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/diy/ - Do It Yourself


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1598302 No.1598302 [Reply] [Original]

Is this structural, or suicide?

I'm making a bolt together portable A frame hoist
Dont worry about sheer forces, I'll brace it depending on where I use it so it doesnt fall over

>> No.1598314

Instead of using the strength of the heavy 4 leg beams, that'll only be as strong as those tiny L beams and the bolts holding them.
Looks like a bad idea.

>> No.1598315 [DELETED] 

>>1598302
It will be as strong as the angle irons in red.
that's all

>> No.1598332

>>1598302
Suicidal. I don't think it can even support its own weight.

>> No.1598342

>>1598314
Idk how else to do it though.
The legs are at a 30° angle which should help some.

I designed it this way because it's all scrap pieces that are different lengths, so I can pair longer and shorter beams together and just put the overhead beam on level. I have no way to cut the beams.
I've made this thing in the past by just using chains and straps to fasten it together, as well as a piece of thin gauge 12in steel well casing for the overhead beam just jambed in the crotches and strapped on.
It held 4000lbs this way, but now I need it to hold up half a car by Friday so I can work under it. So I'm willing to spend a bit of time drilling holes and bolting it together instead.
The car weighs only 2200lbs, and I can just lift it using two points from the top of each A instead of from the beam if it is a big concern of strength.

>> No.1598353

>>1598302
This is stupid anon. Try again.

How much weight do you need to support?
What is your budget?
How tall does that need to be?

>> No.1598357

>>1598353
About 1500lbs
$12
The legs are like 8ft, and the upper beam is 9ft.
The whole thing is only like 6ft tall or so.

You can read my other post, but I basically have all the material laying around. I'm open to suggestions but I have limited tools and time.

>> No.1598517

This is an incredibly bad idea. The whole benefit to using I beams is that they provide strength while cutting cost, but they only work if you put the weight on the flat side. Otherwise all the force is concentrated on a much smaller area that isn't designed to bear weight.

>> No.1598530
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1598530

>>1598302
>I need it to hold up half a car by Friday so I can work under it.

Nigga r u srs? You gonna die.

The most obvious issue I see is the complete lack of bracing against lateral forces parallel to the main span. The fact that those loads would be taken in an unfavorable direction by the weakest parts of the structure isn't helping, either. Even moderate force in that direction is going to cause the thing to collapse sideways. I MIGHT try it for a short lift of a light load, but no fucking way would I ever get under anything held up by that "design".

You'd honestly be better off making a wooden one. Braced appropriately, it would be far safer.

>> No.1598571

>>1598530
I said in the OP to not worry about it, in this case, I'll be joining it to a shipping container using a bit of round or box, like the hoist will stand 3 feet away and I'll just take the bar and bolt it as an extension of the overhead beam to the container.

>>1598517
I can mount the beam in the crotch of the two As, but idk how to attach it well besides run the piece of angle perpendicular to it, bolting it to the legs.
I guess I could do both sides and it would give it a lot more sideways strength. I'll have to draw this tomorrow.

>> No.1598595

jesus christ theres no repair on a vehicle that cant be done with a regular floor jack and some blocks

>> No.1598805

>>1598595
You have obviously never worked on an mr2 then.
I did the block method once before, even with the car about 1.5ft off the ground, it wasn't enough to get all the shit out of the bottom, and it made working up top difficult. With this, I can just raise and lower the rear using hand winches.

>> No.1598819

>>1598805
>With this, I can just raise and lower the rear using hand winches.

pls make a video and have someone who will post it after you die.

>> No.1598820
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1598820

>> No.1598824
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1598824

Is this enough then?
I am not sure if I have the right material for this though, but I can always subtract the angle for some box.

