Running saws at part throttle in the cut

[Trx250r180]

I was not going to post this discussion ,but what the heck ,i have been told running saws at part throttle is bad for them ,i have been doing it for years no problems yet ,why rev the piss out of it if not needed ? ,seems like limbing do not need wide open either ,just a blip here and there and they pop off ,my string trimmer i run the same way ,wide open throws crap all over so i run it at a steady 1/2 or 2/3 throttle to be smoother ,ok and now my sawmill ,the 660 runs fine in a pass at 2/3 throttle ,i get a better finish on the cut ,wide open it bounces more and gives a crappy finish ,so why is it wrong to just use enough of the engine to do the job ? Discuss.............

 

[XSKIER]

...because AS members with many posts say so.

 

[sunfish]

Don't know, but I never run part throttle in the cut, smaller stuff I just lean on it harder. Limbing gets full throttle blips

 

[blsnelling]

I always run the saw at WOT when in a sizeable cut. I just vary the load accordingly. My trimmer it's rarely ever run at WOT. Well it hurt a saw? I have no idea, only what I've read.

 

[Franny K]

I am with Trx250... If I like the sound or the feel or for any other reason I will run the two cycle device as I see fit. I haven't had any problems.
Before reading on this forum I was of the idea that high revs and no load was the worst thing for a two cycle. Here they tune at max revs and no load. Kind of a good reason to buy new. As I understand the logic it is to get the mixture right where in the rev/load most likely to be used one tunes to four stroking at full throttle and a target rpm. The logic seems the design of the carb will have a leaner mixture at part throttle. I have yet to read a thread on here where an exhaust gas analyzer is used.

 

[Trx250r180]

I will add if there is enough load by ear it does get the throttle wide open ,that is normally bucking or falling bigger stuff when it is needed in my case

 

[Brush Ape]

I was not going to post this discussion ,but what the heck ,i have been told running saws at part throttle is bad for them ,i have been doing it for years no problems yet ,why rev the piss out of it if not needed ? ,seems like limbing do not need wide open either ,just a blip here and there and they pop off ,my string trimmer i run the same way ,wide open throws crap all over so i run it at a steady 1/2 or 2/3 throttle to be smoother ,ok and now my sawmill ,the 660 runs fine in a pass at 2/3 throttle ,i get a better finish on the cut ,wide open it bounces more and gives a crappy finish ,so why is it wrong to just use enough of the engine to do the job ? Discuss.............

There's no way you can run these powerful saws at full throttle milling most of the time. The inertia causes enough ring flutter to melt the skirt. I only work on new stuff unless it is my own. But I know the same thing happens to trimmers that are run wide open. For one it has the same effect on your rings and bearings as dry firing a bow. Two, the fins can't sink the heat out of the internals cause you're losing both contact with the cylinder wall and compression at high revs. Three, the blow by of hot gasses which alone can melt aluminum, elevates the operating temp beyond catastrophic limits.

With a lawn mower, it has to operate fully wound to air-cool the heat.

Sometimes with handheld ope you gotta find the balance which prevents the factors that make excessive heat. Chainsaw milling is one of those situations

 

[zogger]

AFAIK, chainsaws have high and low circuits, but no mid range.

I don't know if that is a factor or not.

I keep the RPMs up in mine when cutting, just switch saws to fit size of wood I am cutting. I am not one of those guys who runs a 90 with a longer bar to trim one inch branches, i can bend over OK..hahaha!

Typically on a full size mature eastern deciduous tree (say around three foot diameter, 70-80 feet or so) I very well might use three or four different size saws. Big saw (70-90)for felling and bucking the trunk, then smaller ones (30ish)for light limbing and small keeper branch cutting, then a mid size saw(40-60) for mid size bucking on the opposite trunk end and any big branches. Pretty much max throttle in the cut. the 30s when I am taking off tons of tiny branches I just let it rip and cut, up/down/up/down/across whatever. I milk trees out so I take a lot of smalls and that works the best for me.

 

[farmrboy]

You won't damage a 2 cycle by running it at part throttle unless you constantly overload it, which will shorten the life of any engine. If it was meant to be run only at wot, the mfr should use a switch or choke style lever to take the engine immediately from low to high idle.

 

[Brush Ape]

Big saw for felling and bucking the trunk, then smaller ones for light limbing and small keeper branch cutting, then a mid size saw for mid size bucking on the opposite trunk and and any big branches.

Uh Huh. That's what I been trying to tell her. Guess what she done said then.

"That's OK. I need a surger for sewing pajamas and tops, a 240 for clothes and curtains, a 440 Aurora for quilting and blankets, course I'll need the embroidery attattchment, the software three hundred different size needles, two quilt frames and a room added on for 15,000 spools of thread and six tons of fabric."

Whatever you say zogger.

 

[blsnelling]

There's no way you can run these powerful saws at full throttle milling most of the time.

I don't buy that at all.

 

[Brush Ape]

I don't buy that at all.

That's a eight foot long log. Besides, your saws are exceptional.

 

[blsnelling]

That's a eight foot long log. Besides, your saws are exceptional.

Width is what affects load, not length. Also, the larger and more powerful the saw, the more load would be required. I have no trouble putting sufficient load on this ported 084, even in that smallish log. I for one don't understand the need to run at partial throttle.

 

[Trx250r180]

My 660 revs a little higher than an 880 does ,seems like milling the bottom end grunt pulls the chain smoother than the high rpm/s in the softwoods i cut ,i see how an 880 would be a good milling saw

 

[blsnelling]

This 084 turns more RPMs than many 660s. When cant racing I tune it to 14K+.

 

[KenJax Tree]

It depends on what you're doing on some cuts i let up on the throttle before i get all the way through if i need to control a piece or limb i will feather the throttle after about 3/4 of the way through the piece until it starts to move. Same thing on crane removals feather the throttle at the end so the piece comes off slow. Other than that is WFO balls to the wall

 

[Brush Ape]

There's no way you can run these powerful saws at full throttle milling most of the time.

I don't buy that at all.

I for one don't understand the need to run at partial throttle.

You let off the trigger completely four times in the first 1:30 of the vid.

 

[Trx250r180]

I don't buy that at all.

it looks like you have chisel chain by the rough finish in the wood that will load the saw good in the cut ,when i mill i use ripping chain ,it is a lot slower cutting then my chisel ,but on wood i want a nicer finish on it works better for that ,a lot of people will think i mill with a dull chain it is so slow ,but 10 degrees high rakers ,it almost spits sawdust like a skillsaw would produce ,the slower cutting ripping chain revs too high in the cut for me so i back off the gas some ,here is the finish on a piece of cedar ,this was milled with the 660

 

[blsnelling]

You let off the trigger completely four times in the first 1:30 of the vid.

Lol. I did didn't I That was the first and only time I have ever milled and didn't want to over heat my pride and joy, lol. I'm just not used to extended cut times. I was admittedly being overly cautious.

 

[blsnelling]

it looks like you have chisel chain by the rough finish in the wood that will load the saw good in the cut ,when i mill i use ripping chain ,it is a lot slower cutting then my chisel ,but on wood i want a nicer finish on it works better for that ,a lot of people will think i mill with a dull chain it is so slow ,but 10 degrees high rakers ,it almost spits sawdust like a skillsaw would produce ,the slower cutting ripping chain revs too high in the cut for me so i back off the gas some ,here is the finish on a piece of cedar ,this was milled with the 660
View attachment 354338 View attachment 354339 View attachment 354340

IIRC, that was a Granberg chain made for milling. The poor cut finish was because of a poor inexperienced operator, lol!