Do shorter bars cut faster?

[Analyst Man]

Analyst Man, I didn't notice if you had a particular saw in question or just saws in general. If your talking about swapping an 18" for a 16" on a Wild Thing, I don't think you will see or feel any difference. On my old Homelite 1050 with the 24" bar, I can carry it around by the handle and it is balanced, it's comfortable to use, and is so loud that it impresses the girls and scares the trees. The same saw with the 36" bar, and it is very nose heavy. Just to walk around with it you have to use both hands and the weight pulls on your back noticabley. It's still so loud that it impresses the girls and scares the trees, but it beats my poor 53 year old body to a pulp. It might cut just as fast but it feels like every cut is never ending. When I had to make a living with that saw, I actually have 2 of them, I had a long bar on one, short bar on the other. I would use the long bar only as needed and grab the shorty. I feel that every extra ounce of weight I have to control is worth 10 seconds in a cut. Thoughts of an old fat guy, Joe.

Rarefish383, no particular saw or size, just chainsaws in general. Your thoughts about the extra weight are noteworthy, and it makes sense that at the end of a day you’re going to feel every extra ounce if you do this for a living. But my point was only that I couldn’t see the where you would pick up much speed in the cuts if you went to a 2 inch shorter bar. I read somewhere that some saws perform much better with a 14 inch VS a 16 inch bar, and I couldn’t see how 2 inches could make much difference. If I’m dropping one black oak for firewood, where’s the advantage of going with a 2 inch shorter bar?

 

[SawTroll]

But what about the added drag of the sprocket tip of a bar?

Are roller tip bars faster?




.

Saw racers love the roller-tips, I guess it is for a reason!

 

[VINIFIREWOOD]

Short answer.....YES! Less surface area=less drag, resistance, friction = less power needed to maintain chain speed, which allows more down pressure to be applied= more cut speed. And less chain weight helps as well.

:agree2:

 

[teacherman]

I notice a good deal of power increase with smaller bars. Put a 20" bar on a 460 with DP muffler cover, and it is remarkable. Likewise with a 25" bar on a 660.

 

[Analyst Man]

But what about the added drag of the sprocket tip of a bar?

Are roller tip bars faster?




.

I’m assuming both bars have a roller sprocket so the drag from the sprocket would be the same on a 14 or 16 in bar.

 

[CGC4200]

16" to 18" bar

I like a bar about this long for cleanup sawing; shorter bar will cut
faster, have less cutters to sharpen; I just don't like to crouch over
a chainsaw running WOT; better cutting position for me. Another
sawyer. different fit; use what you like. I do.

 

[2dogs]

Saw racers love the roller-tips, I guess it is for a reason!

I don't have any roller tip bars anymore but I agree with Saw Troll, they are fast.

 

[spacemule]

It's not just about cutting speed, it's about moving speed and control. I can sling a short bar around a tree a lot faster limbing than I can a long bar. Also, the short bar has less leverage against the handles in case of kickback, resulting in more precise and solid operator control. For those that think 2" is negligible, ask your girlfriend if she shares that opinion. . .

 

[TommySaw]

My 346 runs ALOT better with a 16" bar than it did with the 18" on the same chain(Carlton/Stihl semi-chisel .325) in the same wood. I can't explain it but it definitely does

 

[euroford]

It's not just about cutting speed, it's about moving speed and control. I can sling a short bar around a tree a lot faster limbing than I can a long bar. Also, the short bar has less leverage against the handles in case of kickback, resulting in more precise and solid operator control. For those that think 2" is negligible, ask your girlfriend if she shares that opinion. . .

i'll take the opposite tack, and say that i can get allot more work done, more quickly and with less strain now that i'm running a 28" instead of a 20". allot less repositioning, allot more reach and doing everything from a standing position makes a huge difference in time and effort over the long haul.

cutting cookies, yeah go as short as possible. cutting trees, give me a 28".

 

[bogiemsn]

You really have to run this experiment in your mind 'cause you can't cut the same wood twice.

In my thought experiment I cut the same 12" diameter log twice; once with a 16" bar and once with a 20" bar. So the only thing that changed was the length of the bar. Everything else is exactly the same. If you can suspend disbelief a little further you could run the experiment using a chain of zero mass and frictionless contact between the chain and bar. In this scenario there would be absolutely no difference in cutting speed between the long and short bars. This is true because the same volume of wood is removed in each cut. There is no more friction using the long bar than the short bar because there is the same amount of contact between the wood and the chain/bar. Makes sense right?

Now if we take into account the mass of the chain and the friction between the chain and bar, we can agree that the longer bar uses a more massive chain and that there is more more surface area and thus more friction between the chain and bar. Thus greater percentage of the saw's energy is used to simply move the chain around the bar and less of the energy goes into actually cutting wood. So the shorter bar would be the faster.

