Stihl 044 Ring Gap

[Wizard]

That is only two significant figures and less accurate. 0.0390 is better. The 1/25.4 ratio is exact to 3 figures.

I forgot. Do You understand precision vs accuracy? You can have one , the other, or both, measuring things.




I can use calculus to derive it. Don't need to memorize formulas.


I can lay out timber frame joinery with a compass, plumb bob and snap line. No rulers or squares needed, perfectly square.

Can You:

1) a Layout a perfect 1,1, root 2/45o 45o 90o knee brace and tenons, just using a compass and straight line? (A 3 4 5/30o 60o 90o brace, takes a bit more work....)

b) How about the mortices? In a post and tie beam to accept the brace you made in a above?


2) Can you layout a perfect "Star of David" using a line and a compass? Then use it to layout a perfect post,tie beam and connect them?

I can here is a hint, but then the cat is out of the bag..... Drawing copyright MP

View attachment 1187981

It's just basic geometry.........

Interesting post. I don't know anything about framing, etc. An engineer associate used to use hose and 2 boiler gage glasses filled with water to determine level over a distance. So, that's a thought.

Concerning carrying out decimal points to the nth degree, 0.039 IS exactly the same as your 0.0390.

Your 25.4 is actually 25.39.

Have you discovered the new less complicated formula for determining the area of a circle, as I have asked if anyone knew? It is very less tiresome than the common method.

 

[nedsim]

That is only two significant figures and less accurate. 0.0390 is better. The 1/25.4 ratio is exact to 3 figures.

.039 has 3 significant figures -- the zero counts. 1/25.4 is exact, i.e., an inch is defined as exactly 25.4mm. .0390 implies accuracy that's not there -- .0394 is the correct conversion to 4 figures, and plenty close enough for measurements with typical instruments.

 

[pioneerguy600]

I have a friend that was a bike racer mechanic and he strongly recommended that I run a tighter ring end gap so for the fun of it used a .005 gap he recommended on an 046 rebuild , the saw broke the top ring within the first 15 minutes of running on the Alaskan type mill, the broken ring segment did not catch a port and lodged in the bottom of the crankcase effectively stopping the crank from spinning, no damage to either the piston or cylinder. That was the only time I have ever broke a ring. I will stick with the .004 per inch of bore for my rebuilds and I don`t hone a plated chainsaw cylinder, only Scotchbrite clean til smooth and shiny.

 

[Mad Professor]

Being a motorcycle mechanic, I took interest when a fellow hotrodder biker told me that new refits didn't need any end gap at all, and to run at full throttle at first start up. He said the resultant end gap therefore would be optimal (minimum tolerance or thereabout).

I have never tried this, but I believe it might have merit, as my rering jobs would open the gap up closer to max tolerance on next disassembly. If a cylinder has been honed, as many are, you are , right from jumpstreet enlarging the bore diameter as you curl over the peak heights as piston reciprocates.

A hone manufacturer will verify that this occurs.

Where do you come up with this stuff?

Try setting up a few bikes with no ring gap then report back.

Are you still working on old bikes with cast iron liners?

"Honing" a chrome or nikasil plated cylinder does little to bore size. In fact the liners are only a few thousands thick. It just removes any aluminum transfer and carbon residue.

Many years ago I worked at a dealership that had a boring bar. We would bore out cast liners then hone the cylinders to fit the pistons and then end gap the rings. Pistons could be ordered in various oversizes depending on how bad the damage/wear was to the cast iron liner.

The same is true for iron block tractors/trucks/cars. The liner is the block itself. Ever set up/blueprinted a GM/Ford/Chrysler V-8? Old tractor?

You've done that , right?

 

[Mad Professor]

.039 has 3 significant figures -- the zero counts. 1/25.4 is exact, i.e., an inch is defined as exactly 25.4mm. .0390 implies accuracy that's not there -- .0394 is the correct conversion to 4 figures, and plenty close enough for measurements with typical instruments.

Not true. The significant figures start with the first non-zero number, and end with last exact number. Even if it is zero.

"significant figures, any of the digits of a number beginning with the digit farthest to the left that is not zero and ending with the last digit farthest to the right that is either not zero or that is a zero but is considered to be exact"

- Britannica

I taught college chemistry many years. Sometimes analytic.

Often significant figures are limited by the devices used to measure with. For instance a caliper/micrometer or a scale.

In calculations there will often be many numbers generated by things like division or multiplication. The value reported needs to be rounded, up or down, to the correct number of significant figures. Then given an error +/- value

Interesting post. I don't know anything about framing, etc. An engineer associate used to use hose and 2 boiler gage glasses filled with water to determine level over a distance. So, that's a thought.

