Shop Garage Hoist - How it's going to kill me?

[Doggggboy]

You know the old fantasy: Shot by a jealous husband at 90.

Does it still count count if he's only jealous of your new hip?

 

[fixerup]

when i was lifting heavy object with the 2 ton gantry we had at work, I always wondered what weight I was lifting. It was not obvious sometimes, the paper work didn't always follow with the item and even if it did I had no way to check.
So for my homeshop unistrut gantry I bought a digital scale and won't lift anything if it weight more than 200lbs.
Mine is a similar unit and no remote

 

[SomeGuy]

when i was lifting heavy object with the 2 ton gantry we had at work, I always wondered what weight I was lifting. It was not obvious sometimes, the paper work didn't always follow with the item and even if it did I had no way to check.
So for my homeshop unistrut gantry I bought a digital scale and won't lift anything if it weight more than 200lbs.
Mine is a similar unit and no remote

View attachment 68320

I have a 660lb version of something like that, didn't even cross my mind to use it while lifting the welding cart....will have to try that at some point 🙂

 

[Engmaxx]

I'm sure it'll be fine if you use it within reason. Do not side load that at all, as you'll risk spreading the strut. I would love to have something similar in my shop for those awkward things that are just hard to lift and manipulate single handedly. A few of the next couple projects for me are going to be lifting device related, as I'm not getting younger, and the projects seem to keep getting bigger. Of course I said that last year, but other stuff just keeps wiggling it's way into the queue ahead of them. Damn line jumpers.....

Looking at that, the only thing I'd possibly add, which is just me overbuilding/overkilling it, would be some triangular gussets to the mounting plates to keep the strut from potentially spreading if side loaded. Needed? probably not. Worth taking the whole thing down to do it? Probably not either.

No need. These are plenty strong and stiff (1/4 inch thick). Silly me thinking I could hang the brackets first and then try to twist the rail in...not a chance. They all had to be slid on first and then I bolted them to a plate that I had first mounted to the joists. I didn't have the room to slide the rail in after everything was mounted so this was my only way.

 

[Dan Dubeau]

Ya, strut is pretty stiff stuff. The gusset suggestion was me just being nitpicky lol. I DO wonder how much side load it would take to actually spread one and spit the carriers though.......Most likely north of the hoists capacity I'd bet.

 

[SomeGuy]

No need. These are plenty strong and stiff (1/4 inch thick). Silly me thinking I could hang the brackets first and then try to twist the rail in...not a chance. They all had to be slid on first and then I bolted them to a plate that I had first mounted to the joists. I didn't have the room to slide the rail in after everything was mounted so this was my only way.

View attachment 68323

Yup, was aware of these brackets....would have had to figure out how to get threaded rod hanging down from the ceiling first before putting this up, it's the only way that style bracket will work. That's why I just welded on my own so I could bolt from either side, and it had the advantage of keeping the track from being able to rotate.

 

[mbond]

without running the numbers, or seeing your exact setup, it is almost certain that if it fails, the 2x6 joist will split along the grain near the end of your lag screws. when that happens, the load will move to other joists and a loud crack or popping noise will alert you.

the real danger in a system like this is that if that happens, but you aren't around to know or don't fix it, and then lift something else heavy later, it sill start to fail in increasingly dramatic ways. Probably it will take several of these events for it to completely fail, but it would be wrong to say that those loud noises don't matter because they have happened before 😉

The problem is that while 2x6 SPF is quite strong when it supports a load distributed over it's whole length, point loads are particularly bad for wood. And a lag screw that goes only part way through relies on the cross-grain strength of the wood - which is much less than along the grain because of the way trees grow.

then you have lag screws that are close together. Each one produces a 'cone of influence' within the wood that starts at the tip of the screw and gets wider towards the bottom of the joist. if those two cones overlap, then the wood in that overlapping area has to support weight from both screws. the anisotropy of wood (the difference between along the grain and cross grain strength) makes these cones particularly wide and checks and knots makes them unpredictably wide.

to bear the load at all, the joist has to bend. That's how it can develop a reactionary force. The bending creates tension in the bottom part of the joist and compression in the top part. but it also creates perpendicular forces - forces that run across the grain.

in case you hadn't guessed, I am an engineer amongst other things 😉

but taken all together, it would be a big surprise if this failed in any other way. and as long as you keep an ear out for cracking / popping sounds, and an eye out for loose or sagging lag screws, popped drywall etc. it should be safe enough.

but take all of that advice for what it is worth - a guy you have never met who claims to be an engineer on and internet forum and has never seen it 😉

 

[Dabbler]

I wasn't going to get involved. but one member DM'd me, and another asked me questions in person. So here goes. [i have built and tested some lifting equipment, done moves, etc...]

On the surface, this design looks more than good enough. And I think you will be fine for moderate loads. So I'm not being critical here, but:

You have significantly weakened your joists near a stress riser (the I beam). While your unistrut can likely handle 400 lbs, you need to be sure your joists are okay. By avoiding all the drywall work, you cannot say with confidence that the lag bolts are centred, perpendicular, and didn't split the joist during installation

What appears to be simple and reasonable can have catastrophic results. Look up the Hyatt Regency Walkway Collapse.

