iDRY Vacuum Kilns

Sponsors:

How do you guys deal with "chain shot"?

Started by Oregon Engineer, June 14, 2005, 01:10:18 PM

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

Oregon Engineer

I'm curious what you do to deal with "chain shot" and if you've ever experienced it.

Tom

Welcome to the forum, Oregon Engineer.

I've never experienced Chain Shot.  It was a projectile used in Naval Warfare a bit before my time.  A link of chain attached to two cannon balls was devastating to infantry, marines aboard ship and rigging. 

How would I deal with it?   I'd run to beat Hades. :D

Oregon Engineer

Oh, I'm sorry, the "chain shot" I'm referring to is when a mechanized tree harvester breaks a chain and a small portion shoots out at super sonic speeds.

Buzz-sawyer

TOM
Took the words out of my mouth :D :D :D
Welcome to the group!
    HEAR THAT BLADE SING!

Tom

That was fun, Buzz.  Couldn't resist.

:D I was just having a good time Oregon  Engineer.  :)

I didn't really know what you were talking about, but I did know it wasn't about cannon rounds.  :D   I have heard some of the guys on the forum talking about you're kind of "chain shot" and there is at least one thread somewhere concerning the subject.  a search might get something until one of the "knowledgeable"  ones comes along.

;D  That was fun.  :D :D

Here are two links I found.

https://forestryforum.com/board/index.php?topic=9659.msg131764#msg131764

https://forestryforum.com/board/index.php?topic=11029.msg151664#msg151664

Bro. Noble

Welcome OE,

I hope you'll excuse Tom for acting so silly :D :D

If I were around one of those things when it came apart,  I'd run to beat  Hades.

I wonder if that's one of the reasons they have a caution sign that says to stay back a couple of hunnard feet?  The guy in the cab should be shielded by the machinery. 

I'd also wear a hardhat.

Someone will probably come along that knows what the heck they are talking about ;)
milking and logging and sawing and milking

Jeff

Welcome Oregon Engineer. Sumpthin tells me you might know a little about this already? :)
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Oregon Engineer

Yah, yah that's a right good welcome I got from the welcoming commitee. Pouncing on a new comer with a new thread. Kinda like the new hire on the job site with a new lunch bucket and clothes. The crew's out to get him dirty and flatten the lunch bucket. I feel right at home now, thanks!

Yes Jeff, I do know a little bit about chain shot and was hoping to get a feel for the general knowledge base of the forum members.  Based upon the first couple of replies, I figured I had a real job a head of me.

Texas Ranger

Yep, welcome aboard, bout time we had somebody here that really knows about harvesting, and stuff. ::)
The Ranger, home of Texas Forestry

beenthere

Okay OE

You're on deck, now 'splain more about what yer question was, and maybe some here might get 'dirty' with you.  ;D ;D
We sometimes poke holes in 'unidentified flying objects' launched here.  :D :D but we are most times harmless.

I'm bettin' you can feel right at home here. Most do.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jeff

We have a few mechanized loggers out there but it may take more then a day or so to flush em outta da bush.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Oregon Engineer

While we're waiting for the operators to get out of their cabs and onto the computer you can get a quick look at chain shot via a slide show at this web site:

http://www.healthandsafetycentre.org/enews/050516/fse2.htm

Take a look, afterwards you'll duck for cover every time you're in plane with a bar and chain while its in the cut.

Tom

That was a good show.  :)

Sounded a bit  like Paul H. :D

crtreedude

Welcome Oregon Engineer,

I think you are just getting the semi-retired, retired, and on injured reserved people in the middle of the day - eventually you will get the people who still work.

Good group of guys, even though some of them do eat grits - be for warned.

I thought the video was pretty good - the most important thing is to increase the protection. Something bad is going to happen someday - so about the only way to be sure is to make it impossible for it to hurt the operator.

Sure hope no one else is in the field though.

Did you by chance find this while looking for information?

