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Thread: Jib Crane

  1. #1
    Join Date
    Sep 2008
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    Saskatoon, Sask, Canada
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    Default Jib Crane

    I want to build a small jib crane in my back yard that can haold 1ton I want it for unloading my welder when I need the truck for other things as well as unloading steel and such. The plan is to drill a deep hole and pore a cement base to mount the jib crane to. As for the designe of the crane I am open to ideas does anyone have pics of any or plans?

  2. #2
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    Try these for starters...

    http://www.bushman.com/prod_jcran.asp

    http://www.globalindustrial.com/gcs/...unt+Jib+Cranes

    Either should give you the specs and a clear enough picture to do the job. If not, type in jib crane mount on your search engine of choice. These were the first two that popped up.
    Last edited by WyoRoy; 09-18-2008 at 12:45 AM.

  3. #3
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    southwestern ohio
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    Default

    go on northern tool and search item number 103143 this should give some sugestions on size of the jib and the verticle suport. As far as diging a hole goes I would reccomed renting a skidloader and auger with a bit at least 2 feet in diamiter an makesure you can drill at least 4 feet deep. I would set an I beam in this hole with a plate on top of it and bolt the crane to the plate with grade 8 bolts. THESE DEMESIONS ARE JUST THE MINUMUM THAT I WOULD USE IN THIS SITUATION. I AM NOT AN ENGINER,DO NOT QUOTE ME ON ANY OF THESE DIMENSIONS AS BEING SUFICENT.
    Have you thougt about an engine hoist?

  4. #4
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    An engine hoist won't work for me I aready have one but the hight is not enought and you can't move a loaded engine crane on a back lawn

  5. #5
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    You should be able to figure out what you need as far as specs and material on those two links I provided. I worked with a lot less when building one for DDA52...it isn't rocket science by any means.

    http://www.shopfloortalk.com/forums/...ight=jib+crane

  6. #6
    Join Date
    Feb 2008
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    Default

    Is this inside or outside?
    Does it have to swing? (pivot about the vertical axis)
    How far does it have to stick out?
    Does it have to be completely in the clear with one beam, or can it use a diagonal brace?
    Can you make ductile X-ray quality welds using a 7018 rod that you would trust your life with?

    Some may say that the following is overkill, but overhead lifting is no place to experiment because people don't stand a chance when heavy things drop on them from above.

    If this is for use at a business, it must comply with the following rules for cranes: http://www.osha.gov/pls/oshaweb/owad...ARDS&p_id=9830 which makes it basically a "forget about doing it yourself - you've got to buy one" situation.

    It would be wise to comply with those rules though because they save lives.

    You can make a very simple one that does not pivot by driving a steel beam into the ground to use as the vertical member. I'd assume that to unload a truck, you'll want the top to cantilever (stick out) about 6' from the piling.

    1 ton acting at a distance of 6 feet places a tremendous amount of torque on that piling. You'll have to talk to a Geotechnical engineer to see how deep to drive this beam. You'll want it protected from corrosion, so consider having it hot dip galvanized. If you want it to last a long time in problem soils, you'll need to attach a cathodic protection system (sacrificial zinc anode).

    Then you'll need to weld a cantilever beam to the piling. They should be the same section. You'll want to miter the beam so that web connects to web, inside flange connects to inside flange, and outside flange connects to outside flange. Or weld it square and weld a transverse stiffener across the web to connect both flanges. Prep for full penetration 60 degree V groove welds and weld it with baked E7018 rods.

    Sizing the steel: example
    For the rated load, you have a worst case concentrated live load of 2000lb at 6', which is a maximum shear of 2000lb and a maximum bending moment of 12,000 ft lb (12'k).

    Assuming the beam will weigh 400 lb and and act as a concentrated load at its center of mass (3' out) and have 400lb of gear attached to it acting at the end (6'), you have a dead load of 400*3+400*6=3,600 ft lb (3.6'k), and 800lb of shear.

