Looking for some advice. I have a Titan 36" manual thumb that I am looking to install on my John Deere 310C. With many other types of equipment, the underside of the boom appears to be a relatively square flat surface. This is not the case on this 310C, which is a welded construct. It appears to be rather thick stock on the sides, but unknown on the mounting surface. The net shape is trapezoidal; narrower at the bucket-end and wider as it goes up (see pic). The construct is welded on the inside edges of the mounting surface. The side pieces are about 1/2" longer than the bottom piece. The width at the bucket-end of the boom is just a bit over the 5 1/4" width of the base mounting of the thumb (as shown using the 5 1/4" "storage bracket" which is the same width, in the second picture). As a result, a direct weld would end up bonding to the side pieces at the bucket-end, but this would end up transitioning to the bottom piece shortly afterwards. Not sure if I should attempt to just weld it on, and cross my fingers. Otherwise, it looks like another option is to get a piece of steel and weld to the side-pieces first, and then attach the thumb. Doing any sort of bolt-on would get a bit messy, as nothing is square. I am pretty sure that I could weld this to the bottom piece primarily, and to the sides where it is close enough to the base bracket (e.g. the first inch or so). I have zero budget for this and none projected. I have already gotten just about everything else fixed (with the bucket and boom seal sets being a real bear to do alone, without a garage). Anyone weld a thumb on such a structure? Thoughts?
A rectangular plate slightly wider than the widest part of the dipper could be welded to the heavier sides of said dipper. Then weld the thumb base to the plate. I would use a minimum 3/4" plate. Do not weld across the dipper. The sides of it only.
Right or wrong this is how I did mine and it has worked fine going on 6 years. Had some growing pains learning to use it but I couldn't live without it. I leave mine extended full time now. HeavyEquipmentForums
Looks like you had a nice flat surface to mount yours on. Unfortunately this is not the case with mine. Further inspection (looking at the end near the pivot at the main boom) and it looks like the target spot is quite a bit thinner than the sides. I think this is probably the best bet. 3/4" is thicker than just about any other piece on the machine or the thumb itself(I think the teeth are 5/8"). I guess I need to source some steel plate somewhere.
Plates could be welded on the side of your dipper in such a way that the base plate would be square with the dipper and high enough to barely tough the highest part of the dipper. Kinda like a home made channel iron. 5/8" inch would be okay. I like to go heavier to eliminate any chance of it bending. I found good deals for my project on eBay. The vendor sent to them to my post office.
@MarcNH There is a large metal distributor here who has what they call the "Bargain Barn". They sell cutoffs, slight damage, etc by the pound. You pick the stuff you want, they weigh it and off you go. They will even make 1 or 2 cuts for free. They also sell full pieces of everything. I bought all the steel for my backhoe cab rebuild from them. There must be a place like that near you in NH. I would call around.
Note what Tinker said in post #2 about welding across. If you have to weld on the flat, use a fish plate. A broken stick is sad.
I'm curious what the problem is with welding directly on and bridging the flat base and sides. The sides are already welded to the bottom. Is this a extended dipper?
No, it is a constructed dipper. Looks like 1/4" steel on the sides, and much thinner on the top and bottom. It is only about 5" wide at the bucket end, and a bit over 8" just 21 inches up towards the pivot at the main boom. You could actually weld the bucket end of the dipper to the bottom of the bracket, but it gets too wide as you move up.
OMG is steel expensive now! The local guys want $265 and $290 for a 5/8" cut plate (cut to the "trapezoidal" dimensions) that will cover the main mount + the storage bracket. I was actually thinking about getting two smaller pieces on ebay, but would end up doing some cutting (not fun with 5/8). My welder actually has a plasma torch, but I have never used it (I have a Primex CT520). I think I am going to just buy it and save myself some grief. I will give something else up to pay for it. I did mount the thumb with some ratcheting tie-downs, and marked the bottom of the bracket. I came up with this cheesy drawing, which allows 1/4" on each side for the weld (and both guys say they typically go 1/8" bigger).
