Saw Dyno

[malk315]

I think equal scales would be good so it's less confusing. Then the lines will track each other better too.
Those graphs are easier for me to read.

Let's set the top of the scales at 10.0 and see who gets the first "off the chart" saw. Is Lee H in the house?

Maybe what I could do is detect the peak point and set the scales to take up most of the screen, same on left and right. This way a small saw that does more like 4 HP you can see it better. On a scale that tops 10.0 the 4HP will have the entire top half of screen just blank white. It may not be a big deal. I'll have to see what the chart chose for CTYank homelite 150 or whatever that was that hit about 2 HP. It may have chosen the usual 7.0. Seems to like 7 and 14

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[paragonbuilder]

I'll have to see what the chart chose for CTYank homelite 150 or whatever that was that hit about 2 HP.

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Wow! He had high hopes for that saw...

 

[MarkEagleUSA]

That's it... next time the dyno is close by I'm bringing my Mini-Mac. That'll stress test the dyno for sure!

 

[malk315]

Here's the homelite 150 -- and the graph tool did choose a tight scale on the right in 0.5 HP increments.
Doing about 2 to 2.1 HP between 7000 and 5000
That saw had a different vibration sound and maybe it pre-dates anti-vibe features? Thus thinking some of the chopiness in the graph from a different sort of vibration pattern... theory!

 

[MustangMike]

I was talking to my brother, who is a PE, about it, and he generally agrees with your comments. First, he said you usually use the highest run, unless it is really an outlier compared with several other runs. He said it would be very tough to make that call with only 3 runs.

For the saws where I have consistent #s for 2 or 3 of the high end runs, I am confident in the #s. For the saws with one good run and two poor runs, I would really like to re test them.

On another note my brother used my MS440 not long ago, and when I told him about the dyno results (all 3 tests right about 6.7 Hp) he said any time I want to sell that saw to him to let him know. He said it cuts at least as good as his 460 (which also has a dp muff and HD-2 filter) but is noticeably lighter.

I really like that saw, but I have too many, so I may have to take him up on that!

 

[paragonbuilder]

I was talking to my brother, who is a PE, about it, and he generally agrees with your comments. First, he said you usually use the highest run, unless it is really an outlier compared with several other runs. He said it would be very tough to make that call with only 3 runs.

For the saws where I have consistent #s for 2 or 3 of the high end runs, I am confident in the #s. For the saws with one good run and two poor runs, I would really like to re test them.

On another note my brother used my MS440 not long ago, and when I told him about the dyno results (all 3 tests right about 6.7 Hp) he said any time I want to sell that saw to him to let him know. He said it cuts at least as good as his 460 (which also has a dp muff and HD-2 filter) but is noticeably lighter.

I really like that saw, but I have too many, so I may have to take him up on that!

You should have brought him with you Mike!

 

[MustangMike]

Here's the homelite 150 -- and the graph tool did choose a tight scale on the right in 0.5 HP increments.
Doing about 2 to 2.1 HP between 7000 and 5000
That saw had a different vibration sound and maybe it pre-dates anti-vibe features? Thus thinking some of the chopiness in the graph from a different sort of vibration pattern... theory!

View attachment 21767

Also remember those saws were designed to run at much lower RPMs than current saws (about 1/2).

I'm sure this saw goes through wood like it is butter!

 

[MustangMike]

You should have brought him with you Mike!

I tried, he is very busy this time of year, wears too many hats. He is a lawyer, and had a big case in progress, a PE, and a licensed Surveyor.

 

[paragonbuilder]

Also remember those saws were designed to run at much lower RPMs than current saws (about 1/2).

I'm sure this saw goes through wood like it is butter!

I'll stick with something more modern for my cutting needs...[emoji2]

 

[wcorey]

Yikes. That's a large error band. I was looking at the graphs and I noticed you must be hitting a resonance of the brake around 9250-9500. With all the saws I noticed a dip or spike in your data here which indicated that the noise band is larger there then elsewhere. The actual torque generated from the normal force on the brake can shift the frequency slightly and that is why you see it at slightly different RPM for different saws.

I wonder if you can't use a less stiff with more damping material behind the brake pad to help with the noise in the data. Often brakes have an extra shim which is used to offset two eigen modes of the system such that they don't ring off each other.

I have noticed the torque arm resonating side to side a bit when there's near peak load on it, which would obviously be somewhere around peak torque.
Next go 'round I'll watch for it and have Eric watching the rpm to see where it is.
Would be interesting to watch with a strobe on it. Also Eric may be able to get a high speed camera on it at work.
I still feel the most likely major culprit is the rotor and still need to swap a couple more around to see if that changes anything.

I must have some of those ptfe coated anti squeal pads around somewhere, I'll see if I can adapt something. There's also a liquid/paste type stuff for the same application, silicon based maybe, I'll look into that also.

Then I need to make a larger diameter master cylinder to hopefully decrease the brake actuation sensitivity.
We're very over-braked on this thing but I'm concerned about over heating issues with a smaller one.

