Testing Chain Cutting Speed

[Nitroman]

Read on another forum that appears to be dedicated to chainsaw performance about a fellow testing his cutting times when using different fuels/chains. He did it all freehand, or simply timing his cuts. This did not seem very scientific at all as there would be so many variables injected into the tests. Scientific = best.

I believe the best way to test a chain would be to build a fixture that would only allow for vertical movement of the saw. The saw would be fixed to the fixture, and using a recording tach, the time from rpm drop to rpm increase would be the time-in-cut. Since human hands wouldn't be involved, this would really show which chain, or which pitch chain/sharpening method would work the best. All that would be required is the log diameter closely measured so each cut would be the same as the last, and the saw would have to be allowed to cool for a given period of time. But I haven't heard of anyone using something like this. Why?

And...

Why doesn't anyone dyno their saws really wring out what fuel and mixture would give them the best results?

 

[Crofter]

It would be possible but you would need some means of incorporating feedback from engine rpm, chain pull, down pressure etc or you would not get good cut times as the load is not constant through a round piece of wood. Such a device might be a good way of comparing a number of chains to predict speed and eliminate some of the human element but you still have all kinds of variables such as wood hardness and different motor characteristics so it would only apply to compare the chains of that test batch to each other. I have heard some discussion of building just such a machine as part of a University research project but the proposal is to have control and measurements over a large number of variables and incorporate an engine dynomometer. I wonder what the chain manufacturers use to evaluate their research?

 

[Nitroman]

It would be possible but you would need some means of incorporating feedback from engine rpm, chain pull, down pressure etc or you would not get good cut times as the load is not constant through a round piece of wood. Such a device might be a good way of comparing a number of chains to predict speed and eliminate some of the human element but you still have all kinds of variables such as wood hardness and different motor characteristics so it would only apply to compare the chains of that test batch to each other. I have heard some discussion of building just such a machine as part of a University research project but the proposal is to have control and measurements over a large number of variables and incorporate an engine dynomometer. I wonder what the chain manufacturers use to evaluate their research?

"incorporating feedback from engine rpm, chain pull, down pressure"

The saw being fixed is itself the down pressure, and the recording tach would allow for measurement of time. Saw characteristics doesn't enter in as you are checking chains fuels for one saw, the one you are testing. You aren't comparing saws.

This fixture is so simple, and so easy to remove the human variables I don't why it isn't used. Attempting to check how chains work or whether a fuel gives more power by using a stopwatch to time some cuts just isn't going to be definitive.

It would allow for determining if a chain is faster than another in a given wood. If you know you'll race using green oak for example, take some chains and see which pitch, grind, or design runs the quickest. For a different wood, set up again for that wood.

Dynometers are available for under $5k, and for a little more, many parameters can be tested. A saw could be thoroughly tuned for a specific fuel without complete guesswork.

 

[drmiller100]

i am about the most neophyte chain sharpener in the whole entire world, but even i have figured out how to sharpen a chain to bog down any given saw in any given piece of wood.

so, i try one chain that requires a little down pressure to pull the engine down perfectly.
i try another chain which feeds a little too much in a given piece of wood, so you have to float it a little.

which one is faster????

well, on your jig, the second chain will bog out and never finish the cut, or the first will lose and nothing learned.

as far as jetting, the fastest jetting I don't think is "safe" for how i run my saws. A little teeny richer is a little teeny slower, and is a WHOLE lot cheaper.

spend some time with someone better then you, and you will learn a lot. a half day with Adam Clarke and I'm still struggling to process it all.

 

[Crofter]

Snip> Dynometers are available for under $5, and for a little more, many parameters can be tested. A saw could be thoroughly tuned for a specific fuel without complete guesswork.

I thought they were a little more complicated; If you go and take all the guesswork out of chainsaws the postcount on AS will go for a crap!

 

[drmiller100]

a guy could build a dyno REALLY easy.

a positive displacement hydraulic pump, put a gate valve on the output, measure pressure.

calculate displacement based upon RPM, and you could calculate horsepower.

 

[Nitroman]

i am about the most neophyte chain sharpener in the whole entire world, but even i have figured out how to sharpen a chain to bog down any given saw in any given piece of wood.

so, i try one chain that requires a little down pressure to pull the engine down perfectly.
i try another chain which feeds a little too much in a given piece of wood, so you have to float it a little.

which one is faster????

well, on your jig, the second chain will bog out and never finish the cut, or the first will lose and nothing learned.

as far as jetting, the fastest jetting I don't think is "safe" for how i run my saws. A little teeny richer is a little teeny slower, and is a WHOLE lot cheaper.

spend some time with someone better then you, and you will learn a lot. a half day with Adam Clarke and I'm still struggling to process it all.

Well, the idea here assume one has a saw capable of pulling the chain. I don't think professional saw racers are going to be clamping a homeowner saw into this to see if they work.

Let's assume you make a super aggressive chain. Use only the mass of the saw to feed it into the wood. If your saw is strong enough, attach additional mass to the rig. Simple.

This fixture could be made in a garage in a few hours.

The dynamometers I am talking about are the smaller units made for using on snowmachines and other smaller engines. This could easily be modified by the manufacturer to use with a chainsaw motor. The dyno's can be purchased completely instrumented so there is no guessing about carb adjustments, as fuel flow, air flow, exhaust gas temp (and more) are displayed and recorded on your computer.

Gosh, it seems whenever someone comes up with a good idea, people crawl out of the woodwork and try to shoot it down.

