Grapple project OPEN SOURCE

[Zebrafive]

Now my only "problem" is what exactly is the purpose of the grapple. I figured out how to make it 40" tall, how to add 8" cylinder, etc. Easy stuff. Now I have so many options, and no restrictions. So I have to decide my mind. What most people want? Should I go to 36 long one? Are most people need it for brush? Then more volume inside the tines is desired. Need for moving heavy logs? Then smaller, lighter design that will not limit the lifting capacity of the front will match better.
Or decisions on whether design it simple with flat bars? CNC will add to the cost a lot. Even plasma cutter, is not accessible by anyone (it should if one is serious in fabricating tools anyway). Maybe make simple tines from flat bar? But that will definitely affect the strength of the grapple.

I understand that there is not one recipe for all. At least now I have some higher ability to fit ones needs.

My main use of my grapple is hauling and piling brush to burn. I also haul stumps (most were previously dug with a backhoe, hired out), move and pile logs, move large rocks, in that order.

 

[ovrszd]

My main use of my grapple is hauling and piling brush to burn. I also haul stumps (most were previously dug with a backhoe, hired out), move and pile logs, move large rocks, in that order.

Yep, that's my list!!!! Additionally my Grapple is built on a Bobcat bucket so it also serves to get one heck of a load of dirt to stay in the bucket.

 

[BHD]

many times manufactures literature, will have line drawings, and will give one a good set of plans, with out the dimensions, but once one knows the width of one part the rest can be guess-a-estimated with some close accuracy,

and I do many times use the cardboard design method, one can work it through the paces and see what is happening and what could bind or hit,

my two cents,

 

[Zebrafive]

Not trying to jump over LD1.

Measurements with claws closed.
A = distance from barrel end of cylinder pin to ram end of cylinder pin
B = distance from hinge pin of claw to ram end cylinder pin
C = distance from hinge pin of claw to barrel end of cylinder pin
D = distance from hinge pin of claw to tip of claw

Here are the measurements for my RakeMaster grapple

A = 28.25'
B = 23.50
C = 6.25"
D = 31.75"
Cylinder is 2 1/2" x 8"
Tractor has 2250psi

Thanks for bite pressure calculation!

 

[LD1]

Approx. 1300# bite force zebra.

Cylinder is on a 9 degree angle. But since you start off with a 2.5" cylinder...that starts you will 11000# of cylinder power instead of 7800 with a 2".

 

[Zebrafive]

Approx. 1300# bite force zebra.

Cylinder is on a 9 degree angle. But since you start off with a 2.5" cylinder...that starts you will 11000# of cylinder power instead of 7800 with a 2".

Thanks for calculating, interesting to know

 

[polemidis]

I think the force of the 2.5" cylinder is 12600lbs if the initial pressure is 2500psi.

The project is on hold until the end of the week due to the storm that hit Maine. 3 days without power, they said we will be on grid again by Sunday

I had uploaded an better version on the Dropbox, but I do not recall if it the final one. Which will have a 2" think cylinder 8". I will use 3/8" thick metal. All the files will be in Freecad format, but I can export them in .STEP if you want to use them in different CAD. But by keeping them in freecad you can alter them very very easy!
Anyway see you next week guys going back to my primitive living in the dark

 

[Zebrafive]

I think the force of the 2.5" cylinder is 12600lbs if the initial pressure is 2500psi.

The project is on hold until the end of the week due to the storm that hit Maine. 3 days without power, they said we will be on grid again by Sunday

I had uploaded an better version on the Dropbox, but I do not recall if it the final one. Which will have a 2" think cylinder 8". I will use 3/8" thick metal. All the files will be in Freecad format, but I can export them in .STEP if you want to use them in different CAD. But by keeping them in freecad you can alter them very very easy!
Anyway see you next week guys going back to my primitive living in the dark

My tractor is rated 2250psi, which I stated when asking for bite force calculations. I know we have been using 2500psi for a base line.

 

[polemidis]

My tractor is rated 2250psi, which I stated when asking for bite force calculations. I know we have been using 2500psi for a base line.

Oh ok, this is formula I think: Force = Initial pressure * (3.14 * diameter of cylinder^2)/4
So yes almost 11000 with 2.5", 7065 with 2"



Ok, I am back so many days without electricity. Too excusted to do anything, so many things to catch up. But I will finish that thing, it will be sooo useful. I have so much brush everywhere.
I need a little help. Can someone put a link of the pivot pin One that can take grease? I think I am slow, I cannot find it. Or else I will use just plain bolts.

 

[GLyford]

The basic formula is true when pushing out.

When pulling back, you have less force (because of the area of the rod). On a grapple the opening force is usually not a problem (unless you are doing something weird like using the lids as a jack on a tree trunk or something), but I thought I'd mention it anyway.