Gantry Crane Build Questions

[Ty_Rinke]

Wanting to build a gantry crane for my Dad and me to use in the barn. Likely will not be used for anything above 1-ton capacity as our hoist is a 1-ton. Planning to build it to 2-ton capacity due to only a slight increase in the price of a beam and the ability to lift more in the future if necessary. Planning on roughly a 10'x10' opening inside. Found that for this size I will need an S8x 18.4# beam on https://www.lkgoodwin.com/more_info/a_series_gantry_crane/a_series_gantry_crane.shtml

However, I am unsure of what size posts would be required to support this. The plan is an upside-down "T" shape with diagonal gussets going from the horizontal tube to the vertical tube. Also will have castors mounted to each end of the horizontal tube. My mind went to using 3" square tubing with 1/4" wall thickness. My question is if this size of tubing is appropriate for the desired weight rating?

Still new to designing and fabrication but know that I have the ability to make this. Just unsure about material choices.

I appreciate any input

 

[Rob F.]

Make it as tall as you can, your chain hoist and then rigging straps/chains can easily eat up 4 feet of height. So you have something 4' tall in the back of your truck with a bed 3' off the ground all of a sudden your 10' gantry is about 2' to short....
Many good posts here on building gantry cranes, search is your friend.

 

[john.k]

I d suggest "A" frame design ,with base of A near to castors to minimize material cost..........and make the whole structure pin jointed,if possible,so its easy to transport in the future.

 

[Bill D]

Location? I would look at used in the area after you price the steel, casters and trolley. My two ton HTC Engine crane weighs about 600 pounds.
Bill D

 

[mjr6550]

Not the answer to your question, but a W8x18 wide flange beam is about 5.5 percent stronger with the same yield strength steel, and would be more stable regarding buckling. Most likely more common and therefore may be a bit cheaper or easier to source.

Regarding your question, there are plenty of beam calculators online that will handle standard shapes. Limit the stress to 60 percent of yield stress and you should be good (that assumes buckling is not a factor, which typically is not with relatively short wide flange beams or any square/rectangular sections).

 

[DDoug]

archives are full of this same subject, try reading up on them.

 

[RC Mech]

Every time this comes up the consensus is that the beam and column sizing is trivial. The expense and failure mode involves the casters.

5 ton casters aren’t cheap. Unbalanced load and 3/4 of the wheels making contact with the ground are the constraints in load and safety factor.

 

[John Garner]

The guidance I was given, many years ago, is that ALL casters should be INDIVIDUALLY rated to carry the TOTAL weight of the fully loaded gantry: frame, hoist, rigging, and hoist-capacity payload.

 

[Ty_Rinke]

I appreciate all of the input. I will definitely take the advice about the casters and ensure that I have more than enough capacity with them. And As far as those saying to search the forums to find the answer, I have spent several hours the last few days going through threads and have not been able to find any real answers to vertical post size and thickness

Thanks

 

[Ty_Rinke]

Make it as tall as you can, your chain hoist and then rigging straps/chains can easily eat up 4 feet of height. So you have something 4' tall in the back of your truck with a bed 3' off the ground all of a sudden your 10' gantry is about 2' to short....
Many good posts here on building gantry cranes, search is your friend.

I will have to look into this and see if any changes to my plan might be necessary. I do have a slightly taller truck than most stock ones and it will be the most common user of the crane so thank you.

 

[DDoug]

I appreciate all of the input. I will definitely take the advice about the casters and ensure that I have more than enough capacity with them. And As far as those saying to search the forums to find the answer, I have spent several hours the last few days going through threads and have not been able to find any real answers to vertical post size and thickness

Thanks

You won't find an exact answer to your question, however you will find out HOW to figure what you need, on your own, and learning something in the process.

 

[Rob F.]

I will have to look into this and see if any changes to my plan might be necessary. I do have a slightly taller truck than most stock ones and it will be the most common user of the crane so thank you.

Adjustable height with telescoping legs can be good if you need to go inside a lower building sometimes.

 

[Bill D]

I am surprised no one has yet said look at a real one made by a crane company and copy that. They do list cross beam sizes. Off hand my OTC uses steel double the wall thickness of a Chinese one and the beams are maybe 50% bigger. across.
Bill D

 

[TheOldCar]

In addition to height, make sure it’s plenty wide. I personally would make sure it easily clears at least a car hauler.

 

[Ty_Rinke]

Adjustable height with telescoping legs can be good if you need to go inside a lower building sometimes.

No real plans for it to be moved beyond the barn. Also have a 10, 12, and 14 ft door so height shouldn't be an issue.

 

[Ty_Rinke]

In addition to height, make sure it’s plenty wide. I personally would make sure it easily clears at least a car hauler.

That is a great point. I was mainly thinking of trucks since we do not have a trailer ourselves. We may get one in the future and we also borrow them if needed at the moment

 

[Rob F.]

An internet search of your subject with the words practical machinist added to it is a good way to find things here on this site, sometimes the bigger search engine finds things easier.

Seems like you should make it 10' wide and 14' tall, so a 8'6" trailer can easily go through it and will just fit under your tallest door.

 

[Joe Henderson]

I built one several years ago. I copied a friend of mine's which was a copy of a commercial one. He is a retired engineer. It has a telescopic feature on the main beam. The legs are 2x5x5/8" channel welded to a length of 6" heavy 1/2" wall square tube 16" long. His was 18". It's what I could find for a drop. The beam is s8 or 10 25lb. It is on big casters and the main beam is pinned with two pins 3/4". Can't remember the spacing but I drilled holes in both beams at intervals to allow it to be moved up or down. I have a three-ton hoist on a trolley on it. Can't post pictures because I don't have an offsite host. Anyone that wants a picture can send me your phone # and I'll take an iPhone pic and forward it. I have the plans somewhere, but it might take a while to dig them up. Grandson #1 is a welder and has a Lincoln 250 he has loaded and unloaded with it multiple times. i think it weighs around 3K+.

 

[metalmagpie]

I have built a gantry and have had it nearly 20 years. Each of its 4 casters is rated for 3500 lbs. However, I built screw-down feet on 2 corners of one side. This allows me to adjust any side-to-side tilt out of the main beam. It also prevents that side from moving if I'm up a ladder working on the hoist. If I had it to do over again, I'd have leveling screws (I used 1.25" allthread) on all 4 corners spaced as far out as I could. That way you don't need those badass casters, and your crane will be very stable. Sure, you'll still need casters, but only to move an empty gantry.

metalmagpie