Involute Spline Dimensions

[DANIEL.CHASE]

Hi all,

I noticed a discrepancy between what Inventor tells you the spline should be versus what it models the spline as when it adds it to your model.  When selecting the involute spline, Inventor gives you the details of the spline, including the pin diameter and measurement between pins (hub) or measurement over pins (shaft). However, if you go to verify the dimensions in the model (I added a sketch, drew 2 circles at the pin diameter given by inventor, and threw a dimension between the "pins") the result is not what Inventor had given to me.  Anyone else run into an issue with this, or know how to fix it? 

[Anonymous · Accepted solution]

I believe Inventor only model an estimated involute spline.  Hence the model is not accurate.

If you look closer, the "involute" in the model is an arc.

[bob_holland]

@DANIEL.CHASE @Anonymous

Daniel,

I wanted to confirm that what Fredrick states is true.

I have confirmed with our development staff that  involute splines are estimated.

I am sure Fredrick would appreciate it if you acknowledged his input and accept his response as and solution and you can also give him kudos for effort and knowledge.

Have a great rest of your week.

[Anonymous]

I was working on splined hub and looked into this a bit more.

I know using Export Tooth Shape (right in the browser on the gear) will give a better profile.  I use it sometime to get a better fit for laser cut to fit on a hub.

So I went be farther and assemble 2 pins to check the over wire dimension.

It is the same as the dimension in the report!  Look like it is a pretty accurate model profile.

It was done in IV2017.

[DANIEL.CHASE]

I am having a difficult time seeing where you "Export Tooth Shape".  Can you screenshot that so I can see where you are clicking on that option?

[Anonymous]

Right click on the gear in browser in the assembly you create the gears.

This will create another part file with the teeth profile.  Tolerance is how accurate the profile will be.

You can add backlash to make the profile bigger or smaller.

This will help to make a drawing for inspection.

[DANIEL.CHASE]

I don't think this works for involute splines, just for spur gears.  I do not see the Export tooth shape option for Involute Splines. 

Using Inventor 17

[Anonymous]

You're correct.

Spline is handled differently by Inventor.

The spline and hub I work with, usually are gear cut not spline.

[Anonymous]

See if this software works for you: http://camnetics.com

[Anonymous]

I am trying to make involute spline 130mm x 2.5 Module x 51 Teeth but i am not getting accurate model. 

How can i get accurate? 

if anybody knows about it,please help me. 

[johnsonshiue]

Hi! What release are you on? The issue should have been fixed on 2018.2.

Many thanks!

[Anonymous]

Hello

I am using version 2016.

[Anonymous]

Sir

is there any service pack for version 2016 to get accurate spline model?

[Anonymous]

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@bob_holland wrote:

Daniel,

I wanted to confirm that what Fredrick states is true.

I have confirmed with our development staff that  involute splines are estimated.

I am sure Fredrick would appreciate it if you acknowledged his input and accept his response as and solution and you can also give him kudos for effort and knowledge.

Have a great rest of your week.

---

Hi Bob,

Thanks for confirming this. May I ask if this is still the case for version 2019? If it is, do you have any plan on implementing the real spline profile into the design accelerator?

Cheers,

Chuan