Specs are:
>4in tall very thick wall I beam, 1/4in thick
>8ft ish legs at 27° angle
>3in 1/4 angle bracing top beam from both sides
>1.5in 1/8th angle keeping legs from splaying out (was originally going to use heavy gauge wire)
>1.5" 1/8" plates on top for good measure
>All 1/2in grade 8 bolts everywhere, four bolts per attachment point for beam parts, 2 bolt for top and bottom bracing
>>1598819
I'm going to chain it off before I go under it bro, I'm not trusting two $21 hand winches

>>1598820
Wow this actually looks even more simple to do. I'll model it.

>> No.1598827

Do you know how much weight is going on the beam?
Also send all dimensions, beam might honestly fail on its own but I’d have to get my mechanics book back out

>> No.1598839
File: 1.41 MB, 5312x2988, IMG_20181209_155955.jpg [View same] [iqdb] [saucenao] [google]
1598839

The beam is strong as fuck. Far stronger then the mere weight I will be lifting.
It is not normal I beam. It is very thick and heavy stuff. The one 10ft piece I will use for top beam feels like 100+lbs. Here is the only pic I have of the stuff.

>> No.1598841

>>1598839

Won't it damage the doors when you lift it like that.

>> No.1598845
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1598845

This looks very simple, but quite dangerous. there will be a lot of sheer potential on the bolts, and would require a bit of precision drilling to distribute the force to all four equally. I can also just wrap chain around it for safety.
>>1598841
no the beam is not touching the boat at all, just passing through, the lifting was done by a strap that went from the top of each A under the bottom of the boat, with a hand winch on one side.

>> No.1598852
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1598852

I just had a completely different idea.

What are thoughts on THIS design?
Simply take the longest beam, he 10.5ft beam, and bolt it to the roof of the container. Job done. 6.5ft back across the roof, 4ft sticking out.

>> No.1598853

>>1598845
>looks very simple, but quite dangerous. there will be a lot of sheer potential on the bolts, and would require a bit of precision drilling to distribute the force to all four equally.
lel you started this thread with your death trap, and a few posts in you can tell what's dangerous or not just by looking? *every* design you posted you need to worry about shear force and equal distribution of force.
fwiw i say go with >>1598824 and put the low horizontal member even lower because that will resist spreading better. and at least there you have the horizontal ibeam oriented correctly and not at an angle.

>> No.1598868

>>1598852

That might work. My dad had something like that rigged up the day he died.

>> No.1598879

>>1598868
Wow anon, I'm sorry for your loss,

It should work fine, I may brace the end of the beam from the inside of the container using some channel or something that spans the inside width, then just bolt it down generously.
The only difference I guess will be a single point of lift so it will move around a bit more, but should be fine.
The container itself is plenty strong enough, I've hug the entire car before from the inside hooks, but I dont want to work on it inside the container this time. It was too tight and time consuming to work around it.

>> No.1598881
File: 1018 KB, 500x700, animated kangaroo chewing not sure if serious.gif [View same] [iqdb] [saucenao] [google]
1598881

>>1598571
>I said in the OP to not worry about it

No, you didn't. You said "not to worry about sheer forces". One, I think you meant "shear" and, two, what I described is not a shear force.

Anyway, assuming you've got the thing fixed to prevent it from falling sideways, >>1598824 is the least death-trappy death trap you've posted so far, by a longshot. It's actually almost passable for a decent design, if you squint hard enough.

>> No.1598958
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1598958

>>1598881
Well I'll do that eventually then, but that design requires 192 holes to be drilled, and 96 bolts, 96 nuts.
That is the main issue I have with doing it correctly. Why I'm just trying to ask what's good enough or bare minimum, it isnt a lot of weight.
And I have a single night to do it.

So I think I'll go with the container pokey stick for now because that is at most 10 bolts, 20 holes. It's just a lot harder to just say from a good look if it's perfectly fine, or not going to work. I'll find out and report back I guess. Or maybe not.

And considering that THIS is how most overhead hoists I've seen and used are like, mine is far far from a fucking death trap, holy shit.

