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  1. #21
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    Bill D-
    Yeah I researched and learned that there are different trolleys for the different beam types. I had one in mind for the W beam but won't post the link (which would have been for reference ONLY) since I was told not to do that. Good to know that the I-beam trolley wheels are more self-centering laterally, I didn't know that. Regarding cost, well I will have to eat it on this deal. The steel supplier gave me a good price on the H-beam that I have (the W10x30) but they are a structural steel supplier, so they don't deal with I-beams (S) all that often. The W10x30 came in at about $300 IIRC but the S10x25.4 that I ordered today will be about $500. Oh well, I still feel better about going that route, even if I am out a few hundred. I'll try to sell the W10x30 on Craigslist or something.
    Thank you also for the feedback, I appreciate it.
    Jerry

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    metalmagpie-

    This is precisely what I will do if I go that route. I'm also considering another option, but not sure if I'll attempt it. TBD.
    Thanks,
    Jerry

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    Quote Originally Posted by neilho View Post
    Doug is like that occasionally. In time, you'll get used to him. He does know a lotta stuff.
    Ok neilho, thanks, good to know. I was a bit hacked off at a couple of the replies; felt like folk were coming out swinging for whatever reason. I'm the type to swing right back, so I did. "Nothing personal" as the phrase goes.
    Jerry

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    Unless your preference for the S10 x 25 over the WF 10 x 30 is based on some calculations, why waste the extra $200? Load on flanges is just as calculable as the moment load on the beam.

    On which subject, you need to consider (maybe you have) that allowable load is a % of ultimate (failure) load, and that % or safety-factor can be set by applicable codes, or by criteria important to you. Safety-factors are there to account for ignorant abuse, for invisible defects in material or workmanship, for departure of actual loading from the mathematical model used in calculation, for deterioration over time, and for accidents. For devices whose failure can kill somebody, they usually range from 5, up.

    Some examples. If your load ever swings at an angle to the length of the beam (like a kid on a swingset), the beam will flex sideways (the weak way), which will make it fail at a much lower dead load than perhaps you have calculated, by buckling of the upper flange or twisting of the whole beam. If your floor is uneven, the beam will likewise twist, and you will no longer have a pure moment in the calculated plane. If your load is suddenly applied, as for instance if a jack under it fails throwing the load suddenly on the gantry, the stress will be double that for a static load. If a load is dropped on the gantry, as for instance if it falls off a jack or table with slack in the chain, or your load hangs from two chains and one breaks but the other catches the load, the stress will be many times the stress imposed by the same load just hanging there.

    That is why you were well advised to faithfully copy a successful design. I am not trying to discourage you at all, just counseling against overconfidence. Perhaps in trying to be succinct you are not telling all you know. Your uncertainty about WF vs S sections got me a little worried. The calculations themselves will be easy for you. Knowing which ones need to be done is what requires some experience.

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    I strengthened mine up to 2x original build strength by placing two underneath tension rods,offset at an angle either side of the beam,and allowing the trolley to run between them,without reducing the lift or increasing the height....You get the idea looking at an old fashioned railway flatcar with tension rods,and a very light frame.These rods and struts as spreaders also stop rotation of the beam under load..........if you add castors,be careful the frame doesnt collapse inwards ,and also doesnt tip over when you try to move it.......Its actually quite risky moving a loaded gantry ,because the load will pull it over,quite easily...................but welded steel doesnt fail ,it bends ,just straighten out the bend ,add a bit more steel,weld ,and its good as new.

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    magneticanomaly-

    Thank you for the feedback. Well no, calculations aren't the basis for the change-of-horse during the course of the build. In fact, the original plans called for an I-beam ('S' designation letter), so by using the H-beam I was diverting straight-off-the-bat. The aforementioned calculations that I did make were - in fact - based on using an I-beam ('S') and not an H-beam. I did find a reference for how to do the same thing with an H-beam but in the end I somehow didn't feel as comfortable with the numbers; not because they were insufficient or inaccurate somehow but simply because the use of an H-beam is not what is customarily done with a leg-supported gantry, or most gantries for that matter. And it's mostly the latter: folk have been building these things using I-beams (primarily) for quite a long time, so they must do that for a reason. With that general broad-brush notion in mind, along with the other aspects of the matter, it seemed like a rather straightforward decision to make the switch, despite the additional cost.

    Well stated definition of safety margin. IIRC I did the calculations using a load of 10,000 lbs. The deflection of the beam would not exceed the definition of total deflection, but I left it at that. I then divided by 5 and got 2000 lbs. So by saying that the crane would be rated for 2000 lbs, I gave myself the by-5 SF. At least that is what I can recall, roughly, somewhat vaguely as I sit here falling asleep.