LINK 1
and
LINK 2
and
LINK 3
So, how did I end up here anyway?

Kevin

That's definitely preventable.
I would compare it to standing in front of a chain saw bar nose while someone is operating the saw.
A qualified person meaning experienced and knowledgeable should be well aware of the danger.

crtreedude

One other comment - if something is potentially as dangerous as a rifle - DON'T point it at me, and I sure wouldn't use it in a way that it points at me myself.

I think a lot of times accidents happen because someone starts "getting away" with things. Do it enough, and the law of averages will get you.

So, how did I end up here anyway?

Gary_C

I have heard of "chain shot" but never seen it. Without a high speed connection I gave up on the slide show.

Most of the time when a chain comes off, it is either caught in the tree or the head. There is a pin under the drive sprocket and a cage on the back side of the head. Never seen one come off with any velocity. I have had times when I could not find the chain, but that was usually in deep snow and unless you can see a mark in undisturbed snow it is very hard to find. That only happens just after you put on a new chain.  :'(   If you find the chain, you can just put it back on unless it has hit metal. I seldom break a chain, but then I sharpen my own and usually find any cracks or bent links and fix them.

A larger hazard is from those disc saws or "hot saws" as they are called. The disc is a very thick and about four foot diameter steel disc that turns at such high speed that operators say you can shut down the power and still cut down two trees and it will be still spinning. You actually just drive through or push the head thru the tree. The large teeth on those discs will throw many large chunks of wood for hundreds of feet.  :o  :o

The windows on those machines are supposed to be tough enough to stop a bullet. I have accidentially banged logs against the windows and never broken or cracked one yet.
Never take life seriously. Nobody gets out alive anyway.

Frank_Pender

Welcome OE.  It is always nice to have another Oregonian  (and I do not mean the fishwrapper out of Portland) onto the Forum. 8) 8)  Whereabout in Portland area are you located?
Frank Pender

Jeff

Gary_C, I gotta say that that slideshow is an ineffective way to reach everyone that should see it. Frankly, because I think you should have saw it and you couldn't.

Below is a screen shot of where the chain link blasted through the poly carbonate window (bullet proof)  before it struck the operator in the abdomen.

Here is a document that should load that describes a brief discription ofthis accident.
http://publications.healthandsafetycentre.org/html/ib_processor.htm



Another shot that they show is this diagram of what happened.


Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

redpowerd

NO FARMERS -- NO FOOD
northern adirondak yankee farmer

Oregon Engineer

Crtreedude - The guy that got injured was doing many things wrong and put himself in harm's way. The slide show details a few of the things. The articles on your links by Skogforsk are excellent. Ulf Hallenborg has done a lot of work on chain shot in coordination with a Swedish test lab that has a "chain shot" machine capable of generating chain shots on demand. 

The following site shows an artical on chain shot:
http://www.feric.ca/en/ed/May-2002-English.pdf

Gary C - Keep a close watch on broken loops to see if any links are missing. Some articles suggest a chain shot occurs about one in every 50 chain breaks.

Frank_Pender - I live in West Linn and work in Milwaukie, OR.

Gary_C

Jeff  Thanks for the info. I actually dozed of waiting for that slideshow to load and when I woke up, it was still not finished.  :)

From what I see, it looks like that machine is a Timbco tracked harvester. It probably has twice as much horsepower available as my Valmet rubber tired machine. When they have that much power available to drive those tracks, they usually put on huge hydraulic pumps and can out muscle any size tree. The older John Deere tracked machines that were basically an excavator had a reputation for even bending the booms. My point is those high HP machines can easily over power and over speed the saw chains. Most of the harvester heads on those machines use 3/4 pitch chains and those cutters are huge. I can see where chain shot could easily happen and I would not want to be anywhere nearby.

I can not remember any time a chain has broken under power. I have bent a few chains and have broken a very few, but it was in trying to pull the chain (and bar) free.  I do try to straighten bent links, usually the drive links but almost always have to replace parts as they crack either in the drive link or the holes in the cutters. If they are well used, I leave them hanging by the sharpener and only fix them if I get desperate which means short of good chains.

