Drawing a bevel gear.

[Dreke]

I'm drawing an RC car in Invetor since a few days and a have a few parts already. I was trying to make a gear for the diffrential (a bevel gear) but wasn't able to really get it how I wanted it.

I'm new to inventor so I don't know allot of things. But isn't ir wierd that you have to build in in assembly? I would prefer to make it as a part and then add it in my assembly?!?

So I'm struggling with getting the right dimensions of the gear. I doesn't seem that there a diameter tab in the Design Accelerator. When I make the gears they are always way to big for my rc car. I there an easier way to do it other than Design Accelerator? Or Is there a more easy way to make it in Design Accelerator?

What I'm trying to make :

Thanks

[JDMather]

---

@Dreke wrote:

.. But isn't ir wierd that you have to build in in assembly? .... 

Thanks

---

How is that wierd?

What use would it be as just a single gear?  Don't you need mating gears in the mechanism?

If not, simple delete the extra part.

It could be modeled the hard way (manually), but -

You have not provided any specifications for your desired gear?

Will you be manufacturing these gears - or purchasing off-the-shelf, or is this just for "show"?

[Anonymous]

Design Accelerator works at the assembly level so that it can use exisiting geometry to help determine the gear size. For an in-place drop of a standard part, I agree that it's easier to place straight into the assembly using something like design accelerator or content center. Definitely saves you a ton of time compared to finding dimensions and drawing them yourself.

While I do agree with JD that manually drawing this thing would be a pain... I tried it anyway. And he was right lol. Not sure how you would draw this JD but through some trial and error, I got something that works (I think). 

Everything is controlled through sketch1. Since I'm not very familiar with drawing this type of gear (I think I've literally never done this), the driving dimensions might not be correct. Nevertheless, you should be able to alter the way the profile is defined so long as you don't delete any lines. I also set up a user parameter to determine how many teeth are in the gear. If you're not familiar Dreke, the parameters menu is in the application toolbar at the top of the window:

I didn't see if you were using 2014 or higher. Hope you can open my file!

EDIT: In messing around with the file after uploading, I realized that the number of teeth you can apply is pretty limitless given the way that it's drawn. 600 teeth later and the thing looks like an air filter lol.

[JDMather]

If you are going to attempt to model from scratch - you will want to find information on development of a circular involute curve (unwrapping of a string from a circle).

Other search terms

Pressure angle

Diametral Pitch

Pitch Diameter

Addendum

Dedendum

Face Width......

From Gieseck, et al Technical Drafting

[Anonymous]

---

@Anonymous wrote:

If you are going to attempt to model from scratch - you will want to find information on development of a circular involute curve (unwrapping of a string from a circle).

---

So I've never heard of that before. And it took me a second to get my mind around it. But with the help of a wiki (http://en.wikipedia.org/wiki/Involute_gear) and some thought, I think I get what you mean. I'm not really sure how that applies to the design of the gear's tooth profile (though in the wiki, there's a great little gif that pretty well explains what is wrong with my model) but I threw something together to represent an involute curve. I drew it out in a sketch in inventor and splined the resulting curve. Is this what that means?

Also... I don't really know why my spline is fully constrained... I feel like it should still have some freedoms I haven't defined...

EDIT: After seeing your edit, it's quite clear I know very little of gear design. It's interesting though.

[Dreke]

That is so nice ! Is there a way to make this easier with thze Design Acc.? Or is this impossible with that?

I'm not very familiar with the Design Acc. but it seems I can't set an exact diameter for my gear? It makes a gear that is allot to big but I don't have any idea how to resize it in accelerator?

Your gear is awesome and I think I'll use that, but would really like to know how to do these things with accelerator than? Is there no diamter tab or something?

[SBix26]

I just played around with the Design Accelerator a bit.  On the design tab, the Diametral Pitch and Number of Teeth will control the size.  For a small plastic gear as you showed in your earlier post, you will want a very high number of teeth per unit measure.  There are handles on the preview to manipulate width and number of teeth for each member of the set.

Hope this helps-- the Design Accelerators are not very intuitive, but the calculations they are performing are not simple, so perhaps that is as it should be.

Sam B
Inventor 2012 Certified Professional

Inventor Professional 2015 SP1
Windows 7 Enterprise 64-bit, SP1
HP EliteBook 8770w; 8 GB RAM; Core™ i7-3720QM 2.60 GHz; Quadro K4000M

[graemev]

I've done this, from scratch, and can attest to it not being particularly easy.  Feel free to use/laugh at/modify these samples.  The EOP marker has been pushed up to save file space on transfer.  Just push it back down to reveal the geometry.  (Inventor 2014, by the way.)

Edited to add:  In the parameters, scroll down (way down) to the user parameters and you will find all the gear parameters listed in J.D.'s list.