Gantry I-Beam & More

[lovemesomemachines]

I hope everyone is still safe and well. I've been wanting to build a gantry/hoist for some time now for my garage. Of course my garage has limited space so I have to make it so it's not only usable but out of the way when not being used - stowed against a wall. As well, I'm not a welder nor do I have a welder so I decided on using 80/20. I've built a few things with 80/20 over the years and like using their materials. I saw a picture in their purple colored material handling pamphlet on page 33 of one of their customers gantry designs. So I designed one on paper and created a bill of material spreadsheet. Not cheap by any means but nonetheless great for my garage. I have a harbor freight 2000 pound electric hoist I would like to attach to a trolley on the I-Beam for use with the gantry.

The two feet will be 36 inches long of 3030-S with 3 casters under both, two on the ends and one in the middle with a 300 pound rating for each of 6 casters. The two vertical legs will be 73.5 inches high of 3030-S with an 84 inch cross support between them of 1530-S. I will set my I-Beam on this 1530-S cross support. The I-Beam I went with is an American standard beam, ASTM A-36. I've uploaded an attachment for the dimensions of the I-Beam.
A = 5 inches
B = 3.004 inches
C= .326 inches
D= .214 inches
Weight per ft. lbs. = 10
Total length = 84 inches (subtract 6 inches for the two legs gives a total between the legs of 76 inches of usable space)

I have a couple of questions:
1) Would anyone know the usable load the I-Beam can support with the sizing I listed? I'm aiming to be able to lift the most weight I can given the electric hoist lift rating.
2) Seeing I'm going to have to get this I-Beam up on the 1530-S leg cross support, I've seen a scissor lifting attachment in the past that can grab onto the center of an I-Beam and lift it up with a crane of sorts. Anyone know the name of this lifting attachment? I'm looking for a small one that can lift the I-Beam dimensions I listed.
3) I'm not sure which trolley to use considering the I-Beam is also resting on top of a 1.5 inch thick cross support. Any suggestions for a trolley that can handle the 1.826 inch thickness (1.5 + .326)?

Any suggestions on this build would be most helpful. Thank you.

[strokersix]

May want to review your caster arrangement. All six casters are very unlikely to share the load equally. I'd be looking at four casters, 1000lb capacity each.

[lovemesomemachines]

strokersix...Thank you for the reply. I thought of that, however, I was looking for a swivel caster with a brake. The only caster that 80/20 has to match that is a 2334 which is only rated at 300 pounds. The garage floor in this home is not precision level by any means and has slight dips and a really shallow grade towards the garage door. I'm concerned that the gantry could move around on me under load without the brake; at least the brake will attempt to keep it in place.

[reggie_obe]

How much weight do you need to lift? Work backwards from there to determine minimum dimensions. Why is the steel I beam resting on an equally long length of 80/20 1530-S? What does that gain you?

[Ohio Mike]

I think you are looking for a beam clamp?

I hate to be "that guy" but 80/20 is insanely expensive and you can buy the HF 1 ton gantry for $600 right now as a member of the insider track club. This gantry can have its uprights cut down to fit under and 8' tall door.

[SVS]

You’ll hate six casters more than no brakes. Far too often you’ll be applying 2,000 lbs to one 350 lb caster.

Beam is hard to figure because it’s really a composite of the I and the horizontal 80/20.

I beams tend to fail by buckling the compression chord. (Upper web) Hanging I beam under 80/20 and supporting ends with lugs attached to the verticals would be more efficient, and simplify trolley choice.

[reggie_obe]

With the height restrictions, I'd consider a low-headroom hoist-trolly unit like: https://www.amazon.com/Vestil-Combin.../dp/B007NQ4TYC

[BCRider]

From your specs the beam will only be around 80 lbs. Not something I'd want to lift up in one go by myself but with a couple of folks and doing it in a couple of stages (like floor to saw horses then horses to some sort of support. Heck, if you get a few 8ft long 2x4s you could make up two "A" frames and some cross pieces that make a 4 ft wide temporary structure with horizontal "hands" at a few heights and use that to lift the beam in stages up to a height where you can add the end legs. All without any fancy lifting gear.


