Project #1 from DaveO: Lifting tripod

[DaveO]

We had some ornamental evergreen shrubs in the yard that had stopped being ornamental- at one time I’m sure they were tame enough but they outgrew their plot and became scrubby nasty eyesores. After digging one out manually, which turned out to be a *lot* of work, I came up with this labor saving idea: pull them out by the roots.

I ginned up this tripod and used the connecting bolt at the top to hang the cable puller. Stand the tripod over the shrub, wrap some chain around the plant as close to the ground as possible, and start pulling. The horizontal members are bolted to allow disassembly for storage; feet are welded on to prevent the legs from driving into the ground during the pulling process. Cost was next to nothing: keyhole slots in the steel reveal its bedframe origins; the cable puller was already part of the inventory; a few dollars for the chain and hook at the Home Deep.

This worked out very well- I cleared out the remaining 6 or 8 plants in an afternoon with much less effort (but the same amount of poison ivy and snakes), and since then have lent it to neighbors who were removing plants. Another neighbor used it to pull a tree limb out of the ground: a falling tree drove the limb three feet into the ground and the neighbor couldn’t remove it any other way. Made in USA, no patents pending.

[Trip59]

That's an inspiring idea! I have several fence posts to yank out this winter, I was dreading doing it as the last one almost gave me a hernia. I dug it half way down then used a 2x to lever it out, broke the damn 2x and had to dig it the rest of the way. I wonder what kind of loads a bedrail would take?

Trip

[DaveO]

If you try it, there's a couple tips and tricks. The bolt at the top is 3/8" but the holes are larger than that to allow the uprights to twist a little. That little bit of twisting allowed the surfaces of the uprights to line up a little better so the horizontal members could attach. I cut notches on the ends of the horizontals, again to allow surfaces to line up better... I feel like this explanation is going nowhere- if you want I'll post additional photos instead of trying to explain in great detail.

The cable puller is a Harbor Freight 4-ton model, they're always on sale. Are your fence posts set in concrete? That would be a bear to pull out!

[Trip59]

I think I got a solid idea. I was thinking of using steel pipe rather than bed rails, but welding up collars to replicate the horizontals you added...

[everlastsupport]

Ours is 1 1/4" squared tubing and very strong, over 6 feet tall. We can pull a plant or lift mowers, golf cart, etc with it. Will try to post up a picture, though it's quite simple. We're going to build a rolling gantry soon for large electric pump motor lifting a moving, it will be round tube (well it is on the list).

Nice thing about the bed rails, they are cold steel, adds a little more stiffness and many times free.

[Rambozo]

When I've had to pull fence posts, I've always used a chain looped over a truck rim, then pull on it with a tractor. The rim acts as a pulley and the post comes right out.

[Trip59]

Been trying to iron out details for a gantry build, trying to get legit specs from anyone is like pulling teeth. Weights and spans and the local steel places refuse to provide, tell me to talk to an engineer.

We have a huge scrapper community, they patrol constantly, so it's hard to find discards. I have one guy I'm friendly with who keeps an eye out for certain things for me, but he's on some other projects and hasn't been making runs.

[Rambozo]

There are plenty of online calculators to do the engineering math for you. If you want to calculate the moment of inertia, stress, and maximum deflection for steel beams, this site has all the formulas.

http://www.engineeringtoolbox.com/mechanics-t_52.html

[zoama]

When I've had to pull fence posts, I've always used a chain looped over a truck rim, then pull on it with a tractor. The rim acts as a pulley and the post comes right out.

I use a 4x4 post 3 or 4 feet long. You can pull up most things with a truck... just drive forward, it doesn't take much.

[aaxiss]

Hat Dave, long time no see. Nice idea there, only thing i would have done differently is put a $50 hf 2k winch on there , that come along would give me fits.

Sent from my Nexus 7 using Tapatalk 2

[aaxiss]

Hey tripp what kind of loads and what kind of span for the gantry? I designed one for a friend 24 x 24 using 6x6x3/8 I beam for the 2 side rails with a single only in 1/2 for the traverse beam. Pulled a v12 detroit diesel with the allison trans attached with min flex and that was about 7000lbs. Manually moved but with an electric 5 ton winch for the lifting. All of this supported at only 6 points . 4 corners and 2 overhead tie ins in the center of each side rail. This setup is good for 15000lbs mathematically according to the test reports on the steel.

If you come up with some scrap (we'll just assume mild steel) i can do the math for you on spans and loads and have a basic cad drawing and give you max loads ect

Sent from my Nexus 7 using Tapatalk 2

[DaveO]

Nice thing about the bed rails, they are cold steel, adds a little more stiffness and many times free.

Bed frames are cold rolled? I thought that would add expense and strength that a typical bed wouldn't require.

Without getting into the math specifically, do the load / span calculators consider multiple legs in a tripod for instance, whether the legs have cross members, etc? Seems like theres a lot of variables to consider- but that's why we have engineers.

Backatcha, Don, good to have you back!

[Rambozo]

Bed frames are cold rolled?

Without getting into the math specifically, do the load / span calculators consider multiple legs in a tripod for instance, whether the legs have cross members, etc?

I've never seen any but hot rolled angle iron. Usually with the mill scale still on and just painted over. And the newer they are the weaker the steel seems, like cheap recycled stuff, or maybe just thinner.

I haven't seen any that can directly handle a tripod configuration, where there is a mixture of bending and compression loads, you would have to do a few more steps for that as the angle would need to be known to divide the force between compression and bending loads. But for the gantry that was mentioned there are plenty of them for the beam part. Just plug in the support points and the type and amount of load and you will get the stress, and deflection. For a standard steel beam just limit your deflection to around span/250 for a static load and span/360 for a dynamic or shock load.

[Trip59]

Hey tripp what kind of loads and what kind of span for the gantry? I designed one for a friend 24 x 24 using 6x6x3/8 I beam for the 2 side rails with a single only in 1/2 for the traverse beam. Pulled a v12 detroit diesel with the allison trans attached with min flex and that was about 7000lbs. Manually moved but with an electric 5 ton winch for the lifting. All of this supported at only 6 points . 4 corners and 2 overhead tie ins in the center of each side rail. This setup is good for 15000lbs mathematically according to the test reports on the steel.

If you come up with some scrap (we'll just assume mild steel) i can do the math for you on spans and loads and have a basic cad drawing and give you max loads ect

Sent from my Nexus 7 using Tapatalk 2

I may have posted it elsewhere here, but I'm trying to work up a hybrid gantry/jib where one leg is bolted to the ground in the corner between my lathe and mill and the other end rotates (about an 8' span). The pivot point would be able to be swapped out for the other leg to make it a full gantry.

Basically, I need both types, but don't have room for two. Load would need to be approx 4000lbs (loading and unloading lathes, mills, etc.) though if cost prohibitive, next step down a 1000lb working load would be fine and I'll have to come up with another plan for a gantry

[jakeru]

My brother says he's removed stumps using a chain looped underneath the roots of the stump near the middle, and then pulling up on the chain using a "hi-lift" (4x4 truck style) jack. I tried that setup on some small stumps I had, but I couldn't get it to work for me - the jack (with only one "foot" on the ground) was wanting to torque sideways and not stay upright, so I couldn't get enough lifting force.

Your approach with the tripod looks much more effective! Thanks for sharing.