>> No.1598975

>>1598958
>And I have a single night to do it.

please video or at least before and after pics.

>> No.1598977

>>1598975
I will for sure take pics

>> No.1599178
File: 3.06 MB, 3984x2988, IMG_20190424_201357.jpg [View same] [iqdb] [saucenao] [google]
1599178

It is on

>> No.1599179
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1599179

Inside

>> No.1599180
File: 997 KB, 2981x2830, IMG_20190424_221504.jpg [View same] [iqdb] [saucenao] [google]
1599180

It holds up much heavier car

>> No.1599182
File: 2.87 MB, 3984x2988, IMG_20190424_203236.jpg [View same] [iqdb] [saucenao] [google]
1599182

Barely any flex to the beam

>> No.1599186
File: 1.09 MB, 2988x3641, IMG_20190424_223619.jpg [View same] [iqdb] [saucenao] [google]
1599186

This is the beam.
It isn't normal I beam. Much thicker and no taper to it. It is 4in wide by 4in tall, and looks to be 1/4 in on the crosses and 3/16 on the spine.
Pretty strong stuff.

I have it sticking out 4 feet, and 6ft 5 inches of it across the roof. Bolted twice every foot.
I will screw on eyes to the last two bolts and maybe exchange them to grade 8, then install two 3000lb ratchet straps down to a lower set of eyes on the container. All on the inside. This will make it very strong, eliminating the worry of the roof not being strong enough, and put the work solely on the beam itself with a 40% reduction in weight too.
And the door frame itself is much strong enough to handle it but I will additionally leave one door shut for even more strength.

>> No.1599187
File: 1.21 MB, 3931x2976, IMG_20190424_221327.jpg [View same] [iqdb] [saucenao] [google]
1599187

Also, old drill press does not make holes very well. First time using it but I either need a replacement 1P motor, or a bigger VFD. It struggles with 1/2in.

>> No.1599190

Why is there a shipping container involved now? Was the situation not bad enough?
Im fukin scared bros i'm out

>> No.1599192

>>1599190
It is the better way. The only better way is two shipping containers and place beam in between.
Or three shipping containers and use container as the beam.

>> No.1599195

>>1599178
>>1599179
>>1599180
>>1599182
>>1599186
>>1599187
Congrats for delivering, glad it worked out for you!

>> No.1599196

>>1599190
>Why is there a shipping container involved now? Was the situation not bad enough?
>Im fukin scared bros i'm out

Scared? Fuck that, OC Rekt thread coming up!

>> No.1599292

>>1598805
I have a 1st Gen mr2. I used the harbor freight low profile jack and normal jack stands. I have a stool to stand of for working from the top.

>> No.1599340

>>1599292
Yes' but I need to drop the trans on mine in under 3 hours so I can go drinking later the friday night.
Ideally in 2 hours.

>> No.1599884

>>1598342
Use a car jack or you are going to turn your upper body into a nice jam.
If you need it much higher I have no solutions.

>> No.1599889

>>1599340

anyone who drinks alcohol is a complete idiot

and here you think youre being more efficient, when its just to hurry up and trash your insides and make yourself look like a tool

>i save 1 hours but worst case i spend the rest of my life as a parapalegic or best case im a retard alcoholic!

>> No.1599962

>>1599889
Well the best case is I die and the worst case is it takes longer then expected, but ok. And drinking is a term for hanging out at a mates house with a few other boys around a bon fire and maybe playin some beer pong or N64 or something.

>> No.1600788
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1600788

Worked fine for the job, but it got extended by a week for parts, so I guess it's going to hang for a week.
Stress test at its finest.

>> No.1600808

>>1598302
>no mechanical/structural holding of the cross beam up

it's gonna break and fuck something up

>> No.1600848

>>1599186
that w beam

>> No.1600917

>>1600848
Huh. So it is.
Well it definitely seems strong enough.

>> No.1600923
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1600923

>>1598958
>192 holes to be drilled, and 96 bolts, 96 nuts.

