Propping a Pine

[NickfromWI]

I few months ago I got some idea from you guys about building a prop for a small apple tree. The prop was eventually built, installed, and the client is super happy with it. (old apple tree made it through some CRAZY wind storms we had in December)

Well, I'm at it again. I have a client with a much bigger tree this time. I want to run the tree and the design by you guys and see what improvements y'all can make.

First, here's a couple pictures of the tree. They aren't the best pictures for getting the whole picture but you're clever, you'll figure it out.

The tree is about 35' tall and spreads about 30' wide. It's an Italian stone pine (Pinus pinea). The trunk is approx 36" dbh, depending on how you're measuring that. For frame of reference, the shed is about 8x8x8.

At first it looks like the tree fell on the shed. That is not the case. The tree has been very slowly lowering itself onto the shed. The client said it's been about a decade since they noticed the tree touching the shed. Note the limbs in the canopy are all pointing straight up as you'd expect in a "normal" upright tree.

 

[CurSedVoyce]

Holy Moly that's a lot of pine to prop!

 

[NickfromWI]

Yeah. So what's my plan?

Well, when I started the thread about the apple tree prop, SouthSoundTree pointed out that in the BMP's for propping they recommend no cup to hold the tree. Rather, they recommended a hole in the tree and the tree resting on a peg/bolt. Here's a pic:

 

[Paul B]

Nick, you are a dreamer. Have fun!

 

[NickfromWI]

So this is what I presented to a welder today:

 

[NickfromWI]

The plan so far is to pour concrete with bolts upward facing inset in the concrete. When dry, prop would rest on concrete and get bolted in place. As you can imagine, I have a few questions to answer still:

What size materials should the system be made of? The diagram shows 8" beams. Welder recommended 6" beams with 1/4" walls, but I'd rather pay a little extra for piece of mind. The base plate is 1/2". Again, welder recommended 1/4". I have 2" bolts down below and the big bolt at the top is 3" threaded rod.

How do I connect the threaded rod in a way that will hold weight AND be adjustable? Right now I have a block of steel at the top where the beams come together. Ideally, the top block would have a threaded hole in it. I insert the top rod/peg, screw it in low, put the prop in place, then crank the top peg until it's putting pressure on the hole in the tree. The welder suggested that the threads might just give out. I'm not a metal expert, but this sortof makes sense to me. He suggested some ways to perhaps achieve the goal, but they seem convoluted, so I won't share them. I want to see what you come up with.

Can you think of any adjustments you'd make? Would you scrap the design and change it completely?

I'm sending this all to another welder tomorrow for a second opinion.

love
nick

 

[NickfromWI]

Nick, you are a dreamer. Have fun!

Damn straight! I like saving trees. Lady got 4 quotes for removal (all over $4,000) and I was the first one to even ask if she'd be interested in keeping it. You should've seen her smile.

On 12/1/11 we had some scary wind storms and this tree lost a couple big limbs, but the whole system remained intact. I see no reason why not to pursue keeping the tree.

 

[MasterBlaster]

I don't like the bolt idea nor the small footprint of the support.

 

[NickfromWI]

The bolt idea is recommended in the BMPs and the ISA is never wrong!

I'd be down with pumping up the base area. There are some space limitations with the sight, but there's room to grow.

 

[MasterBlaster]

I'd have the limb nestled into a padded cradle.

 

[Paul B]

go for it Nick, if you figure you can retain it.

 

[Thor's Hammer]

Couple of thoughts -

Trust your fabricator on the material sizes. He knows this stuff better than you.

Go for round tube rather than box section. You'd be surprised how much better it looks. Its also far more commonplace when building industrial braces and ties in steel buildings, and you will be able to buy the fittings off the shelf.

As much as I like steel, consider doing it in timber with steel slit brackets.

Go for a wider footprint, with the legs further apart. Try not to use to much concrete - tree roots hate concrete. Use a semi dry mix when pouring to reduce runoff.

I think its excellent that you have offered to do this!

 

[PCTREE]

I think you should just put more stuff in the shed, done deal

Good to see you posting again Nick

Are you going to do an end reduction too??

I concur about a wider footprint, shame you are so far away or I would tell you to come get some white oak 4x8s Ive got, use 2 of those to form an X and build tripod deal on that. All you are trying to do is disperse the load so you don't have so much point pressure. You could even put a hanging plant hook under it and make it a feature

 

[woodworkingboy]

I often see ancient trees propped up. Wooden supports...usually round poles with cradles, as Butch suggested. The supports look obligatory, not really obtrusive.

