Full-Circle Crankshaft in Stihl Chainsaw

[Funky sawman]

Jees, what's happened to this world, folks getting bent out of shape over a forum discussion. Come on people, lighten up, life is too short to sweat this small stuff, and this is small stuff!!!!!!

 

[cus_deluxe]

Then let him pm me are call me if they are his. Not for nothing once they hit the web everyone has them and they are not private unless the the guy has a patent, trademark or something. How does he know someone has not already copied his work? Point is I have heard nothing from the guy.
I didn't say he was a bully. I said his buddy's getting on with all that I got you back shi... was bullying in open forum.
I suggest until you and your friends stop jumping to conclusions and reach out to someone privately. Especially before you start jumping on the wagon insinuating something was done. The original post from the so called maker of the crank was just fine until his so called buddies started posting. If that's you then let the man deal with his business and stay out of it. It was fine until you put your nose in. And if you are an example of this site I am through with it. You enjoy your secrets. Tell your buddy to get a patent.

man…you have no idea what youre talking about.

 

[cus_deluxe]

anybody thats met luc will tell you hes a straight shooter and about as good as it gets at what he does. if he says its his work, its his work. take your lumps and move on but dont start getting indignant, thats not gonna go very far here.

 

[Al Smith]

FWIW full circle cranks go back almost as far as two cycle engines .It's certainly not something some genus dreamed up recently .Fact if you look at a Harley twin that is a full circle crank which acts like an internal flywheel except it's not a heat/shrink fit like a chainsaw pin . On that it looked like top notch work on that picture . I might add there are no secrets on two cycle engines in spite of what some people might think .

 

[Dolkitafreak]

FWIW full circle cranks go back almost as far as two cycle engines .It's certainly not something some genus dreamed up recently .Fact if you look at a Harley twin that is a full circle crank which acts like an internal flywheel except it's not a heat/shrink fit like a chainsaw pin . On that it looked like top notch work on that picture . I might add there are no secrets on two cycle engines in spite of what some people might think .

In the fastest race saws out there there sure are a couple secrets. Yes full circles aren’t new, no there aren’t many making billet full circles for 3120’s!

 

[Al Smith]

The idea is a full circle takes up volume in the crankcase making higher crankcase pressure ,faster transfer .Heavier weight,doesn't wind up as fast .Spinning up it becomes potential energy but in action it becomes kinetic energy .It's just physics in action and certainly not used much besides racing .I might add usually on those stroked 3120's they use a trapaziod style 084 Stihl connecting rod .However I'd well imagine somebody could make a billet rod just as strong .Just about anything is possible mechanically speaking especially in this day and age of CNC machining . I don't think I'd try it on my model M Bridgeport milling machine that was brand new around 1940 .BTW the mill has a brass tag,Mall Tool Company Chicago .How it found it's way to Ohio I haven't a clue .

 

[LBracing]

That got a bit out of hand

Thanks for the kind words guys , Kevin , Ethan , Custer much appreciated.

 

[drf256]

Too bad this went awry. Coulda been a decent conversation.

They just act like case stuffers to reduce case volume and you get better primary compression.

 

[cus_deluxe]

Too bad this went awry. Coulda been a decent conversation.

They just act like case stuffers to reduce case volume and you get better primary compression.

still can be. my knowledge of this is pretty basic, but there must be somethin to it. husky has only been doing more saws with stuffers it seems like. isnt one of the only differences in the 545 vs 550 the absence of stuffers in the 545?

 

[Dolkitafreak]

still can be. my knowledge of this is pretty basic, but there must be somethin to it. husky has only been doing more saws with stuffers it seems like. isnt one of the only differences in the 545 vs 550 the absence of stuffers in the 545?

Yep, the early 545’s didn’t have rev boost but in mk2 the only significant difference is stuffers. I wanna say it makes a .2-.3hp gap?

 

[Woodpecker]

I don't know any of you folks, what you do or where you are. The pics where shared with me by the installer/purchaser.
No trying to let out anyone's secrets. If you want to PM me and explain yourselves lets do it.
Do you have a Patent? Anything to prove this is yours? I don't know who built this, but I really don't care for your approach and I don't care if you care. If someone on this site has a question, concern, advise you can PM me and lets talk about it or I can give you my phone number and we can talk on the phone. Hel.... I will give you my address. But do not do this kid crap of ganging up on someone and trying to bully them.

Nobody is ganging up in you bud. I edited your post and removed the pics at the owner of said pics request. Do you have a problem with that? You seem to be the only one here getting bent out of shape.

 

[Woodpecker]

Then let him pm me are call me if they are his. Not for nothing once they hit the web everyone has them and they are not private unless the the guy has a patent, trademark or something. How does he know someone has not already copied his work? Point is I have heard nothing from the guy.
I didn't say he was a bully. I said his buddy's getting on with all that I got you back shi... was bullying in open forum.
I suggest until you and your friends stop jumping to conclusions and reach out to someone privately. Especially before you start jumping on the wagon insinuating something was done. The original post from the so called maker of the crank was just fine until his so called buddies started posting. If that's you then let the man deal with his business and stay out of it. It was fine until you put your nose in. And if you are an example of this site I am through with it. You enjoy your secrets. Tell your buddy to get a patent.

I’m not his buddy. I happen to be a Moderator here. I can tell you with this attitude you’re not going to be welcome here long. Just relax there’s no reason to fly off the handle.

 

[wcorey]

Whenever the subject of stuffers and/or crank case volume comes up, what comes to my mind isn't so much what the effect is but rather why it does that. What it does seems reasonably well established but getting my head around the why has been elusive.

