Franko's Hf Engine Hoist Mod

[Just for fun]

This morning I finished the welding.
The long legs were clamped with a long pipe clamp and tacked.

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A slightly different set-up to clamp the short pieces. I used one of the wood wedges I made to cut them to give flat purchase for the clamp.

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After tacking, I MIG welded everything. The welds came out ok for me.
I'm pretty happy with the fillet weld on the right. They aren't my forte.

View attachment 113273 View attachment 113274

As an experiment, I tried out the non-automatic helmet. I was supposed to be able to see better with.
As you can see, I couldn't see anything and totally missed the joint and had to make another pass.
I cleverly did this on the bottom where it won't be seen.

View attachment 113275

I installed the legs to see if they work. It seems to be okie dokie. Nothing left to do but paint them.

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Here it is with the legs in the stowed position.
Oops. The bad weld is showing. Looks like I'll have to grind some before painting.

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Phase one of the hoist mod is done but for the painting.
Phase two will be a knob for the jack screw. To be continued...

Good looking modification Franko! So after 5 years how's it holding up? I see there has been some concern about sturdiness. I wonder if adding another set of casters on the legs just in front of the pipes/extensions would add to the strength.

 

[Tmate]

I have a Bluebird 1,200 lb hoist with a very long boom and only one hook position. The legs of the hoist are straight and 37" apart on the inside.
The only problem with lifting my incoming 2,000 lb Bridgeport mill off the pallet is the lifting capacity. The frame and boom are sufficiently sturdy (American made - 1/4" wall).

I made some calculations based on measurements of other hoists with multiple hook locations. The amount of increase in lifting capacity from a relatively small decrease in boom length is remarkable.

If I move my hook location only 15" inward, the lifting capacity is theoretically tripled. Although it has a 3 ton jack, it should be enough for 2,000 lbs. I would through bolt a 5/8" industrial lifting eye to accommodate the hook. I should still have enough height given the 99" maximum hook height with the stock configuration.

Is there anything I'm overlooking?

 

[hman]

PLEASE re-check your math. If you get 3 tons (6000 lbs) at 13 3/4", by my calculation you'd get the following distance vs. capacity results:

13 3/4" (1 "distance unit") ... 6000/1 = 6000 lbs
27 1/2" (2 "distance units") ... 6000/2 = 3000 lbs
40 1/4" (3 "distance units") ... 6000/3 = 2000 lbs
54" (4 "distance units") ... 6000/4 = 1500 lbs

Be careful out there!!! (per the desk sergeant in Hill Street Blues)

 

[Just for fun]

I don't know if what your planning is a good idea. Even if moving the hook back to gain some on the boom, the area I have circled doesn't look very strong.

Tim

 

[wrat]

If I move my hook location only 15" inward, the lifting capacity is theoretically tripled.

Uh, yeah, I'm not seeing that. I'm seeing that to provide equivalent margin on a 2,000 pound load, you must move the hook in to the 27inch distance (27.528) from the cylinder attach - another 3 inches inward from what you're proposing.
And, even though this is basic static truss method, you'll notice the arm swings, but gravity never does. So depending on the position of the arm, the exact loads will change, with the most egregious position being exactly horizontal, of course.
Now sure, if this is legit 1/4" wall thickness, you're probably just fine (assuming no heat damage and over-stress conditions in the life of this rental piece).
And that's just the main lifting arm. Who knows about the hydraulics, eh?
Still, at the risk of being trodden on by the Safety Monitors, I might remind you if it says it's "1200 pound" rating, it means it can do that all day, every day, full travel, in any conditions and still be safe by a comfortable margin.
You, on the other hand, want to bring one machine to the ground at a speed less than a free fall. The dynamics of that scenario may be complex, but in some quick calculations, I'd bet you'll do fine.
IOW, if you get the machine all harnessed up, and use this lift to raise it off the pallet, even a half inch; then pull the pallet out and lower the thing; you'll get away with it (not as now, but after moving the hook). Even if you're lowering it onto 1 inch pipes to move it with, you're still talking what... 4 whole inches of descent? No sweat.
Now, if you're taking this off the back of a truck, or maybe even a trailer, the price of a rented forklift might be cheap. But off of a pallet already on the ground? I think you got it.

 

[Tmate]

I didn't calculate the capacity figures. I imported the above right photo into a cad program and measured the distances between the various attachment holes on the boom. Any errors in the labeling of the different boom holes are replicated in my figures.

The photo of the Bluebird hoist is one I copied from the Internet. My own hoist was new when I got it and has only been used a half dozen times, so wear/stress shouldn't be an issue.

I appreciate all your input. I think I'll know if this will work by the time I lift the mill 1/2" or so.

 

[epanzella]

I aree with the concerns of JUST FOR FUN in post #54. I've never seen a hoist just rely on the torsional rigidity of a single cross piece. On my hoist the upright is supported in three places, two of them in tension. If you hoist looks like the one in the picture the circled area is the weakest link and it should be reinforced.

 

[wrat]

If you hoist looks like the one in the picture the circled area is the weakest link and it should be reinforced.

Alternately, if all you're gonna do is lift it up and set it down without a pallet underneath, and not move it around, you needn't fab and weld on your hoist.
You can just stick a couple of 2x4s under the joint in question and those blocks will transfer the load to the ground. If it matters at all.

If you wish to suspend the machine and move it around with that hoist, I think all the concerns expressed thus far are entirely valid.

 

[hman]

You can just stick a couple of 2x4s under the joint in question and those blocks will transfer the load to the ground. If it matters at all.

I think the hazard with that joint is the torsion, not the straight downward force. Just as a first approximation, assume the hook is attached to the horizontal bar at the 48" point, or 4 ft. With a load of 2000 lbs hanging from the hook, the torsion on the weld joint will be something like 4 * 2000 = 8000 foot lbs. That's a scary large number to be held by just a couple of weld joints!

If you look at the picture, you'll see that where the legs attach to the lower cross bar, there are a couple of triangular gussets welded in ... and there are two such weldments, so each is carrying just half of the torsional load. The joint at the mast does not appear to be reinforced at all.

 

[Tmate]

Here's a better view of the joint in question.