    Using LRFD, I'd modify the live load factor to 2.0 to take impact into account, and leave the dead load factor at 1.2, thus...
    ultimate shear Vu is 2(2k)+1.2(.8k)=4,960lb
    ultimate moment Mu is 2(12k)+1.2(3.6k)=28.32'k

    Assume the piling projects from the ground 12'. the total unsupported length from the ground to the end of the crane is 18'. Using the steel manual, the following A992 wide flange beams that can support that bending moment over that unbraced distance:
    W10x22 10 1/8" deep, 1/4" web, 3/8" flanges
    W8x21 8 1/4" deep, 1/4" web, 3/8" flanges

    But these need to be checked to see of they can also carry the combined shear...
    Mu/φMn+Vu/φVn must be <1

    W10x22 φMn@Lb->18=41'k
    φVn=73.2k
    (28.32/41)+(4.96/73.2)=.758 OK

    W8x21 φMn@Lb->18=37'k
    φVn=62.1k
    (28.32/37)+(4.96/62.1)=.845 OK

    Either one will cost about $20 per foot. Galvanizing is about $0.60 per pound. Remember this is just a guide for the process. This might not work for you. Conditions at your location may vary, so it would be wise to consult a professional engineer. It's not really as much trouble as one would think.

    Whatever you do, don't ask a rocket scientist. 33% failure rate may be good enough for the space shuttle, but I wouldn't get under a crane with those odds!
    Last edited by Bodybagger; 09-20-2008 at 03:43 AM.

    80% of failures are from 20% of causes
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  7. #7
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    Well if you must build one yourself be very careful. I work on cranes for a living and there are a lot of "homemade" jobs out there that just plain suck and I'd be afraid to use it.
    Osha 1910.179 ONLY applies to cranes with a capacity over 6000 pounds. His one ton unit is not required to be inspected at all. But one ton will kill you just as fast a three.

    that said go with WyoRoy's design I'd certify that crane. Very well built. Finally someone that gives a darn about the quality of work they produce and the lives they may save by thinking through the job.
    Last edited by kcstott; 09-20-2008 at 08:06 AM.
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  8. #8
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    Quote Originally Posted by Bodybagger View Post




    Sizing the steel: example
    For the rated load, you have a worst case concentrated live load of 2000lb at 6', which is a maximum shear of 2000lb and a maximum bending moment of 12,000 ft lb (12'k).

    Assuming the beam will weigh 400 lb and and act as a concentrated load at its center of mass (3' out) and have 400lb of gear attached to it acting at the end (6'), you have a dead load of 400*3+400*6=3,600 ft lb (3.6'k), and 800lb of shear.
    The crane needs to support 125% of it's rated load where it will produce the most beam deflection OSHA 1910.179 ref ANSI B30.2 so it needs to support 2500 lb. at the end of the beam. It also needs to be built to a safety factor of at least 2:1. lifting equipment will have a safety factor of no less then 5:1 (that's automatic, all your chain slings and synthetic slings are rated correctly so long as they come from a reputable supplier)
    Miller Syncrowave 200 W/Radiator 1A & water cooled torch
    Millermatic 252 on the wish list
    Bridgeport Mill W/ 2 axis CNC control
    South bend lathe 10LX40
    K.O. Lee surface grinder 6X18
    Over 20 years as a Machinist Toolmaker
    A TWO CAR garage full of tools and a fridge full of beer
    Auto shades are for rookies
    www.KLStottlemyer.com

  9. #9
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    Default

    now we're talking this is the kind of info I have been looking for.I'll answer as many of your questions as I can. It is for home use In my back yard and is for unloading my welding skid from the truck for when I want to use the truck for just a truck.

    The boom must be able to have about 180 degree swing.
    The boom can have a brace on top of it extending to the verticle member(sorry if I am using the rong terms I am not a crane guy hense why I am asking for help )
    I would like the boom to be about 12' hight (a little less will be ok if need be)
    The verticle beam can extend higher than the boom but I don't want it to go to high I don't want the neighbers to have a problem with it.
    And as far as the welding goes thats realy not a problem I trust my welds with my life and if i can't trust my welds then i realy need to quit my job
    And before I forget I would like a boom length of 10'-12' as long s its long enough to unload the welder and any steel thats to heavy to lift by my self out of the truck then that will do.

  10. #10
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    Did you ever even check out the link I posted in post #5? I believe Don or I gave most, if not all, the dimensions of the stock we used, prep for welding and installation. Sorry if it doesn't meet your design needs, but it would appear to be what you were looking for.

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