The beam's maximum load ability would be determined from the engineering model where you have a single point load in the middle of a end supported beam. Go to THIS CALCULATOR and from there follow the link (say no to the advert) and get the numbers to fill in from the chart of standard size beams to find your max load. The calculator only tells you the deflection though. Not where it would fail. But I'm sure there is some other chart or table where you can find a list for the failure point in pure load.

But loads are almost never pure. And that's where I'd have an issue with your idea of two "T" shaped end legs and no diagonal bracing of the 1530 to 3030 sections. The lengths of the pieces is going to produce very high leverage ratios on the fittings when you start pushing and pulling on the verticals to move a heavy load around. And aluminium simply isn't good at that sort of thing. It would need some pretty good diagonal bracing or large gusset plates to spread out the loads.

I'd be thinking more of the end supports being triangle shaped with the frame done with two legs of 1530 to a lower foot that closes the triangle of 1530. It would likely mean making your own special angle gusset plates for the corners but it would do a lot to avoid side wracking loads at the joints.

The I beam would then be suspended from the frames instead of perched on top which would also allow you to put on some nice diagonal braces. And your trolley for the hoist could then roll without any issues along the lower flange.

Did up this sketch over a coffee for you to consider. The end triangles are from 1530. The purple diagonal braces are 1515 with a standoff spacer which would give you free movement of the trolley for the hoist from leg to leg. The rusty colored gusset plates would be from something like 1/4" aluminium or 1/8 steel. The upper plates could likely be done from some well cut angle iron so the flanges were able to be drilled and bolted to the I beam. As shown though they are just flat. Note that the angled legs actually catch under the upper flange so the weight is not taken by any of the screws that go into the extrusions. Thanks to the diagonals you take a lot of the deformation loads at the fasteners away. you would be able to pretty safely push this around with 1000 lbs on it I'm thinking. I still have my doubts about 2000 lbs though. Strictly due to the use of the 8020 sections. I don't think they will perform during twisting flexure during pushing around under very heavy compressive loads like proper square or rectangular tubing would do.



For the casters don't go small. Even if this means having to shift out of the "80/20 system". You want... no... NEED larger easy rolling casters so you can roll over small bits of debris on the floor easily due to the length of all the parts there is a LOT of leverage. And a switch to something like I show in the sketch would mean you only need four casters because the triangle end frames put the load at the ends of the side legs with no load in the middle. From my own times moving machines around on my engine hoist I would suggest at LEAST 3". And even that is not great. I've got a set of 4" hard PVC tire casters that I'm planning on transplanting onto my engine hoist to replace the 3" cast iron casters that love to stop dead when they encounter a grain of sand or a sesame seed size piece of metal swarf. Go big as you can on the casters, within reason, you won't regret it.

I know you said you don't weld. But my gut feeling is that you would be far better off with square or rectangular steel tubing. And to replace the welding part you cut gusset plates and bolt the whole thing together. The square steel tubing would be far stiffer and resistant to side loads and twisting. And you could then safely use the whole lifting capacity of the hoist you have.

[J Tiers]

Not welding has no disadvantage here. Too many people who CAN weld, think they can do structural welds, leading to some pretty scary constructions.

Bolts are known, their shear is known, a bolted joint is fairly easily calculable. And there are no unknowns about the welds, since there are no welds.

I don't know why you would want to go with a "system" that is extremely expensive for what you get. Use smaller I beams for the verticals, figured on area they will never get close to compression limits, and they will also be good for buckling at the height you want. (So are pipe and tubes, which you should consider also) All the needed data is in the various steel construction handbooks (see ebay, or garage sales, which is where I have found mine). Those give all the various moments etc for each cross section and size.

Yes, brace them to the crossbeam. It takes a little out of the travel, but you want it to avoid failures from the joint collapsing.

Lifting equipment is not where you want to cut corners, whether you will be nearby, or if it maybe "only" drops the machine you are moving.

[lovemesomemachines]

reggie_obe...Thank you for the reply. The reason I'm resting the I-Beam on the 1530-S is so that I don't have to drill and tap the I-Beam. With flat plates bolted onto the sides and end of the 3030-S, I can create a cradle of sorts on the tops of both legs to keep the I-Beam stationary. As well, I can then mount an item such as an 80/20, 2577, from the leg to the 1530-S the I-Beam is resting on for further support. I neglected to mention this in my initial post as I didn't want it to get too busy. I looked at the harbor freight trolley, measured it, and I believe it will fit the I-Beam and the 1530-S. I already have the 2000 pound harbor freight electric hoist. Thanks for the link though.

