Saw Dyno

[wcorey]

How about some sort of brake booster?

That would most likely make it worse, less feel, more sensitivity.

 

[RI Chevy]

Ok. I was thinking some sort of linear progression brake booster. Not sure if one even exists.

 

[wcorey]

We've discussed using a linear actuator on the brake with some sort of closed loop control through the software.
The accel/decel curve could then be programed in... someday...

 

[mdavlee]

The big stihls and dolmars are 14mm slots.

 

[wcorey]

One problem is that the saw power output isn't linear, so you can't just apply even pressure to get an even deceleration.

 

[malk315]

Jason and Kevin's saws were putting out max torque of like 7 ft-lbs or so. I think the peak was 7.8 on one of Kevins (probably from brake grab reaction which is fine).

You take that and multiply by 5 to get how much it's pushing on the load cell -- so 7.8 x 5 = 39 lbs. The load cell is rated for 20kg or 44 lbs.

Thus the most torque a saw can put out before breakage risk is 8.8 ft. lbs.

A saw doing 10000 RPM producing 8.8 ft lbs would do 16.75 horsepower.
Same thing doing 9000 RPM producing 8.8 ft lbs would do about 15.1 horsepower.

If not making spikes in force we should be able to do up to 12HP saws at the magic 9K to 10K range without to0 much risk of breakage.

As bill said -- if we break the load cell the one were using only costs like $7. We have a couple of spares

 

[MasterMech]

Jason and Kevin's saws were putting out max torque of like 7 ft-lbs or so. I think the peak was 7.8 on one of Kevins (probably from brake grab reaction which is fine).

You take that and multiply by 5 to get how much it's pushing on the load cell -- so 7.8 x 5 = 39 lbs. The load cell is rated for 20kg or 44 lbs.

Thus the most torque a saw can put out before breakage risk is 8.8 ft. lbs.

A saw doing 10000 RPM producing 8.8 ft lbs would do 16.75 horsepower.
Same thing doing 9000 RPM producing 8.8 ft lbs would do about 15.1 horsepower.

If not making spikes in force we should be able to do up to 12HP saws at the magic 9K to 10K range without to0 much risk of breakage.

As bill said -- if we break the load cell the one were using only costs like $7. We have a couple of spares

So what about comparing some vintage saws to modern day stuff? 6-7k Rip 'ems and 100cc+. I can see quite few of @Lee H 's saws sending your load cell into orbit.

One problem is that the saw power output isn't linear, so you can't just apply even pressure to get an even deceleration.

Would def have to have the actuator driven by a fast sampling PID controller to avoid sudden drops in speed when the engine falls out of its powerband.

It's been very interesting to read how you guys are dealing with the characteristics of the friction brake mechanicals. I'd love to see a hydro setup compared alongside.

 

[Definitive Dave]

If you guys need a sacrificial big mount bar , just say the word and I will send one wherever it needs to go.
There are 3/8" sprockets made for dang near any saw these days. If you need anything in that regard let me know.
I want to see my ported 084 and 076 on a dyno one day

 

[Deets066]

090 is 13 hp stock I believe. After some machine work and a little grindin. Ground the vain governor. It might be close to that 15 hp

 

[Deets066]

090 is 13 hp stock I believe. After some machine work and a little grindin. Ground the vain governor. It might be close to that 15 hp

Wishful thinkin

 

[paragonbuilder]

So what about comparing some vintage saws to modern day stuff? 6-7k Rip 'ems and 100cc+. I can see quite few of @Lee H 's saws sending your load cell into orbit.



Would def have to have the actuator driven by a fast sampling PID controller to avoid sudden drops in speed when the engine falls out of its powerband.

It's been very interesting to read how you guys are dealing with the characteristics of the friction brake mechanicals. I'd love to see a hydro setup compared alongside.

Well get on it already... Build one!

 

[MasterMech]

Well get on it already... Build one!

Time and money friend. More so time right now. My job has figured out the best way to keep me out of trouble is a healthy dose of OT. But I sure do like watching this one take shape!

 

[paragonbuilder]

Time and money friend. More so time right now. My job has figured out the best way to keep me out of trouble is a healthy dose of OT. But I sure do like watching this one take shape!

Same for me ...[emoji19]
But I will build one![emoji2]

 

[jmssaws]

Same for me ...[emoji19]
But I will build one![emoji2]

Build 2!

 

[paragonbuilder]

Build 2!

How did I not see that coming...

 

[RI Chevy]

Do you need a running saw to do a ported saw? Or can it have one with motor issues?

 

[paragonbuilder]

Do you need a running saw

For what?

 

[RI Chevy]

Quoted me to quick.

 

[jmssaws]

Doesn't have to be running

 

[RI Chevy]

Cool. I got my eyes open for a good used one. Any advice for me on a particular model? Just a few basic models for Stihl I was looking at. 440, 660, etc?