Now for the good news. I see you put a lot of thought into your design. It appears to be very well done! it certainly is very clever.

 

[SomeGuy]

I wasn't going to get involved. but one member DM'd me, and another asked me questions in person. So here goes. [i have built and tested some lifting equipment, done moves, etc...]

On the surface, this design looks more than good enough. And I think you will be fine for moderate loads. So I'm not being critical here, but:

You have significantly weakened your joists near a stress riser (the I beam). While your unistrut can likely handle 400 lbs, you need to be sure your joists are okay. By avoiding all the drywall work, you cannot say with confidence that the lag bolts are centred, perpendicular, and didn't split the joist during installation

What appears to be simple and reasonable can have catastrophic results. Look up the Hyatt Regency Walkway Collapse.

Now for the good news. I see you put a lot of thought into your design. It appears to be very well done! it certainly is very clever.

Thanks for commenting!

I'm aware of that Hyatt Regency thing, how walkways were supporting the loads below them when that was not the original intent of the engineered design.

Yup, there is risk with the way I lagged things in, have been aware of that from the start of this project, and part of why I liked going with the plates and 16 lags to hold it, even if I missed on a couple of them or had a split, the rest would pick up the slack (since unistrut can handle spans on its own). At one point I considered opening the ceiling and getting metal up above spanning the 2x6's and dropping supports down through the drywall...ignoring the pain of drywall work, I was also concerned with what this would do for the fire break it is supposed to provide if I had holes through the ceiling like this and then also how to deal with lateral movement not just tearing up the drywall and making the holes worse. I also considered putting a ground supported beam all the way across, but when I started doing the math, the beam was getting quite big and I'd have lost a lot of lifting height.

It's definitely a bunch of trade offs...at least it looks as though I didn't do anything overly stupid.

 

[Dabbler]

I think you did fine. Without inspection, care should be exercised. I'm thinking you should be concerned about the lag screws. you can get lag studs ( I'm not sure of the current term) these have threads instead of hex heads, and are grade 2. lag screws are ungraded, and must be suspect. with the large number of screws, it could be put off for a while for light loads. if you are going for a planned heavier lift, then changing out might be wise.

 

[jorogi]

Get a pallet, load it with the appropriate number of concrete sacks, or a water barrel, or 5 gallon buckets and hoist it an inch off the ground in 6" intervals across the length of the beam. If your roof bangs you on the head, you got it wrong so don't do it again.

 

[SomeGuy]

I think you did fine. Without inspection, care should be exercised. I'm thinking you should be concerned about the lag screws. you can get lag studs ( I'm not sure of the current term) these have threads instead of hex heads, and are grade 2. lag screws are ungraded, and must be suspect. with the large number of screws, it could be put off for a while for light loads. if you are going for a planned heavier lift, then changing out might be wise.

As mentioned in the thread, I have an engine hoist...so anything actually heavy will get picked with that (how I lifted my lathe/mill/car lift/air compressor/etc.). I can swap out for longer lags easily enough (and have some 4" ones on hand, maybe even some 5", I'd have to check) but my concern with that was keeping them centered in the 2x6 all the way through and I'd have to pick up a longer drill bit for the pilot hole (yes, I used the proper spec'd size).

 

[Susquatch]

As mentioned in the thread, I have an engine hoist...so anything actually heavy will get picked with that (how I lifted my lathe/mill/car lift/air compressor/etc.). I can swap out for longer lags easily enough (and have some 4" ones on hand, maybe even some 5", I'd have to check) but my concern with that was keeping them centered in the 2x6 all the way through and I'd have to pick up a longer drill bit for the pilot hole (yes, I used the proper spec'd size).

I agree with that. Longer ones won't actually increase the loads you will actually use. Pushing their length will only give you a false sense of confidence anyway.

I sort of like @jorogi's idea of proof testing them with 3 times your planned maximum load. The only downside is a false sense of confidence and/or an actual failure. If you do proof test it, I wouldn't do it every 6 inches. I'd apply the load for the entire length continuously - once for each side and once down the middle. Then put a label on it with the date, the load test, and the rating at 1/3.

 

[whydontu]

Not an engineer, but I've spent the last 40+ years arguing with them. If I was doing this with the construction screws you used, I would do a test of the screws. Grab a chunk of 2x6, a u-bracket, some wire rope, a nice solid bench vise, and your scale. Screw the bracket to the 2x6, put the 2x6 in the vise, wire rope between bracket and scale, and use a comealong to a suitable fixed anchor. Pull until it fails, if you can. Now you know roughly how well the screws will support a load. Derate 3 or 4 to a safe working load. My guess you will be surprised by the strength of the screw/wood connection, either way higher or way lower than anticipated.

 

[Dabbler]

I used the proper spec'd size).

That's great!, Less likely to have spit your joists.