Tractoring a revver saw

[Bart_]

I think generally saw rpms have gone up through the years but a little voice tells me not to always run equipment at 100% because if it's going to wear out and break that's the most likely time for it to occur,

However, I met a west coast guy who said he blew up his big saw by "dogging it in too hard" which I presume also tends to rpm bogging.

I've recently been using lower revs on my MS260 which is a revver. Any thoughts on revving vs tractoring?

 

[Reach]

I think generally saw rpms have gone up through the years but a little voice tells me not to always run equipment at 100% because if it's going to wear out and break that's the most likely time for it to occur,

However, I met a west coast guy who said he blew up his big saw by "dogging it in too hard" which I presume also tends to rpm bogging.

I've recently been using lower revs on my MS260 which is a revver. Any thoughts on revving vs tractoring?

Modern saws are generally rev limited , and my opinion is that they cool themselves better at higher RPMs because they can move more air that way. Working an air cooled engine too hard at a lower speed will tend to cause it to overheat. Therefore, I run full throttle all the time at least in bigger cuts, and try to keep the RPMs up near the top limit.

 

[ATH]

I was taught a long time ago (so maybe newer saws are different), that chainsaws were designed to idle or full throttle. I pretty much never make cuts a lower rpm.

 

[Bart_]

I run a climbing saw all over the rpm range usually for reasons of cut control. Interesting point about cooling air quantity, but doesn't heat/hp generated also directly rise with rpm? Meaning the overall heat load is lower at lower rpm too? I've always heard of two strokes holing or melting a piston, or seizing at wot except for a cold seize (tight piston clearance build, applying full power too soon before cylinder has warmed up and expanded while piston already rapidly expanding - on race engines).

 

[ATH]

You don't want to run it WOT without a load (cutting in wood) for too long (more than a few seconds at a time). Again, they weren't designed for that...they are designed to cut full throttle in the wood.

Cut control comes from how quickly you move the saw into the wood...not how quickly the chain moves across it.

 

[Reach]

I run a climbing saw all over the rpm range usually for reasons of cut control. Interesting point about cooling air quantity, but doesn't heat/hp generated also directly rise with rpm? Meaning the overall heat load is lower at lower rpm too? I've always heard of two strokes holing or melting a piston, or seizing at wot except for a cold seize (tight piston clearance build, applying full power too soon before cylinder has warmed up and expanded while piston already rapidly expanding - on race engines).

Heat does rise with hp generated, but cooling air quantity also rises. I suspect those that have melted a piston are using the wrong fuel/air mixture or the wrong fuel type, allowing them to overheat the cylinder. If an engine seizes, it probably is being worked too hard, pulling the RPMs down too much for air to get in, or the engine speed isn’t being held up high long enough to cool down after a hard work cycle.

After I push a saw long and hard, I like to hold the engine speed up a bit for a short time to allow the fan to push air through and help cool the engine. Not full throttle, but a high idle. Airplanes do something similar, though most air cooled aircraft engines use constant speed propellers, allowing the engine to run at the same speed regardless of load, to keep up cooling air flow.

 

[Matias]

I have been told that the newer computer controlled units learn how you like to run, and adjust to your style to some degree. I run my saws wot except when blipping it to tickle out a few fibers at a time and not have the throttle too high while not cutting much wood, and I have never had a single issue with my main workhorse that I have had 7 years now, the 550xp mk2.

 

[Bart_]

Another point of observation - if you never take your saw right up to max cutting load you'll never bog it because it will always have more power on tap than you need. Max load is probably determined by chain type, bar length engaged in the cut and species of wood. Under that scenario, any cut you make is going to be less than 100% load abuse on the saw. Also lower throttle just drops the cut speed as expected - and lowers the mechanical stress on the saw (?) Less power, less force - maybe not, force same x velocity lower = power lower. clear as mud. doh