topic Involute Spline creation - part in Inventor Forum

Involute Spline creation - part

0x3FA5 — Tue, 02 Jul 2019 17:30:23 GMT

Hi,

I was looking for quite a while for the information about the Involute Spline creation in Inventor.

Most of the answers start with "Go to Design Tab..", but as I understand this tab only appears in assembly mode, so I cannot really use it, since I have no idea where this splined shaft is going to be used.

Please help.

Thank you.

Re: Involute Spline creation - part

Frederick_Law — Tue, 02 Jul 2019 17:59:06 GMT

Doesn't matter where the shaft is used.

The assembly will create parts you can use in other assembly.

More important, why do you need to model the spline? Are you using the model for machining?

Usually the model is reference. Gear cutting vendor will use the spec to cut the spline, not the model.

I had laser, plasma, waterjet, 3D print a few gears, clutch couplings.

Its trial and error.

Re: Involute Spline creation - part

JDMather — Tue, 02 Jul 2019 18:02:56 GMT

Involute Spline can mean different things in Inventor.

If you are referring to creating a curve, that can be done by laying it out geometrically (at least two ways that I know of) or with an equation curve.

If you are referring to a shaft spline joint then that is done within the Assembly environment but does in fact create a part file in the assembly.

What exactly is your Design Intent?

Re: Involute Spline creation - part

0x3FA5 — Tue, 02 Jul 2019 18:04:26 GMT

@Frederick_Law wrote:
Doesn't matter where the shaft is used.
The assembly will create parts you can use in other assembly.

More important, why do you need to model the spline? Are you using the model for machining?
Usually the model is reference. Gear cutting vendor will use the spec to cut the spline, not the model.

I had laser, plasma, waterjet, 3D print a few gears, clutch couplings.
Its trial and error.

The assembly will create parts you can use in other assembly.

So I need to create assembly even if I really don't need one?

More important, why do you need to model the spline? Are you using the model for machining?

I am using the model for a very quick and handy reference to match parts. Just a reference, but saves me some time.

I general, I think I found the solution, the problem is the spline that I need to model is not listed among the standard splines in Inventor:

30 DEG

34 TEETH

16/32

2.125 PD

Re: Involute Spline creation - part

0x3FA5 — Tue, 02 Jul 2019 18:07:58 GMT

I think I am referring to this:

If you are referring to creating a curve, that can be done by laying it out geometrically (at least two ways that I know of) or with an equation curve.

I would like to use the curve in other parts as well, so I I need to save it as a separate sketch.

Thank you.

Re: Involute Spline creation - part

JDMather — Tue, 02 Jul 2019 18:13:33 GMT

@0x3FA5 wrote:

~~30 DEG~~

~~34 TEETH~~

16/32

~~2.125 PD~~

I understand all of these numbers (and I think that is all the information needed), but what is the 16/32?

Also, what version of Inventor are you using? 2018? 2020?

Re: Involute Spline creation - part

0x3FA5 — Tue, 02 Jul 2019 18:21:43 GMT

I am using Inventor Professional 2018.

The 16/32 is the addendum info:

Thank you!

Re: Involute Spline creation - part

Frederick_Law — Tue, 02 Jul 2019 18:27:59 GMT

@0x3FA5 wrote:
So I need to create assembly even if I really don't need one?
Yes

I am using the model for a very quick and handy reference to match parts. Just a reference, but saves me some time.
So Inventor model is good enough.

I general, I think I found the solution, the problem is the spline that I need to model is not listed among the standard splines in Inventor:
30 DEG
34 TEETH
16/32
2.125 PD

Just let you know, with all the spline shaft I worked on, over 90% are NOT spline shaft profile.

The "spline" in fact is gear profile.

They're usually 8" and above PD.

Re: Involute Spline creation - part

0x3FA5 — Tue, 02 Jul 2019 19:05:55 GMT

The "spline" in fact is gear profile.

Never thougth in this direction, thank you!

Re: Involute Spline creation - part

Frederick_Law — Tue, 02 Jul 2019 19:27:06 GMT

Remember its good only for reference.

Don't use the model for manufacture.

Need to use "export" teeth profile to get good spline.

One more part file to get a better model.

I usually make internal "spline" to fit the shaft, clutch and brake plates.

So we'll laser cut the profile and test fit on the shaft. Then make adjustment, re-cut and test again.

If you'll do this a lot, check out Camnetics GearTrax. Really good software.

Re: Involute Spline creation - part

JDMather — Wed, 03 Jul 2019 12:21:34 GMT

@0x3FA5 wrote:

The "spline" in fact is gear profile.

Never thougth in this direction, thank you!

You marked this as "Solved" but I suspect that either you have not fully described your problem or you do not fully understand the implications of what @Frederick_Law is suggesting.

The Gear Generator does not create true involute profiles by default - there are special (hidden?) steps to export as spline curves. Otherwise the output will be circular arc approximations (might be close enough for your need).

You might be able to find the formula for an involute curve to use in the 2D Sketch Equation Curve, but in the attached I started a method of geometrically laying out an involute spline. You should be able to figure it out from my start (the 5°point plot is up to the user to choose angle of resolution). This can also be done geometrically by using a Trace function in Dynamic Simulation, but while this solution is easy once set up - it does require knowledge of Dynamic Simulation environment.