weld the bucket hook correctly

[skyking1]

No. There is a world of difference with what you can get on the end of the stick and what you can get at the end of the boom.
EJ Rody and sons had a Komatsu 1000 here in the county. Now it is at the pit by the dump off the end of the runway, but in it's heyday, it was the biggest thing working utilities around here. They had a Bucyrus Erie, a pretty big one that was dedicated for pimping for that hoe.
They pulled the stick off it and put a hydraulic winch on the end of the boom, for picking the boom and stick of that 1000 and putting it together where it went.
It sucks that the internet does not have any pictures of the Rody machine. When I was working on the East Main bridge job, they happened to be crossing the road about a mile away.
They were setting 8' drain tile, and they took a break for lunch and left the bucket in the center turn lane of a 5 lane and ran traffic under the boom for a while. It was pretty damn cute.

 

[Welder Dave]

The pic. of bucket in question doesn't look at all like it's anything exotic. Just look how scalloped the cutting edge is. If the rest of the bucket was T1 or AR400 I think the cutting edge would be in better condition and possibly even a more wear resistant material.

 

[trombeur]

AR400 Plate | Abrasion Resistant | Specialty Steel Co.

AR400 Wear Plate. We offer High Definition Plasma Cutting of custom shapes. Call us at 800-321-8500 for a quote or any questions you have.

www.specialtysteel.com

?

 

[Welder Dave]

Forget the first video. Lance is more of a mad scientist/experimenter than a welder. It's hard to know what is accurate and what isn't. You can buy hooks specifically designed to be welded on. Welding chain hooks could fail if they are high grade chain like most gold colored chain is. I didn't watch the 2nd video but I'm not sure welding a hook on the bucket link is a good idea or the strongest place to mount a hook. Hooks are put on buckets all the time.

 

[Willie B]

Few welds are engineered. Engineers have proven many times they don't calculate every condition. Those who engineered the World Trade Center, Those who diverted the stream near my house failed to factor beaver dams 8 miles away. Engineers aren't always correct.

We weld a hook on a bucket, hope it holds. Some of us take steps to be sure it'll hold. A Compact Utility Tractor does not have enough lift to break a basic hook.

I favor a simple plate with a hole in it. You use a shackle in the hole. Keep a dedicated shackle in the machine along with wire to be certain it doesn't loosen. If you are stupid like me & leave it in place, sooner or later it'll loosen up & fall off. I don't know of anyone dropping a load because of it, but losing a shackle can happen. Ask me how I know.

 

[Nige]

I favor a simple plate with a hole in it. You use a shackle in the hole.

I agree. This photo shows an OEM lifting point installed on a Cat bucket.
The lifting point is only welded to the outside of the bucket.
Note from the close-up that the lifting point is only welded down the sides (longitudinal weld) and not across the ends (transverse weld). You can see the rust bleeding out from behind it.
The first rule of structural welding is NOT to weld transverse across the structure.
This weld would have been made with E7018 low-hydrogen electrodes (field installation) or AWS A5.20 E70T-1 wire (factory assembly).

 

[trombeur]

in fact the best solution would be to buy the bucket already prepared from the factory, I have seen that many manufacturers weld the hook on the connecting rod that controls its opening and closing, what do you think of this solution?

 

[skyking1]

If you read through the thread again NOBODY LIKES OPEN HOOKS!

 

[Nige]

The first one is a "grab hook". Designed as more of a tie-down/restraining device than a lifting point.
Below an image of grab hooks being used for their designed purpose - tying down a machine on a lowboy.



The second type - not recommended for the reasons given by @skyking1 and @Willie B among others.

See my post #26 just above your last post. In my opinion that is the type of lifting point that you should be installing.

 

[Entropy1]

Nige, the bucket attachment on the CAT you linked on post #26 is well designed.

I did some back-of-the napkin calculations this morning (aka Microsoft Paint) - showing why this design is sound. The concept of stress-concentrations is often difficult to visualize. It's best to do a side-by-side comparison - with some numbers attached.

See attachment.

 

[CM1995]

There are 3 lifting points on our new 325.

Most of the time we'll drop the bucket and use the eye on the QC with a shackle and swivel locking safety hook.

