Minimum Branch Diameter TIP

[JosephLobdell]

I'm still a bit new to rope work within tree tops and get a bit sketched out when using a TIP. The problem, I believe, is due to a lack of knowledge surrounding vectors and maybe even tree anatomy. Any information on either and in-between would be greatly appreciated. Thank you so much.

 

[jefflovstrom]

Too vague, expand on your question. Too many variables.
Jeff
It was a beautiful day!

 

[TheTreeSpyder]

So, closeness of the said diameter to parent connection and both their sizes, angle of branch, branch/bell flare and if codom or other deformity all players here; species of course in the mix too some.
If terminates only to climber and support doesn't need as much strength as if going from climber over support to lower tie off w/ 2x load force potential in that geometry.
i believe non codom, 30 degrees or less slant, wrist wide and at trunk, is a common benchmark.
>>30 degrees would retain 86.6% vertical column strength(cosine) and take on 50% cross axis load(sine)
>>wood is ~30% weaker in tension than compression* >>this slant roughly allows 86% column compression and about a 3rd less side forces....
Follow same parameters for rigging forces on support angle, deformities, distance from trunk etc.
Turn termination on support to a control leg induces more load>>2xPotential reduced by friction.
More vertical elliptical will support more against downward force
>>while equally imperfect round of horizontal elliptical would be weaker on vertical and stronger on horizontal pulls



* compression vs tension strength especially watched on bridges
steel showed as miracle when it came of age: as has ~equal strength in compression and tension!
But originally, we wanted to make longest lasting bridges out of non-malleable stone etc., masonry etc.
>>which is great in compression, but sux at tension
>>necessity being such a mother maid us discover the power of the arc(h)
>>arc bridge carries stresses virtually all in compression!
Rope arc is same only in tension direction
>>but can use ALL of tension, sine and cosine multipliers of tension for support and friction just as compression arc in bridge...
.
And once again as always and all ways: "Nature, to be commanded, must be obeyed" -Sir Francis Bacon !
.

 

[old CB]

It varies considerably from one tree to another. I was taught nothing less than a 4" limb, but I throw my climbline over smaller limbs than that.

What might be a strong enough limb size in a white oak would not satisfy me in a poplar or box elder. And it makes a huge difference whether your rope is several inches or more out on the limb, as opposed to snug up close to the main trunk. Angle of limb (like TreeSpyder says) makes a big difference.

TreeSpyder's info looks sound, but makes my head spin.

 

[Del_]

One mm per I.Q point Sanford-Binet

 

[JosephLobdell]

Too vague, expand on your question. Too many variables.
Jeff
It was a beautiful day!

I wanted to leave it vague but I will put some more serious thought into it and respond back promptly.

 

[JosephLobdell]

One mm per I.Q point Sanford-Binet

Well I would assume somewhere around 120mm but that may be a tad generous.

 

[JosephLobdell]

It varies considerably from one tree to another. I was taught nothing less than a 4" limb, but I throw my climbline over smaller limbs than that.

What might be a strong enough limb size in a white oak would not satisfy me in a poplar or box elder. And it makes a huge difference whether your rope is several inches or more out on the limb, as opposed to snug up close to the main trunk. Angle of limb (like TreeSpyder says) makes a big difference.

TreeSpyder's info looks sound, but makes my head spin.

Thank you so much!

 

[JosephLobdell]

So, closeness of the said diameter to parent connection and both their sizes, angle of branch, branch/bell flare and if codom or other deformity all players here; species of course in the mix too some.
If terminates only to climber and support doesn't need as much strength as if going from climber over support to lower tie off w/ 2x load force potential in that geometry.
i believe non codom, 30 degrees or less slant, wrist wide and at trunk, is a common benchmark.
>>30 degrees would retain 86.6% vertical column strength(cosine) and take on 50% cross axis load(sine)
>>wood is ~30% weaker in tension than compression* >>this slant roughly allows 86% column compression and about a 3rd less side forces....
Follow same parameters for rigging forces on support angle, deformities, distance from trunk etc.
Turn termination on support to a control leg induces more load>>2xPotential reduced by friction.
More vertical elliptical will support more against downward force
>>while equally imperfect round of horizontal elliptical would be weaker on vertical and stronger on horizontal pulls



* compression vs tension strength especially watched on bridges
steel showed as miracle when it came of age: as has ~equal strength in compression and tension!
But originally, we wanted to make longest lasting bridges out of non-malleable stone etc., masonry etc.
>>which is great in compression, but sux at tension
>>necessity being such a mother maid us discover the power of the arc(h)
>>arc bridge carries stresses virtually all in compression!
Rope arc is same only in tension direction
>>but can use ALL of tension, sine and cosine multipliers of tension for support and friction just as compression arc in bridge...
.
And once again as always and all ways: "Nature, to be commanded, must be obeyed" -Sir Francis Bacon !
.

