lifting point question for jig

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I have a question on lifting eyes for a jig that we are building for holding pilings vertically in the water while a hammer is being mounted to the crane and then the jig will be removed.  the jig weighs around 1000 lbs and will be lifted by crane the bottom plate is 3/4 with part of it doubled.  looking at putting 2 pad eyes on it to lift the device so that the counterweight hangs down while being lifted.  what thickness of material would be recomended to lift the device would 4"x4"x1/2" angle maybe 6" long mounted long ways with a 3/4 hole in it for a shackle work if its over kill thats not an issue i was thinking the angle for the ability to weld along all four surfaces to the 3/4 plate.  There will be concrete weights added to the doubled 3/4" plate once it is in position. Attached Images
Reply:Looks to me like you only need some standard lifting lugs made up and welded at the balance point.  For a thousand pounds half inch thick should be more than enough with consideration of the abuse piledriving crews apply to equipment.  I am sure that angle iron could be used with a fillet all around.  There are some unknowns here however.  In most cases loads on fillet welds are not in the direction it would be on that angle.  Maybe someone with engineering background can chime in.  I have never  built anything for proper lifting using angles... it has always been proper plate lugs with holes and weld size spec'd  I am inclined to suggest that you use a plate for the lifting lug with bevelled edge and then welded. Spec the amount of bevel to increase size of weld and then spec the fillet also.  There are standard tables giving the dimensions of lifting lugs and size of welds required.  My boilermaking manual had standard sizes and capacities but I have given it away.http://www.winsafe.com/files/products/10_520920.pdf   Since this is going to be around work crews and not something used by farmer John in his back forty it might be prudent to use standard lugs.    http://www.liftingonline.com.au/products/DECKPL   Also very important that you spec some sort of preheat when welding onto thick sections like that.  Anything over one inch MUST be warmed up a bit.Last edited by lotechman; 03-03-2012 at 10:44 AM.