FEL Grapple from Scratch W/ Lots-O-Pics

GuglioLS · Oct 13, 2009

bucmeister said:
Thanks for the quick response. That is some fine looking cutting work on the parts for the new grapple, looks like the holes in the cylinder guard plate and the tine stabilizer plate were cut to serve as hookless chain attachment points. The pins show your usual attention to detail and quality of workmanship.......SNIP.....SNIP...

Thanks bucmeister,
Those in fact are hookless chain keyholes, pretty cool stuff huh? The only limit to CNC plasma cutting is your imagination. Glad you enjoyed this.

washita said:
excellent grapple, my brother in law wants me to build a grapple for his orange machine,how did you determine the capacity or opening for the jaws when closed, I would like to keep him from grabbing a tree of to large a diameter and tweaking his fel arms or over loading the lift. diameter of tree vs weight or is this not a design issue to be concerned with? he also has a screw jack capable of 500lb lift do you think this would provide adequate clamping force?

Personally I would ditch the 500 lb jack screw idea and go with a least a 2" ID dia hydraulic cylinder. Forces at the jaw tip are greatly reduced by the negative lever force as a result of pin geometry, i.e. the relationship between the hydraulic cylinder anchor point on the bucket, the jaw pivot point at the bucket and the connection of the cylinder near the jaw tips. Depending on the exact geometry forces at the tip can easily be reduced by 20:1 or more. Meaning if you have 7000 lbs of cylinder force you could get as low as 350 lbs of clamping force at the tips.

When designing a grapple the best approach (IMHO) is to obviously get the jaws to close all the way onto the cutting edge, next is to get the jaws to open wide enough so that the tips of the jaws are equal to or further back from the vertical plane of the bucket cutting edge. Doing it that way still allows the bucket cutting edge to make contact with a vertical object such as a wall or tree without the jaw tips hitting first.

In short make the jaws open as wide as possible, there are many times when that is needed to take a big bite out of a light brush pile etc. Your BIL is going to have to realize even though the jaws can open wide enough to grab a giant redwood or the rock of Gibraltar doesn't mean that he should.

SuperDuty335 said:
Do machine shops charge by the hour/piece/etc. for plasma cutting? I am planning a skidsteer grapple and would like to get a ballpark total. Thanks

Generally depending on several factors I think you will find shops that have a CNC plasma cutter will charge ~ $60 / hour for setup, cutting and removal of the sheet and finished product from the work table. Add in cost of material usualy based on the best fit outline of all the parts. CAD design services can be had starting at about $80 / hour more or less depending complexity of project competition, and locality.

As with any one-of-a-kind project it is rarely worth the initial expense to have it professionally designed and fabricated. If on the other hand a person was going to make many of the exact same thing, then of course the cost can be spread out between all units to make it worth while. If you have the ability to draw it up, save the file in a format that the plasma cutting software can read then CNC plasma cutting for individuals like us is relatively affordable.

Larry

J_J · Oct 13, 2009

SuperDuty335 said:
Do machine shops charge by the hour/piece/etc. for plasma cutting? I am planning a skidsteer grapple and would like to get a ballpark total. Thanks

Like Larry said, plus, after putting the DXF drawing on a USB thumb drive/CD, etc, take it to the steel place with a plasma cutter, and ask them for an estimate, and tell them what kind of steel you want. They may even have a laser cutting machine. More precision. There will be a set up fee, and then after that, the price will include the amount of steel used. If you asked for say 20 units, the price may change and be lower per piece. If you brought your own steel, the price will be different. They usually keep a copy of the cutting files, and you can order more at a later time. If you have several plasma cutting places in town, go to each and give them the file and ask for an estimate.

bucmeister · Oct 13, 2009

Our local steel supply is using some kind of cutter that uses high pressure water and grit. The hydraulic shop was telling me the pieces come out ready to use.

Brad_Blazer · Oct 13, 2009

I was just at a trade show where they had some water jets doing demos. The guy from Jet Edge said water jet is about 10x the accuracy and cost of flame cutting, and about 1/10 the accuracy and cost of wire EDM. Water Jet uses about 60,000psi generated by a hydraulic over water system. It actually compresses the water by more than 15%!
JET EDGE Waterjet Systems - Water Jet Cutting Machines, Surface Preparation
I got a cool little race car profile cut out of 1/4" SS

. There is still a slight taper to most of the cuts.

That said, I can personally attest to the fact that the quality of the plasma parts cut by Larry is wonderful for what we are doing.

Brad

GuglioLS · Oct 13, 2009

Hi Brad,Glad you found this thread. Hope you didn't mind me showing off your top secret grapple parts? You did a good job designing everything and your chain keyhole idea is really neat. I still like my five point military style star idea though, as well as the skull and flames. Perhaps I'll get to use that on a future grapple project.Thanks for the quality plasma cutting compliment, for 3/8" thick plasma cut parts they did come out decent and I'm flattered that you think so too. Of course the jaw pattern you came up with is totally cool. Hope you get to start building it soon. I think allot of members might be interested in seeing it go together. You need to blow everyone away by posting your animated 3D model and show off your CAD welds. Larry

Brad_Blazer · Oct 14, 2009

Thanks Larry,
I am just about ready to start assembly. My cross-fencing project is about finished. I thought I WAS finished - but after I caught all of the goats, gave them shots and wormer, and separated the boys, (I was only bleeding a little) they busted back through my gate.

Anyhow, look for me starting a new grapple thread soon. Thanks again for all of the help. Threads like this are a great resource - nice work as always.

Brad

SuperDuty335 · Oct 17, 2009

I can draw everything up in AutoCAD, which would be a DWG file by default and convert this to DXF. I need to call around. Thanks guys!

bucmeister · Nov 4, 2009

GuglioLS,

I have a question about the way you post your pictures in the article vs the way most of us do. When I click on one of your pictures it automatically opens in a new tab whereas most other pictures on the entire site when clicked will open in the current tab or window unless I right click and manually opt to open in a new tab.

Is this a feature of your hosting site or the method you us to include the photos? Thanks

3RRL · Nov 4, 2009

I can answer that if you don't mind Larry...
Most of the guys post their photos using the TBN features.
Larry posts his thumbnails using his Photobucket account. There is a pretty good thread about using Photobucket in the Photos or Related Topics forums (can't remember which one). You can do a search on "Photobucket" to find it.