 

[paragonbuilder]

I have noticed the torque arm resonating side to side a bit when there's near peak load on it, which would obviously be somewhere around peak torque.
Next go 'round I'll watch for it and have Eric watching the rpm to see where it is.
Would be interesting to watch with a strobe on it. Also Eric may be able to get a high speed camera on it at work.
I still feel the most likely major culprit is the rotor and still need to swap a couple more around to see if that changes anything.

I must have some of those ptfe coated anti squeal pads around somewhere, I'll see if I can adapt something. There's also a liquid/paste type stuff for the same application, silicon based maybe, I'll look into that also.

Then I need to make a larger diameter master cylinder to hopefully decrease the brake actuation sensitivity.
We're very over-braked on this thing but I'm concerned about over heating issues with a smaller one.

It hasn't even gotten hot to the touch yet has it Bill?

 

[wcorey]

More like not too hot to touch, briefly...

 

[paragonbuilder]

More like not too hot to touch, briefly...

So probably perfectly sized!

 

[MustangMike]

I finished crunching the #s on my saws last night, but was too tired to post afterwards. As a reminder, under MustangMike's method, at least 7 continuous data points are averaged to compute Hp (sometimes I use as many as 12 data points). I'll go in order of saw size. Also, usually the best chart is what should be used, but maybe not always. Many of my air filters were so dirty I'm surprised my saws did so well.

My little MMWS 362 C produced a best (chart 102) of 6.26 Hp, and a second best (chart 105) of 5.97 Hp. It is not as strong as the ported 262s, but to have a 60 cc saw with M-Tronic and spring AV produce about the same Hp as a stock MS460, I'll take it.

My modified (but not ported) MS440 produced the most consistent results: 6.76 Hp, 6.67 Hp, and 6.7 Hp. I was very impressed with those #s from a 70 cc saw w/o porting.

044#1 is also unported and has the exact same mods as MS440, and it hit the ball out of the park. I have owned this saw since new, and it has always been a strong performer, and just got better with the mods. The best two runs produced 7.56 (#116 after eliminating a high #) and 7.356 (run 115).

My MMWS 044#2 only had one good run that produced Hp of 7.538 Hp (run 107-1). Knowing how this saw compares to 044#1, I believe this run accurately reflects the power of this saw.

Now we come to my 3 ported 76.5 cc saws, and things get VERY INTERESTING.

MMWS MS460/046-D There were 5 runs for this saw (only 3 for all the rest) and they resulted in both the best and worst Hp #s, respectively for my ported 77 cc saws. The worst run (#130) produced 7.26 Hp, the best run produced 8.16 Hp (#129-3), narrowly edging out the saw Al did. The remaining 3 runs were very consistent, producing 7.66 Hp, 7.63 Hp and 7.57 Hp.

MS460/146-D Ported by Dr Al This saw provided the second most consistent results, and the highest average Hp with #s of 8.142, 7.98 and 7.787. This saw will put a smile on your face every time you run it.

Smittybilt 046 The best run from this saws produced 7.57 Hp, with the other two runs close behind.

Now here is were I have a little problem with the numbers. This reflects that the Smittybilt saw has about the same Hp as my two 044s. Let me assure you, all 3 of my ported 046-460s will easily out pull my 044s. Also note, that if you took the lowest 3 runs from the MMWS 460 they average about the same as the 3 Smittybilt runs, yet the MMWS also produced a run of over 8 Hp.

As my brother stated, 3 runs is a small sample. When you cut with the Smittybilt saw, it is noticeably stronger than the 044s. With more testing I am confident this saw would produce a run at or near 8 Hp.

I thank everyone involved in this project for providing us with such great information. This was very enlightening and I really enjoyed it.

 

[paragonbuilder]

I think that often the saws were slowed to quickly with the touchy brake and did not have a chance to "catch up" with the fuel air mixture at rpm. I think that with a smoother braking system and a slower run things will clear up nicely. We are getting there. Actually I should say they are getting there! Bill and Eric have done an amazing job thus far!!


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[malk315]

I finished crunching the #s on my saws last night, but was too tired to post afterwards. As a reminder, under MustangMike's method, at least 7 continuous data points are averaged to compute Hp (sometimes I use as many as 12 data points). I'll go in order of saw size. Also, usually the best chart is what should be used, but maybe not always. Many of my air filters were so dirty I'm surprised my saws did so well.

My little MMWS 362 C produced a best (chart 102) of 6.26 Hp, and a second best (chart 105) of 5.97 Hp. It is not as strong as the ported 262s, but to have a 60 cc saw with M-Tronic and spring AV produce about the same Hp as a stock MS460, I'll take it.

My modified (but not ported) MS440 produced the most consistent results: 6.76 Hp, 6.67 Hp, and 6.7 Hp. I was very impressed with those #s from a 70 cc saw w/o porting.

