Friction system

[12_bravo]

Good morning everyone, Im a rookie arborist here, topped my first tree a few days ago, was in the corp of engineers for a while and did some tree climbing there. im looking to do some design work and machining of tools that may help. Ive designed this tool as a friction system to aid in lowering trees down, or as an anchor point for multiple tie offs, any suggestions or feedback on this?

its for 4x holes that are all 1.5in dia with large radii lead ins, overall its 8" long and 5.5" wide and 1.25" thick, and weighs 2.1lbs

I do alot of my work alone, im not part of a crew or anything, mostly working at home, so If I top a tree I wanted something I could manage lowering it down myself (im sure its super dangerous since I should be focused on not falling out of the tree) but I wanted something to help with the safety aspect.

let me know what you think.

 

[Yarz]

Did you design that from scratch?
I ask because it looks similar to the Notch Triple Thimble or the Safebloc.

Having used neither, (only seen them in a few videos) I'm curious if you had improvements in mind when designing yours vs. those.

 

[MrTreeGuy]

What software you used?

 

[12_bravo]

@Yarz, ive not taken inspiration from either of these, just had the idea in my head. I wanted something that you didnt have to feed the running end through to make it work. which I have since modified to have more of an anchor style to it. ill post pictures later tonight.

@MrTreeGuy I use SolidWorks. Im a Mechanical Engineer in my daily job.

Im also working on a system that keeps longs attached to the tree while doing negative rigging until the log is 180 degrees from its starting point. the hope would be to reduce the amount of energy released into the ropes before the log drops.

 

[MrTreeGuy]

@Yarz, ive not taken inspiration from either of these, just had the idea in my head. I wanted something that you didnt have to feed the running end through to make it work. which I have since modified to have more of an anchor style to it. ill post pictures later tonight.

@MrTreeGuy I use SolidWorks. Im a Mechanical Engineer in my daily job.

Im also working on a system that keeps longs attached to the tree while doing negative rigging until the log is 180 degrees from its starting point. the hope would be to reduce the amount of energy released into the ropes before the log drops.

The x rings/safebloc is one of those products that creates friction to lessen the peak loads on the main anchor point. Before, they used a block and pulley system which places a strong load on the anchor because the friction was mostly at the bottom of the tree.

 

[12_bravo]

This is the update I made to mine.

I also gave machining a rope wrench a try, and it worked out pretty well! im acutally really really pleased with the end result. I just used 2 skate board bearings for the lower bearing, and a machined pin and cotter pin for the upper pin.

 

[Mid TN tree]

Are you selling these or just showing off

 

[12_bravo]

Well, I was honestly testing the waters. I would be willing to sell for sure. but wanted to see if there was any interest.

also looking to see if there is anybody who has ideas that needs assistance making them or engineering them. I have FEA tools at my disposal as well as the CAD tools and Engineering experience.

 

[ZinTrees]

I would be willing to sell for sure

looks like a decent idea, I have nothing to say that I think is super important other than get product liability insurance, load test and certify them with a MBS, and have a good lawyer incase one ever fails

other than that, really seems like a handy little tool

 

[12_bravo]

What do you mean by MBS?

 

[ZinTrees]

What do you mean by MBS?

minimum breaking strength, by far the most important calculation in any rigging system, from this you get your swl (safe working load) which is usually 10-20% of the MBS

static rigging we generally use 20% of a device's MBS, all tree work is done with dynamic rigging so we use 10% (unless its crane work, then we follow the slings rated capacity)

E.G a rope with a 25,000 pound MBS would have a safe working load of 2500 pounds, but a crane sling being used for a "static" load of the same MBS would be 100% acceptable to lift upto 5000 pounds

 

[ZinTrees]

basically, make a batch of 20 or so, and break them on a break test machine with a loadcell inline tracking peak pull, whichever the weakest one breaks at is the MBS, this test should be done for every batch produced, and needs to be done any time you change any part of the design or material

 

[12_bravo]

I got you, yea I ran some basic static FEA on another pulley system im using and im using a FOS (Factor of Safety) of 3x. using 45KN and its only deforming 2mm. next I need to run fatigue calculations on it and check the life of the part. but ill run the same on this, but given how beefy it is, i cant imagine it deforming much at 100KN. Ill see what I can scrounge up. We use alot of labs where I work to do fatigue testing and static testing.