Cosmetic thread or Model threads?

[89ers]

Hey all,

I'm trying to find the correct way to call out the thread I want on a custom water bottle that will be manufactured overseas. This file will be sent to a mold maker and I just want to do whatever I can do ensure that the threads come out right. The only standard i've found helpful is the one SPI one for the bottle industry, but it didn't give me anything particular.

What I'm trying to do is create a thread for a 55mm diameter hole. The thread would be a double start lead thread with a 3mm pitch and it would need to travel at least 4.5mm in height on 1/2 turn revolution.

I've had such a headache trying to figure out how to call out the threads, but what if I just leave the threads modeled into the solidworks CAD file? Will this be fine or should I find a professional to help me with the thread call out?

 

[CheckerHater]

Unless your thread is following widely recognized standard, don't bother with the call-out.

Plastic industry in it's current sorry state rarely follows any.

Check this place:

http://www.bevtech.org/threadspecs-downloads.asp

If you won't find thread you like, make-up your own. Model it and provide dimensioned drawing if you want your thread produced to certain tolerances.

 

[3DDave]

I agree with CH - if there isn't one you can find that's already documented, create your own thread drawing. I suggest looking at existing screw thread drawings as examples. They will have solved most of the problems with defining threads and will be a good guide for you.

The problem with only leaving them in the model is there is not likely to be a good tolerance description. You may also want to contact a stress engineer to analyze the forces and strains applied and resulting stresses that result from tolerance limit conditions. For example, you are looking at a double lead thread, but unless the plastic deforms enough only one of the two threads may actually take any load. The stress analysis will tell you how closely made they need to be and how perfect the closure surface has to be to work correctly.

 

[dgallup]

When you are sending a file to a mold maker you should model the thread. It's one of very few times I would do that but if you don't they will have to and who knows if they will do it right.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[CheckerHater]

Our mold-maker sometimes attempts to model his own thread even if we DO send them our model. Ugh!