How big an I-Beam do I need for machine lifting?
Plan to run a 20' I-Beam to move machines inside my shop from off a trailer sitting outside. Will support the beam at 1' , 10' and 19'.
How much I-Beam to handle 4,000 pound machines. Will use two chainfalls rated at 2 tons and dollies to match.
What dimension of cross section should the I-Beam be? How thick should the beam be?
For your sake, the machine's sake, and the sake of whomever else is unfortunate enough to be involved in this, consult a licensed and bonded engineer. Or rent a damned forklift to do it, it'll be cheaper than the beam anyway.
Simple answer, look at a Wallace crane catalog.
there are numerous beam calculators on the internet. decide what your acceptable deflection will be and calculate away.
it wont take a very large beam to do what you want, but it would still probably be cheaper and much easier to rent a fork lift.
I have 2 4" channels [ light channel .180 web thick ] bolted back to back spanning a 14 ' open area. I have used this to lift 2500 # suspended from a single trolley. I imagine this would be entirely sufficient for what you describe. ---Trevor
My armchair engineering says that's grossly overloaded.
Originally Posted by t.jones
So long as its well anchored and won't drop on anyones head or any part of the lifting system that could hurt someone, then its a matter how little deflection you want in it.
It also depends on how you support the beam. If you just plan on putting a post under the beam in 3 spots, you'll have problems. It's better to hang the beam. Minimum is probably going to be an S12X40. About 800 lbs of steel.
I am betting that you where off on your weight calc.
Originally Posted by t.jones
At a minimum, you need a fairly good understanding of the engineering principles and/or a background in physics / statics to begin to accurately evaluate loads. Not only is there the dead weight of the machine, but there is the braking effect of the chain fall when you are lowering that will dynamically introduce a multiplying effect on the downward load on the beam.
You also don't state how the beam will be supported - presumably you are hanging it so as to practically use trolleys. Welded joints to other beams? Bolted joints to other beams? Attached to wooden beams?
Typical allowable deflection is L/600 . . . you have 108 inches between support centers - the allowable deflection at midspan is 108/600 = 0.180 inches. More conservative crane designers go with L/1000 which would allow 0.108 inches.
You will also need to know the minimum distance between trolleys that you expect combined with the maximum load shared between those trolleys - this will give you two point loads that should be considered equidistant from the mid-span location.
If it were me, I'd figure out the recommended beam with the supports you have planned and your max load concentrated at mid-span and then upsize one beam size.
Not too helpful are we? A seemingly simple question but considering it's lifting geat and weights capable of doing real damage should they get out of control arouses safety in the minds of all who engage.
The two 4" channels mentioned earlier is a disaster waithing to happen. Work the math. WAY overloaded. The man is blind lucky. When steel beams fail under load there is no Hollywood creaking and groaning and slow sagging. A steel beam buckles on the upper flanges and fails in milliseconds: crash! and its over with. Anyone caught up is bleading and broken on the floor.
OK your circumstances are 20 ft span? Less a foot to fit supports under the ends? (Makes a difference.) 4000 lb machine? Worst case is center loading, concentrated load. Allow 3 to 1 safety factor. A36 steel yields at 36,000 PSI. Consulting my handy Beam Boy calculation utility:
A 10 x 25.4# S beam 19 ft between supports with a 4000 lb concentrated load will sag 0.266" at 9190 PSI. Safety factor is roughly 4 to1 (36,000 yield - 9200 lb load) well within the 3 to 1 safety factor
An 8 x 18.4# S beam 19 ft between supports with a 4000 lb concentrated load will sag 0.572" at 15850 PSI. Safety factor less than 2 to 1 = unsat.
From this I conclude the minimum safe beam would be 10 x 25.4 Sbeam (Am Std) for this specific application. Supporting the load from two trolleys slightly improves the loading.
I would still laterally stiffen the upper flange. A side pull or a swing can greatly enhance any tendancy for the upper flange to buckle. Jumper stays and strut ala sailboat mast occurs to me.
Find an engineer and bribe him with a box of beer and a pizza to pronounce on your plan. Ask the guys on your favorite website and there's no telling what kind of expertise you will find. I've done lots of fancy iron work where load calcs entered the picture and I've never had a failure. I may sound competent but I'm no engineer and certainly no stress analyst. Few of us on PM are.
Any of you guys PE's? Got words of wisdom?
The forklift is sounding better isn't it?
Last edited by Forrest Addy; 07-11-2012 at 04:47 PM.
Since you do mention intermediate support at the ten foot point, here is an S7 X 15 supported at points 8 foot 6 inches apart that has had about 4200 (a 16" G&E Toolroom shaper) hanging generally central with no noticeable distress or large deflection. Since you are supporting further apart I would definitely go bigger. Its a pain to get anything up there, so why not get a big one you don't have to wonder about? Have the P.E. pal bless your thoughts before spending money on iron.
(the yellow gantry left rear)
Last edited by johnoder; 07-11-2012 at 02:21 PM.
Reason: wrong load
Other than renting a forklift or a Carry-Deck crane when you need one, another option would be to look for a used gantry crane with casters. I have one that normally lives over my welding table, but I can roll it to a truck when I have to unload something - I pick the load up, the truck drives out, and the load is lowered. If the load is more than I can handle, its fork lift time.
Thank you all for your answers.
digger doug ... thanks for the Wallace Crane suggestion.
johnoder ... your photo and description give me a clear idea.
My max weight will be a 3,400lb Hardinge AHC.
I also have nine other machines to move, one at a time, to my new shop. Will establish something to make it cost effective and there when I need it.
I'd go ahead and build your beam hoist. But add two movable legs, so you can span just outside the machine you're lifting. That takes nearly all the problem away.
For my two cents, I size beams based on the stresses in the metal. That depends on the bending moment applied by the load and supports and the section modulus of the beam. Stress = bending moment / section modulus. The bending moment created by suspending a 4000 lb load in the middle of a 20 ft beam (worst case) equals the load times the length (in inches) divided by two. So, M = WL/2 which equals 480,000 inch-lbs. I like to limit stresses to 20,000 psi and that allows me to calculate the minimum section modulus. SM(minimum) = M/stress = 480,000/20,000 = 12 in^3. That allows me to use a steel handbook to find a beam with a minimum section modulus of 12 in^3. I built up a beam a couple weeks ago to lift my new 3 ton milling machine - it worked...but if I wasn't lifting it from somebody's front yard, and if I could have afforded it, I would have rent a forklift.
That is interesting Marty ! I dont like paying for forklift rentals at home. I have spent about a thousand dollars on steel and lifting apparatus and that stuff is going to do my lifting jobs for decades whenever I want.
As a hobby machinist, with many machines now, I have faced this delemma on too many occasions in the past. I have consistantly looked for inexpensive, affordable solutions instance by instance. In the end, the total cost of these has been significant. Three months ago I realized that my search for the proverbial sky hook has been in vain and on occasion, unsafe. So I decided to buy an old STILL forklift and restore it. I have bitten the bullet. I am almost finished with the restoration. Even if I use this 2 or 3 times a year, it will be worth it and after doing the arithmatic, cheaper.
for the money john's definitely on the right track
big 'ol mobile gantry could toat a lotta loads cheap
then a smaller beam in the ceiling for day to day 1/2 to 1 ton picks is much more affordable
charts say a 1ton 16ft span is S8 x 18
every one else that said "know what the heck your doing" are also saints in overalls trying to save your ass
In my BP manual the suggested method of lifting is a single threaded hole located on the top of the ram. The diagram shows a single eye bolt to lift the machine. I know a Bp only weights about 2400 but WTF?