Advice on load capacity of JIB crane

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Hi guys.I'm about to construct a 360 degree JIB crane for the workshop, and am having trouble calculating the max load on a UB 150 (6") beam.  I'm not going to be lifting anything crazy.  Most of the time it will just be used for my Lincoln remote wire feeder.  But I'd like to be able to lift 750 to 1000lbs should the need arrise.The hinges (2)...Plate is 20mm 350mpa, pins are 26mm dia. and around 10" long.The distance from the top of one hinge to the bottom of the other will be 2.5'.  They are to be welded to a 3" square post, 3/16" wall ( or better ).Jib will be 6' long, and top braced either by UB150 or 5/8" round bar with turn buckle.I've got no issues welding the assembly.  In another life i made telescopic booms/jibs for crane trucks.  My concerns are based around design, and general load capacity of the small 6" beam.Keen to hear your thoughs.Peter
Reply:Your biggest problem will be how to fasten the mast to the ground.  1000lbs @ 6' of reach is a tremendous moment arm(rotational force) at the base of the mast.  If you haven't considered it yet, you're likely to need to pour a large concrete footing to attach this crane to.  I've seen similar jib cranes with lower load capacity installed.  The crane I saw, the base plate was 24" in diamete with 4 large triangular gussets to stiffen the connection between the base plate and the mast.  This particular crane was anchored with something like a dozen redhats into 10" thick poured concrete floor.  I recall the crane installer saying it was a near thing with needing to pour a cubic yard(36"x36"x36") of concrete for a footing for the crane.If it were me, I'd take my crane specs to a company that installs cranes and get them to run some calculations on their most similar produc,t to determine what kind of foundation you need to safely support those loads.  I suspect you'll find that you need to substantially lower the load rating unless you can install the necessary foundation footing/counterweight.Maybe you can compensate them for their time and expertise by purchasing any other hardware or rigging equipment you need from them?  Hopefully your design is based off of an engineered product so you know that your beams are sized appropriately for the loads you're thinking of lifting.  If you're just guessing or using material that's ready to hand, I'll strongly encourage you to find someone who can run the calculations for a safe working load limit for the entire system; or at least look at similar industrial equipment and base your load limit on what someone else's similar product is rated to lift.Please follow through on the investigation for the mounting or foundation for this equipment.  Your crane is only as strong as the weakest link from the foundation to the rigging.  You can build the best crane in the world, but if it upsets with a load on the boom and crushes you or someone else, it won't matter.  That's all the preaching I'll do on the subject...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:1000 pounds over a 6 foot length and float a whole 360 degrees....that is going to need a serious base. Most of the ones I have seen use some other structure to help support the the vertical portion, but that limits the swing as well. Like Dab said you really need an engineer to competently design and rate the crane. I think you would be much better off making a movable gantry style crane.Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:Listen to a_dab_will_do. I looked at installing a modest commercially built 1 ton 360 jib in my shop... the foundation detail required cutting the floor and pouring a massive footing. The concrete work was more than the jib.  I'm also not clear on your design. Most 360 jibs use an upper bearing/bushing and lower wheels that run around a vertical round mast. Hinges make me think it's 180 degree design.Here's some stuff that may help you play with some numbers. I ran your beam at 1000 lbs without taking into consideration a safety factor or the 5/8 support rod. It's deflection is about 0.20736" at the unsupported end. The rule I use for max deflection is lengh/600 so 72/600=0.12"... so the beam by itself may slope too much. Remember too much deflection and you could have a run away trolly. It's a good idea to use the 5/8 rod to support the beam this will certainly help with deflection. I'm not sure how to calculate this. Without support this beam will deform (bend) at just over 1.5 tons on the end (about 5/8" deflection in this case). Your beam choice is kinda light without support. With support you might be ok.http://sketchup.engineeringtoolbox.c...beams-c_6.htmlhttp://www.engineersedge.com/beam_be...m_bending9.htmhttp://www.engineersedge.com/beam_be...flection_9.htmhttp://www.engineeringtoolbox.com/mo...on-d_1331.htmlI'm no engineer but I think it's important to be able to size something up. Beyond beam deflection you have mast deflection and footing calculations to do. I don't think a jib is a good place to go blindly. I'd buy one or work off an engineered design.Years ago I was given a 2k wall mounted jib. After a lot of thought and finally consulting with an engineer I put it in the band saw and made a gantry out of the beam.  Turned out my masonry walls would never support the load. Last edited by forhire; 12-18-2012 at 01:12 PM.
Reply:Sorry guys, it was late when I typed this out.I should have given more info on the post/ mast.It is an existing structural column, and has atleast a 10'x2' pier of concrete at the base.  The top is secured to the beams for the floor above.Thanks for the replies thus far.  Seems most of the concern is surrounding the footings of the post.
Reply:Now you changed the game somewhat. Side loading an existing structural column means the column needs to be looked at as well. Most columns are designed to only take a vertical load. Start trying to bend a column and you could end up with buckling issues even if both forces by themselves aren't a problem. Hoists and cranes are not simple to engineer. There's a lot more to this than simply pulling a beam out of a table and just winging it..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks.I'm not overly concerned about the post.  It has been filled with high strength concrete, and does not support any load baring walls.  It is also possible for me to strongback the post.I'll run this past some local crane builders in the newyear.Thanks for your comments.Peter