 

[pigwot]

My thoughts:
Definitely agree with a wider base, especially if there is wind movement to consider
Use a stainless steel threaded peg at the top running in a smooth section of stainless tubing rather than threaded block, with jam nuts on the top and bottom - easier to 'adjust'
I agree more with your assessment of material thickness for strength than your welder's
Structurally, triangular cross-section is best for stability, followed by round, then square, in my experience
A peg, which is 'point-contact' does less damage to the cambium than a cradle*
(* unless there is a lot of movement with wind then either will tear and damage the trunk)

 

[Jack]

Hi Nick - glad to see you're posting again, especially with such a wonderfully interesting problem - I like the prop solution. It makes it an engineering problem as much as a pure arborist problem. So, I've got some additional questions:

It looks like there might be a high point load where the prop contacts the tree. What is the exact species? Can it take the compressive load?
What are the, worst case, soil conditions; weight bearing capacity?
What are the, worst case, environmental conditions (temp, precipitation, wind)?
Do you have a picture of the root plate? It would be good to see it from that angle.
Where exactly do you plan on placing the prop?
What weight to you expect the prop to bear?
Might there be some need for more than one prop?
Will the prop need to tolerate stem movements in the wind?

Kudos to you! Saving trees is good ...

 

[pantheraba]

THIS is gonna be a fun thread to watch...great problem to pose. That is a fine looking tree. I, too, would like to see the root area...that last shot of the trunk in the dirt is impressive...what is downstream of that?

And I certainly don't know much about it but instinctively, a cupped, semicircular cradle that could swivel / gimbal would give you some latitude of movement in case of wind, further settling. A fixed cradle would bite into the tree if the tree settled on it too much.

From wikipedia:

"A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to remain immobile regardless of the motion of its support (cf. vertical in the first animation). For example: on a ship, the gyroscopes, shipboard compasses, stoves, and even drink holders, typically use gimbals to keep them upright with respect to the horizon despite the ship's pitching and rolling."

This idea would give one axis of swivel...not sure how you would get two axes. http://sailboxes.com/f18-swivel-hull-cradles.html

 

[sotc]

Where are you planning to place the Props? I like your idea on materials except I would probably go with 3/8 plate for the base, 3/4" bolts at the base. Have you done a RCX (again!) to see whats going on to keep the tree from anchoring? Don't put the prop too close to the base or you create a fulcrum that will uproot the tree in the wind and rain.

 

[Old Monkey]

I think the Willie's fulcrum point is the fly in the ointment on this one. That tree probably started leaning because of a lack of scaffold roots on the lean side. It's been pulling the far side roots this whole time to stand up. Unless you can prop it beyond the center of gravity, the force vector on the roots will change from the direction it has been pulling all these years. You'll be making a pry bar basically. I think you could actually make the tree fail more readily by doing this.

 

[sawinredneck]

I'm "mister overkill" and I don't like making things twice, so my thoughts:
I'd make the base wider and add a third leg away from the root ball, keeps the wind from pushing the whole sheebang over.
Stainless, while I understand the recommendation, is incredibly soft, and in this application I would be hesitant of the thread root being strong enough not to just shear the threads right off!
Hot galvanized all-thread is soft enough, no need to go softer!
As for the gyro, a simple "ball and socket" would suffice for this, around a 3" ball, or half ball, fitted into a cup, shouldn't be that hard to find something to work for that at a scrap yard or elsewhere. The gyro is a neat idea, but I don't think you will be able to raise the tree enough to need the extra movement it provides.
I'd weld a nut on the top of the top plate for the adjustment, another nut on top of that to lock it and another welded onto the bottom of the adjustment rod. Simple and strong.
Just my .02

 

[Monkeywithasaw]

With the fulcrum in mind you may have to build more than one prop kinda like a train tressel each one a little bigger than the next and all tied together. Second on the the middle picture on top one lead looks like it has a split or decay that will only delay the inevitable

 

[pantheraba]

As for the gyro, a simple "ball and socket" would suffice for this, around a 3" ball, or half ball, fitted into a cup, shouldn't be that hard to find something to work for that at a scrap yard or elsewhere. The gyro is a neat idea, but I don't think you will be able to raise the tree enough to need the extra movement it provides.

So...I wonder if an automotive ball joint might provide a base for a cradle? Maybe tractor/trailer size?

 

[sawinredneck]

I'm thinking simple Gary!

 

[pantheraba]

That is cool..I googled images for ball joint but didn't get that...how'd you find that?

 

[MasterBlaster]

He's a Magic Man!