Omniblock abuse

Stumpsprouts

Branched out member
Location
Asheville
Yesterday I finally broke one of my 2.6 omniblocks which I had used heavily for 6 years.

For most of those years I have used a 14mm rope in it even though it’s only rated for 13mm. Tsk tsk. I’ve used it as the terminal rigging point in negative blocking trunk wood up to about 25” in diameter.

Yesterday I did a little bit of larger negative rigging with it. Switched to tree no 2, and sometime between it getting tied on and me installing the block in the tree, the button that holds the side plate in place went missing, rendering the block useless.

I take full responsibility for bending the rules and getting away with it for so long, and was lucky to find it fail in this fashion rather than during a rig! I will say I went to our local saw shop today and was able to compare the sheave size of several blocks. The Buck side swivel, for instance, is rated for 16mm rope and is only just slightly wider. I have always been surprised and skeptical of the 13mm rating, but thems the facts.

It was time to upgrade to a proper block for large wood so I grabbed the smaller DMM impact block. Just wanted to put this info out there to folks who might run the omniblock and a 14mm. I shared that with a company I contract with this morning, they were just about to buy some omniblocks based on my long history of using them with 14mm and glad I was able to find this out before they did.
 
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Stumpsprouts

Branched out member
Location
Asheville
In fact. Looking closer at how the button seems to be secured to the block, I wonder if the a replacement button could be installed.... ? Regardless I will retire this from professional use.
 

Chris Schultz

Participating member
Location
Minturn
I don’t negative rig into my omni blocks, but I have exceeded the rope diameter specs..... my thinking is a 14 mil rope under tension is about a 13 mil or less right?! Love those things, but you are right that rope diameter is quite limiting factor in their use... What do you think ultimately lead to the button failure though? Negative rigging? Exceeding rope specs? Cycles to failure? Curious to hear your thoughts.
 
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Stumpsprouts

Branched out member
Location
Asheville
I am glad to hear I’m not the only one using 14mm in the omniblock. Who makes a 13mm rope anyway?

I think good old fashioned cycles to failure for this one. The button seems to be held in by a small screw with an Allen head. The button was lost to the forest floor so who knows what state it is in. If negative rigging with a diameter rope too large, I imagine the button is receiving more of the load than it is designed for, especially in that initial moment when the piece is inverting. Not to mention getting whacked back into the trunk of many trees over the years once the piece has completely inverted and the load is going downward.
 

evo

Been here a while
Location
My Island, WA
This can be a grammatical/industry language issue.

For Arborist, block or anything with that term does commonly mean ‘can take dynamic loading, aka shock loading’. Most are fairly inefficient pulleys with bronze bushings as strength is the determining factor. (Same is true in logging)

What we call pulleys are commonly needle bearings or ball bearing, and used for static loading, directional changes, and mechanical advantages. Mostly used in other rigging industries such as event rigging, industrial access, and rescue applications. Not a tool that can be abused or dragged through the mud etc.

I love Omniblocks but I do have a little chip on my shoulder about RE’s choices to call them blocks when marketing to our industry without specifying their limitations.
 

Stumpsprouts

Branched out member
Location
Asheville
I love Omniblocks but I do have a little chip on my shoulder about RE’s choices to call them blocks when marketing to our industry without specifying their limitations.
Right! That’s what I’m discovering. Like, would you say the huge 4.5 omniblock should not be used for negative rigging, because it is still not designed for shock loading?
 

flushcut

Branched out member
Location
Delavan, WI
This can be a grammatical/industry language issue.

For Arborist, block or anything with that term does commonly mean ‘can take dynamic loading, aka shock loading’. Most are fairly inefficient pulleys with bronze bushings as strength is the determining factor. (Same is true in logging)

What we call pulleys are commonly needle bearings or ball bearing, and used for static loading, directional changes, and mechanical advantages. Mostly used in other rigging industries such as event rigging, industrial access, and rescue applications. Not a tool that can be abused or dragged through the mud etc.

I love Omniblocks but I do have a little chip on my shoulder about RE’s choices to call them blocks when marketing to our industry without specifying their limitations.
I think RE's choice of calling it a block is that it can be directly connected to a textile/sling whereas a true pulley can not.
 

