Create threads to fit two separate components together

[joshuadhorner]

Hi everyone,

I'm very new to Fusion 360, and the world of 3D printing. I wasn't too thrilled with what I found online for dice vaults with (1) room for a miniature (2) a lid that could double as a rolling tray and (3) that didn't use magnets to hold itself together.

So I tried making my own, following some online tutorials on basic Fusion 360 usage. I've ended up with a project document that has two different named Components, one for the bottom and the other for the top. But now I'm kind of stuck... I want to be able to add screw threads on the outside top half of the bottom component, and the inside top half of the top component, so they can screw together to stay closed.

But, each time I try using the Create -> Threads command, nothing I do seems to ever make it so that they'll fit together right. Either it cuts way too close to the cuts already in the bottom piece, or, it super-thickens the walls of the top piece. Everything I look up for tutorials on screw threads is always talking about little bolts and nuts, and to be honest I'm not sure how to translate them to what I'm trying to do.

You can see the two pieces in my two screenshots below. Here's the public link for the project. I think I shared it correctly. I'd love any pointers or feedback you have. Was making it two different parts a big mistake? 

[jhackney1972]

You might want to explore using the coil command to try and create your threads. You will probably have to add some material to you body and cap to accommodate the thread cut/addition you want and need.  This will not be a quick placement as you will need to first create the thread dimensions you want and them create matching internal and external coil cuts.  Of course you are free to create your thread design but you may want to look at some standard thread designs for guidance.  I have attached my simple example model for you to take a look at if you would like.  I did not look at your model, except for the screen captures so I really do not know the size.  The model I did in 4" in diameter.

[TheCADWhisperer]

I think I would use either a knuckle thread or a trapezoid thread for this design.

[laughingcreek · Accepted solution]

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@joshuadhorner wrote:

... Was making it two different parts a big mistake? 

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No, but I would model them in place. as if they are already put together.

If you want to use a standard thread, make half of it (probably the bottom), and play around with the thread choices.  use the final choice to inform how the top is made. 

I would also stay away from using the primitives like cylinder.

here's yet another example-

[joshuadhorner]

@laughingcreek - I've been working through your attached file, and I have most of it down, I think. The part I can't figure out is how you created and constrained the arc-slot in the bottom sketch. I've attached MY version, for reference. I'm missing two things: (1) did you create tangent constraints for the left and right circle ends of the arc-slot to your construction lines? (I'm guessing that's what the 2mm and fx: 2mm are?) And (2) how did you constrain the line between the two center points of the arc-slot? (Yours is black; mine is brown) 

I feel like I'm so close! It's a shame I can't just see the "history" of your actual sketch; then I'd learn it faster. My goal would be to constrain the left and right circles of the arc to the tangent lines, like you did, but then to also constrain the "size" of the holes with a specific distance from the outer and inner circle. (In essence, giving the arc-slot 2mm "margins" on all four sides, instead of just two) 

[laughingcreek]

maybe this helps-

[TheCADWhisperer]

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@joshuadhorner wrote:

It's a shame I can't just see the "history" of your actual sketch; then I'd learn it faster.

@joshuadhorner 

See the Attached *.f3d file.

Die Vault

Trapezoid Thread

[joshuadhorner]

This (and your previous answer) were so amazing. Thank you so much! 

[TheCADWhisperer]

@joshuadhorner 

I added some finger grips to aid in separation and slots to use coin or other tool if they get stuck.

[laughingcreek]

Going to have to find a dime if it gets stuck

[TheCADWhisperer]

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@laughingcreek wrote:

Going to have to find a dime if it gets stuck

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Increase the slot width to fit one of your gold coins. 💰