Concerning carrying out decimal points to the nth degree, 0.039 IS exactly the same as your 0.0390.

Your 25.4 is actually 25.39.

Have you discovered the new less complicated formula for determining the area of a circle, as I have asked if anyone knew? It is very less tiresome than the common method.

25.39 used in a calculation, would generate a maximum of four significant figures.

Avagadro's number is generally given as 6.022 X 10 ^24th. Four significant figures. It has been calculated more accurately.

Pi has never been determined. Mathematicians/scientists generally round it to 3.142 or 3.1416 depending on precision needed.

 

[Wizard]

Are you still working on old bikes with cast iron liners?

"Honing" a chrome or nikasil plated cylinder does little to bore size. In fact the liners are only a few thousands thick. It just removes any aluminum transfer and carbon residue.

No longer doing boring, honing, ring jobs. Went back to my major trade working in the power houses. I bored cast iron cylinders and fit pistons and rings for desired (no callback) results. Never had a callback.

Concerning honing, running a ball hone is not considered to increase bore diameter, only meant to provide a suitable surface for seating the rings and taking out the hills and valleys from the boring operation. To increase bore diameter via honing would require a parallel hone for best case scenerio. Flexible flat stone hones would not be desired for this.

 

[Mad Professor]

Are you still working on old bikes with cast iron liners?

No longer doing boring, honing, ring jobs. Went back to my major trade working in the power houses. I bored cast iron cylinders and fit pistons and rings for desired (no callback) results. Never had a callback.

Concerning honing, running a ball hone is not considered to increase bore diameter, only meant to provide a suitable surface for seating the rings and taking out the hills and valleys from the boring operation. To increase bore diameter via honing would require a parallel hone for best case scenerio. Flexible flat stone hones would not be desired for this.

I believe by current standards the meter, hence millimeters is determined to 9 significant figures.

"Building upon these and other advances, the meter was redefined by international agreement in 1983 as the length of the path traveled by light in a vacuum in 1/299,792,458 of a second. This definition also locked the speed of light at 299,792,458 meters per second in a vacuum. Length was now no longer an independent standard but rather was derived from the extremely accurate standard of time and a newly defined value for the speed of light made possible by the technology developed at NIST."

https://www.nist.gov/si-redefinition/meter

P.S. One of my mentors, a Physics teacher, had a great quote: "Scientists think, Engineers memorize"

 

[Wizard]

I believe by current standards the meter, hence millimeters is determined to 9 significant figures.

"Building upon these and other advances, the meter was redefined by international agreement in 1983 as the length of the path traveled by light in a vacuum in 1/299,792,458 of a second. This definition also locked the speed of light at 299,792,458 meters per second in a vacuum. Length was now no longer an independent standard but rather was derived from the extremely accurate standard of time and a newly defined value for the speed of light made possible by the technology developed at NIST."

https://www.nist.gov/si-redefinition/meter

P.S. One of my mentors, a Physics teacher, had a great quote: "Scientists think, Engineers memorize"

So, is this timed measurement in 1983 when they went from one inch being 25.39 mm to 25.4mm? They gotta quit f'n with us, don'cha know!

 

[Mad Professor]

So, is this timed measurement in 1983 when they went from one inch being 25.39 mm to 25.4mm? They gotta quit f'n with us, don'cha know!

It went to 25.3XXXXXX 9 sig figs. Most people don't have anything that can measure 0.001", let alone 0.0001 inch +/- 0.0001".

Then you start having to worry about things like temperature of the instrument and the piece being measured........

Volumes more so. Put some warm water in a volumetric flask, just to the fill line, then let it cool to 25o C, where the flask was calibrated to.........it's not full anymore.

A professor asked a class if they knew how to measure things with a micro-pipette. They all raised their hands. Then he asked if they knew how to do it properly..........

 

[Wizard]

Yes temps do matter, both static and dynamic, therefore prescribed tolerances are needed.

Something like type material, coefficient of expansion, per degree, per foot.....

Gotta know the drill if that incursion resides in your ballpark.

 

[Wizard]

Area of a circle;
Dia. squared x 0.7854

Also, something to ponder;
2" circle squared x 0.7854 = ?

 

[huskihl]

Dude wanted to know proper ring gap on an 044, not get schooled in algebra, geometry, and calculus again.

Lol

 

[Wizard]

Dude wanted to know proper ring gap on an 044, not get schooled in algebra, geometry, and calculus again.

Lol

I didn't do it for him. I thought it might help everyone.