i need some advice on building a jib crane | The Garage Journal

I have installed dozens of these - you are in over your head on understanding what is needed to balance forces and keep things safe.

There are ways to do without needing a big brick of concrete & rebar but I am not going to engineer it over a forum.

I will second the forklift recommendation - way more flexible, way more lifting power, they really aren't that big (my 3k clark isn't much bigger than my riding mower.)

I have both a Jib and a forklift, rare is a day that I turn on the air to the hoist. Most of the time I just use the forklift because it will go anywhere in the shop and the jib only covers a 14' radius half moon.

I'm building a small jib crane but it will only be lifting things unter 200lbs. It's swing is only wide enough to go over my lathe and mill so help take off chucks and other heavy attachments... What do you need this to do? Pull engines? lift a push mower onto a cart?

Based on the questions you are asking and proposals on how to build all indications are that you are in over your head. You are right I don't know your overall qualifications but your questions tell a lot about the background knowledge you have.

You can buy the parts for building this at grainger - but it still doesn't mean that you won't tear it off of a wall or overturn a mast.

A 20' jib for # takes a giant beam/truss just to handle the cantilever bending loads in the jib. Concentrating those loads onto the mast gets huge. Then the Anchor loads have to react 20,000ft-lb plus moment created by the jib arm (which is likely to be 10-15,000ft-lb) and dynamic effects.

Typical lifting equipment is designed around a 5:1 factor of safety to material yield.

Ask your engineer the questions and your fab ideas - he has to do the math based on the materials that you want to use.

Having a large diameter base plate compensates a lot. If you work out the mechanics, a rough estimate for strength of the base plate anchors is b/x times the load you are trying to lift, where b is the length of the boom and x is the diameter of the baseplate. So if you have a 10 foot boom and a 2 foot baseplate and try to lift lbs, then you need anchors that can withstand lbs of pulling force. This is not an unreasonable load, especially if distributed over several anchors . One thing to consider, though, is the strength of the concrete.

I am not an engineer, and this post is not engineering advice, but OP says he has an engineer friend to check his design. In this case I see no reason why he must be "in over his head."

Having a large diameter base plate compensates a lot. If you work out the mechanics, a rough estimate for strength of the base plate anchors is b/x times the load you are trying to lift, where b is the length of the boom and x is the diameter of the baseplate. So if you have a 10 foot boom and a 2 foot baseplate and try to lift lbs, then you need anchors that can withstand lbs of pulling force. This is not an unreasonable load, especially if distributed over several anchors . One thing to consider, though, is the strength of the concrete.

I am not an engineer, and this post is not engineering advice, but OP says he has an engineer friend to check his design. In this case I see no reason why he must be "in over his head."

i found a very similar jib crane on my local c/l and the thing is massive for only 2k lbs.

There's a reason for that, as kwb described. You really are about one full magnitude off of what is required to make this work. Pickup axles, back of the envelope calculations and 4" slabs aren't going to cut it here.

The standard foundation for a Gorbel 2,000lb self-supported jib crane with a 20' radius is four feet deep by seven feet square. Roughly a truck load of concrete. If you bolt a crane of that size down to your 4" floor you'll rip a hole in it and drop a couple tons of steel on your head!

https://www.gorbel.com/resources/products/jibcranes/ibeam/documents/FS-Jib.PDF

I suggest if you really want a free-standing jib crane you go buy one. Regardless of whether you're capable of engineering and building an adequate solution or not, jib cranes are so damned cheap on CL and Ebay there really is no point in trying to build one. Get the installation manual for the crane and follow it. Problem solved!

This may help you. Look at Spanco's wall mounted jib crane. Also the parts manual will give you a good idea on how they provide for the pivoting action. This type of assembly may able to mount to your post/column.

http://www.spanco.com/cm/streamfile.aspx?id=e382c1be-ffec-4c1a-a606-934b9ff7a590

http://www.spanco.com/cm/streamfile.aspx?id=51cb23cf-bbca-48db-8ee3-b6acf31

http://www.spanco.com/cm/streamfile.aspx?id=4e592e24--4c07--20ac5b8ac555

For what it's worth if your engineer friend is only looking at the size of the outrigger beam then that is essentially the easiest part of the job and not good enough. The devil will be in the rest of the details/assembly and of course the required foundation that typically needs a factor of safety of 1.5 against overturning which others have already mentioned.

The Spanco .pdf's will probably get you and your engineer friend down the right path though.

Good luck

I used a lb load rated one at a former job 8 inch schedule 80 rise pipe bolted to the baseplate with 10 one inch grade 8 bolts welded to rebar put down in 4 ft X 2 ft pad in the floor the jib its self was 10 ft out into the shop BUT it also had 2 anchor cables run from the top out through the wall out side at a 45 deg spread buried in 3 yards of concrete 6 feet deep we over loaded that thing on a daily basis for years and it never failed.

If you don't need to swing the beam with the load on it, just run the trolley back and forth, you could add a hinged leg to the end of the beam to help support the load at the end. That would decrease the load on the pivot the times you have to pick a heavy load.You could even add a wheel if you need to move it. The leg could be hinged out of the way when lifting lighter loads.