Real world, the extra mass of the chain and the added friction of the longer chain/bar combo is probably insignificant when compared to the friction between the chain and the wood. I doubt you could even measure the difference even with a stopwatch.

All that other stuff about less bending, fewer cutters to sharpen, less weight, balance between power head and bar, personal comfort, etc. are probably all more important than the difference in the speed of cut.

 

[Meadow Beaver]

Shorter bar cuts as well as a long bar, because a bar doesn't cut anything, the chain does.

 

[troutfisher]

Shorter bars are faster. I've seen it on a stopwatch. I guess it's less rotating weight, same reason they put aluminum wheels on a racecar.

 

[J.Walker]

I’m assuming both bars have a roller sprocket so the drag from the sprocket would be the same on a 14 or 16 in bar.

Yes I see what your saying.

 

[Curlycherry1]

I work in abrasives for a company that invented abrasives. So we know abrasives and saw chains are nothing more than a specialized abrasive.

First off feet per minute of abrasive going past a given area is the #1 critical parameter for abrasive performance. Pressure is a very close second and some would argue pressure and FPM belt speed are neck and neck.

ANY cutting item that gets hot in the process of cutting will have it life and hence its performance cut short. Take a belt sander and push down real hard on the belt while sanding and see what happens. The belt burns and the abrasive is shot. Yet, lower the pressure and it will cut just fine. Now speed the belt up and it will cut more but keep speeding it up and it gets to a point where the abrasive belt cannot cool down sufficiently between revolutions and one gets burning (dulling) and again the belt is shot. You can get the same results with a circular saw. Faster rpms and it cuts better, get going too fast and the teeth dull. Pressure on a circular saw yields the same results as with belt sanders.

Big industrial sanding equipment always has big belts between the idler and drive wheels. The most common belt in existance in the world is a 3"x180" belt and there are literally millions of them sold around the world each year. The reason is that is a good length to allow sufficient cooling during each revolution to prevent the abrasive from overheating.

All those same principles apply to chain saw chain. Too much pressure will dull the teeth because they cannot cool down. Too fast of a rotation will also shorten teeth life because friction from the bar and from the cutting operation. In a perfect world all those parameters are balanced to yield optimum cut, mininum friction, optimum speed and thus longest life.

Unless you are passing a saw chain at EXACTLY the same speed over a given cut surface at EXACTLY the same pressure then all comparisons are meaningless. A 1% change in abrasive pressure can lead to a >15% difference in cut. Belt speed is often bell shaped with some optimum speed where maxium cut can be obtained, and lower cut is obtained when higher or lower belt speeds are used. So unless people use the same size bar at exactly the same pressure and exactly the same feet per minute chain speed, all these comparisions are kind of meaningless. Sorry, but you gotta compare apples to apples, chain feet per minute to feet per minute, and your pressures have got to be exact. We control our abrasive test equipment's pressure to fractions of a pound per square inch, very small fractions. We have found over the decades that not have that level of control makes any comparison testing completely and utterly useless.

Miles steel and Stainless steel are cut with abrasives using fairly high belt speeds. Titanium is cut with less than 1/3 the same belt speed (and it makes awesome white spark showers!).

 

[2dogs]

Spacemule is on my ignore list so I can't quote him but I was able to read his post thanks to Euroford. Space you are once again absolutely wrong when it comes to working a falling saw. A short bar is a recipe for disaster when teamed up with a big powerfulm saw. For instance a 16" bar on a MS660 will be one heck of a kickback hazard compared to a 36" bar.

Stick to what you kanow which is... I don't know what.

 

[Gypo Logger]

Although shorter bars have less rolling resistance than longer ones, it's ultimatly the chain against the wood that will slow it down more, as will not so sharp chain and the pressure that is being applied. 16" bars on big powerheads are best for racing and GTG's or fast blocking of firewood. I think more injuries are caused by shorter bars, but this may be just a learning curve thing.
John

 

[chad3]

Drag must be minimal. I'm one to believe that the RPMs being the same, the same amount of teeth are going through the wood at the same time. That being said, a larger saw will be a worse choice in wood than the saw that just has the end peeking out. If you figure gas and oil for the larger saw, I'll cut with the smallest saw that can get through the wood. Better gas and lighter weight.
MPO.
Chad

 

[Gypo Logger]

Shorter bar cuts as well as a long bar, because a bar doesn't cut anything, the chain does.

Bars do so cut, that's why they call them blades! Lol
John

 

[isaaccarlson]

My 28" takes a split-second longer to spin up than my 20"

and the top end is slower. I like having that extra 8" so I can stand up rather than have to bend over. I use the 20" to cut up smaller stuff when I am feeling up to it, or when I am not cutting any big trees. That 28" is nice when limbing though....