 

[drmiller100]

\

Gosh, it seems whenever someone comes up with a good idea, people crawl out of the woodwork and try to shoot it down.

that's cuz we are out to bum your high dude.

i watched a pro level chainsaw guy get another .5 to 1 second out of MY saw on a 7 second log.

i have hundreds of hours on my saw.

i made my best cut 4 times. i asked him to try. he walked to the log with my saw, made 3 cuts, all were .5 to 1 second faster then i did.

all from feeding the saw correctly into the wood.

but hey, make your jig, spend some time, and win races.

 

[romeo]

Seems like a waste of time to test any other way than video tape and stop watch. Your not racing a jig, a hydraulic pump, or a robot, or a dyno. You are racing a human, the best and most scientific way to do it is to build it to the operator, and a clock is what you are racing against. Some operators like a peaky chain that runs through faster when you ease through, some (me) like a chain you can shove on.

A peaky hungry chain will cut a faster cookie for me, but when I can push hard in the center of the cut I can use the momentum to speed up my changeovers. Some operators are the other way around and like to run it through with light pressure. There is no right or wrong way to set the chain up, just what works best for the operator.

The two biggest invariables in saw racing are wood and operator.

 

[Nitroman]

that's cuz we are out to bum your high dude.
i watched a pro level chainsaw guy get another .5 to 1 second out of MY saw on a 7 second log.
i have hundreds of hours on my saw.
i made my best cut 4 times. i asked him to try. he walked to the log with my saw, made 3 cuts, all were .5 to 1 second faster then i did.
all from feeding the saw correctly into the wood.
but hey, make your jig, spend some time, and win races.

Seems like a waste of time to test any other way than video tape and stop watch. Your not racing a jig, a hydraulic pump, or a robot, or a dyno. You are racing a human, the best and most scientific way to do it is to build it to the operator, and a clock is what you are racing against.

Yeah, I apologize for wasting bandwidth. If we were meant to fly, we'd all been born with wings. Sorry.

 

[romeo]

Yeah, I apologize for wasting bandwidth. If we were meant to fly, we'd all been born with wings. Sorry.

Not a waste of bandwidth at all, or worth apologizing for, You are supposed to tell us to "stick it" then prove us wrong I like being proved wrong since I am most of the time.

 

[timberwolf]

Problem is chain and saw can not be separated and tested in issolation and give much indication of what they will do together.

Example (real world) take 2 saws I have and 2 chains.
Saw A 359 running 8 pin gear
Saw B 066 running 10 pin gear

If I put chain A on on saw A it is faster than chain B, yet If I put chain B on saw A it is slower than chain B.

Maybe if you wanted to set up a test jig to look at chain building alone it would be better to drive it off an electric motor. Beter in terms or constant RPM, constant torque, not affected by weather, fuel, tuening, easy to measure Voltage and Amps to analyse power draw and loading.

Isolating some variables can certainly help in the R&D of one aspect. But it was one of the racers, that said "No race is won on a dyno." I think that statement stands, what counts is the cut time in the wood on race day. Even if the absolute best chain was made for some test jig thing, it might not work best on any given saw.

 

[drmiller100]

the electric motor is a great idea.

with the motor, you could measure actual power requirements to cut a given log.

might also teach us quite a bit about chain losses due to speed, wood filling up the chain, and raker height.

 

[timberwolf]

Wonder if an electric motor would have value for a fire would processor like yours?

Gas is getting pricey and saws not cheep either.

2 or 3 real hp of electric is likely going to do the same work of a mid to larger sized saw. No fumes, less noise, lower cost. On and off at the push of a button...

Just set the oiler up gravity feed, run maybe 4:1 or 5:1 off the electric motor to get some decent chain speed.

 

[24d]

Wonder if an electric motor would have value for a fire would processor like yours?

Gas is getting pricey and saws not cheep either.

2 or 3 real hp of electric is likely going to do the same work of a mid to larger sized saw. No fumes, less noise, lower cost. On and off at the push of a button...

Just set the oiler up gravity feed, run maybe 4:1 or 5:1 off the electric motor to get some decent chain speed.

and you could test chains while you cut!

 

[drmiller100]

hmmmmmm..........

 

[joesawer]

When I was involved in auto racing, one of the biggest problems I had with our engine builder was dyno results. He wanted great dyno numbers and I wanted the engine to act a certain way. I wanted to have decent top end numbers and a fairly flat curve, but needed to dial torque out of the mid range. That went against every thing he believed in and we went round and round about it.
When we got the engine I wanted we won three races in a row. What looks good on a dyno wont always win. But the consitant measurement of power is a huge help in developing new and better technology.
I personaly feel that I could learn a lot from a machine that measured the resistance a cutter pulled in a consistant repeatable way.

 

[Ghillie]

a guy could build a dyno REALLY easy.

a positive displacement hydraulic pump, put a gate valve on the output, measure pressure.

calculate displacement based upon RPM, and you could calculate horsepower.

WOW, just what I need.... Another project to chase numbers with!!!

Even if you couldn't get real world numbers (ie HP) you could use it to compare modifications to see how you are doing. Hurting or helping performance.

.............I like it!

 

[super3]

Wonder if an electric motor would have value for a fire would processor like yours?

Gas is getting pricey and saws not cheep either.

2 or 3 real hp of electric is likely going to do the same work of a mid to larger sized saw. No fumes, less noise, lower cost. On and off at the push of a button...

Just set the oiler up gravity feed, run maybe 4:1 or 5:1 off the electric motor to get some decent chain speed.

Or....you have hydraulics on the splitter,how about a hydraulic motor and a harvester bar and chain