More vertical elliptical will support more against downward force
>>while equally imperfect round of horizontal elliptical would be weaker on vertical and stronger on horizontal pulls

When you say elliptical do you mean the give of the branch as it begins to bear load?

 

[TheTreeSpyder]

Growth pattern, branch might flex some but not deform.
If not perfectly round, against gravity load/vertical down tall elliptacal
>> if long axis is vertical, has most leveraged support ,
>>of greatest distance between compression lower
>> and upper tension
Then also weaker against side load / as strength maximized to vertical axis.
>> just as wide horizontal oval weaker against vertical load.
.
Distance from parent perhaps next multiplier of load against support branch.
>> wood has certain strength peak, further limited by genetics and condition.
>> also wood 30% less tension tolerance than compression as rule of thumb.
.
Codom growth pattern gives shear line rather than ball socket or dovetail joint model
>> shear line typically divides to 2 wide half circles ,
>> weaker on narrow axis, stronger on wide by virtue of leveraged distance.
Ripped large codoms folks cry and think included bark is decay, demand to know why failed.
>> heck that is easy, cuz if look at it really well;
>>generally can't explain how it lasted that long...

 

[Tigwelder83]

What no one has asked is what the climber weighs... hard to choose without relevant info

 

[JosephLobdell]

What no one has asked is what the climber weighs... hard to choose without relevant info

I weigh around 220. 6'4".

 

[JosephLobdell]

Growth pattern, branch might flex some but not deform.
If not perfectly round, against gravity load/vertical down tall elliptacal
>> if long axis is vertical, has most leveraged support ,
>>of greatest distance between compression lower
>> and upper tension
Then also weaker against side load / as strength maximized to vertical axis.
>> just as wide horizontal oval weaker against vertical load.
.
Distance from parent perhaps next multiplier of load against support branch.
>> wood has certain strength peak, further limited by genetics and condition.
>> also wood 30% less tension tolerance than compression as rule of thumb.
.
Codom growth pattern gives shear line rather than ball socket or dovetail joint model
>> shear line typically divides to 2 wide half circles ,
>> weaker on narrow axis, stronger on wide by virtue of leveraged distance.
Ripped large codoms folks cry and think included bark is decay, demand to know why failed.
>> heck that is easy, cuz if look at it really well;
>>generally can't explain how it lasted that long...

Thank you for your wealth of knowledge!

 

[laddo]

Check out this paper by Robert W. Farrell “Structural Features Related to Tree Crotch Strength”. Google it. If you cant find it let me know and I can send a pdf.

A lot of interesting info. It talks a lot about branch aspect ratio to the parent stem. The findings were that the larger the difference between the diameter of the trunk/parent branch and the side branch, the stronger the connection. It goes into much more detail as well as other theories. I tested the theory a month or so ago and found a .5 inch branch coming straight out the main trunk (I was climbing MRS and there was a 6” limb directly underneath the tiny limb I was testing, so I included the 6” limb inside my loop....for safety). Trimmed 4 or 5 limbs climbing on that .5 inch branch...even tried bouncing and attempted to pull it out but couldnt!!! Crazy!

Regardless of the size of the main TIP, I always try to have my line around the trunk and over a branch (in some fashion).


Sent from my iPhone using Tapatalk

 

[bck]

If it’s a white oak, I wouldn’t worry about any crotch 3-4 inches growing straight up. White oaks can get leggy and then I would be careful climbing on something growing more horizontal

 

[bck]

If you’re worried just throw a 2nd climbing line in the tree and make sure you’re always tied in twice.

 

[JosephLobdell]

If you’re worried just throw a 2nd climbing line in the tree and make sure you’re always tied in twice.

Check out this paper by Robert W. Farrell “Structural Features Related to Tree Crotch Strength”. Google it. If you cant find it let me know and I can send a pdf.

A lot of interesting info. It talks a lot about branch aspect ratio to the parent stem. The findings were that the larger the difference between the diameter of the trunk/parent branch and the side branch, the stronger the connection. It goes into much more detail as well as other theories. I tested the theory a month or so ago and found a .5 inch branch coming straight out the main trunk (I was climbing MRS and there was a 6” limb directly underneath the tiny limb I was testing, so I included the 6” limb inside my loop....for safety). Trimmed 4 or 5 limbs climbing on that .5 inch branch...even tried bouncing and attempted to pull it out but couldnt!!! Crazy!

Regardless of the size of the main TIP, I always try to have my line around the trunk and over a branch (in some fashion).


Sent from my iPhone using Tapatalk

I found the PDF and am thankful. Have a wonderful day!