Grapple project OPEN SOURCE

[Zebrafive]

Yea, that makes a difference.

Previously your cylinder was on a 7.1* angle, giving 970# of force at the cylinder for being on such angle, resulting in ~776# clamp force at the tines.

With the new measurements, You are on a 12.4* angle. Giving 1688# of force at the cylinder for that angle, resulting in ~1350# of clamping force.

Amazing what just a few inches and few degrees can make.

Interesting LD1 calculated my "bite" at 1300lbs using my tractor's rated pressure of 2250psi. In post #115

 

[ovrszd]

Yea, that makes a difference.

Previously your cylinder was on a 7.1* angle, giving 970# of force at the cylinder for being on such angle, resulting in ~776# clamp force at the tines.

With the new measurements, You are on a 12.4* angle. Giving 1688# of force at the cylinder for that angle, resulting in ~1350# of clamping force.

Amazing what just a few inches and few degrees can make.

Thank you very much for babysitting me thru this!!! I owe ya!!!

 

[LD1]

Im late to the conversation so i might be saying whats already been said but my little homemade grapple attachment shows a really simple example of the math behind cylinder placement. i set it up to rotate through 90 degrees so with 4" stroke cylinders the cylinder pivot point is set back 2 inches and set up 2 inches to achieve 90 degrees of travel. the pushing force of both cylinders combined is slightly under 8000 lb so with a 20" distance between the pivot and tooth i get around 800lb at the tooth when fully shut and fully open with the max force being around 900 lb at 45 degrees (i dont remember exactly). Its certainly no double lid root grapple but for being made from scrap and made to get tossed in my toolbox and forgotten most of the time, it serves well.

View attachment 529554
View attachment 529555

Cannot see the pictures

 

[Xfaxman]

amhicks21, read this for loading pictures: http://www.tractorbynet.com/forums/photos/107314-photo-posting-how-3.html?highlight=#post3967120

 

[LRomero]

Any progress? Looking to build a grapple myself and looking for plans or a CAD drawing.

 

[polemidis]

Any progress? Looking to build a grapple myself and looking for plans or a CAD drawing.

I have pause developing it for now, I am focusing on another project. It is in a good stage though. It needs:
a) a bracing plate/cylinder protection sheet in front of the cylinder
b) gussets on the tines or they will bend

At the BOM, hydraylic hoses, and the dxf file for the CNC are missing. Feel free to add that info to the spreadsheet if you end up building it.

Grapple - AGreekulture Farmstead Wiki

 

[pwborst]

Any more progress? I just skimmed and most formulas seem sound. Maximum torque will be present when a right triangle is formed. Who picked the required bite force? It seems owners are happy regardless of what the math says but maybe they don't have any other experience to compare to.

Research your material choices carefully. It would be such a waste to go to all this work and use a36 mild steel when AR 400 has at least 3 times the yield strength and Better impact and abrasion resistance. Or save a little money and use a572-50.

Id be happy to cut your files for you polemidis

 

[texasranger556]

Any more progress? I just skimmed and most formulas seem sound. Maximum torque will be present when a right triangle is formed. Who picked the required bite force? It seems owners are happy regardless of what the math says but maybe they don't have any other experience to compare to.

Research your material choices carefully. It would be such a waste to go to all this work and use a36 mild steel when AR 400 has at least 3 times the yield strength and Better impact and abrasion resistance. Or save a little money and use a572-50.

Id be happy to cut your files for you polemidis

OP started another thread on this subject here:

http://www.tractorbynet.com/forums/showthread.php?t=390754

Edit: Looks like you already posted in the other thread!

