What's a reasonable workshop gantry beam?

graham-xrf

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This is exploring the beginnings of what it takes to conveniently lift stuff around a workshop. I can still (just about) manage a 25kg cement bag under each arm, but I strain a few valves on the way. I get it that one can have a hydraulic arm thingy usually used for car engines, but its a tad inconvenient in that it needs to put it's legs and wheels somewhat under benches, and needs a lot of space around it.

My notion was to provide each side of a 6m long little shop (that's about 20ft), with RSJ steels up at the ceiling level, hooked to every joist, and figure out a gantry beam with rollers each end, and a winch. To be able to grab onto a winch hook, and move heavy stuff just anywhere seems attractive, even if it's just a heavy chuck I don't want to drop on the ways.

So the question is .. what is a reasonable size beam to span the 3.65m width, (about 12ft), and expect to lift (say) a mill drill or other stuff up to about 220kg (that's about 480lb)? I suppose one might throw in a bit for unknown future heavy stuff, and some for a factor of safety.

Another related question is, what is a reasonable deflection it can have when fully loaded? One does not want the thing to very visibly sag, but it would be nice to know a reasonable number. My instinct says 1 or 2 mm, but what is the norm with this stuff?
 
You would need to have a structure engineered to not fail at 5 times the expected max load. That is the standard safety margin for overhead lifting devices. This avoids issues with metal fatigue, etc. From an engineering prospectiv, ceilings that are not part of a floor for an above story have almost no weight bearing capability, even if it includes attic space. So you will never get an engineer to approve such an arrangement.

People have obviously made such things work, but at some risk. If I were doing such an arrangement I’d think about maybe 100lbs max load and plan on moving anything heavier with a engine hoist or light duty gantry crane available say via Amazon. For the 100 lb load, attaching barn door track or unistrut type track and a light duty dolley is your best bet. Inspect regularly and realize that you are assuming the risk if it fails and drops on someone.
 
One of the best things you'll ever install. My shop is 24 wide so the beam is about 11 foot. Have one in each bay. Designed for 500 pounds with a huge safety factor.IMG_0308.jpg
benmychree is correct, or spec it yourself, there are beam calculators on the net that will give you the size. Strength isn't the determining criteria but deflection as you mentioned, probably 2 or 3 mm is a good number, much more and the trolley will want to roll to the center.
I often see tapered rollers to match the inside face of the flange, that doesn't work. Angle a flat roller to mate flange.
Allow the ends to float or variances in width and debris on the flange will make it bind while rolling.

Greg
 
Have a poke through this site, you may find something to build on (hehe). Called "ModTruss" and it's truly impressive stuff. I had the opportunity recently to be involved with a construction out of it for the motion picture industry ( I was an active bystander, the riggers were building ) and it's pretty neat. Really small section for the amount of weight it can carry, and the end plates are rated as well so you can literally bolt the ends of box beam sections together and have the beam bear load without additional side plates. Pretty wild. No idea of cost, I suspect the amount that I saw was rented for the specific task, but the rental place still had to buy it from somewhere. For reference we were using the 6" aluminum box sections with maybe an 16' span. Load was estimated at around 600 to 800 lbs, deflection of the member was about 3/4" at full stop. A seven foot length of box beam weighed maybe 20lbs.


-frank
 
In my own shop, I use either a "Sky Hook" that can attach to Aloris tool posts or machine table adaptors with the same configuration as Aloris tool holders that are fastened via a stud in the tee slots of machine tables, I also use barn door tracks suspended over my lathe and mill that use a HF winch to change chucks and mill tooling.
 
I bought a George C Gorton rotary table from Benmychree a while back.
It's getting to the point where I can't lift it safely. This sucker is heavy.
I need to figure out something. I look for excuses not to use it.
A gantry like F350ca would be sweet.
 
I bought a George C Gorton rotary table from Benmychree a while back.
It's getting to the point where I can't lift it safely. This sucker is heavy.
I need to figure out something. I look for excuses not to use it.
A gantry like F350ca would be sweet.
I saw a setup some years ago in a book, where the guy had a bench in back of the mill with a hinged "drawbridge" from the bench to the table, where you could just slide the dividing head or whatever to or from the mill and bench, and hinge it up out of the way when not in use. Personally I go with your feeling to avoid having to use the rotary table.
 
The easy (i.e., cheap) way out is to use a $99 engine hoist........
 
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