【转帖】hread orientation dimensioning

yang686526

thread orientation dimensioning
hi,
i am to draft drawings for parts which has a male and female threads. these parts are required to be orientated using the threads, i am not aware of dimesioning threads with a tolerance to the orientation. the tolerance however is + or - 4.5 degree and both the threads are to start from 12 o clock i.e 0 degree. are you aware of any dimensioning practise for this purpose. need more info please let me know.
mechotron
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i'm not exactly sure about your situation, but in general, i would use a guide pin in your piece to locate a threaded holes, and not use the thread itself. just my two cents.
if this is not possible, locate your datums, and put a feature control frame on your hole note as you would on a regular, drilled hole. locate the position of your threaded hole within Øx of datums a, b, etc.
this is how i would do it, unless i'm completely missing the situation.
good luck!
v
mechanical engineer
"when i am working on a problem, i do not think of beauty, but when i've finished, if the solution is not beautiful, i know it is wrong."
- r. buckminster fuller
mechotron may be trying to locate the orientation of the thread start.
i don't know of any way to do this other than an explanatory note.
i could also be completely missing the situation.
we generally use gd&t on the pitch diameters.  practically impossible to measure but it gets the point across.
hard to tell how to apply in your case without more detail of the part shapes involved.
aha--thank you ewh, i think i may understand. i agree with ewh--an explanatory note may be the best way. good luck trying to get the threads to end where you want them. if there is some other way to line them up, i would suggest exploring it.
v
mechanical engineer
"when i am working on a problem, i do not think of beauty, but when i've finished, if the solution is not beautiful, i know it is wrong."
- r. buckminster fuller
i have dim'd a thread before like this. the only way is to add a note for start position, but with a loose tol.
chris
solidworks 08 0.0/pdmworks 08
autocad 06
i agree with ctopher.  
using the thread in this manner and applying a start position is practically not practical.
matt lorono
cad engineer/ecn analyst
silicon valley, ca
thanks for you replies. the dimension has to reference the start point of the thread.
i persume that a text is possibly the best way. can i ask you what is a gd&t.
mechotron
geometrical dimensioning & tolerencing???????
mechotron
yes.
chris
solidworks 08 0.0/pdmworks 08
autocad 06