The fuck? I count all of 32.

>considering that THIS is how most overhead hoists I've seen and used are like, mine is far far from a fucking death trap, holy shit

Because it's a predictable, efficient design. The stress on the main beam is trivially easy to calculate. The stress on the supports is trivially easy to calculate. There are no potentially unaccounted-for forces acting on the structure when used properly (most critically, that the hoist be in line with the load's center of gravity). A fairly accurate picture of its capacity and safety factor can be derived with a high level of confidence. >>1598824 is okay (not good, okay) for the same reasons, with a few caveats that shouldn't matter for a 1000lb load.

Most of what you've posted is sketchy specifically because they produce stress concentrations in ways that do not sit well with anyone keeping tabs on them, or may allow the structure to shift enough to completely fuck itself up while it's holding a weight most easily measured in tons. They're PROBABLY fine. But "probably" is the last thing you want to hear when something breaking means, at best, damaging expensive equipment and, quite easily, someone being grievously injured or outright killed.

I mean, it's only your ass on the line, I assume. So go nuts, but realize there's good reason nobody is encouraging this kind of "yeah, that looks fine I guess" attitude when it comes to rigging.

>> No.1601321

>>1600923
Well I still need to eventually build a portable hoist. I've needed something like it at least 10 times now in my life, and each time, I had to resort to even more dangerous solutions.
I mean I'm open to any design proposals, but it just needs to generally look like my designs because half of the use cases, it's been loading and unloading trailers, like I can just construct the hoist over the front of the trailer, strap the load up to it, and lift the rear of the load up with a tractor. Then just pull the trailer out.
Some of the loads have been a container, an water tank, some building materials, stuff like that.

>> No.1601454

>>1598302
Just stick the beam on top ya fuckin knob

>> No.1601554
File: 50 KB, 350x262, 1510784017623.jpg [View same] [iqdb] [saucenao] [google]
1601554

>>1599186
This HAS to be a larp, right?

>> No.1601570

>>1601554
I have posted enough pictures to show otherwise.
I can't imagine it is a new idea to most. Barns have had the same thing for hundreds of years to get heavy stuff into the loft. And that was all made of wood.
I was not concerned at all even when laying under the vehicle or climbing on top of it to access the top side, everything felt solid.

I actually recommend anyone with a shipping container just do this, I already am coming up with many use ideas for it. Even simple things like unloading a heavy object from a pickup. Just back over by the container and winch it up, easy.

>> No.1601701

>>1598342
>No way to cut the beams
>Want to work under a car supported by this abomination
>Chains and straps only method of fastening
You're insane, and not even in a "git-er-done" way. This is Zimbabwe tier.

>> No.1602898

>>1598824
All the stress on the IPE will be on their weakest part... maybe use tubes.

>> No.1602973

>>1598530
>>1598302
TUMBLING DOWN TUMBLING DOWN TUMBLING DOWN
if you do get this thing up and holding a car, set up a camera and a stream so we can watch you die c:

>> No.1602974

>>1598852
Alright, now you're just fucking with us

>> No.1602975

>>1598958
weld it you mong
cook yourself before it collapses on you so the dogs have something to eat

>> No.1602977

>>1601570
That shit was for lifting hay bales you mongo, not cars>>1599182
And plenty of flex in the roof of the shipping container

We'll come back to this thread in a couple of days and if he ain't dead all op will have to say is a surprised pikachu

>> No.1603046
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1603046

>>1602977
Well it's been up half the week holding the car.
Hoping I can get the parts by weeks end and get back under the car to finish it.

>> No.1603051

>>1603046
>Well it's been up half the week holding the car.

In general, you should use jack stands or blocks or something under the frame or wheels once you get it lifted. Keep the strap there, but ideally you ease off on it a bit so that the stands or blocks are the primary support and the strap is just added insurance.

>> No.1603101

>>1598302
do you even lift?
see you in diy hell