 

[skyking1]

that's nice when you can get rid of both the bucket weight and also just having it to work around. I have not had that option in a long time.

 

[Welder Dave]

I don't think welding a lifting point on a bucket is in the same category as welding on the boom. I've seen lugs and hooks welded all around on many buckets and even the instructions for some weld on hooks say to weld all around. None of them cautioned not to weld the top and bottom. It could be because steel plate doesn't have a specific grain structure direction like structural members. Bucket ears are usually welded all around. Adding a reinforcement plate under the lug or hook is a good idea if the bucket is of marginal thickness. Whether or not the top and bottom are welded isn't as critical on a bucket as long the welds are of sufficient size and the proper weld procedures were followed. If you're lifting things heavy enough to potentially rip the lug/hook off or rip the bucket open you probably shouldn't be using a bucket as the lifting point.

 

[Welder Dave]

in fact the best solution would be to buy the bucket already prepared from the factory, I have seen that many manufacturers weld the hook on the connecting rod that controls its opening and closing, what do you think of this solution?

That's not the best video of how to weld a hook on. He's wearing a coat and you can see his breath so it's below freezing. He should have preheated the bucket and hook. He's also using short circuit transfer Mig which isn't even qualified for structural welding and on top of that he's holding the gun in an awkward position. Would be easier to stand beside of the bucket and hold the gun normally. It was hard to tell if the weld beads were smooth across the top where they overlapped. A proper multipass weld shouldn't have any valley's between the beads. It should look like one really wide bead. There's enough weld the hook shouldn't come off but there's better methods of doing it.

 

[Entropy1]

There is a classic structural engineering example where less weld is technically desired (see attachment). A gusset is weld-attached to prevent folding over a 90-degree joint when a large force (red arrow) is applied. The weld stress resulting from the applied force is maximum at point 3 and goes to zero at point 1. The weld provides negligible opposition to the applied force between points 1 and 2. In fact, the weld at point 3 will fracture before the weld at point 2 even yields.

Simultaneously, residual stress from welding is maximum between points 1 and 2 (on Gusset A). This residual weld stress is often high enough to initiate & propagate cracks - particularly when the applied force results in cyclical fatigue of the gusset (think cars driving over a bridge). Thus the proper way to install gussets is shown with Gusset B - because this method specifically eliminates the stress-risers from welding in the corner - a corner which also provides negligible contribution towards overall joint design strength. Simply put - Gusset B is stronger than Gusset A.

For the padeye attachment Nige linked in post #26. Considering the thickness of the padeye and the length of the attachment welds - the vertical welds alone have likely exceeded the minimum design strength. More specifically, the pin will likely shear, or the eyelet will likely tear out, long before the padeye attachment weld fails. Welding the top and bottom only provides negligible strength returns, but will introduce high residual weld-stress at the ends of the attachment (residual weld stress that would otherwise not be present). It would not surprise me if the CAT field installation instructions specifically directed to avoid welding the ends of the padeye.

 

[Entropy1]

Just for chit-chat (subject related) -

When making a weldment out of carbon steel (machine piece or machine foundation), residual stress from welding is guaranteed. The stress is caused because the weld transitions from liquid to solid around 2800 degrees F, at which point it shrinks 6.8 x 10^-6 inches per inch-degree F - until it reaches ambient temperature. Normally this shrinkage is within the elastic range of the steel (aka the weld doesn't yield during cooling), but the strain/stress from weld shrinkage remains nonetheless. This means if your weld is already stressed to 40% of yield just sitting there, the weld is going to get extra fatigue when external loads are applied to the weldment.

By placing the weldment into the oven at about 1100 degrees F and heat-soaking it (200 degree F per hour ramp-up, hold at 1100 degree F for 1 hour per inch of thickness, then a 200 degree F per hour cool down) - you will almost completely eliminate all of the residual weld stress. The heat is high enough to permit the steel's grain structure to creep/slip (aka stress relief), but not high enough to distort the part, or damage/alter the steel's grain structure (generally speaking - obviously outlier exceptions can be found for certain steel alloys that are not suitable for stress relieving).

Machinists love working on stress-relieved weldments, because when you cut them, they are dimensionally stable. Stress relieved weldments will also endure appreciably more abuse (particularly with impact & cyclical-fatigue loading) than their non-stress-relieved counterparts.

