Grapple project OPEN SOURCE

Rustyiron · Nov 8, 2017

I just joined in late, you math guy's make me wish I had paid more attention in school. polemidis, if you would like to see a 7' grapple that I bought over 15 years ago (Lofflin mfg) that has spent it's life on a 115 hp skid steer w/tracks to observe how a hillbilly can abuse one and the results after all those years, I'm a few hours "down the road" from you.

In all seriousness, I have abused it (done things it was not intended for) and I only have "tweeked" one of the lid's a few inches from closing "square". That was pulling logs out from the end and turning. Very good post here and welcome to tbn!

jmc · Nov 8, 2017

Rustyiron said:
In all seriousness, I have abused it (done things it was not intended for) and I only have "tweeked" one of the lid's a few inches from closing "square". That was pulling logs out from the end and turning.

If that's not one of the warnings in every grapple owner's manual, it should be!

texasranger556 · Nov 8, 2017

polemidis said:
Yes, I forgot it, thank you! But vertical or horizontal? Maybe laminate them to make them thicker too?

Thank you. Is something common usually on the tractor side?

It doesn't really matter because you would be attaching to your tractor hydraulics with quick couplers (which have a range of options there too). You can buy hoses with ORB/SAE on one end and JIC on the other if you want. I stick with JIC on both ends where I can then use adapters so I can interchange hoses in a pinch.

For reference my John Deere uses metric ORB for some connections, ORFS for others, square thread pipe for a lot of the backhoe connections.

ovrszd · Nov 8, 2017

LD1 said:
Need to gusset the lower tines

Also needs more bracing in the claws unless heavy high tensile steel is used. Might incorporate a cylinder protector into that part cause it can't be used without one.

Zebrafive · Nov 8, 2017

polemidis said:
Got you. I am wondering if it makes the lid more stiff, and if that worths the extra weight. Anyway, I just used the simple approach with bolts/ nuts instead of a tube with a greasable pin. If that fails soon or needs too much greasing I will upgrade it with the enclosed pin.

I think the design is almost complete. I just need some bracing on the lid, some expanded metal at the back and some protection below the cylinder. But I am tired, I need a break from CADing. I will start working on the BoM. What I am missing is a easy way to do the nesting for the CNC. Freecad's nesting tool is in development and does not work well yet.

Here is the step file.
Here are the original Freecad files if someone wants to edit them (needs Freecad v0.17)

With these 2.5" cylinders I get 2130lbs at the closed position
or 1360lbs with the 2" cylinders
And thats the geometry. The cylinder at the closed position is not 100% extended, it has a little travel yet thats why the lids look like they are overlaping the tines.
View attachment 527741

I love the colors! hahaha
View attachment 527742

I have no opinion on SAE vs NPTF ports. Other than the SAE uses a o-ring that seals easier, but the NPT has more fittings available??? What are the fittings on the 3rd function of a tractor does anyone know plz?, I found similar cylinders with SAE ports I can replace them

I would skip the expanded metal for the back. Use sheet metal for under the cylinders. And NOT use NPTF threads/fittings!

texasranger556 said:
IMO go with SAE/ORB fittings. They seal better and are much nicer to work with especially if you have to take then apart in the future. Generally I like ORB male to JIC male 90 (or 45) degree fittings on cylinders then get female JIC hoses which come with swivels.

There is also ORFS (o-ring face seal) which is about the best for sealing and serviceability, but they aren't as common and more expensive.

Also JIC and ORB use the same thread pitch so in a pinch you can add an o-ring to a JIC male fitting and thread it into an ORB port.

Agree!!!

texasranger556 said:
It doesn't really matter because you would be attaching to your tractor hydraulics with quick couplers (which have a range of options there too). You can buy hoses with ORB/SAE on one end and JIC on the other if you want. I stick with JIC on both ends where I can then use adapters so I can interchange hoses in a pinch.

For reference my John Deere uses metric ORB for some connections, ORFS for others, square thread pipe for a lot of the backhoe connections.

Agree! I like hoses with Female JIC swivels, reusable, do not leak, replacement hoses easy to find.

skills4lou · Nov 9, 2017

Zebrafive said:
I would skip the expanded metal for the back. Use sheet metal for under the cylinders. And NOT use NPTF threads/fittings!

Agree!!!

Agree! I like hoses with Female JIC swivels, reusable, do not leak, replacement hoses easy to find.

Just to throw a monkey wrench in...
Did you consider placing the cylinder(s) behind the bucket? Your clamp would pivot at the top of the bucket, with some extra length sticking out the back for a lever that the rod actuates. It solves the angle problem by pushing nearly perpendicular to the lever arm at full clamped position.

LD1 · Nov 9, 2017

skills4lou said:
Just to throw a monkey wrench in...
Did you consider placing the cylinder(s) behind the bucket? Your clamp would pivot at the top of the bucket, with some extra length sticking out the back for a lever that the rod actuates. It solves the angle problem by pushing nearly perpendicular to the lever arm at full clamped position.

But you'd have a heck of a lever disadvantage. So unlikely you would gain much in the long run if anything

skills4lou · Nov 10, 2017

LD1 said:
But you'd have a heck of a lever disadvantage. So unlikely you would gain much in the long run if anything

Not really. Maybe I explained it poorly. Google "clamshell loader bucket" for pictures. Compact design, cylinders are protected, and plenty of clamping force. It also avoids the large lever arm going up above the back portion, which is usually the part that gets torn off on large farm equipment that is working round bales.