Saw speed

[Firewoodjoe]

3/4 Oregon says 7000 ft/min max
.404 says 8000 ft/min max. So why do all the new harvesters that run .404 are like a laser compared to the 3/4". I understand the kerf is much larger but are the saw motors just that much slower? Why not speed the 3/4" saw motor up. 

[Riwaka]

Cutting trees that require a 45 inch saw bar length, 3/4 chain felling head, the hydraulic saw motor torque is also a consideration.



 

[ehp]

Its not the same but I switched a firewood processor that was 3/4 Pitch to .404 and gained alot in cutting speed . Lot narrow curf. Took less power to drive the chain and way less sawdust that I had to move . I geared the head up to I bigger diameter .404 gear and ran a 16 tooth gear . If I could of gotten the 18 tooth gear I would of used that .  Weight is what kills chains .3/4 pitch weighs so much you cannot spin it fast or it breaks . .404 can handle alot of chain speed but it does wear out faster . I have seen unreal. Hain speed on bikesaws but I have also see chain explode on them as well and it is scarey on how far a piece of chain can travel and how much energy is behind it when it hits something

[barbender]

Yep that's why harvesters have warning stickers in them warning of "chain shot". They can send a link through 1" polycarbonate.

[Firewoodjoe]

But Oregon spec says it's close to 404 rate speed. Assuming the power and rpm was there it should cut good. I'm just going by looks and some 404 processors are twice as fast. Easy. Not one 3/4 seems fast. Just curious thanks.

[ehp]

I can tell you that most have no idea on how much energy is behind a piece of chain doing well over 200 mph and on some gear setups we tried we were way faster than that , have to find out at what speed the chain basically quits cutting and does not cut any faster , 24 tooth setup in .404 quit cutting any faster .  I have sen .404 break and stick in a tree that no way could we pull it back out , it was way over an inch into the wood of a tree so if it hit you in the chest you would be a goner . Bikesaws scare the hell out of me , I have build some , fixed lots and ran 1 once at a contest  that is how much I hate the dam things

[Firewoodjoe]

I'm comparing factory harvesters not race saws or getting killed. 

[ehp]

yes but its still cutting speed , 3/4 inch weighs to much to handle fast cutting speed , its a stronger chain but way to wide of a cut , very costly and bars are real costly up here . some of the heads run a 18 tooth gear running .404 , that will cut pretty fast 

[Firewoodjoe]

I understand all that. But I'm going by Oregon spec. The people that built it says it can run almost the same speed as .404. So are the .404 harvesters like a h8 running the chain faster than Oregon spec or is the 3/4 harvesters running it slower? 

[Firewoodjoe]

Ok Oregon spec for 3/4 says 7000 feet per minute max. That's 116.6 feet per second. Just looked on the skidmore head spec and it says 51 feet per second max. That's half of what the chain manufacturer saws it can run. I understand it would take a lot of power two double it. 

[chevytaHOE5674]

I believe that it comes down to having the hydraulic motor power to spin 3/4" fast enough. 3/4" is a lot of weight to spin up and maintain speed while hogging out a huge kerf. 

[barbender]

Someone refresh my memory, what is the purpose of 3/4 pitch?😁

[Ianab]

Someone refresh my memory, what is the purpose of 3/4 pitch?😁

I think it's a heavier type chain to take the higher power of things like harvester heads? At some point the torque at the sprocket would simply destroy a more puny chain. A bit like you don't run thin kerf LP chain on a 120cc saw. It would chew it up and spit it out. More steel in a chunkier chain can take the stress. 

[barbender]

Ian, that was tongue in cheek as we often debate .404 vs 3/4 pitch chain, which are both used on harvester heads.

[ehp]

but the heavier chain wants to become a circle as the chain speed increases and the heavier chain will pound the tie straps , the type of gear that drives the chain plays a lot into how the chain reacts , spur gear types will pound the tie straps and make the chain want to kink up pretty bad 

[Firewoodjoe]

I'm going to just throw this on here rather than a new post and see if anyone bites. These factory specs seems a bit off to me when deciding on what to buy. The saw is one speed factor of a head. The feed roller speed is another. Some fixed heads claim about 20 feet per second feed. And some dangle heads are 20 or so claimed speed. This is all in the manufactures spec page. But yet again those 20 feet per second dangle heads are much faster when watching. It don't make it very easy for a guy to pick. 

[barbender]

I've never got see a big fixed head work. I'd like to, just to see how they do in big hardwood limbs. All I've been around is a variety of Ponsse processors and a couple of John Deere rubber tire machines. 

[chevytaHOE5674]

With all types of equipment the specs on paper don't always match real world performance.....

[Dom]

Specs are a guideline, but it varies in the real world.
The 20 feet per second feed could be max speed. Doesn't say how long for the motor to get to that speed, or under what load.
My info is 15 years old, so it's dated. Back then the Logmax wheel motors had variable displacement so they would get to speed quicker than fixed displacement motors. Because of the variable displacement they had better torque when starting to spin. A motor that can accelerate quick is equally as important as max speed. 


In the end, trying to find studies on machine output is the real results. That's hard to find as there's so many factors. Here in New Brunswick the University of New Brunswick (UNB) does studies on forestry machines,  I'll see if I can find anything. For tractors I like the Nebraska tractor test lab. 

[Nealm66]

Madsens in centralia wa. Said Oregon has stopped making full skip chisel 404.