    Anyway thanks again.
    Jerry

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    You might want to reconsider that 10' height. Truck body is likely 7', a chainfall, trolley, spreaders, etc. will use up most of the remaining 3', which leaves very little of actual lift remaining. The plans look overbuilt and heavy, but this is from someone who had to put up and take down portable rigging on a daily basis. Our company purchased aluminum rigging to help with that chore. It was extended upward while not under load by a cable comealong on each side and secured with 3/4 pins in a series on holes.

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    I hope I am not hijacking the thread here, but I saw this the other day when visiting a friend's shop and thought it was the smartest, cheapest, and simplest gantry crane I ever saw someone whip up on the fly, and figured I would take a picture and post the next time I saw someone contemplating a home made gantry crane in the future. You can get pallet racking really cheap with a good load rating from the factory. I bet it wouldn't be too hard to rig up a trolley to go along it though in this case he just had some cross beams bolted and secured in the middle as he had a special little lift he was working on.

    Only thing I wonder if it really needs is a little cross bracing to keep the legs from kicking out. None the less I thought it was a pretty cool idea and worthy of passing along, so hopefully someone can use the idea.


    20181230_234413.jpg

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    Jerry, I don't know how I missed your thread before, but I like it. I haven't read the design detail, but may in the future. I have a Vestil gantry crane that I use in my shop. One of these days, I'm going to pull the fuselage off of my airplane wings and do some major work inside. The Vestil won't cut it by itself, so I'll probably end up building something custom. If I remember correctly, the maintenance manual for the plane even gives plans.

    Regarding the above post about using shelving for framework, wow! I see some serious deficiencies with that. If you have shelving stacked up with canned vegetables and dog food and it collapses, you haven't lost much. But it sure isn't made to support moving loads above people! What a lame-brain idea!

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    Quote Originally Posted by deltap View Post
    You might want to reconsider that 10' height. Truck body is likely 7', a chainfall, trolley, spreaders, etc. will use up most of the remaining 3', which leaves very little of actual lift remaining. The plans look overbuilt and heavy, but this is from someone who had to put up and take down portable rigging on a daily basis. Our company purchased aluminum rigging to help with that chore. It was extended upward while not under load by a cable comealong on each side and secured with 3/4 pins in a series on holes.
    Yup, my standard rule of thumb with trolleys and cranes is simple:
    Bottom of beam to highest hook point is no less than 3'.
    That is, a standard trolley with chain fall.

    Remember also, that hook height is just that, the highest point the hook will go.
    You will probably have a sling, spreader bar, etc. so your getting lower yet.

    Yes you can sneak it up closer (less than 3') using a couple of tricks, but only after you been painted in a corner.

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  14. #31
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    digger doug and deltap-

    You both make the same good point. I thought about it a bit today during the commute. IIRC my F350, which as I mentioned is the primary reason I began researching and then embarking on this endeavor stands just above my head (6'2") at the highest point on the cab. It retains its factory suspension, ergo no lift. Taking your 3' reference into account, I would be able to lift it only a few inches with the gantry at max height. Yeah that's not so good. Well ... actually all I need it to do is to clear the frame so that I can roll the frame out from underneath, then set the cab onto a trailer or a set of dollies, whatever. So that might work. Just the same I attempted to develop ideas ... and really I came out with only one good one, though the others are possibles.

    1) I have to be realistic with myself, even though I have listed that W10x30 on Craigslist, no one is going to buy the thing. It's too specialized in nature. I'll end up eating that one for certain. It happens. I mean how many common Joes have a need for a 450 lb beam? And sure enough, not so much as a nibble; granted it's only been a day but in my experience if something is gonna sell, it'll do so quickly. So. The likelihood that I could re-use the 5x5x1/4 SST on another project in the future is significantly greater than the likelihood of needing the H-beam. With that in mind, one option to gain height would be to cut the H-beam and use the bulk of it as the bases. This will net only about 5.5 inches, but hey, every little bit counts. And as magneticanomaly alluded to, adherence to the original design is a good thing; as it so happens the original design I purchased specifies an H-beam to be used as the bases (read vertical supports).

    2) Extend the height of the outer and inner verticals. Not keen on this since the inners are already cut to length and the outers will be too with only one swing of the chop saw blade (if I can get it to cut 5"). So I'd need to augment the length of those components via a weld. Sure that can be done and I am confident enough in my abilites, but I just don't like the idea.

    So in the end I'll likely go with #1 and ditch #2. And perhaps look into taller casters...

    Thank you for the feedback, good call.

    Jerry

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    Just quickly- another thought I came up with regarding the height increase issue was the possibility of running the trolley on the top of the beam. I have seen that done during my research, but it didn't seem all that common. Any feedback regarding why that is and/or whether or not it's an ok thing to do?

