Rotax Robert
Addicted to ArboristSite
Oregon Engineer asked me if I had one on the Predator, I am sure it is a harvester attachment but what is it? and what does it look like?
Rotax Robert
Rotax Robert
Chain Shot Guard
- Thread starter Rotax Robert
- Start date
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The Oregon Engineer has 2 threads in the Forestry and Logging Forum on chain shot. Explanation , pics of chain shot damage and chain shot guards.
http://www.arboristsite.com/search.php?searchid=282503
http://www.arboristsite.com/search.php?searchid=282503
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Oregon Engineer
ArboristSite Operative
Rotax Robert, did you find enough information under the other threads to help you figure out how to place a guard on your saw??? If not, I can post other pictures or schamatics.
I have a short computer simulation showing the dynamics of the loop as it breaks for the first time and one end gets whipped.
I also have a high speed video of an actual chain shot showing parts coming off the end of the chain. The test lab creating the chain shots advised me that the vast majority of parts came off the chain at the same location with very similar angles of trajectory. The point of departure was 30 cm back from the center of the drive sprocket and 5 cm down.
I have a short computer simulation showing the dynamics of the loop as it breaks for the first time and one end gets whipped.
I also have a high speed video of an actual chain shot showing parts coming off the end of the chain. The test lab creating the chain shots advised me that the vast majority of parts came off the chain at the same location with very similar angles of trajectory. The point of departure was 30 cm back from the center of the drive sprocket and 5 cm down.
Oregon_Native
ArboristSite Operative
that video sounds intresting to say the least.
i am building a hot saw and would be intrested in that information to.
i am building a hot saw and would be intrested in that information to.
Rotax Robert
Addicted to ArboristSite
Oregon Engineer, I got your info, it would be possible to build one but we always have a blast fence at shows and no one is allowed in front or back of the saw. I have experienced chain shot once up in canada but another time it seemed the chain broke after the drive sprocket and the chain just slapped the far side of the log. The chain shot guard would probably have to be fairly beefy as my chain is turning 18,000 fpm or 200+ mph. I'm assuming we are just barely exceeding the recomended chain speed. I was able however to get some good pics of what they look like and how they work and will put it on my things to do list. Thanks
Rotax Robert
Rotax Robert
Rotax Robert
Addicted to ArboristSite
Make that 253 posts to go, and all on topic.
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Rotax Robert
Addicted to ArboristSite
Gypo quit using my password
Oregon Engineer
ArboristSite Operative
Rotax Robert said:
Barely exceeding the recomended chain speed????? HA! You are running at 2.57 times faster than our maximum reccomended speed. At our normal reccomended speeds the chain shot will hit 800+ mph and put holes in 1/4" thick steel plates. I have to tell you that chain shots coming of at an inital chain speed of 200 mph could be hitting Mach II+, I don't know how thick the steel would have to be to stop that chain shot. Treat both ends of the bar like a rifle, don't place any thing in line with the bar that you don't want a very big hole in.
The nice thing about the chain shot guards is they stop the chain before the end whips, only on the drive sprocket end. It does not take that much steel to stop the chain before it whips. But once the end undergoes the dynamic acceleration assocaited with the whip the chain shot parts are typically 10+ times faster.
HHHHHOOOOOOOWWWWW thick is that BLAST fence??????? Are you, or any part of you, in line with the bar while the chain is moving?????
ross_scott
ArboristSite Guru
rotax are you talking about that V8 powered beast that everyone has been posting links about if so I just managed to see that clip tonight on a relatives broadband and happened to have a hot rodder there aswell it is one awesome saw if it is the one being talked about in this thread
Oregon Engineer
ArboristSite Operative
Movie on chain dynamics and chain shot
The two attached movies are related to chain dynamics and chain shot.
The ocs_11H_3 shows a computer simulation of the chain dynamics just after the loop breaks for the first time and the resulting whip to the end. Note closely the sudden reverse in chain direction as the chain undergoes the whip.
The smp_08 shows just the point where the chain parts depart from the rest of the chain during a chain shot. The movie is a high speed movie taken of an actual chain shot event. Please keep in mind that is takes about 2700 lbs to pull a link off a new .404 chain and around 7000 lbs for a 3/4 pitch chain, the whip action provides forces that high.
The two attached movies are related to chain dynamics and chain shot.
