Fa according to ANSI B92.1

[[Ja...]]

Hi,

Is this correct way to evaluate spline profile according to ANSI B92.1 ? Tolerance class 5

How does GearPro evaluate ±Fa ??? Where does the numbers come from?

Couldn`t find any information 😞

[[Ch...]]

Kind of confusing compared to gears, basically + or - from pitch point to TIP and + or - from pitch point to TIF.

 

[[Ro...]]

+/-Fa is special, yes.
The picture from the standard (Chris posted it) shows how the calulation has to be done.
It begins with the definition of the "contact" point.
In GEAR PRO you can influence the "contact" point in the subdialog of +/-Fa as follows:

After that the actual profile is aligned on that diameter.
For the calculation of +/-Fa the nominal contour is moved parallel to the max and min deviation of the actual curve.
From the "contact" point into plus direction describes +F, in minus material direction -F.
The sum of both is Fa (as usual for involute gears).

[[Ja...]]

Thank you both 🙂 now it is more clear!

[[Ed...]]

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Hi again,

It looks like I have managed to make a program according to ANSI B92 for profile measurement.

But I still don`t understand how does it calculates results.

This example is from internal splines, so, on the right side(tooth #28), for me it looks like +Fa should be bigger than -Fa

For me it looks like for every teeth +Fa should be bigger than -Fa in this example with internal splines? 

[[Ch...]]

it actually looks decent to me, however not sure if the pitch point is determined by the actual trace or the regression. however L#3 does appear to have some +Fa according to the regression line at the TIP.

 

I still wish there was an option in Gear Pro to analyze/evaluate the actual trace vs. regressions only; we all know how the law of 'averages' work.

 

[[Ro...]]

For me it looks correct. 

Green: Nominal contour (in this case just the involute without e.g. crowning) aligned at the pitch line
Blue: +Fa line aligned at the max + material inside of the evaluation area 47.2 ... 45.2
Orange: -Fa line aligned at the max - material inside of the evaluation area 47.2 ... 45.2

[[Ed...]]

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Good morning,

Thank you, like always great explanation 🙂 

You should add this type of explanation with examples to user manuals. 

BR