I’ll toss this out here as pure conjecture, unsure if I can put it into words comprehensible to how I picture it…

I’ve never really understood the mechanics or necessity of having any ‘extra’ crankcase volume at all, seems like there shouldn’t be any more or less movement/induction of the intake charge than what the area/volume directly under the reciprocating area of the piston creates anyway.
I can only guess that the space in the crankcase that’s in excess of piston swept volume is needed for some sort of timing/resonance/delay/storage effect?
Like that having the extra volume acts as a buffer/spring, storing energy as the downward traveling piston compresses the charge, then releasing it in a more metered fashion/curve when the upper transfers open and conversely allowing for more stored negative pressure/vacuum on the up stroke.

Picture one of those paddleboards with the ball attached by a rubber string, takes a certain rhythm to make it reciprocate smoothly, lose the rhythm and it fights itself. Make the string stronger/weaker/longer/shorter and it changes the rhythm needed...

Here the crankcase volume effects the string tension…

So... The volume of the suction/compression that the piston produces in the crankcase is a constant either way but with greater/lesser crankcase volume the pressure generated would be subsequently lower/higher, so obviously how it gets pushed out the transfers changes. I'd think one effect would be either the higher pressure burst with a shorter duration or lower overall pressure but over a longer duration, where the slower charge can take advantage of a longer time port opening due to lower rpm while the faster charge can be fully utilized with the shorter time open at higher rpm. Maybe inducing a lower but wider power band as opposed shorter peaky one, while of course realizing a small peak power gain at the higher revs. Also seems like blowdown numbers would want to change along with cc volume...

 

[huskihl]

Whenever the subject of stuffers and/or crank case volume comes up, what comes to my mind isn't so much what the effect is but rather why it does that. What it does seems reasonably well established but getting my head around the why has been elusive.

I’ll toss this out here as pure conjecture, unsure if I can put it into words comprehensible to how I picture it…

I’ve never really understood the mechanics or necessity of having any ‘extra’ crankcase volume at all, seems like there shouldn’t be any more or less movement/induction of the intake charge than what the area/volume directly under the reciprocating area of the piston creates anyway.
I can only guess that the space in the crankcase that’s in excess of piston swept volume is needed for some sort of timing/resonance/delay/storage effect?
Like that having the extra volume acts as a buffer/spring, storing energy as the downward traveling piston compresses the charge, then releasing it in a more metered fashion/curve when the upper transfers open and conversely allowing for more stored negative pressure/vacuum on the up stroke.

Picture one of those paddleboards with the ball attached by a rubber string, takes a certain rhythm to make it reciprocate smoothly, lose the rhythm and it fights itself. Make the string stronger/weaker/longer/shorter and it changes the rhythm needed...

Here the crankcase volume effects the string tension…

So... The volume of the suction/compression that the piston produces in the crankcase is a constant either way but with greater/lesser crankcase volume the pressure generated would be subsequently lower/higher, so obviously how it gets pushed out the transfers changes. I'd think one effect would be either the higher pressure burst with a shorter duration or lower overall pressure but over a longer duration, where the slower charge can take advantage of a longer time port opening due to lower rpm while the faster charge can be fully utilized with the shorter time open at higher rpm. Maybe inducing a lower but wider power band as opposed shorter peaky one, while of course realizing a small peak power gain at the higher revs. Also seems like blowdown numbers would want to change along with cc volume...

Your thinking is inline with mine. I also believe there is a case capacity to bore/stroke ratio that we should try and stay within for the task at hand. Too little case capacity could drive the rpm so high to where we’d be lowering exhaust and transfer heights to the point that one function would be fighting the others

 

[Mastermind]

Stuffers are simple technology.

Air is compressible, and stretchable. Without stuffers, more compressing and stretching which makes transfer action lazier. With stuffers, transfer action is snappier.

Simple.

 

[jacob j.]

Stuffers are simple technology.

Air is compressible, and stretchable. Without stuffers, more compressing and stretching which makes transfer action lazier. With stuffers, transfer action is snappier.

Simple.

That's a great way to describe it. There were some two-stroke motors in the 60's and 70's that had huge crankcases - mainly snowmobile engines. They were designed to produce a wide power/torque band and have good power in a lower RPM range. They were kind of lazier motors though - they didn't wind up well or even have the greatest acceleration. But they did make good, consistent power at a fairly low RPM range where the machine was designed to run.

It was the same situation with some two-stroke water pump motors used in the fire services - they would be run at a constant RPM that was fairly low (6-8,000 rpm).

 

[cus_deluxe]

That's a great way to describe it. There were some two-stroke motors in the 60's and 70's that had huge crankcases - mainly snowmobile engines. They were designed to produce a wide power/torque band and have good power in a lower RPM range. They were kind of lazier motors though - they didn't wind up well or even have the greatest acceleration. But they did make good, consistent power at a fairly low RPM range where the machine was designed to run.

It was the same situation with some two-stroke water pump motors used in the fire services - they would be run at a constant RPM that was fairly low (6-8,000 rpm).

i think of it like the difference between a 55 rancher and the closed port version, or a 346 and the 353 i think was the open port version on that chassis? doesnt wind up as high, but good usable power for the average person. stuffers are on the other end of the spectrum in my mind. higher peak performance in a narrower window. that makes me think case compression/volume is pretty important to the desired result.

 

[cus_deluxe]

maybe thats why husky has had good results w stuffers in xtorq engines. best of both worlds kind of thing.

 

[BonScott46]

Wow.

 

[Wonkydonkey]

Hoe Lee

He’s no friend of mine


Maybe be joining that sassyspoonmadam soon