Ohio Mike...Thanks for the reply. A beam clamp could be it. I just need something that I could clamp to the middle of the I-Beam and then use my engine hoist/crane to lift it up and set it on top of the 1530-S. I'll do some searching to see what I can find. You are correct that 80/20 is extremely expensive. I don't like it either but it's what I've got. I was at harbor freight earlier today and measured their gantry and it's too big for my garage. I have a townhouse and the ceiling is completely uneven not to mention the length of the feet would take up way too much room. That's why I had to go with the design I have with 80/20.

SVS...Thank you for the reply. I'll check into other casters and see what I can come up with.

BCRider...Thanks for the reply. I'll check out the calculator. I did leave out the diagonal/triangle supports from the feet to the legs and the legs to the 1530-S. I just didn't want my thoughts to get too busy or not easy to understand. 80/20 has a 2577 that I can use from the legs to the 1530-S and from the legs to the feet. Granted, the 2577 is only 18 inches long at 45 degrees but with my dimensions, that's all I have. 80/20 does have some 30 and 60 degree angle plates that I did some calculations on but with the dimensions I have, it doesn't give me that much more. I apologize that I don't see your sketch but would really like to see it.

J Tiers...Thank you for the reply. I really don't want to go with a system that's so expensive. I'm guessing the local fabricator would charge me about the same for it as the parts from 80/20. I'll check with them though, it couldn't hurt.

[BCRider]

You should be able to see the attachment in my post. Not sure why it's not showing for you.

I assume that if you have a way to cut the 80/20 material that you could also cut steel tubing. That not the case? I don't know the prices on the 80/20 stuff but you could easily do the whole set of legs and braces with two lengths of 2x2x1/8 square tube with some left over. And even up my way that's only about an $80 cost.

[lovemesomemachines]

BCRider...I even tried a different computer and still can't see your sketch. Not sure why I can't see it either. My loss.

I still don't have a welder and don't know how to weld. If I had a welder and knew how to weld, this would all be moot. There is a steel yard not too far from me where I can buy all of the material myself. Another loss .

[Arcane]

BCRider, your sketch doesn't show up for me either.

[Fasttrack]

Just for sh*ts and giggles, I ran a quick simulation. The beam is supported at either end by a 1.5" by 3" bearing surface and the load is concentrated to two 1/2" by 1" pads on the bottom web, mimicking the contact area by a number of ball bearings in a trolley.

At 4,000 lbs, the von Mises stress exceeds the yield strength in a few localized areas above the bearing surfaces and may be an artifact of the sloppy simulation. See attached image. Anything in red is above the yield strength of A36. The deflection of the beam has been magnified to make it easier to visualize. According to the simulation, the maximum deflection is about 2mm.

But keep in mind that you will need a large factor of safety, especially if you have a trolley. A trolley that moves can place significant dynamic load, several times greater than a pure static load. I think some tweaks to the design could make it suitable for a WLL of 1000-2000 lbs.

But... I'm not a PE. Proceed at your own risk!

[J Tiers]

........

But keep in mind that you will need a large factor of safety, especially if you have a trolley. A trolley that moves can place significant dynamic load, several times greater than a pure static load. I think some tweaks to the design could make it suitable for a WLL of 1000-2000 lbs.

.........

It seems that the "factor of safety" ought to be about 5 for hoisting equipment, due to the number of unknowns involved, plus not wanting to have problems.

And, once you figure that, forget all about that factor of safety once you have the thing finished. Treat it like it really has the lower strength. Never let a buddy know that factor..... Otherwise you may get to pushing it farther and farther toward the actual limit, which is not good.

Columns need to be figured for static compression, but also for the buckling (Euler) limit. And then also, the deflection of the crossbeam will have the effect of setting the verticals off vertical a bit. The fact that the supports are on casters means that some calculations may need to be done differently to how they might be done if the column was set in a concrete base.