general question on splines 1

[Rob1970]

How do I determine what spline is on an existing shaft? Is there a tool to measure the spline or a standard method of measurement. Does anyone have a resource for finding standard spline dimensions? Thankks in advance.

 

[dimjim]

Knowing the od and the number of teeth, you can use the
general equation. OD = (N+.8)/DP (DP =Diametral Pitch)

Splines are similar to 1/2 of a stub system as to Addendums
and Dedendums. Metric

So the equation can be revised to
OD x DP = N +.8 and then
DP = (N +.8)/OD

This assumes no profile shift correction.

 

[israelkk]

dimjim

You forgot the pressure angle

 

[WoodyPE]

ANSI has a standard publication for spline fits.

http://www.angelfire.com/planet/gadgetforum/index.html

 

[dimjim]

Israelkk,
I do not understand why pressure angle would influence the
od of a spline. Wouldn't the od simply be pd plus two
addendums? Were you confusing this with dimensions over pins or balls?

 

[dimjim]

Israelkk,
It just came to me what you were inferring.
Yes the equation would give you the DP of the spline,
but you would have to check the pressure angle by
using dimensions over pins and then probably require
two different ball sizes. I am so used to working with
30 degree involute splines, I often forget there are
other standards as well. Thanks.

 

[Rob1970]

Well, the most difficult thing about this shaft is the size of the splines, they are very small. It is a motorcycle shifter shaft if that helps. I'm trying to determine the size for a female mating end.

 

[dimjim]

Rob1970,
Small is relative. What is the od and number of teeth.
Can you tell if the external spline has a straight or
curved surface? There are Metric Splines as well.
Do you think the mortorcyle was made domestically or
abroad? Internal Splines are kind of like the reverse
image of an external spline. The tooth space must
exceed the tooth thickness of the external spline
by on a few 10 thousandths or 10 hundreths depending on
size. What happened to the old part? Totally destroyed?
It might be a standard SAE type spline if made domestically. If so, then the information would be available in one of the SAE books governing Splines.

 

[gearguru]

First we need to know, if it is an involute pline. There are also standardised splines with triangular shaped teeth and also splines with teeth created with parallel straight lines.

 

[EnglishMuffin]

There are also metric involute splines which have addendum shifted teeth as standard.