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SebastianH.1-Visitor
1-Visitor
February 21, 2010
Question

Proper display of a screw

  • February 21, 2010
  • 1 reply
  • 6687 views
Hi there! I am a student in a technical school and we are using the pro E 4.0 student edition. (Datecode M092) At the bottom I've put a picture of my problem. As you can see, the core thread is displayed, but the external one on the countersunk bolt isn't visible. (yes, I made one.^^) This is a problem, which sometimes occurs in our class. Till now I've never had any problems with these things. Can you give me some hints, how to fix the problem?

    1 reply

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    Anonymous
    February 22, 2010
    PTC provides a full explanation of the settings and methods for achieving proper display of threads in drawings here: http://www.ptc.com/cs/cs_27/howto/vew849/vew849.htm I should also note that what you see on the screen is not exactly what you will get on the hardcopy drawing when you print. The printing funciton does additional cleanup and line font changes. Depending on what you are printing to or exporting there are print settings that can also affect the thread views... for example... if you export a PDF file you must choose "Dashed Hidden Lines" in the Settings. A personal note about threads from many years of exerience, which runs a bit counter to the link I gave you above... I have always recommended that externally threaded objects be created with the Solid shank at the MINOR diameter, and the cosmetic thread at the Major dia. Internal threads would be "normal" with the drill dia into the solid, and the cosmetic thread at the Major dia. Why? This avoids the hidden line removal headaches where lines randomly disappear when solid parts interfere. PTC knows this... just download their Basic object library and look at their threaded fasteners... they were all created this way. See attached screw model I created (student version).
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    DELETEME1-Visitor
    1-Visitor
    February 22, 2010
    'Couldn't get to the link. I have a counter opinion. We have always drawn (hand-drafted and AutoCAD) and modeled external threads at the major dia with cosmetic threads at the minor dia and internal threads at minor dia with the cosmetic threads at the major dia. Yes there is an "interference". But this is typical drafting convention (for probably 100 years or more) for a good reason: This is the way the actual fastener geometry will behave. For example, a 1/4" screw will only fit thru a minimum of 1/4" hole straight hole. A dowel pin that will pass thru a 1/4" threaded hole will need to be .1894" or less. I would ABSOLUTELY NOT advise modeling fasteners and holes as mentioned above. It would be very misleading. Just deal with the erratic hidden line behavoir.
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    Anonymous
    February 22, 2010
    Attached is a copy of the web page from that link. A "drafting convention" is just an agreement on how to symbolicly represent real geometry. A "CAD modeling convention" is just an agreement on how to symbolicly represent real geometry. You really should look at the model I sent and see what it looks like, and what it looks like on an assembly drawing. I don't think it's misleading at all. If you want simulate reality then go ahead and model the actual threads. (And get a bigger computer).
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