Shop Gantry Crane

[Bill Adamsen]

The building that houses my shop is a traditional New England timber frame barn (attached panoramic photo of ceiling). The center bay is flanked by two oak bents. I have often thought it would be nice to have an XY gantry system that could lift ... as much as possible. Four hundred pounds would be nice, a thousand even better. I would use it to lift boats (off trailers and overhead) to be able to get them out of the way. The bottom of the bents are at ten feet above the floor, and the fan and lights are at fourteen feet. While fourteen would be the limit for the top of the gantry, practically it would be twelve feet or even less.

I cobbed together this design and am opening myself up to critique. The brackets are meant to slip over the bent beams - they would have a single lag bolt on the outside to be affixed once in place. Bracket and tab steel would be three-eighth inch mild steel. The "rails" would be steel pipe, at least one inch (almost 1.32 inch outside diameter). The rails would have tabs welded on the bottom - in specific locations - to match the location of the brackets, and to allow some vertical height adjustment when affixing. The beams are quite straight, but shims between the bracket and rail tab could allow sideways adjustment. The gantry would have four wheels with round channel to match the pipe of the rail to which it mates. The two wheels on each rail would be separated by perhaps two feet. The beams are twelve feet apart, so rails would be slightly less than that. The gantry is shown as an I-Beam, but it would probably be welded up pipe just like the rails. There would be some height and a web to provide structure and resist deflection. The hoist would be a lightweight 1/2 ton chain-fall.

The idea was to find a solution that was cost effective, light enough to install as components myself, and not mar the aesthetics of the timber-frame barn. So for instance, I can't put a track on top of the beams and I don't want the track on the bottom of the beams. I am quite happy with the system in just the central bay.

[Matthew Sherman]

I would consult an engineer first to check the limit on what you can hang from the beams. Any failure in those two beams would be catastrophic for the structure. It might be OK for it to support 400 or 1000 just by guessing, but you also need to calculate how much weight the whole gantry is going to weigh as well.

[Bill Adamsen]

The bents are designed to support a floor load of 60#/ft square. So extrapolated over the whole, 9 tons. I've point load lifted a ton and a half with no issue. With the assumption that a 500# +/- is not an issue, does the design look workable? How might the design be improved? Does anyone have a home-built crane, and what was their design?

[Steve Rozmiarek]

I have no idea on the crane, but I love the space!

[David Gutierrez]

A couple of things come to mind. The load is applied to the beams eccentrically, which will result torque on the beam. typically beams are designed to be top flange supported to eliminate this type of force. Also this is not a straight beam design because the forces on the beam have to account for the fact that it is also the bottom chord of the truss. There is also a very big difference in a uniform static floor load and a dynamic concentrated load.
You really should have an engineer look at this and he should be familiar with timber framing. This is not a simple wood beam design and the rules of thumb may not apply.
Great looking shop!!

[Bill Adamsen]

David: The high-bay connectors connect to the Queenposts (web) with thru tenons to resist the torque, and the purlin plate knee brace for same. The oak truss struts and main girt knee braces also resist twist. But point well made. Before investing any more time in the idea, I'll reach out to the original designer (ka-ching, ka-ching). Thanks for looking and providing thoughts.

[Mark Bolton]

I would be very concerned with the movement of the structure throughout its life and the seasons affecting how smoothly the crane would roll. It seems like an awful lot of work for 400-100lbs. If it were me (and just if it were me) I would be looking into a traditional I beam gantry that could raise much more weight than that.

Beyond that I may be a little concerned as well with the saddle design and any (even minute) amounts of twist/roll being induced and again affecting how smooth the crane would roll.

It just seems to sketchy to me rolling anything on a structure that has a potential for movement.

[steve joly]

First off what an amazing workspace! I am interested to see what you come up with as I am also planning on a crane in my shop, although my walls are concrete and I designed them with this in mind. I would think you should have 2 goals in mind when designing this... Eliminate twisting on the beams and spread out the load across the beam to eliminate point loading.

That being said the loads you are hoping to lift are so small I wouldn't even hesitate to build what you are describing. For years farmers have lifted tractor motors and such by putting a strap around one of those beams and not thought twice about it....

this is is just my .02 I am not an engineer but I have removed a few engines from beams smaller than what you have there.

[Larry Frank]

I am an engineer and even stayed at a Holiday Inn Express. It is a beautiful work space and I would not risk damaging it. Insurance probably would not cover any damage. Is it worth the risks? Yes, many have "gotten away with doing it with smaller beams" but..........it just is too unique of a place

[paul cottingham]

If it were my shop (and I wish it was!) I would build a frame to hang the crane from independent of the building. I'm pretty sure most of those members are under tension, and hanging stuff off them seems like a bad idea. I'm not an engineer, and I've never stayed in a Holiday Inn.

[Tim Offutt]

For what it is worth I have sold overhead cranes and jibs for nearly thirty years and have seen many things, both good and bad. Based on this experience I would not do what you are proposing. Several others have mentioned the cantilever loading that you will be placing on the beams and they are spot on. The two beams you would like to hang from are engineered to either be in compression or tension. Not torsion or twisting loads.

Crane manufacturers design and build brackets to clamp onto beams but they are not slip on with only one bolt. They are brackets that clamp around the beam with redundant fasteners.

A structural engineer could give you a design that would work and be safe and this is money well spent. But even if you get a safe hanger design the proposed round runway construction is very concerning. What you are proposing is called a top running crane. This design is usually found in heavy cranes and they use a railroad rail profile that rests on heavy I-beam. Small cranes like you want are mostly enclosed track with internal trolleys or what is called Patent Rail. Patent Rail is basically a special I-beam engineered as crane rail and the trolleys clamp around the bottom web of the beam. Bottom line, a round runway rail will be very easy to derail and drop.

With any bridge crane the runways must either be a consistent distance apart or one end of the bridge must have the ability to float as the spacing varies. Without this the bridge will bind and stick. Commercial cranes have this ability to float one end of the bridge or they have pivoting end trucks.

You have an absolutely gorgeous building and it deserves a safe and proper crane. Take a look at the Gorbel, Demag, Unified or Knight Industries websites to get some ideas. All of these products are top notch and are used in industry. Because they are so widely used they show up for sale everywhere. Check ebay or better yet Craigslist in your area. Maybe a local scrap yard. You can buy used rail and accessories for pennies on the dollar and it will perform better than anything you would build.

I hope this info helps and I did not want to be too critical but I am also concerned about your safety.

[David Gutierrez]

Bill I would be interested in what the timber frame designer has to say. please keep us posted.

Thanks