The "thumb"

[WinterDeere]

BTW, it seems some might not have caught that this is not a fresh build. I'm just modifying a fork set I already have. Here's what I already have minus the pair of tangs I stuck on top for this thumb:


(click for full size)

These are 3-point only, so I just picked up a pair of JDQA adapters, which will be welded to a pair of extension gussets, and attached to this frame:

 

[shooterdon]

I would want the grapple curved like mine is, it makes a difference in how you can pick things up.

Picking up a 6' high load is no problem with mine.

And yes, you do want it greaseable, mine is all bushed too.

SR

I did not explain "six foot high" very well. This is what I have to pick up once the splits are loaded into totes:

 

[WinterDeere]

I did not explain "six foot high" very well. This is what I have to pick up once the splits are loaded into totes:

View attachment 777120

Those totes usually have an ID somewhere around 38" x 46", which when filled to 5'6" depth (for 6' total height) with fresh-cut oak (63 lb./cu.ft. at 66% stacking density), will contain about 2780 lb. of wood, and weigh a total of 2900 lb. When dry, that wood weight will drop to about 1900 lb., making the loaded tote weigh about 2030 lb. Either way, I'd probably be moving them with the forks on my 3-point hitch, not the loader, esp. over my hilly property.

But you bring up a good point, in that this thumb will be easily removed by pulling two pins. This was the reason I had asked if they needed to be bushed and greased, as pulling greasy pins is always less fun than dry. Perhaps rather than making the cylinder and arm removable, I should make the arm extendible, such that I can just remove the extension (rather than the whole assembly), when needing to grab something taller.

 

[shooterdon]

Those totes usually have an ID somewhere around 38" x 46", which when filled to 5'6" depth (for 6' total height) with fresh-cut oak (63 lb./cu.ft. at 66% stacking density), will contain about 2780 lb. of wood, and weigh a total of 2900 lb. When dry, that wood weight will drop to about 1900 lb., making the loaded tote weigh about 2030 lb. Either way, I'd probably be moving them with the forks on my 3-point hitch, not the loader, esp. over my hilly property.

But you bring up a good point, in that this thumb will be easily removed by pulling two pins. This was the reason I had asked if they needed to be bushed and greased, as pulling greasy pins is always less fun than dry. Perhaps rather than making the cylinder and arm removable, I should make the arm extendible, such that I can just remove the extension (rather than the whole assembly), when needing to grab something taller.

I have estimated the capacity of the modified totes at 1.4 cords. I have never lifted one higher than two feet off the ground. My loader is rated at 2700 lbs and has been handling them. But I have flat ground and go slow and easy. Next year I am moving to 1/3 cord bulk bags but they still stand about 6' high.

An idea I had was to mount something like a rotating jib crane with a thumb at the top of the pallet fork frame. By rotating it 90 degrees, it will not interfere with picking up a tall load. When I need the thumb to pick logs, I am not handling a a lot of weight... 300-800 lbs. I only need to pick up a bag or tote every 20-45 minutes when processing logs. I can manually rotate the jib or use a diverter value on the 3rd function circuit to rotate the jib.

 

[WinterDeere]

I have estimated the capacity of the modified totes at 1.4 cords.

I think you must have an error in your math. If we assume ID = 38 x 46" for the standard 40 x 48 inch totes, and you manage to cut your wood to fit without even 1/4" gaps (like Tetris-perfect), your best case 0.52 cords while keeping the total height at the 6 feet you had mentioned early. In reality, given your wood is probably not of a length that perfectly fills the tote, it's probably a bit under 0.50 cord.

My loader is rated at 2700 lbs and has been handling them.

Another indicator these are not 1.4 cords per bin. Check the cord weight of firewood, your 2700 lb. loader would get 1.4 cords of most species off the ground. Figure nearly 5000 lb. per cord for green oak, or 3600 lb. after drying. Your estimated 1.4 cords per bin would be 5000 to 7000 lb. per bin.

In any case, my tractor (JD 3033R) is too light to move that kind of weight on the loader, so not relevant to the design of this particular thumb. If I have to move something anywhere near that heavy, it'll be on the 3-point!

 

[Smokeydog]

Several miters of tubing with side plates or gussets would make a strong, curved beak. Flat bar would also give some bite to prevent side slip. A concern on my hillside.

Thick wall DOM tubing to fit your pins for bearing and hubs. Drilled for grease zerk. Spread the load forces and gives good service life.

Nothing like handling trees to test your equipment’s toughness. Hard to beat a long bottom log grapple to handle, rotate and gently place long logs cleanly.

 

[Tinhack]

AutoCAD used to present a blank screen, way back in 1980's - early-1990's. Sure you're not thinking of that?

That was probably it. The timeframe is about right. I know it was early Windows.

 

[WinterDeere]

I had CST busy running another project (something that actually MAKES money), so I decided to play with the Sim tools in SolidWorks, when I had a few free minutes. They're actually much simpler to set up.

On a side note, SolidWorks now has a Makers edition for < $10/month (I think it's $99/year), so you guys may want to check it out for any implement design work you have. Just verify it has the Static simulation tool before buying, as I did this in the Pro version of the product.

Anyway, I was worried that my rather light connections planned between the JDQA adapters and the existing fork frame would be too weak, but it appears that the stresses are all pretty low there. Shown here with 2000 lb. evenly distributed on the forks:


(click for full size image)

You can see the stress peaks are all within the existing (factory build Titan Attachments) fork frame, not on any of the components I'm adding for the JDQA. Yes, it's showing 55 ksi at some of the welds on the fork frame itself (Titan's part), which is beyond the yield strength of most steel tubing, but that's really only because I didn't bother to really model the added thickness created by weld beads. The actual stress within my components is all < 10 ksi.

In terms of deflection, again my added JDQA brackets and mounts are not flexing in any measureable way, at 2000 lb. Tip of forks move 0.7 inches, but I re-scaled to 0.2 inch maximum, to get better resolution back at the frame, where I was trying to detect flex of the JDQA bracket mounts:



So, the JDQA mount part of the design looks good to go. Thumb analysis, next. Maybe after that, if I have time to kill this evening, I might circle back and learn how to model the welds at those high-stress joints.

 

[Sawyer Rob]

I did not explain "six foot high" very well. This is what I have to pick up once the splits are loaded into totes:

View attachment 777120

I understood what you meant, and I can pick 6' high totes no problem.

SR

 

[4570Man]

I would want the clamp to be able to open flush with the pallet fork back frame to at least the height of a standard pallet. I had one of these and I quickly grew tired of it damaging pallets and took it off and used my regular grapple instead.