 

[Welder Dave]

On bucket hooks or lugs it likely doesn't make a lot difference if the top and bottom are welded or not. If it were a big issue the hooks specifically designed to weld on excavator buckets would have warnings and cautions in bold letters not to weld the top and bottom. If one were to follow the same protocols applied to welding on a boom either the ends wouldn't be welded but the welds on the sides would extend past the piece welded on and make an outward fish hook looking weld or if the ends were welded the piece would be curved either concave or convex or made more triangular shaped with a rounded end to weld around. If other potential stress risers were considered, welding the sides and ended the weld at the end of the piece leaves a notch effect where a crack could start. Very vew bucket hooks would ever be stress relieved. Things like bucket hooks are most often just welded on without much thought given to what is technically the most proper way to mount them. The most important aspect is a sound weld by a qualified welder using the proper filler metal and basic technique which may include preheat. The larger the machine the more stringent the welding needs to be and in actual practice the welds are generally oversized from what is technically considered the proper size. This gives some piece of mind while can also can give an over estimation of the strength if the weld is quite a bit bigger than what is considered the proper size. IE/ if the bucket is 3/8" plate a 3/8" fillet weld would be the required size to meet the strength of the plate. Many would put a 1/2" weld but it wouldn't really be necessary. If someone put a 3/4" weld thinking it would be that much stronger they would be very mistaken. It some instances it could be weaker because of too much heat into the base metal. Preheat and interpass temperatures can be extremely important depending on the type of steel and even the welding process. It took a long time for dual-shield flux-core to be approved for use on pressure vessels here. One of the issues I think was that it put too much metal down too fast compared to stick welding.

 

[Entropy1]

When you see fabrication welds on machinery (dozers, excavators, cranes, etc) that are incomplete - e.g. the sides of a bracket welded only, in lieu of all-around - or only the sides of a lifting eye, in lieu of all-around, or a plate that's stitch-welded in lieu of full-continuous welds - you can almost bet the bank that it was an intentional decision. Was it done because welding all-around is harmful? Probably not. . . . It is most likely that all-around welding was simply deemed unnecessary.

Classic Example: plate/sheet in structural applications (e.g. shipping & cargo containers) is increment stitch-welded in lieu of full continuous welds.

 

[Welder Dave]

Things like bridges the welding is very critical. There are purposely stitched welded so the have enough flex. Welding them solid makes them too stiff and instead of flexing will crack and the crack(s) will extend down the weld. In some applications stitch welds limit potential cracks to just that weld. Some things it's a waste of time and money to do continuous welds. Warping is another issue. On the topic of bucket hooks it doesn't make a lot difference in most cases as long as the welds are sound and of sufficient size.

 

[Old Growth]

I'm with skyking. Never weld an open hook on a bucket. Use an eye and shackle. I've heard of to many times someone rolled the bucket to far in search of a little more lift and the chain slid out of the hook. Same thing as throwing a chain over a tooth. Just don't do it, ever.

I love my open hook on a 160 sized hoe.
Its primarily used for handling logs/timbers, slings of lumber/timbers and odd equipment at the yard.

My go to rigging is a chain that is 6 feet long with open hooks on both ends.

I can hook one end and let the other end dangle to hook the on straps and many other random things. Or I sometimes use BIG log tongs to load/move big timbers/logs to and from the mill deck and place both hooks on the open bucket hook and hang the tongs from middle of the chain that hangs down.

Then when I'm done I can swing over to the pile and set the tongs upright against the deck and curl by bucket all the way under with the stick brought in and give it one little shake and the hooks slide right off.

Same for slings of lumber/timber. Ill toss a strap around the unit of wood and over my OPEN bucket hook. then set it on a trailer and curl under and unhook it, leaving the strap on the lumber and then swing the machine back to the mill deck by the next unit to load. Then get off the machine go get my strap and wrap the next unit and toss the strap back onto my hook and start again.

As I get older, I look for ways to cut down on the amount of times I have to climb these old knees into/out of any of the bigger machines on site.

Maybe I'm just part of a rear breed that can remember not to CURL UNDER all the way with the stick pulled in when I hanging a load, lol!