Guessing Wood Weight

[brendonv]

I find myself always taking tiny pieces onto the block in the tree, to stay within the SWL of 1k lbs of my 1/2 Stable Braid.

I just went outside and measured a good chunk of spruce I had cut the other day. At 21" each end, 4' long, the log weight chart figures around 500lbs....I was amazed.

I can, in reality, take a piece 8' long on such a small line. I think I have been wasting my time with tiny pieces, and need to step it up a little to put these lines to real use.

Any advice on trying to judge brushy tops/chunks when using the false crotch system?

 

[brendonv]

Another thing that got me was, the 5/8" max with GRCS use. Just watching the video Greg sent me made me rethink log weight too.

 

[SkwerI]

Log weights do not equal shock loads. A 500 lb chunk falling a couple of feet can put well over 1000 lbs of load on the rope. Drop it 3-4' and you can expect shock loads over 2000 lbs.

 

[brendonv]

Ah ha. Heads up on that one. Isn't that why arborist ropes SWL are 10% tho?

 

[sotc]

brendan, those charts are not very accurate here. i found that by doing a few crane jobs you can learn weight by species in your area more accurately

 

[wiley_p]

I always took notes of weights when doing crane jobs, the Park Service chart that is in the EHAP book, Sherrill catalog, etc. is off by a fair amount. Depends on time of year, butt logs are always different than the chart. Treespyder hooked us with the log calculator at Woodweb. Between those charts and my notes I stay right close when doing crane picks and have a much firmer idea of rigging forces being generated.

 

[stehansen]

500 lbs. is a pretty good size chunk to be roping.

 

[brendonv]

500 lbs. is a pretty good size chunk to be roping.

That's what I think too. This chunk here in the pic is the one I figured weighs around 500lbs, from the chart, and the fact that the mini was teeter tottering with the log. I think the mini has a tipping cap. around 500+/-.

I would never take that piece on my line. This is all just making me think a little bit. Taking small pieces is probably the way to go.

 

[No_Bivy]

http://www.woodweb.com/Resources/RSCalculators.html
Here's a link to get the log weight. If it's a crane removal then the weights are accurate. If you are roping it out....go lighter. This is where a good ground guy comes in. Let it run = less impact force. I keep a green wood weight chart on the truck for reference.....USFS chart I think, Burnham may know. I think in most situations, the rigging is more bomber then the rigging point. You have to consider that for sure.

 

[brendonv]

Thats the chart I use btw.

 

[No_Bivy]

500 lbs. is a pretty good size chunk to be roping.

depends.....500 can be light, all things considering

 

[MasterBlaster]

I've roped way bigger pieces with my 1/2" Stable Braid Plus, but I don't shock load it for sure.

 

[sotc]

brendan, if this is your machine the tipping cap. is around 1200 lbs
Thomas 35DT
Engine Kubota
Fuel Diesel
Horsepower (net) 25
ROC (lb.)* 420
Operating weight (lb.) 2,350
Hydraulic flow, auxiliary (gpm) 14
Hydraulic pressure (psi) 3,000
Bucket volume (cu. ft.) 3.8
Bucket hinge-pin height (in.) 68.75
Travel speed, fwd (mph) 4.4
Track width (in.) 9.05
Track-on-ground (in.) 30.25
List price w/std. bucket $18,490
* Rated Operating Capacity @ 35% of tipping load.

 

[brendonv]

brendan, if this is your machine the tipping cap. is around 1200 lbs
Thomas 35DT
Engine Kubota
Fuel Diesel
Horsepower (net) 25
ROC (lb.)* 420
Operating weight (lb.) 2,350
Hydraulic flow, auxiliary (gpm) 14
Hydraulic pressure (psi) 3,000
Bucket volume (cu. ft.) 3.8
Bucket hinge-pin height (in.) 68.75
Travel speed, fwd (mph) 4.4
Track width (in.) 9.05
Track-on-ground (in.) 30.25
List price w/std. bucket $18,490
* Rated Operating Capacity @ 35% of tipping load.

Na, thats the big boy. Mines just the plain jain 25g. Shoot the manual is right here.........operating capacity--475lbs, tipping is probably 1200lb. I cant see that chunk weighing that.

 

[JIML]

Ive never figured weight before, I know we have roped some huge pieces on 1/2" 3 strand and never broke one. Seen the rope get skinny a few time though! Sometimes we will break out a 5/8" rope or bigger if we think its needed. I have seen a 5/8" rope break, never seen one of the 1/2" lines break though. I personally thought it was a crappy rope that broke. Just felt cheap in your hands.

 

[TreeRhino]

(pi r squared) times length times weight per cubic foot always works for me. And I always estimate high. Tops and brush are a different animal though. Hard to estimate. I've taken some pretty big pieces of tulip poplar on 1/2 inch. Probably bigger than i should have. The line will usually hold but its life diminishes much quicker when you overload it. and eventually, it will break and thats ugly. Especially if you're next to the block when it come flyin back up.