SeanRuel

Branched out member
Location
Portland
Ask @Serf Life all about the marvels of 1/2" rigging. Never used an omni block but that's a glowing recommendation in my mind. Test to destruction, the only really accurate arborist test
 

Jonny

Been here a while
Location
Buffalo
I am glad to hear I’m not the only one using 14mm in the omniblock. Who makes a 13mm rope anyway?

Oh there’s tons of them out there, but most folks call it 1/2 inch. Not truly 13mm I guess. 12 and 16 strand climbing lines are great for rigging with the Omnis. I like my 2.6” material handler and the 1.5” is handy as well too. I never load them dynamically.

FWIW, I’m pretty sure there’s no difference in construction between the orange Omniblock 2.6 and the red material handler Omniblock 2.6. Just rated in different units of measurement.
 

evo

Been here a while
Location
My Island, WA
I think RE's choice of calling it a block is that it can be directly connected to a textile/sling whereas a true pulley can not.
I'm not placing blame or fault, but trying to articulate that their choice of wording when and how it applies to "common" nomenclature within our industry leaves us with statements of "I think." I am suggesting however for this to be realized by any and all manufactures, and that it should be spelled out to our numbskull industry that makes up its own terms.
The argument isn't unlike the "double rope"/"doubled rope", "DRT"/"DdRT/MRS" crap. At the end of the day who really cares what it's called as long as the function is known. This seems to be a direct link to logging terminology, and even likely with nautical roots. Definitions are important but pointless without explanation such as a block is a block until it is "like a block, because of...."
 

evo

Been here a while
Location
My Island, WA
Right! That’s what I’m discovering. Like, would you say the huge 4.5 omniblock should not be used for negative rigging, because it is still not designed for shock loading?
I would say its discretionary and a calculated risk... Personally if I were taking a large oak down with a GRCS (which I don't) the bigger omni would be perfect to hang as a high point for lifting and lowering big wood/limbs, but it should be switched out for spar work/negative blocking/drop catching.
But if rigging out a tall conifer tip tying, or overhead lowering and then lowering a smallish top all on a large omni where it can run slowing it down to the point the apical bud just kisses the ground hell yes! Cut and chunk the wood from there or switch out if needing to negative rig the bigger/heavier/lower shit.
 

evo

Been here a while
Location
My Island, WA
Meh....I would never use an omiblock for rigging. They are designed for rescue scenarios using mechanical advantage. Blocks or rigging rings.
I use mine all the time, but rarely do I negative rig. They really shine for redirecting winch lines with the quick line in/out without dropping parts etc.. The swivel is very nice but a complicated un needed moving part and a extra potential failure point as textile slings often allow for rotation.
 

Stumpsprouts

Branched out member
Location
Asheville
This has been really helpful info, thank you all for chiming in. Given my experience using it in negative rigging, I’ll probably keep using it as a terminal rigging point for brush pieces but not for any wood.

While I got you all in the phone, let me ask you this- I also use it all the time in double whip / span rigging due to its easy on and off. Surely that’s a shock load though, and I’m wondering if that also is a misuse of the hardware?
 
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evo

Been here a while
Location
My Island, WA
This has been really helpful info, thank you all for chiming in. Given my experience using it in negative rigging, I’ll probably keep using it as a terminal rigging point for brush pieces but not for any wood.

While I got you all in the phone, let me ask you this- I also use it all the time in double whip / span rigging due to its easy on and off. Surely that’s a shock load though, and I’m wondering if that also is a misuse of the hardware?
I don’t do big stuff anymore. But I would say it all boils down to technique. Span rigging can be top tying the load or facing material almost 90 degrees to the rigging, taking slack out or laying it into the rigging.
Same goes for double whip, but if double whip on spar work I say hell no.
 

Tree-Taylor

Branched out member
Location
Canada
I emailed RE years ago about using a larger line in the omni block At the time their marketing was using 9/16 Sterling Atlas. Here's their response:

"You have a sharp eye! Your questioning of the compatibility of the rope diameter with the indicated appropriate rope diameters marked on the pulley are correct. This photo was a mistake in showing a larger diameter rope used than is approved with the pulley. Not that it's going to introduce any major concern or risk to have a slightly larger rope in there, along with elongation reducing the diameter once under load, but it's still not what we suggest be used with our pulleys.
Regardless of the rope brand and model, we suggest you stay within the markings on the pulley for optimal performance."
 

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