Built a quick and dirty thumb.

[Gordon Gould]

Very nice professional looking job. You will learn to love it !!

gg

 

[nybirdman]

Just curious why you didn't make it a bolt on.I have a Green's Machine Thumb,great tool for sure but it doesn't open as wide as yours.

 

[BukitCase]

"Understanding the flow rate between .040 and .050 for example is significant!!! "

Yeah, Richard - I just did the math and that small change would make a difference of 1.5625 TIMES as much flow at any given pressure - unless the #60 hole is 'WAY too slow, I'd probably only go up in size maybe 2-3 numbers at a time... Steve

Actually, I'm usually too impatient for a lot of "cut and try", which is why I ordered a needle valve for my (yet to be installed) grapple :laughing: ...Steve

 

[aarolar]

Well thanks for all the compliments but I'm afraid I have some bad news, I've already broken it. I was trying to grab a pile of brush and had the thumb half open and pinned it against a tree and rolled the bucket down at the same time and bent the rod and tore the mount off. I was a little worried about the welds on the mount tearing out being I used AR plate and I know how to fix that issue but there ain't no fixing a bent rod. Now I gotta decide if I'll cut my losses and buy a dedicated grapple or invest in a new cylinder to fix this.

 

[ovrszd]

The bend might be fixable. Can't tell from the pic.

There are operational lessons to be learned about using a Grapple. First and foremost is never apply more pressure to the cylinder and it's mounts than the hydraulics can apply. But you know that now.

 

[aarolar]

The bend might be fixable. Can't tell from the pic.

There are operational lessons to be learned about using a Grapple. First and foremost is never apply more pressure to the cylinder and it's mounts than the hydraulics can apply. But you know that now.

I knew that before I just couldn't tell what the heck I was doing up there just raking around blindly. Plus I didn't know what the mounts could stand but I do now

Next attempt will have a nice fat repad between the AR and my mount, the cylinder is another issue however.

 

[aarolar]

Fix or toss? Ovrszd

 

[RNeumann]

I'd run it bent till I got all the kinks with the grapple worked out. It can't get worse. Fix the weld and drive on. I wouldn't mind the weld being the weak point. Easy to fix a weld. More costly to replace a ram or other more serious damage.
When I was Jeeping we saw guys with expensive and strong hubs. They would break u-joints, axles or gears. I carried an extra couple cheap hubs-easy to change (don't even have to remove the tire) and cost very little. Same concept with sheer pins in some attachments.
Another option would be a relief valve on the hydraulics.

 

[olPete]

Fix or toss? Ovrszd

View attachment 499802

Reckon that tweak would press right out have seen crowd rods bent a lot more than that

 

[aarolar]

I'd run it bent till I got all the kinks with the grapple worked out. It can't get worse. Fix the weld and drive on. I wouldn't mind the weld being the weak point. Easy to fix a weld. More costly to replace a ram or other more serious damage.
When I was Jeeping we saw guys with expensive and strong hubs. They would break u-joints, axles or gears. I carried an extra couple cheap hubs-easy to change (don't even have to remove the tire) and cost very little. Same concept with sheer pins in some attachments.
Another option would be a relief valve on the hydraulics.

Had the same thought about the welding last night as I was settling down I think I'll just reweld it as is but maybe add a little preheat to the AR before I do. Here's the pics of the pin you wanted I took them then got sidetracked with broken stuff.

 

[aarolar]

Reckon that tweak would press right out have seen crowd rods bent a lot more than that

Yeah I believe I can fix it easily enough at work. I'll take it and use the 300 ton press to straighten it and keep it as a spare or use it on a tree shear or something.

 

[ovrszd]

Reckon that tweak would press right out have seen crowd rods bent a lot more than that

What Pete said. Extend the cylinder all the way and use a press. Protect the ram to prevent scratches and scrapes while in the press. Wood works best.

I wouldn't use it bent. Risk destroying the seals.

 

[RNeumann]

Thx for the photos!

 

[k0ua]

I think the consensus is "press out the bend in the rod, weld up the bracket, and go forth and sin no more!"

 

[Sysop]

I agree with everyone here about having the rod pressed straight, welding it back together, and continuing on. But I think I might add a set of triangle shaped gussets to the front edge of the mount. Not only would it add extra support to hold it square, it could also act as a barrier/deflector of sorts to push it aside of various obstacles.

Fantastic job so far, I'd not abandon something that's so near completion. Anyone who's ever made anything from scratch will tell ya that you've done a marvelous job. Work out the kinks and be proud of yourself.

 

[ovrszd]

I agree with everyone here about having the rod pressed straight, welding it back together, and continuing on. But I think I might add a set of triangle shaped gussets to the front edge of the mount. Not only would it add extra support to hold it square, it could also act as a barrier/deflector of sorts to push it aside of various obstacles.

And might add some torsional strength to prevent twisting the claw.

 

[Sysop]

And might add some torsional strength to prevent twisting the claw.

Yea, that's the technical engineering term for my hillbilly-speak "holding it square".

 

[Big Barn]

I agree with everyone here about having the rod pressed straight, welding it back together, and continuing on. But I think I might add a set of triangle shaped gussets to the front edge of the mount. Not only would it add extra support to hold it square, it could also act as a barrier/deflector of sorts to push it aside of various obstacles.

Fantastic job so far, I'd not abandon something that's so near completion. Anyone who's ever made anything from scratch will tell ya that you've done a marvelous job. Work out the kinks and be proud of yourself.

This bears repeating: "Work out the kinks and be proud of yourself".

Well done!

Terry

 

[olPete]

What Pete said. Extend the cylinder all the way and use a press. Protect the ram to prevent scratches and scrapes while in the press. Wood works best.

I wouldn't use it bent. Risk destroying the seals.

Yep, local engineering firm has hardwood vee blocks for that purpose. Apparently there's a number of farmers around here that could join TBN to learn how to back drag

 

[ovrszd]

Yep, local engineering firm has hardwood vee blocks for that purpose. Apparently there's a number of farmers around here that could join TBN to learn how to back drag

Here too Pete......