 

[polemidis]

pwborst I wrote a new reply on the other thread. A572 is the material of my choice. AR400 would make a perfect choice if you think that we can weld it. How much more expensive is it? And I would happily go with 1/4" instead of 3/8 with that alloy!
That offer of cutting the files cannot overlooked!!!! hahaha! where are you located? PM me plz

 

[suncoast]

Maybe I'm not P.C. ,I thought the very purpose of this site is for people who own / use farm & construction equipment a resource to share, teach, help, learn....
Maybe some input from others who read this. If someone shares construction plans or cad files here and 1000 people read this post.
Say perhaps 500 of them will purchase a grapple attachment in the next 3 years. (These #'so don't matter)
Out of these 500 people, how many do you think will build their own grapple rather than outright purchase? Saws, grinders, welders, drills, paint sprayers, time, etc
I don't believe the attachment builders, sellers here have anything to worry about.

 

[polemidis]

Maybe I'm not P.C. ,I thought the very purpose of this site is for people who own / use farm & construction equipment a resource to share, teach, help, learn....
Maybe some input from others who read this. If someone shares construction plans or cad files here and 1000 people read this post.
Say perhaps 500 of them will purchase a grapple attachment in the next 3 years. (These #'so don't matter)
Out of these 500 people, how many do you think will build their own grapple rather than outright purchase? Saws, grinders, welders, drills, paint sprayers, time, etc
I don't believe the attachment builders, sellers here have anything to worry about.

Hey man! Thats an old post that you dig out From my point of view, I really do not care if any attachment manufacturer has to worry. Since open sourcing these projects is helping humanity to go further, nothing else matters, actually, IF open sourcing does not violate any laws (patent laws included)

Anyway I still have a plan to create a big repository of open source implements and tools, but I have been stuck a bit because I enrolled to college for mechanical engineering, and my free time goes there.

In this specific implement, after 2 years of use(abuse), I believe I have some feedback:
a) AR400 is weldable even from beginners like me if you be careful on heating/cooling. I have zero cracks on the metal.
b) 1/4"=, even AR400, will bent if you use the grapple as a dozer blade! haha! But If you use it to move stuff around, I think its fine. Od course, if you have a tractor bigger than a compact one and you have enough lifting force available, go to 3/8. Its removes the stress factor.
c) The top square tube has to be 1/4" thickness at least. The 1/8" will rip like newspaper when you grab something with the 2" cylinders at 2500psi. Literally like newspaper!. I was not paying attention and I didnt do stress analysis there. Combine this with my zero experience on metal fabricating, resulted in a big fail on the top square tube. I say 1/4" at least, because I doubled the top face of the cylinder between the lid hitches) with a 1/4" flat bar to avoid another breakage.
d) The front round bar that goes between the tines was a simple sch 40. Wrong. It bent at one edge at some point. I would go with both sch 80, and one diameter size up.

Anyway, just a few thoughts after working with the grapple. I use it in the forest as I am thinning to make piles of limbs, and to load the firewood processor.

 

[suncoast]

What drives the I know better than all of you dissertation here. To caution the cost of building your own / one off project is worthy input but why continue to beat a dead horse?
“It’s not worth it to do your own” , “just buy one from a manufacturer”.
If Edison listened to this discourse, we would have an abundance of oil lamps and candles.
Perhaps think that this “one off build” discovers a great improvement to the status quo.
Do you know how penicillin was discovered?
Have any of the negative input people here even met the person undertaking this project? Yet he’s destined for failure, right.
Advice - absolutely, input - definitely, cost consideration advice - bravo.
Verbal beat down destined for a failed task -
childish, selfish, obtuse.
Wish I were a Mensa member like so many here think they are.

 

[BASSIN20]

I agree with texasranger556, I try to build as much of my attachments and things that i can to try and stretch my dollars as much as possible. but there are things you can not physically fabricate yourself, as he says basically hydraulic systems in a nut shell can get down right expensive. what i have discovered is if it has hydraulic attached to it or some other fancy mechanical operation that requires some sort of machine work to fabricate the couple hundred one might save to fabricate their own, most times it just not worth the effort to do it yourself. After all ones time is worth something, my2cents!