Non-standard splines
Non-standard splines
(OP)
I'm trying to draw a hub and shaft to look at the quality of fit and can't seem to find calculations for non-standard splines.
The shop making the hub told me they are cutting a 24 tooth spline with a 7/9 diametral pitch and a 27.5 degree pressure angle. Yes. That is correct. That's what I was told.
The shaft has a 24 tooth Grob spline with a nominal diameter of 3.250" and a chord of 1.021".
Any help will be appreciated.
Thanks.
The shop making the hub told me they are cutting a 24 tooth spline with a 7/9 diametral pitch and a 27.5 degree pressure angle. Yes. That is correct. That's what I was told.
The shaft has a 24 tooth Grob spline with a nominal diameter of 3.250" and a chord of 1.021".
Any help will be appreciated.
Thanks.





RE: Non-standard splines
Is this a span measurement over two teeth?
RE: Non-standard splines
If I had the data on the mating hub, I could be more sure.
RE: Non-standard splines
This is one I've never come across.
To work it out I'm going to need more information.
Can you get hold of data for both hub & shaft such as: major & minor diameters, fillet radii of internal & external cutters, measurments with pins, required clearance/fit and the amount of profile shifts.
Also, can you confirm the span dimension over 3 teeth by measuring the shaft? If so, what are span measurments taken over 2 teeth and 4 teeth?
RE: Non-standard splines
Grob spline with 24 teeth
3.250 nominal diameter
3.362/3.358 major diameter
3.140/3.125 minor diameter
.015 root radius
1.022/1.020 chord
And I have less on the hub. Over the telephone I was told, "involute spline with twenty four teeth, seven nine diametral pitch, and a twenty seven and a half degree pressure angle. And, the hub has a minor diameter of 3.150/3.155."
This is the part I'm having trouble with. All the formulas and tables I've found for involute spines are for 30, 37.5, and 45 degree pressure angles and are for standard types where the stub pitch (denominator) is twice the diametral pitch (numerator).
As for trying to confirm any dimensions on the shaft, all I have is a worn shaft to look at and 1.021 over three teeth looks like it's what it might have been new. Trying to get the span over two or four teeth would only be a guess as over half of each tooth is worn away.
I know the shaft and hub, as described above, are not intended to work together. I'm trying to see just how bad the fit is.
RE: Non-standard splines
RE: Non-standard splines
At the base, which is all that's left on one side of the teeth, I measure .625 across 2 teeth and 1.400 across 4 teeth.
RE: Non-standard splines
Number of teeth 24
Normal module 3.6286
Pressure angle at normal section 27.5000
Dedendum reference profile (module) 0.268
Tooth root radius Refer profile (module) 0.10
Addendum Reference profile (module) 0.508
Addendum modification coefficient -0.7416
Reference diameter (mm) 87.086
Major diameter (mm) 85.390
Minor diameter (mm) 79.760
No of teeth over which to measure 4
Base tangent length 36.041
Pin diameter (mm) 6.500
Dimension over two rolls (upper) 91.204
Chordal tooth thickness 2.898
Reference chordal height (mm) -0.826
RE: Non-standard splines
How would I adjust these dimensions for the mating hub?
And, what about the 7/9 Dp? How does one generate the rest of the specification based on this and the 27.5 degree pressure angle?
Is there any way for me to paste this image into an AutoCAD file as anything but a picture?
RE: Non-standard splines
The gear is hardened PM with an internal spline. The shaft is not hardened, and the the gear is pressed on the shaft thus generating an intimate spline. The spline shape can be anything you desire, preferably shallow.
RE: Non-standard splines
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