My 3rd and hopefully last log splitter

[franklin2]

How big is your main beam? Have you used that before with success(or have seen others use it)? When I made my splitter, I didn't have a large enough I beam for the main beam. It was only like 3 inch I beam. So I had to make a "truss" below the beam to strengthen it. I used a 1/2"x6" thick piece of flat to rest the wood against(my wedge is on the cylinder) but found out that was not thick enough and had to double it up.

I found out a sure sign something is not strong enough is when you use the splitter, the split wood "flies" out of the splitter when you are using it. I found my wood laying on either side about 3 or 4 ft away from the splitter till I found the weak areas.

 

[mikefromnh]

It is 6x8 x1/2". I think around 41 pounds a foot.

I haven't used a box beam before, but some commercial units are made with them. From what I've read a box beam is more resistant to the twisting forces then a 10" h-beam would be. From what I understand most of the bending strength is from the web of a beam. And since a box has beam two sides vs the single web of an h-beam a box beam gives the best of both for a splitter. Better bending strength for a given height/weight and more resistance to strength.

 

[LD1]

It is 6x8 x1/2". I think around 41 pounds a foot.

I haven't used a box beam before, but some commercial units are made with them. From what I've read a box beam is more resistant to the twisting forces then a 10" h-beam would be. From what I understand most of the bending strength is from the web of a beam. And since a box has beam two sides vs the single web of an h-beam a box beam gives the best of both for a splitter. Better bending strength for a given height/weight and more resistance to strength.

Some of your information is correct, some isnt.

The web is NOT where the strength of an I-beam comes from. The strength is in the flanges. The top flange is trying to compress and the bottom flange is trying to stretch apart. The web just keeps them separated. The taller the web, the more the top has to compress and the more the bottom has to stretch for the beam to deflect, thus a stronger beam.

Look at trusses like they use on flat roofs. What would be the "web" is mostly hollow. Or look at the beams that actually have large holes (to make them lighter) in the web.

The I-beam is the most efficient shape for loading in 1 direction. IE: strongest with the least material. Modulus of Elasticity (i4) in combination with the height (depth) go into a formula to calculate the strength. Your 6x8x1/2 tubing is 42# per ft, and has an i4 of 103.

A similar weight I-beam shape of 8" depth is about 50% stronger. With an i4 around 150. And to match the strength of your tube, you could get by with about 12# per ft less. OR about 1/3 less steel.

But you are absolutly right about torsional stiffness. Tubing resists twisting MUCH more. BAsically you have the strength of an 8" I-beam that would have 6" wide by 1/2" thick flanges. That "extra" web does little to the strength in that direction, but does wonders for torsional strenght. I think you will be fine. And an 8" I-beam is about the heaviest you will find on most commercial large splitters with 5" cylinders. I know you are going 5-1/2", which gives you the "ability" to develop more force, but doubtful that you ever will.

 

[mikefromnh]

Some of your information is correct, some isnt.

The web is NOT where the strength of an I-beam comes from. The strength is in the flanges. The top flange is trying to compress and the bottom flange is trying to stretch apart. The web just keeps them separated. The taller the web, the more the top has to compress and the more the bottom has to stretch for the beam to deflect, thus a stronger beam.

Look at trusses like they use on flat roofs. What would be the "web" is mostly hollow. Or look at the beams that actually have large holes (to make them lighter) in the web.

The I-beam is the most efficient shape for loading in 1 direction. IE: strongest with the least material. Modulus of Elasticity (i4) in combination with the height (depth) go into a formula to calculate the strength. Your 6x8x1/2 tubing is 42# per ft, and has an i4 of 103.

A similar weight I-beam shape of 8" depth is about 50% stronger. With an i4 around 150. And to match the strength of your tube, you could get by with about 12# per ft less. OR about 1/3 less steel.