 

[MasterBlaster]

Other than crane operators that have been doing a lotta treework using a load indicator, "guessing wood weight" is just that... guessing.

I'm asked that question a lot, and my answer is hell if I know.

 

[lumberjack]

Brendon, if your bro is decent at running the ropes, I would rig that nugget down (arrow) on 1/2" without worries. I've auto-roped pieces on 1/2" (porty up in the tree with me running it) that I had to cut in half for the mini to pick up with me on the back.

I haven't used anything but my 1/2" stable in a while. Tomorrow I gotta pull out my high mod 1/2", but that's to pull some fairly heavy leaners with the winch.

Longer pieces are more of a issue that fatter pieces. The piece in the grapple is about as big as I'd normally go on 1/2"

The GRCS's winch is best suited for 1/2-9/16" ropes, the bollard can take up to 1" with out worry.

The tipping capacity of your machine is right around 1400lbs, but that's assuming a 180lb operator (more than you and less than me) and the attachment is the regular dirt bucket.

I eyeball weights and for normal sized wood (3' and under) I can normally get within 10% in my area. Crane jobs help "calibrate".

I get out of school in early May (like the 6th) or I can miss a week or two (nice having classes only 2 days a week) of school depending on when... anywho, get up some rigging jobs and I'll come back up with my GRCS and some other toys and we'll play. I promise not to roll my Jeep again and get there all banged up. I gotta burn that voucher before August and Ash has been dying to see me

 

[Koa Man]

Nothing wrong with taking smaller pieces. I was never a believer is taking as big a piece as you can. I prefer smaller and safer. I warned a guy I was subbing for not to let his climber take that log in one piece. He told me the rope is rated for 6000 lbs and the log was less than a 1000. I tried to explain to this idiot that his pulley was 2 ft. below the log [to no avail.] Well the rope snapped and the log ended up on the living room floor of the neighboring house. [after going through the roof and ceiling] Luckily, the elderly couple living there was in the kitchen at the time. They could have easily been killed. This was back in 1990, and the cost to repair the house was about $5000. The removal of the big tree was $1800.

 

[Frans]

Great story to learn from Wesley!

I have never dropped a piece through a roof but I did let a chunk loose on a steep hill. It ran down the hill, through the livingroom window, rolled across the room and ended up inside their big T.V.----which they were watching at that time!
This was back in the late '80s.


I sure like the 1/2" double braid but I have noticed that folks over use it. when a 9/16" would give a better safety factor

 

[Burnham]

Don't forget to calc your drop distance to the COG of the piece...longer wood makes for greater drop distance, so even if the weight is the same, say a skinnier chunk, the dynamic forces have grown over that of the same rigging scenario but with a fatter short piece to catch.

 

[Frans]

Very good reason for using a ratcheting capstan lifting lowering device is being able to take up the slack and then release the line as the line excepts the load.

I call it: Rapid Slack Removal. Also, Quiet Rigging

Shock loading is a killer

 

[Al Smith]

Well,along the same lines of thought,you would be surprised if you knew how hard your noggin will hit the ground just falling 6 feet . A fall from a 6 feet tie in ,for example,puts one hell of a load on your safety line .

I'm not a tree climber,never claimed to be.However if and when I do I use a piece of 5/8" Sampson for a life line and keep hitched close .

Now I kind of wonder,being an old sailor type 3 strand kinda guy.Would the elasticity of 3 strand be better than braided for deceleration of shock loading?

 

[Bounce]

I regularly use a green log weight chart to help figure out what size log to cut. I like to keep things as close to 1000 lbs as I can, with 9/16" Stable Braid. In Douglas fir, I can cut a 2' diameter piece almost 6 ft long and be right around 1K lbs.

The WLL is 1/10th of the rigging system's strength in order to account for potential shock loading and strength loss over time due to wear and tear. If you assume the worst case scenario (groundie has the piece snubbed off at the porty & doesn't let it run, and perfectly static lines), this 10:1 design factor is accounting for a 6 ft freefall distance before being caught by the rope. Since it's usually pretty simple to keep freefall distances under 6 ft and rope isn't perfectly static (and hopefully the groundie can let it run a bit), I figure I'm pretty safe cutting 1000 lb pieces. I always have to remember though that it's the unknown strength of the tree that all this hinges upon (literally). I think about how Peter Donzelli died every time I do butt hitching like this.

 

[Banned by Squirrels]

I just retired my 200' 3/4" tenex after much use/abuse and it never failed me. Toward the end I even tried to break it, (under normal circumstances) taking bigger and bigger pieces and just would not break... I must have taken a 12 footer about 22" diameter of Island Pine at one point and it took it!