Matching Threads

[Anonymous]

Hello,
I am a freshman in a high school women’s engineering academy where we are currently completing year long projects. My partner and I are trying to 3D print a model of a bottle cap that we have designed where a screw like piece twists into the whole of the the cap. However, we present this week and still have not been able to print a successful cap because the pieces do not fit together because of the threads in the hole. Any help would be greatly appreciated as we are way behind and struggling as young engineers.
Thank you

[The_Angry_Elf]

First, Welcome!

Is it possible to post the file(s)?

I'm assuming you have the bottle cap and the bottle it needs to go onto, correct?

I am also going to assume the obvious that the thread designations on the bottle and the cap are the same, correct?

[Anonymous]

I am not able to post the file at this moment. But, we were not able to directly connect the cap to the bottle, we are simply trying to make the pieces of the cap that screw together. So, the bottom piece of the cap has a hole, like a nut, and the top piece of the cap has an extrusion with threads, like a screw. But, we cannot get the pieces to match as we have no experience with designing thread so on inventor.
Thank you

[TheCADWhisperer]

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@Anonymouswrote:
I am not able to post the file at this moment. 

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When you are able to Attach the files it will be possible to provide step-by-step instructions. You will become familiar with the Coil command.

[Anonymous]

We are using the thread modeler program but we don’t know what size to make the parts so that they fit together once the threads are attached.

[TheCADWhisperer]

I assume you are referring to CoolOrange thread modeler.

I would not use that for bottle threads.

[Anonymous]

We are not using threads to connect the cap to the bottle, and we do not have time to learn to model the threads on our own. We are only trying to create a threaded hole and a screw part that connect, but are unable to get them to line up.

[Anonymous]

Here’s a picture of a model that we printed.

[TheCADWhisperer]

Can you ask your instructor to join this discussion?

[Anonymous]

No, not at this time. He’s just as new to the subject and doesn’t know how to help.

[Anonymous]

We really need help in completing this project as we are very quickly running out of time and are unable to complete it on our own!!

[TheCADWhisperer]

Can you Attach your file(s) here?

[Anonymous]

Here is the file. 

[TheCADWhisperer]

stl files are only for 3D printing.

You will need to attach your *.ipt files to get assistance.

[Anonymous]

Our flash drive is in the printer producing more models, if these do not work I will get it and send the ipt files. 

[Anonymous]

looks to me based off this picture that the threads might not be whats causing the issue. Threads, especially ones so small, are a very precise thing and small errors can cause things to bind and not connect correctly. You might try taking the one with a hole to your woods teacher and ask for help to use a very thin band saw and cut it in halves. Then lay the top part inside and look to see where the issue is. This would let you know if it is a design issue or if its a issue with trying to 3D print these parts and the inherent error/Roughness of 3D printed parts.

this would also help you see if it is the thread, if its the major,minor, or pitch diameter of the thread that's off, or the pitch itself. 

[Frederick_Law]

Simply put, everything in the cap need to be a bit bigger then the bottle.  The thread need clearance to slide together.  You can't fit a 5mm pin into a 5mm hole.

Next problem is the 3D printer.  They don't produce 100% in dimension.  A 5mm pin maybe bigger or smaller.  You need to measure and adjust your model so it'll work.  It'll take some trial and error.