Saw builds

[Deets066]

If a saw has ☓ amount of tourqe at 12000 rpm it's going to be a fast self feeding saw but another saw with the same amount of tourqe at a lower rpm will be the one that you can dog on. It has everything to do with what rpm it makes said tourqe at,set a chain up for both of them and they can be equal at different rpm's.

Ok, then what about a pipe saw with an exhaust height of 85? It will be fast as hell in a cant. But you won't put a 36 on it and dog it in

 

[paragonbuilder]

So I just watched the videos from that day again. Starts at post 1226 in the CT gtg thread.
I couldn't see the tach on the 661 with the Mike Lee chain, but with Kevin's 36" .404 it was clearly holding 1000 rpm more self feeding. The other saws were all very close.
And I was running them in all the videos.
So the torque is higher on the 661, but it didn't like cutting pulled down past 10k with that chain. It would just stop. The others would still cut down to 7500 or so, but were happiest between 8-10k.
That's what I mean by torque. And what I prefer as far as how a saw feels.



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[paragonbuilder]

Another example was the 262's at the gtg.
All tuned at 14k, but one clearly had more torque and pulled like a freight train.



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[Iron.and.bark]

Torque is the reason to own a vintage dolmar

Torque to me is maintaining same/similar chain speed going from (to pinch from another thread) 1500 to 3000 Janka timber or a 20" bar to 32" when fully buried. This is why for some it's pretty irrevelant.

 

[paragonbuilder]

Length of bottom bucking spikes make all the difference between which saw handles a load better if they're both good saws. Longer spikes put more torque against the chain causing it to pinch the bar a little bit. It's like a stronger vise so to speak.

Bottom spike isn't in the wood all that much in my experience.


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[paragonbuilder]

Torque is the reason to own a vintage dolmar

Torque to me is maintaining same/similar chain speed going from (to pinch from another thread) 1500 to 3000 Janka timber or a 20" bar 32" when fully buried. This is why for some it's pretty irrevelant.

Don't get me wrong, I like a fast saw. But when it only cuts when you hold it back or stay in small wood, to me it's only good for a cant saw.



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[jmssaws]

I know what you guys are saying and I know some saws have more tourqe than others.

 

[jmssaws]

My point is max tourqe is at a certain rpm and 2 saws with the same amount of tourqe but at different rpm's will be very different in the wood. That's why we have hp which is tourqe and rpm.

2 saws with the same amount of tourqe but one has more hp than the other it will be the strongest.

 

[exSW]

Every other internal combustion engine I've ever been around the main determining factor in torque was stroke. IH 400 series longer stroke,broader and stronger torque range. John Deere 400 series,more bore,more rpms,peakier torque curve. AMC 401,six inch stroke ,surprise everybody. Ford 5.0 oversquare,force the air and catch them on the big end. So saws are different?

 

[paragonbuilder]

My point is max tourqe is at a certain rpm and 2 saws with the same amount of tourqe but at different rpm's will be very different in the wood. That's why we have hp which is tourqe and rpm.

2 saws with the same amount of tourqe but one has more hp than the other it will be the strongest.

I know you know what strong feels like because I've ran 3 saws you've built, and they all have gobs of torque and are fast as well!


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[Iron.and.bark]

My point is max tourqe is at a certain rpm and 2 saws with the same amount of tourqe but at different rpm's will be very different in the wood. That's why we have hp which is tourqe and rpm.

2 saws with the same amount of tourqe but one has more hp than the other it will be the strongest.

Don't mean to be picky..

HP = torque x rpm ÷ 5252 (had to do a quick google to rember this number).

Torque = HP x 5252 ÷ rpm

 

[Definitive Dave]

Not to be a kangaroo molesting argumentative housewife but isn't rpm king of the castle ?
If I dog in a fast saw and the Rpms drop all I am doing is cutting slower right?
The wood doesn't get softer just because it. Respects how much torque my saw has
I have only seen one saw that ran stronger when dogged in and that was the wankle in NY.

 

[exSW]

Torque

RPM

 

[jmssaws]

To much rpm is king

 

[Iron.and.bark]

Using what I could find for some big saws..

Torque ratings assuming max rpm = max hp

Dolmar 166

7.9 × 5252 ÷ 7500 = 5.539 (7.50nm)

Husky 3130

8.4 x 5252 ÷ 12000 = 3.67 lb-ft (4.97nm)

Stihl 088

8.5 x 5252 ÷ 12000 = 3.720 lb-ft (5.04nm)

 

[Time's Standing Stihl]

Equations are silly. I just use my heavy hands. If I can dawg in and the chain don't stop. ....it's got some serious torque

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[Iron.and.bark]

Without Equations we would not have chainsaws or this forum to ramble on about them

 

[paragonbuilder]

Don't mean to be picky..

HP = torque x rpm ÷ 5252 (had to do a quick google to rember this number).

Torque = HP x 5252 ÷ rpm

I'm pretty sure he meant max torque lands at a particular rpm on each saw. Each saw that rpm is different.


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[paragonbuilder]

Not to be a kangaroo molesting argumentative housewife but isn't rpm king of the castle ?
If I dog in a fast saw and the Rpms drop all I am doing is cutting slower right?
The wood doesn't get softer just because it. Respects how much torque my saw has
I have only seen one saw that ran stronger when dogged in and that was the wankle in NY.

Here is an example. A saw with bad rings and low compression may start and tune very fast. But touch it to the wood and it stops. It really can't produce any work.


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[malk315]

Picking the max HP as the place to look at torque may not be what you want (if you are just looking for where it makes the most torque regardless of HP) -- it's the RPMs that are giving you the HP at that point and not so much the torque. Peak torque is at lower RPMs from what we've seen on the dyno. That jives with the dolmar saw showing higher torque than the others in the post above doing the equations.

A good example -- Jason's 064 that he sent us to play with Max torque in graph below is close to 7 ft-lbs at around 7000. HP is still above 8 on this run when the saw is doing 11,500 with torque just above 4 ft-lbs. Note the torque sampling is not as quick as the RPMs due to needing to a large software filter to get rid of noise in the load cell data. Hoping the hydraulic dyno that is in the works solves that!