But you are absolutly right about torsional stiffness. Tubing resists twisting MUCH more. BAsically you have the strength of an 8" I-beam that would have 6" wide by 1/2" thick flanges. That "extra" web does little to the strength in that direction, but does wonders for torsional strenght. I think you will be fine. And an 8" I-beam is about the heaviest you will find on most commercial large splitters with 5" cylinders. I know you are going 5-1/2", which gives you the "ability" to develop more force, but doubtful that you ever will.

Great description of beam strength, obviously I'm not an engineer . I kind of 'knew' what you are saying but couldnt really explain it clearly.

So the 6x8 box beam beam is similar in bending strength to an 8" tall h beam with 1/2" flanges? But at a greater weight/cost?... But in exchange has greater twisting resistance?

 

[LD1]

So the 6x8 box beam beam is similar in bending strength to an 8" tall h beam with 1/2" flanges? But at a greater weight/cost?... But in exchange has greater twisting resistance?

Correct.

Tubing of anykind is exceptional for torsional strength.

But there is a reason you dont see alot of it in structural applications. Because it is heavy for its strength. When only dealing with loading from 1 direction. I-beam or C-channel can give the same strength with a lighter member. And since what you pay for steel is pretty closely related to weight......

Think of it this way: IF you were to remove one of the 8" sides of the tube and add that material to the top and bottom evenly, then shift the remaining side to the middle you would make an i-beam of the same weight, but would be MUCH stronger in the vertical direction. But weaker in the horizontal and torsional directions.

Logsplitters have force primarily in the vertical direction. That is why I-beams are used. The horizontal and torsional forces are more modest in comparison and nothing the beam cannot handle. IF you are building with what you have, thats perfect. The added strength in the horizontal and torsional aspects certainly isnt gonna hurt anything. But if paying for steel, And I-beam is more bang for your buck with a splitter IMO.

 

[mikefromnh]

I found that used 6x8 (10' long) for $70. I am planning a tall 18" wedge and 4 or 6 way post so I figured it was a good choice.

I'm not sure the height of the wedge matters for torsion forces, but figured it would hurt.

Does adding the 1" plate for half the length add any significant strength?

 

[franklin2]

I found that used 6x8 (10' long) for $70. I am planning a tall 18" wedge and 4 or 6 way post so I figured it was a good choice.

I'm not sure the height of the wedge matters for torsion forces, but figured it would hurt.

Does adding the 1" plate for half the length add any significant strength?

That 1 inch piece you are using as the guide? My guess is no, since it does not go all the way back to where the rear of the cylinder mounts. If it ran all the way back the whole length, then I would say yes it would add some strength. This is my backyard engineering guess, let's see what someone else says. I am learning a little bit here.

 

[mikefromnh]

A little more progress on the out feed table, log lift and side table.

The out feed table is removable to save a little space in the barn.

I made the side tables at a 45 angle and removable. Hopefully by making them at angle I can raise a log with the lift and have it roll into place without having to touch it.

I also will be able to swap the side that the log lift is on.

 

[s219]

Some of your information is correct, some isnt.

The web is NOT where the strength of an I-beam comes from. The strength is in the flanges. The top flange is trying to compress and the bottom flange is trying to stretch apart. The web just keeps them separated. The taller the web, the more the top has to compress and the more the bottom has to stretch for the beam to deflect, thus a stronger beam.

It's a chicken and egg thing, and you can't have an I beam without a web connecting the top and bottom flanges. So I don't really see a distinction or any portion of the beam that is more important than the others. For traditional top-down loading, the top flange carries the max compression load, the bottom flange carries the max tension load, and the web carries the max shear load at its center. Without a web interconnecting the max compression and tension elements, you wouldn't have a beam. And if the web wasn't capable of handling the shear load directly associated with the top compression and lower tension, you wouldn't have a beam. So it's one of those things where all the pieces are important together. Separately, not so much.

 

[Stihl Man]

Just about the same.. Just to show you that you are not the only one going that route. Many many advantages using box over I beam.
Glad to see you used cross tube type of cylinder over the tie rod end type.
Keep up the nice job can't wait to see it run..