Creating [modeled] Threads

[corsair2014]

I use Inventor for all my CAD creations, but the lack of thread modeling (specifically 2018, the CoolOrange plugin doesn't work yet) made me download Fusion 360 for creating modeled threads.

Basically I'm trying to create a cap that will fit a Wide Mouth mason jar.

3 3⁄8 in (86 mm) outer diameter

3" or 86mm continuous thread

It is probably my own ignorance of how the threading tool works, but every time I create a test 'lid' (round ring with threads) and 3d print it to test fit, it is either to small or too big. I've noticed that when i 'model threads' it resizes the inner diameter of the 'ring' i've created... 

What exactly happens when i 'model threads'? Does it resize my ring?

Can anyone point me in the right direction for creating these threads to fit the mason jar? I can provide my current Fusion file if needed.

Thanks in advance,

Colton

[HughesTooling · Accepted solution]

Fusion expects you to draw the OD for holes and for external threads so 85mm for both. The problem you're going to have is there's no 86mm thread in the library. What pitch do you need, you might get away with a 2d scale to increase the diameter of an 85mm thread, try 1.011 or maybe a bit more for added clearance.

Mark

[HughesTooling]

Just noticed there's a 3 3/8 ANSI Unified thread in the library. You still might want to use a 2d scale to increase the diameter a bit to give a bit more clearance.

[corsair2014]

Thanks for the reply.

So what diameter should I use (inner diameter) for the 'lid' to clear the OD of the jar?

[HughesTooling]

That will all depend on the pitch you select. In the image I attached I made a ring with a 86mm hole, when the thread's added 12TPI I end with an ID of 83.563 mm and OD of 85.725 mm. Changing the pitch will change the ID.

[corsair2014]

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@HughesTooling wrote:

That will all depend on the pitch you select. In the image I attached I made a ring with a 86mm hole, when the thread's added 12TPI I end with an ID of 83.563 mm and OD of 85.725 mm. Changing the pitch will change the ID.

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Okay interesting... So the 'minimum ID' will be determined by the threading size/pitch, correct? I.E. the 'gaps' in the thread will still be the modeled diameter right?

[HughesTooling]

Threads are specified by the OD of the screw, the minor diameter will change to match the pitch. Try googling thread size chart

Mark

[YanivBA]

How do you specify the center location of the thread, starting in sketch? I need 2 threads on the vertical plate and 2 on the horizontal and I know the centers of all 4, it's going to be M6

[HughesTooling]

You need to create holes first. You can use the hole tool or create a sketch with circles then extrude cut.

Have you gone through the tutorials?

http://help.autodesk.com/view/fusion360/ENU/?guid=GUID-7BD8CD24-27C1-4427-8499-29CC6827B902

Mark

[YanivBA]

You are the best, I'm always trying SW methods (don't know better), this is much better