    Thanks!
    Jerry

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    Cm makes a low headroom trolley that adds a few inches of height. Better yet is an army type or cyclone trolley/hoist with the trolley and hoist integrated in one for more hook height.
    Bill D.

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    You can cut head height by removing hooks from chain hoists and direct coupling,and I reduce height by using a compact lever hoist......the lever hoist also eliminates the haul chain of a chainblock thats always getting tangled.

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    Thanks John K and Bill D. Question: are there any disadvantages to using one of these compact/integrated trollies? I mean, can they support the same amount of weight as their conventional counterparts?

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    Well I've been making slow but steady progress on the gantry crane build. The main beam gussets are cut and the first top plate has been welded to both of them. Ran a 6010 root, 2 7018 stringers over that, then 3 more 7018 strings plus a 7018 cap (which was unnecessary but ... eh, why not?). Will 'prolly run the remainder like that too but we'll see. May leave off the cap. Anyway during the past two nights I have found time to cut the legs from the W10x30 H-beam and the outer verticals. The good news is that I found an acceptable (to me) way to extend the height of the bottom of the main beam to 11' (from 10'). I didn't really want to go any higher than that; somehow 11' was my comfort ceiling, so I left it there. The recent cutting however lead me to a question:

    Admittedly, I had it in my head that the length of the legs was 6' so I made the cuts using that value. Always remember to check your drawings, which I didn't do. On those I had the legs at 60" (5')! Crap. I could of course just hack off another foot, but then I thought that it might be a good idea to cover the ends with some old rubber tubing of some sort to prevent them from scratching stuff as well as potentially chewing up my shins when I inevitably smack into them. Ok good. However, the casters would be 6" inboard of the ends of the H-beam. My engineering spidi-sense questions whether or not that is an acceptable thing to do. I mean, the casters will be placed directly under the contact point at which the 45-degree gussets for the verticals contact the H-beam, but would having that extra length on the ends cause some type of issue? Part of me says 'no' and part of me says 'eh, maybe' so I thought I'd see if anyone has any feedback.

    Thanks,
    Jerry
    20190331_180431.jpg

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    In the interest of keeping posts short, I have divided this overall update into multiple posts. FYI.

    So with things reaching the point of final assembly, I revisited the caster aspect of the build. I had settled in on a set from Caster City and was generally 'good' with the choice. Then a local supplier sent me mail stating that she had some heavy-duty casters that were used in the warehouse/distribution center of a local supermarket chain. They were 6000 Lb capacity each, mfg by Superior Tire, made in USA. Top mounting plate was 1/2" thick, with side plates that were 1/4" thick. 5" diameter x 2.5" wide tire and a ride height of 9". Pictures follow:
    20190405_204825.jpg
    20190405_204906.jpg

    Because my gantry will live outside 24/7, I had decided that I would use steel-wheeled casters. When I saw these however, the wheels were some type of poly, though obviously capable of supporting the rated load. The supplier made me a heck of a deal on them so I decided to get a set even if I didn't use them on this gantry project. I have two concerns:
    1) Design. These casters are the "lift" type (for lack of a better phrase) and even as a caster newbie I recognized that this was for shock absorption of some kind, even though these particular casters don't have springs on them. So the question is: would this type of caster design be suitable for a gantry crane?
    2) Wheel composition. Not sure that the poly wheels are a good idea to roll around on a slightly uneven asphalt surface, where loose pebbles are ever present. I suppose I could find an equally-sized set of steel wheels and swap those in, but I dunno, it almost seems like you should run the wheels that the casters came with, else choose different casters. Ya know? So...any feedback on that?

    Thanks,
    Jerry

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    Finally, I have made a couple of videos during the past 2 or 3 months regarding the build. The last time I posted a link to the initial video and doing so generated some flack. That surprised me, since I know that I am not spamming anyone, nor am I attempting to promote my own videos on YouTube. Hah! Laughable. My videos have so few views and I don't generate videos that often, so the assertion was absurd (and how). Anyway, someone did chime in and mention that the insertion of the video directly into a post on practical machinist would be an acceptable thing to do. So with that in mind, this post and the following one (to keep things short) will contain those embedded videos. And before any of you truspots start, no this isn't spam, no I am not trying to increase my view count, no I am not a YouTube content creator, no I have never received a penny from YouTube, no to whatever you come up with.

    These videos and the entire thread for that matter are merely an attempt to pass on my experience with building a gantry crane (from the perspective of someone who has never done so previously) and the lessons I learned. That's it, nothing more. If you're a seasoned machinist or other individual for whom the building of a gantry is old hat, I'd prefer that you don't watch (and then complain and want your click back, etc.).



    Thanks,
    Jerry

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    Last post for tonight.

    Thanks,
    Jerry

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    I need more friends


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