Trouble Creating Large Gear

[Anonymous]

I am having a great deal of difficulty creating a large gear (5 m across).  I cannot get the spur gears to create on that big and I have been unsuccessful creating one in other programs and importing them into sketches.  They import into hundreds of small lines, usually, and are not corrected.  

My current attempt is attached.  It is a simple gear that is a sketch, but will not extrude.  I have no idea why not. Any ideas?

[Mark.Lancaster]

@Anonymous

When posting always indicate which version of Inventor you're using.  In your case its Inventor 2017..

Here's one quick suggestion..  (I will assume other users will have other suggestions as well)

Instead of trying to do the entire gear in one sketch and extrude it, break it up into smaller chunks/sketches..  Make a simple sketch of the gear diameter and extrude.  Make another sketch and do one of the gear teeth.  Extrude it and then pattern it around.  Use the modeling tools to your benefit and not throw everything into one sketch.  Keep it simple.. 

If you know the design information of your gear you can also create it through the gear interface under an assembly model.

[JDMather]

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@Anonymous wrote:

I am having a great deal of difficulty creating a large gear (5 m across).   

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Looking at your sketch - I am not sure what you are referring to as 5 m?

Let's start from scratch.

This is the primary formula that I will use.

D=N/P

Where:

D=Pitch Circle above

N=Number of teeth, in this case = 29 according to your sketch.

P=Pitch

I need two variables.  Is the 5 m that you refer to the D?  I can calculate P if I know D or the other way around.

What pressure angle (normally 20° or 14.5°)?

Don't worry about all the others, they are all functions of the 4 parameters

Pressure Angle

N

D

P

[WHolzwarth]

Your imported sketch is not good. Where does the IGES file come from?

Try this:

- Edit Sketch 2

- Select the shape of the gear

- Right-click and Break link

- After some waiting time you see a new shape, that can be extruded

But sadly, that's not the shape that you want

I've made a workaround, 2017 file attached. Now the gear can be done, but it's not good.

Try this instead:

Make a 29 teeth gear with gear generator, but only 1% or 10% in size. IMO, this wold be done.

After having the basic shape, make a derived part of it with scale factor 100 or 10.

Walter

[Anonymous]

Thanks all,

  I may have to make it from scratch as Mark says, but it is beyond me why these simple things do not function properly.

@Mark.Lancaster@: The spur gear does not accept the diameter I need and I cannot scale it up.  Perhaps I do not understand the interface well enough, but I was not able to generate the gear I need.  The spur gear should work in sketch and modelling, IMHO.

@JDMather: About 4 m diameter in this case.  Pressure Angle: 20.  Teeth 29. Pitch Diameter: 3.739 m   Diametral Pitch: 0.197   Attached is a photo of one of the gear generators I tried, but could not create a gear with.

@Anonymous : I was exported from Maya.   Attached is a dxf output from a gear generator.   Thanks for the workaround, but it seems very heavy.

>After having the basic shape, make a derived part of it with scale factor 100 or 10.

I was not aware of this capability.   I can make a derived part for a spur gear?  

Overall, this process has been very frustrating.  Simple things that should just work, don't, and there is no indicator as why.    Coupled with capabilities that come and go, depending on the mode, is a real headache.  I want to be able to select and delete a piece in every mode.  I know what I want to accomplish and spend a huge amount of time fighting the interface to get what I need.  All pieces should be created in the same place, not scattered around in different sections.   

After 15 years of development, I would think Inventor would be much easier to use and would do simple things without effort.  What I am trying to do is trivial and should "just work".

/rant

[JDMather]

Your numbers don't make sense.  Oh wait a minute, you have a mix of m, mm and cm  back in a few....

Your image isn't using the same numbers as your text?

Plug them into the formula.

D=N/P

All of this looks so very suspicious to me.

What do you really really really want?

In your text you refer to a Pitch Diameter of 3.739, but in your image you have an Outer Diameter of 3.937

Looks suspiciously like transposed digits to me, but on top of that - these are two very different features of the gear?

What do you really want for your Pitch Diameter or your Pitch?  Once I know one - I can calculate the other.

[Anonymous]

I will worry about the exact configuration of the gear later. What I am
trying to do is much more basic: "How to I make a gear that is 5 m in
diameter"?

[JDMather]

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@Anonymous wrote:
... What I am
trying to do is much more basic: "How to I make a gear that is 5 m in
diameter"?

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I am trying to present a general solution to any spur gear.

What is the 5 m measurement? 

Is this the OD or the Pitch Diameter (gears are normally specified by Pitch Diameter).

It would be difficult to use any gear generator if the numbers aren't understood.

Do you want a Wellman's Odontograph solution 

or

do you want a true involute solution?

This should head you in the right direction.

[JDMather]

Oops, I made a monster mistake in that example.

Back in a minute.

I forgot the Whole Depth (Root Diameter) in the previous posting.

[Anonymous]

Thanks. 5 m pitch diameter and involute.

@JDMather This picture is what the gear interface should look like within Inventor.  Nice job.   Each should have a slider so we can see what the gear is going to look like as we change parameters.  This is modern UI methods and I hope Autodesk would make it simple to create a gear.

[Anonymous]

I should have posted the 5 m pitch diameter screenshot. Here it is.  Sorry for the confusion.

 

[JDMather]

Your Diametral Pitch in that image is incorrect.

[Anonymous]

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@Anonymous wrote:

Your Diametral Pitch in that image is incorrect.

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Interesting.  This is what is calculated from the program when I type in 5 m for pitch diameter.

Here is another program I used: (5.8 for Diametral Pitch)

http://geargenerator.com/#300,300,100,6,1,0,3451.4999999996594,4,1,29,5,5.8,20,-90,0,0,16,2.7586206896551726,5.8,20,-60,1,1,12,1,12,20,-60,2,0,60,5,12,20,0,0,0,2,-809

[JDMather]

See attached.

The Pitch is 5.8

[Anonymous]

Thanks.  This is the type of gear I need.  How did you generate it?  I could not get the spur gear generator to work.

[Anonymous]

Today I made a gear in connection with my assignment. I made one teeth and circular pattern to get many. I don’t know whether it is helpful to you.

[JDMather]

@Anonymous

What is the application for your "gear"?  Is it for a belt drive?

The tooth profile is almost certainly incorrect. 

Philosophical question, "Why are you learning to use Inventor?"

To make pretty pictures?

In this field pretty pictures are not as useful as 3D geometry files.

[Anonymous]

This gear is made to assemble a model and to create a WELDMENT. Gear is made to according to dimension given in the drawing.

[Anonymous]

who can teach me how to draw if can email chngsam42@gmail.com Thanks so much 

[JDMather]

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@Anonymous wrote:

who can teach me ... 

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Are you a student of Centennial College - or is this simply an (incorrect) example that you found on-line?