Spline Evaluations

[[Re...]]

I need some help on spline evaluation per ASME Y14.5-2009. I have several questions, but I would like to get a clear cut answer on each one before I go onto the next. I have an ID spline on on a cylindrical part. The pitch diameter of the spline is the primary datum A and the face of the cylinder is the secondary datum B. Per the standard can someone point me to where it calls for the evaluation method needed for these two features on a perpendicularity callout. The perpendicular callout is B to A. I normally have the plane as outer tangential and the pitch diameter as maximum inscribed. What does the standard call for, and where is it spelled out.
Thanks,

[[Ch...]]

Hi,

Excellent question. I have a good amount of experience with gears and splines. I see these callouts a lot. However I don't think you'll find anything in ASME Y14.5.

I am curious how you measured the pitch cylinder : drawing gage ball size in all gaps top and bottom? / or Gear Pro pitch test & recall?

I can't comment on evaluation, I normally use LSQ if I have to measure this way.

Since we have a lot of gear/spline teeth/gaps that involve clocking or tertiary, I would like to see ASME Y14.5 or AGMA document the appropriate way to establish this, I can think of about 5-7 different ways.

I've also seen MMC of a gear tooth itself, as well as MMC of the P.D. Yes, it can be calculated, sort of ....
However P.D. is technically theoretical. They should probably grind/cut the minor to the P.D. for perpendicularity, and to control perpendicularity of P.D. perhaps use 'lead error' to Datums AB or CB, etc...

Good luck.

[[Re...]]

Hi Chris,
I have a probe diameter that will make contact very, very, close to the pitch diameter. I use a self centering routine to establish the clocking. Then I use self centering pattern points at the top of the cylinder to establish a circle, then the same at the bottom. Then I create a 3-D line to represent my Datum A pitch diameter. My next question was going to be what method of evaluation should be used on these circles to satisfy the standard. I know lsq is to be more controllable, but should I be using max inscribed to satisfy the standard?

[[Re...]]

Folks,
My next question is there somewhere in the standard that calls out the ratio of size for datum to a feature? My example is that I have a pitch diameter on a spline (datum A) which is only 1/4th as large as the length of the feature that has a perpendicularly callout back to datum A. There should be some sort of limit on this ratio, but I can not find it in the standard.

[[Ke...]]

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I'm presuming that you are using midpoints, for you self centering point.
I use Max Inscribed/Outer tangential, because it *is* a Datum...I know a lot of prople would probably use LSQ.
FYI: I now ITP has non-standard probe sizes that correlate with the over/between pin sizes... at least the ones that I have needed to use (but, last I checked, you have to special request them)... Zeiss probably does too

[[Re...]]

Since I'm unable to find the required evaluation methods per the standard. And since print does not spell out if I'm to measure the part for process control or fit and function. I then should be able to chose any method of evaluation that will satisfy most everyone, but myself. Along the same principle, I then should be able to set the filters and outlier settings, to give the most favorable measurements for everyone, but myself. As most of you know, when numbers do not look good, it's always the fault of the cmm or the program. And when I'm unable to back anything up in black and white within the standard, then I'm unable to convince otherwise.

[[Re...]]

Keith,
I do use Mid-Point for these Self-Centering Points. Good question, because I have made that mistake in my past. I actually have a big reminder on my wall not to make that mistake again. lol