bike saw in the works soon

[romeo]

That's nuts! That frame doesn't look like it's built for that! Are those snow tires?!?!

I have no idea, he is a nice guy but he is a few cards short of a full deck. I think that the frame started life as a bed frame. This is NOT the worst he as done. He built a motorcycle out of an Allison aircraft engine and that one almost killed him, I don't think he even got 50 yards out of that one.

 

[Oregon Engineer]

For all the adrenaline junkies out there who are running saw chain (designed for 2 to 7 hp saws), with engines that were previously propelling people at high speeds, a little note of caution. Think about all that horse power concentrated and delivered to a drive link and tiestrap pair, its called "chain shot". It will put a hole in 1/2 inch thick bullet resistant glass and still shred your innards.



Do a search under "chain shot" in the forums and you will see several good threads on how to reduce your chance of injury. Or go to
http://www.oregonchain.com/tech/chain_shot.htm

http://www.cmeig.com.au/engineering/CMEIGpp04.pdf

For a slide show go to:
http://www.healthandsafetycentre.org/media/fss/harvester/slideshow.htm

Install a "chain shot" guard on your saw (shown in the website) and point the bar only at things you want big holes in.

 

[troutfisher]

Here's a cool thread, lots of bikesaw stuff.



http://www.arboristsite.com/showthread.php?t=38552&highlight=bikesaw+pics

 

[romeo]

Install a "chain shot" guard on your saw (shown in the website) and point the bar only at things you want big holes in.

I completely agree with you. I make mine out of plate steel. I have seen some really pretty aluminum ones but aluminum can shatter where the plate will give. I also try to position the frame where I will not be standing in line with the bar. Here is the pictue of the top guard I built for a YZ (it is meant mainly to keep shot debree from the uper torso and right arm, the bottom also gets a guard, I use 1/2" hardened steel round stock to catch the bulk of chain, there is no debree shield undernieth, no corners to catch chain either. The worst place you will break a chain is durring an up cut on the top of the bar, you must try and forsee the whip efect of the chain if it breaks this way. Other than that, common sense, no one in front and no one behind the operator.

 

[romeo]

Here is a view of another I built on a CR. The top guard is to catch the bits while the leg on the stand extends to catch the "whip". Yes you better wear chaps when running these. This saw belongs to Mike Koers, Last year he experienced a chain shot with it. Debree went through 4 pieces of 1/2 plywood and he probably needed a fresh pair of chaps after that, it still has some nasty skars in the chassis.

 

[troutfisher]

The worst place you will break a chain is durring an up cut on the top of the bar, you must try and forsee the whip efect of the chain if it breaks this way.

Thats where those competition chaps come into play, eh?

 

[romeo]

Here is the scariest part of the cut, when you are pulling through the top of the up cut. This is the area where you have the least protection. I try to make sure that I am not inline with the bar during this cut, it was tough at this competition due to the height of the log stand.

 

[romeo]

Thats where those competition chaps come into play, eh?

actually, I hope they never come into play. Also, with a new bike saw (or a new chain), I will probably make at least 20 down cuts before I give an up cut a try. Bike saws will radically stretch the chain in the first cuts. The first 5 cuts are one at a time then check the tension.

 

[troutfisher]

That saw is set up LEFT handed!! The chain seems to be staying in the bar groove, do you let off the throttle between cuts?

 

[Chopwood]

Here is a view of another I built on a CR. The top guard is to catch the bits while the leg on the stand extends to catch the "whip". Yes you better wear chaps when running these. This saw belongs to Mike Koers, Last year he experienced a chain shot with it. Debree went through 4 pieces of 1/2 plywood and he probably needed a fresh pair of chaps after that, it still has some nasty skars in the chassis.

I saw this happen. The chain went through 4 pieces of plywood and was finally stopped by hitting the ground. It broke into about six pieces. Would have gone through someone if they were in line with it.

 

[romeo]

That saw is set up LEFT handed!! The chain seems to be staying in the bar groove, do you let off the throttle between cuts?

Yup, its a lefty, and the only way I could get a lefty is to build it. I used to let off the throttle but I have been getting braver and I just hold it wide open now. That saw used to be a 280cc but its gaining 12cc's and a custom built head right now. The great part about a lefty saw is no one wants to run it.

 

[Oregon Engineer]

Romeo -
Thanks for posting your chain shot guard designs.

I used the 16 tooth drive sprocket as a scale to measure the length and location of the chain shot guard on your YZ saw.

The top guard will not stop a chain shot. Testing on harvesters showed the common break point that released a chain shot was 12 inches back and 1 1/2" below the drive sprocket center line. Your guard is only 8" from the center line but most importanly it will not interfer with the chain as it comes straight back from the bottom of the drive sprocket. The guards must interfer with the chain as it comes straight back from the drive spocket. The closer to the drive sprocket the interference the better.

I'm hoping your bottom guard blocks the path of the chain as it comes straight back from the bottom of the drive sprocket. The picture is from a chain shot test machine in Sweden and shows the path of the chain after the first break, the "crack the whip" creates the second break which is a chain shot.

The chain shot prevention guards on the harvesters are kept as close to the drive sprocket as possible so the chain crashes into the guard. If the chain is allowed to "crack the whip" then a chain part will be released from the chain traveling as much as 700 to 800 miles/hour.

The following picture is a good example of a guard that prevented chain shot during testing in the chain shot machine.

 

[husky394]

I've posted this before, but it bears repeating.

I saw the chain on a bikesaw come apart during a demo at the Cherry Springs, PA show many years ago. I don't know if it was a chain shot or not, but it sure looks like what was described. There were no guards in place and chain pieces flew behind the saw into the crowd and injured at least one person serously. Blood was everywhere, the ambulance was brought onto the field and the person was taken away. I heard years later that they survived.

Never ever run without chaps, and always protect the crowd and other racers.

 

[romeo]

I've posted this before, but it bears repeating.

I saw the chain on a bikesaw come apart during a demo at the Cherry Springs, PA show many years ago. I don't know if it was a chain shot or not, but it sure looks like what was described. There were no guards in place and chain pieces flew behind the saw into the crowd and injured at least one person serously. Blood was everywhere, the ambulance was brought onto the field and the person was taken away. I heard years later that they survived.

Never ever run without chaps, and always protect the crowd and other racers.

Ouch. Injuring the crowd doesn't help the sport much at all. We run guards front and rear here at our show. And keep the access cut off from the shot zone. This year they will be expanded metal and lexan. If we injure crowd here we might as well hang it up.

 

[troutfisher]

did some more work............

 

[Sprig]

did some more work............

Very nice work so far trout, maybe a nice scrolled-out fishy-type head in the remaining plate, just fer fashion
Awesome thread gents, nice ta see the inventive minds at work! Romeo, yer buddy with the cart is lucky ta be alive, iyiyiyiyiyiyi & yi, crazy man with a pre-bent frame lolol! Your saw is sweet btw, for a lefty (yep, I'd run it given a chance!)

 

[computeruser]

Looks like a fun project. Hopefully it will be done and running when you host a fall GTG that I can actually make it down to...

 

[thomas72]

I believe the 1984 model yz 125 had the chain drive on the other side. I had that model bike and what a lemon.