log grapple design/dynamics? 3 pt

[jigs_n_fixtures]

The one pictured has a single double acting hydraulic cylinder to push the jaws open and pull them closed. If you have power to the rear, or a kit is available for your tractor to install it, it would be quite easy to get power to it.

 

[Gordon Gould]

This is another homemade grapple design. Created by a very capable fella.

Heading in a new direction..more like a circle.

Heading in a new direction..more like a circle.

forestryforum.com

gg

 

[arrow]

With 100 feet to move, time and fuel are likely not a large issue.
"A small parcel" was mentioned by the OP.

Ok. Let's do the math and the op can judge for himself:
A rear grapple might grab two of these stem pieces, He will have to maneuver backward to position the logs to line up the rear grapple especially for a multiple log "bite" so a lot of back and forth movements. A turn will be 200' and I will discount the back and forth for positioning because he would do that anyway to load a trailer but his loading work will always be in front of him.

So he carries say only 6 logs on a trailer but that is 400' saved or more than the length of a foot ball field. If he carries 8 logs, that is two football fields saved. It adds up surprisingly fast.
How long in time is a turn?
How many logs does he have?
How large in diameter are the stem pieces?
Does the op even care about time?
Whether it'd be a small wood plot or 90 acre logging parcel, forwarding logs has it's place.

As far as logistics, he already has a front grapple. All he needs is a small trailer and he doesn't have to fabricate anything. Heck, he can even load a ground chain, wrap up the chain and skid those out.
I'll leave it up to him because no one here knows the variables.
The op might just love to tinker and make things so creating a rear grapple simply adds joy to his life.
I, being a retired logger, looks at things in time only because time was money.
My boss even frowned upon (and that's putting it mildly) his guys "blipping" a chainsaw because that wasted fuel.
Efficiency was king so right or wrong, that is the approach I bring forth.

 

[davedj1]

Well said Arrow.
Time is not that important, I am doing it for my own and the landowners use not selling any firewood.
I do enjoy spending time building things in the shop, I build and sell the grapples for the front of tractors, skid steers and I have even built one for a mine excavator. I am thinking if this works well I could market it as well. More of a R&D really.
I did have a thought this afternoon, for maneuvering's sake I could use this on the front so I am thinking about making it convertible or at least the boom, take it off the top of the 3 pt set up and move it to a quick attach plate on the front.
I can't really just drive up to a lot of the pieces and use the front grapple, too many stumps, deep ruts from the big skidder etc.
If it was my land I would have had it logged a bit different, I would have had the logger drag the entire tree to the landing, cut the logs off and leave the top where it is, repeat. It's only a 5 acre lot and I feel they made more of a mess than was necessary although I do understand they are pressing to maximize profits.
So far no one has really addressed my initial concern of the actual geometry of the working grapple part. It doesn't matter now as I have it welded up today, a single double acting cylinder above the pivot point so it will close up on push and pull to open. I happen to have a 2.5" bore x 6" stroke cylinder here. I used the PAD method (plywood aided design) LOL I'll get a pic or two tomorrow as I am whipped.
I do understand that I won't have 270* of rotation and will pretty much have to back up to them straight on, I'm ok with that, I have cut a stump or two here and there so I can get around.
If I had help I would just park the tractor with winch at the landing area, run the cable out to the short pieces and drag them in and repeat. It's too much work alone and I have bad knees.
I am going to add some sliders and hooks to the cable so I can haul 3 or 4 pieces at a time.
I'll keep ya all posted!
Thanks,
DAve
ETA: I can't see getting a trailer around in there although I would love to build a small forwarding trailer with a grapple on it.

 

[arrow]

Well said Arrow.
Time is not that important, I am doing it for my own and the landowners use not selling any firewood.
I do enjoy spending time building things in the shop, I build and sell the grapples for the front of tractors, skid steers and I have even built one for a mine excavator. I am thinking if this works well I could market it as well. More of a R&D really.
I did have a thought this afternoon, for maneuvering's sake I could use this on the front so I am thinking about making it convertible or at least the boom, take it off the top of the 3 pt set up and move it to a quick attach plate on the front.
I can't really just drive up to a lot of the pieces and use the front grapple, too many stumps, deep ruts from the big skidder etc.
If it was my land I would have had it logged a bit different, I would have had the logger drag the entire tree to the landing, cut the logs off and leave the top where it is, repeat. It's only a 5 acre lot and I feel they made more of a mess than was necessary although I do understand they are pressing to maximize profits.
So far no one has really addressed my initial concern of the actual geometry of the working grapple part. It doesn't matter now as I have it welded up today, a single double acting cylinder above the pivot point so it will close up on push and pull to open. I happen to have a 2.5" bore x 6" stroke cylinder here. I used the PAD method (plywood aided design) LOL I'll get a pic or two tomorrow as I am whipped.
I do understand that I won't have 270* of rotation and will pretty much have to back up to them straight on, I'm ok with that, I have cut a stump or two here and there so I can get around.
If I had help I would just park the tractor with winch at the landing area, run the cable out to the short pieces and drag them in and repeat. It's too much work alone and I have bad knees.
I am going to add some sliders and hooks to the cable so I can haul 3 or 4 pieces at a time.
I'll keep ya all posted!
Thanks,
DAve
ETA: I can't see getting a trailer around in there although I would love to build a small forwarding trailer with a grapple on it.

Well Dave, those are the "variables" I mentioned.
I agree w your premise of leaving whole stems as opposed to what they did. That is so weird to me that they did that unless someone told them to cut up the stems but why was there no landing established? That was one of the first things we did..
My crew would never log a parcel the way you describe plus we had a company who wanted the slash so clean up was almost immediate.

You sound as a very skilled metal worker so my hat's off to you in that regard and you're right, your geometry question remains up in the air unless it's hidden in one of the example build plans some contributed.
Too many people here (including me) telling you what to do instead of answering the question.

 

[Xfaxman]

I have searched but have come up empty handed. Just the open/close part I need help with. Thanks

Have you done an image search? 3 point log grapple drawings - Image Search

 

[davedj1]

Have you done an image search? 3 point log grapple drawings - Image Search

Yep, first thing I did. I think I have it figured out. Of course it would probably have been a good idea for me to see one in person prior to attempting this..lol
Anyway, I just braved the cold and went out to the shop and snapped a couple of pics of what I have so far.
Notice the pivot holes are not on the same plane, this seems to be needed so the will bypass each other instead of smashing ends.
The whole thing is about 24" tall
Instead of using chains I think I am going to use to 3/4" D rings like one of the pics I saw.

 

[Xfaxman]

That looks like a good start.

 

[ROUSTABOUT]

I'm going to build a 3 point log grapple, I have never really seen one up close so I don't know how the geometry is for opening and closing. Anyone build one or have a schematic of one? I have searched but have come up empty handed. Just the open/close part I need help with. Thanks
It will be this design:
View attachment 770272

We run a grapple for decades. We put a winch on the grapple. No longer use the grapple part, it is the winch carrier now. Winch was so good, we bought a FARMI, and it's really good. Winch is a lot better. My brother and I used to have short wood pulpwood trucks with cable loaders. I can't stress enough how much better the winch situation is. I been at it since Jimmy Carter was president.

 

[Sawyer Rob]

If I would want to haul full length trees for a good distance this is what I would want ... a logging winch is good if you can't access the tree to haul it out to the trail but not skidding it for 3000ft

I totally disagree with that, what do you do with that grapple arm when you can't get the tree through a muddy spot, or up a hill?? With a winch, no problem at all!

I'd MUCH rather have the winch on that small tractor...

SR