044#1 is also unported and has the exact same mods as MS440, and it hit the ball out of the park. I have owned this saw since new, and it has always been a strong performer, and just got better with the mods. The best two runs produced 7.56 (#116 after eliminating a high #) and 7.356 (run 115).

My MMWS 044#2 only had one good run that produced Hp of 7.538 Hp (run 107-1). Knowing how this saw compares to 044#1, I believe this run accurately reflects the power of this saw.

Now we come to my 3 ported 76.5 cc saws, and things get VERY INTERESTING.

MMWS MS460/046-D There were 5 runs for this saw (only 3 for all the rest) and they resulted in both the best and worst Hp #s, respectively for my ported 77 cc saws. The worst run (#130) produced 7.26 Hp, the best run produced 8.16 Hp (#129-3), narrowly edging out the saw Al did. The remaining 3 runs were very consistent, producing 7.66 Hp, 7.63 Hp and 7.57 Hp.

MS460/146-D Ported by Dr Al This saw provided the second most consistent results, and the highest average Hp with #s of 8.142, 7.98 and 7.787. This saw will put a smile on your face every time you run it.

Smittybilt 046 The best run from this saws produced 7.57 Hp, with the other two runs close behind.

Now here is were I have a little problem with the numbers. This reflects that the Smittybilt saw has about the same Hp as my two 044s. Let me assure you, all 3 of my ported 046-460s will easily out pull my 044s. Also note, that if you took the lowest 3 runs from the MMWS 460 they average about the same as the 3 Smittybilt runs, yet the MMWS also produced a run of over 8 Hp.

As my brother stated, 3 runs is a small sample. When you cut with the Smittybilt saw, it is noticeably stronger than the 044s. With more testing I am confident this saw would produce a run at or near 8 Hp.

I thank everyone involved in this project for providing us with such great information. This was very enlightening and I really enjoyed it.

Hey Mike -- on your runs there is an option that says "Dyno" for the graph type when you hit the "Go" button.
Take a look at some of your graphs like the stock 044 and change the "Dyno" option to "Time Based" and hit go to get the Time based graph.
This will show the slope of the RPM curve which gives you a good idea of how Bill got the brake to bring the saw down.

On the 044's the slope of that RPM drop is pretty steep over a short period -- one of them is like 11K down to 6K or below in only 0.5 seconds (the time based puts the time on the bottom and the RPM as 3rd line on the graph) A steep slope over a short time I think confirms what Dan is saying.

Bill the wizard of fabrication is thinking of making a bigger master cylinder for the brake to help get more gradual lug downs of the saws. I don't think you can get a bigger master cylinder off the shelf so he's going take on making one.

I haven't looked at your RPM bringdown curves for all of your runs, but take a look and maybe that will help further clarify what you're seeing.

See ya Mike! Always a pleasure spending time with you at GTG's. Already looking forward to having access to your saws again.

 

[srcarr52]

I think that often the saws were slowed to quickly with the touchy brake and did not have a chance to "catch up" with the fuel air mixture at rpm. I think that with a smoother braking system and a slower run things will clear up nicely. We are getting there. Actually I should say they are getting there! Bill and Eric have done an amazing job thus far!!


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As fast as they are decelerating in some of the runs you'd probably have to correct the torque by the inertial force due to decelerating the dyno.

You can calculate the inertia of the dyno by getting it up to speed with a saw and then letting off the throttle so the dyno it free spooling. Then you can brake it down to see the torque generated to decel just the dyno.

T = I * omega**, so I = T/omega**.
T = torque
I = inertia of system
omega** = rotational acceleration, rate of change of RPM.

Once you have the inertia, you can estimate the parasitic loss (simple torque) of the dyno by spooling it up and letting it decel on it's own.

 

[paragonbuilder]

More like not too hot to touch, briefly...

Bill, would it work to make the brake lever longer so that you had more control over it?

Or what about a threaded actuator with a t handle? It would take longer than pulling a handle but much more steady and I think a little extra time may help accuracy.

 

[malk315]

On Jason's run we get a solid 3 seconds of the saw in the power band with lots of points to characterize what's up. The blue RPM slope is pretty gradual over 3+ seconds of time.



On this run of the the stock 044 run #116 we can see it was taken from 10K to 5K in only 1/2 second.
If we could get the brake to drag down for 3 seconds we would get a whole bunch more data points.
You can see the blue slope is much more steep. The more "pulse" from the brake the more sudden the power for brief time.



I have a clip from where Bill did a "dump the clutch" of the brake w/ his Makita at 12.5K and we hit the load limit of the load cell and risked breaking it

We're still learning a lot -- enjoying it.

EDIT: whoops forgot the screenshot for Mike's run 116

 

[paragonbuilder]

It seemed really hard to accurately bring the saw down with the hand brake, especially when switching saws. Like was mentioned earlier the torquier saws were easier to do.
I think the threaded actuator could really work, with a fine thread, to control it better...


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