There are a few places around, but not a whole lot of places that carry the real thick stuff. I am going to see how open that the place that I am going to buy the plate is to letting me have the leftover pieces from cutting this form (which is seriously thick). They do have a section on their web page "bargain bin" with some other stuff as well. I do need some stock to repair some rust-out on one of the fenders, and to repair some of the panels inside the cab. I would hope that they are a bit more open once you have bought from them. There are a few other unrelated projects where I need some custom brackets (e.g. LED light panels to upgrade a power-hog of an outdoor fixture) and certainly do not want to pay Lowes or Home Depot prices for Hillman stock.
I'm a hobby welder. so take my words with some salt. Have you ever held a piece by hand while you welded it on to something? As it cooled, you would have felt it pull towards the weld bead. When you weld a bead across the bottom of the stick, your welding produces tension stress in the bottom plate since it is held immobile by the rest of the stick. Then, as you pull the stick toward you digging, the whole bottom plate is in tension. The weld bead area is already in tension stress and the stress concentrates. Eventually, the area will develop a crack, that propagates across the stick. When it breaks, it is ugly and severe since you won't know it until the stick falls off.... A fish plate directs the stresses at an angle across the stick, spreading the tension stress. OR you could heat the whole stick to reduce internal stress.
I am also a hobby welder with no technical training. Many, many, years ago I attempted a continuous weld with a stick welder only to find the whole piece bowed up to unusable when I got to the end. Most all my welding these days is done with a 100 amp mig. I tack in several locations before applying any continuous heat. Any long areas are stitch welded. I don't attempt a continuous bead. If I need strength I will vary from area to area and build on top of the existing bead. I don't recall ever having a critical weld break on me including my thumb install. It probably endures more stress than any other thing I have welded.
This is the one lesson I have also learned; tack it first, check and make dang sure everything is lined-up, and weld modest areas at one time. One of the thumb videos I saw online actually indicates the problem with warpage pretty well; the pins would not fit without widening-out the holes. I certainly do not want to grind-out a weld, just as I am not inclined not to go through the work needed to cut two +-35-inch pieces off a 5/8" or 3/4" steel plate (or to buy the tools needed to do this). I am confident that I could do it, but I am getting too old for that sort of thing. That is why I am inclined to buy a plate cut how it is needed. And to do it rather slowly. And do it once. I am a hobby (or is it hobbled!) welder also. But I have also never had a failure, either with smaller jobs or the now extreme duty stuff I do with this beast. I think of the stress that either the welded hook on my backhoe bucket goes through, or the hooks I welded on top of my loader bucket. I have picked up/moved some pretty crazy sized logs, and there have been more than a few jarrs/bumps along the way.
The weld on bracket for the 36 inch titan is only 5-1/4 inch wide. I don't see any reason not to weld directly to your boom. I set mine up by curling the bucket all the way in and crowding it back towards the cab. I set the thumb and storage bracket on and pinned in the stow position and the thumb teeth mated with the bucket teeth. It didn't have to be strapped on or anything.
The pins definitely need to be in the mount before doing any welding on it has been my experience. The first thumb that I installed the mount still had warpage with the pins in it. The last one I did, I used grade 8 bolts with nuts on them for pins. I tightened the nuts slightly before welding on it. I still had a negligeable amount of distortion. A small amount of polishing of the bolts made it possible to easily remove and reinsert them in the bores. The OEM pins were to soft to resist bending in the first thumb I installed. There has been no bending of the gr 8 bolts.
The weld on bracket for the 36 inch titan is only 5-1/4 inch wide. I don't see any reason not to weld directly to your boom. I set mine up by curling the bucket all the way in and crowding it back towards the cab. I set the thumb and storage bracket on and pinned in the stow position and the thumb teeth mated with the bucket teeth. It didn't have to be strapped on or anything. I can see that the dipper on your Ford is a smooth section on the mounting surface. It would also stand to reason that the thickness of all four sides of your dipper are the same. This is not the case on my JD; the top and bottom (where you would weld) are thinner steel than the sides. It is a welded dipper made out of 4 pieces of steel. You can see how this is constructed by expanding the pictures I sent out. It was a concern of mine, and the opinion of smarter people than me, that a plate is the way to go.