so.......if i were to slightly tilt the ram push plate backwards about 5 degrees this would be better? seems like i will have to be sure it has some good support plates behind it because this would be putting pressure on the top slide...correct?

now, the wedge....they are usually just straight pieces welded to the beam. i never gave that much thought. that should be on an angle as well? or did i misunderstand that?


___________\_______\____ would this be basically what i'd be looking at? the first ( \ ) is the ram plate the second ( \ ) is the wedge. simple drawing...i know.

Wedge design: My thoughts, take it FWIW.

The wedge should have 'wings' starting about 1/3 back from the the point of the wedge and spreading out. Theory is that the sharp point starts the split and then the wings take over to force the block apart. That usually results in the piece splitting well before the ram makes a full extension. The "1/3 back" bit will allow the point to contact and shear through knots if you have enough power (and you do).

My wedge is 6" long by 9" high with wings starting 2" back from the point and speading to 3 1/2". Doing it over I would start the wings a bit further back. I would also re-do the entire splitter to build it bigger, taller and with more power but that is another matter.

Re: the "angles" thing. While there are real engineering reasons for it, in real life it doesn't matter for this application - just 'gilding the lily'. Any theoretical gain from angling them is going to be too minor to worry about. Or if it will matter, the entire design would need some serious re-design. Angle or not you won't know the difference other than in the satisfaction of knowing you built it with good engineering if you do angle them.

Oh, Yes your diagram is correct for the angles.

Harry K

 

[Patrick62]

Interesting discussion!

"now, the wedge....they are usually just straight pieces welded to the beam. i never gave that much thought. that should be on an angle as well? or did i misunderstand that?"

What I have done regarding this "slight angle" is prop my wedge up in the back with a hunk of something that makes it lean a little bit foreward. I have built the pusher straight up so far. I see no real advantage to making it any other way. When I upgrade my beam on the critter, I am going to mount my cylinder a little higher and in a straight line with the center of my interchangable wedge idea.

Overkill can be a good thing, sometimes. With my 5" cylinder at 2500 rated pressure it would be 49075 pounds of PUSH :hmm3grin2orange: I have never had to crank it up past 2000 for the stuff I have around here. It is capable of splitting logs sideways.

As far as a strap to keep the cylinder in check in relation to the beam, that is what the pusher is for. If something breaks, it tells you that it wasn't strong enough.

My $0.04 worth!
-Pat

 

[mga]

thanks...to everyone. i'm just trying to build something that i won't have to worry about later on. as i design it, i'll keep all the suggestions in mind.

and, while looking around, i found this rather amusing...enjoy: (pdf format)

http://www.mech.utah.edu/~me3910/homework/problemSet5-ConceptSelection.pdf

amazing what some people can think of.

oops...one more question: should i use a rod clevis to attach to the slide, or can i mount the rod directly to the slide with a pin?

 

[cord arrow]

The simple reason for Ramsplits pusher angle is to ease forces to the beam and the guides by making the bottom get the most push, MOST of the time.

sorry if i was unable to make myself clear, this is basically what i was trying to say.

if i appeared to jump bad, it was unintended. long day, late night.

 

[turnkey4099]

A picture is worth...much easier than explaining it.

This is on my splitter. I don't think it would be possible to make a removable 4 or 6 way head to slip on it. As I said in my prior, I would start the wings back further were I to re-do it.

Harry K