The ocs_11H_3 shows a computer simulation of the chain dynamics just after the loop breaks for the first time and the resulting whip to the end. Note closely the sudden reverse in chain direction as the chain undergoes the whip.
The smp_08 shows just the point where the chain parts depart from the rest of the chain during a chain shot. The movie is a high speed movie taken of an actual chain shot event. Please keep in mind that is takes about 2700 lbs to pull a link off a new .404 chain and around 7000 lbs for a 3/4 pitch chain, the whip action provides forces that high.
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Oregon_Native
ArboristSite Operative
that is very informative and shows were the chain goes in relation to the cut i was a little confused befor but all is right now.
Rotax Robert
Addicted to ArboristSite
Ross, that would be the saw we are talking about, I hope to have some more video out real soon (hint russ) as for our backstops we usually have wet straw bails, 3/8 steel plates, or a big dirt bank. Nobody gets to stand in front or behind the saw although with my setup the chain most likely can only go forward. Check out the predator hotsaw thread to see the complete buildup from short block to finish.
http://www.arboristsite.com/showthread.php?t=1926&highlight=predator+hotsaw
Rotax
http://www.arboristsite.com/showthread.php?t=1926&highlight=predator+hotsaw
Rotax
Gypo Logger
Timber Baron
Robert, I haven't used your password since the time before last time that I was banned when I got caught red handed using Ken's, your's and Dennis Harvey's password and started a fight while I stood on the bar room stool.Rotax Robert said:
ross_scott
ArboristSite Guru
Rotax Robert said:
awesome robert I will definitely have a look at the thread relating to the building of that saw she is definitely one mean machine and I would hate to be near it if the chain broke on it shame we dont get to see saws like that being demo'd here in new zealand infact i am not even sure if there is hotsaw racing in my country. ooops sorry about the off topicness
Lawn Masters
Addicted to ArboristSite
I agree about the predator, one of the coolest saws ever built.
Oregon Engineer
ArboristSite Operative
I want to clarify one point regarding chain shot as it is being discussed on a CHAINSAW forum. To my knowledge chain shot was first made apparent by mechanical timber harvesters. The mechanical timber harvesters have the available power to move chain at speeds sufficiently high to cause a chain shot when the chain breaks. In my experience the factory marketed chain saws do not have sufficient power.
This thread is dealing with a HOT SAW having an available power output that dwarfs mechanical timber harvester saws. The chain is being operated at speeds and feed loads well out of the design envelope for the chain. I'm terrified to see the chain being operated so far from what it was designed to withstand. I can't stop it, but maybe I can make the operators aware of just how far they have exceeded the limits. This may help get them to add more safety equipment and operating procedures than they otherwise would have.
Chain shot is a valid concern for HOT SAW operators and strong measures should be taken to protect the operators and bystanders.
This thread is dealing with a HOT SAW having an available power output that dwarfs mechanical timber harvester saws. The chain is being operated at speeds and feed loads well out of the design envelope for the chain. I'm terrified to see the chain being operated so far from what it was designed to withstand. I can't stop it, but maybe I can make the operators aware of just how far they have exceeded the limits. This may help get them to add more safety equipment and operating procedures than they otherwise would have.
Chain shot is a valid concern for HOT SAW operators and strong measures should be taken to protect the operators and bystanders.
Rotax Robert
Addicted to ArboristSite
Ok Oregon Engineer, I'll stop grinding the rivets off and dog-boneing the tie straps. Just kidding...All of the unlimited racers take great care as to the direction were aimed as well crowd placement. In truth the two safest people are the two operators. So I call on you to make a stronger chain (we sure could use it). Sure hope the 3/4 dont go by the wayside like the 1/2 pitch. Sure would be ugly trying to run .404
Thanks for your concern and another taught here on arboristsite.
Rotax Robert
Thanks for your concern and another taught here on arboristsite.
Rotax Robert
ross_scott
ArboristSite Guru
I can agree with Robert a stronger chain needs to be specially designed for the unlimited racers to reduce the risk of a chain shot and I can understand having to take all of these kinds of precautions to protect the audience aswell as the actual operators of the unlimited class machines.
Oregon Engineer
ArboristSite Operative
ross_scott said:
The reality is: IF a stronger chain is made, YOU will use a bigger saw!!!
The better chain leads to a bigger saw issue or a bigger saw leads to a better chain has been going on since chain saws and chains were first invented. Likely that senario will continue!