I use a .404 harvester chain loop that costs about $15 each and the bar is $45-60 each. For comparison, the 3/4 pitch chains are $35 each and the bars are $310 each.

I must either be lucky or don't have enough power to have experienced "chain shot" yet, but there are certainly no guarantees. I also have cut right outside the side windows at times and I will make sure that rifle is not pointed at me the next time.
Never take life seriously. Nobody gets out alive anyway.

caryr

I have only experience chain shot once and it was on a many 100 HP chainsaw using ¾ chain (yes that is many hundreds). Sorry the exact HP is classified, but it is statistically the fastest saw on the planet!  I'm not sure what type of information you are after, but here are some observations and comments.

When the fragment of chain (our guess was 3-6") went out of view it was about 300' out, at least 75' up and it appeared to still be heading for apogee. I have some pictures of the fragments that stayed with the saw if you are interested.

To me the major contributor to chain shot is as you try to go faster you use more HP, but this extra HP can ripe a chain to pieces if it binds in any way. If you want to minimize the damage reduce the HP driving the chain and slow it down. I guess that's basically what Gary said above. Reducing the HP should minimize the chance of fragmenting the chain and slowing it down reduces the kinetic energy. I'm also curious how you get the chain supersonic? I understand how you get some acceleration as the unconstrained chain whips past the sprocket, but there is usually not enough room around the sprocket to get things going that fast. If there is a lot of room a shroud around the back of the sprocket should help limit the exit chain speed.

Like I said earlier. I'm not sure what you are after, but I hope this helps.

Regards,

Cary

Ianab

QuoteI'm also curious how you get the chain supersonic?

I'd guess thats it's the same as getting a stock whip to CRACK (the tip of the whip goes supersonic at that point) When the chain breaks there must be a situation where the loose end is whiplashed to extremely high speed, and the end link or 2 break off (again) and make like a bullet  :o

I've seen the web write-up about it happening with that V8 hotsaw, the loose fragment went thru a pickup tyre and punched a hole in the engine sump, anyone in the way could have been killed.

Cheers

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

crtreedude

Something that I have observed down here is that you probably wouldn't have machines that could do that - honest. There is an interesting attitude down here that many foreignors hit that really perplexes them. No one is going to engage in a dangerous job for very long or deal with bad employers - they just leave and do something else.

The reason? You can't starve or freeze to death down here. There is always stuff on the trees to eat and a whole kilo of cheese can be bought for a couple of dollars. Never gets cold and for most of the country, doesn't get hot either. No one is going to put their life on the line just to make a few more bucks.

Since it takes nearly a signed letter from God to get a loan, very few people have debt either. Also, family is very strong, so if you need something, family will help.

When I lived in the USA I was always seeing people push production to the point of danger, just to make some more money, and often not for the person working, but for the shareholders, etc. Honestly, when people are talking about sweatshops - they should look at the USA. Just my not so humble opinion. I own a tree plantation down here and I can not imagine being willing to have a machine that could kill someone like that.  No amount of profit is worth me having the guilt of someone dying on the job because of a dangerous piece of equipment.

Down here just about EVERY wage has a minimum wage - want a raise? Get better educated - no kidding. For example, if you know English, then you get paid better BY LAW, even if your job is a housekeeper. Because of this all the night classes are full of people learning English and other skills - it really is amazing.

I guess what I am wondering about is, if higher rate of speed and power causes such a dangerous event, perhaps the real answer is slow down...  If I drive a car at 100, and get a blowout, I am probably dead - but at 30, nothing much normally happens. Is it really necessary to cut the tree down that much faster?  Just wondering out loud.

Sometimes the question is wrong, not what to do about it - but should we be doing it...

Just my dos colones,

Fred


So, how did I end up here anyway?

Thank You Sponsors!