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Threads real?

Discussion in 'Using Alibre Design' started by pridbor, Dec 12, 2020.

  1. pridbor

    pridbor Member

    I'm trying to create a Plug with threads, see coarse draft design.

    I picked and applied a standard size of 36mm 1.5 to the "rod" portion.

    Is this a true thread i.e. if I send this to a 3D print will it come back as a usable thread, or is this just for show?

    Thanks in advance

    Preben
     

    Attached Files:

  2. Lew_Merrick

    Lew_Merrick Guest

    Hi Pridbor -- The "Cosmetic Thread" shown in your Part exists only to pass threading information to a Drawing. What you need to make "3D Printable" is a BOOLEAN Subtract (or, though it is slightly harder to accomplish, a BOOLEAN Add) to modify your Model. (A) I deal nearly always in inches and (B) I basically only make such "BOOLEAN Revisions" to (shall we say) non-60°-Vee Threads to make them "leap out and bite the machinist that an "uncommon Thread" is being used. However, if you look through my postings under Resources you should get an idea as to the approach I use. -- Lew
     
  3. HaroldL

    HaroldL Alibre Super User

    You can perform a Boolean operation as Lew suggests or create threads using the Helical Boss tool. I have a crib sheet in the Resources that may be some help in that regard.

    When you print threads do you need to "resize" them to allow for printing? I know that for the printer they have where I retired from we had to reduce the thread size and diameter between .010 and .015 depending on the layer thickness.
     
  4. pridbor

    pridbor Member

    Thanks, both, I shall search the resource area.

    I have never done a print with threads before so I have no experience in that unfortuately.

    If I do get to make my part I shall be happy to share my findings here

    Thanks again

    Preben
     
  5. Lew_Merrick

    Lew_Merrick Guest

    Hi Preben -- I am located on the west coast of North America (GMT-8). I have a GoToMeeting account so, should it be helpful, you & I could do a GoToMeeting to get things clearer for you (if so, e-mail me a proposed date and (GMT?) time to tangent@olympus.net). -- Lew
     
  6. bigseb

    bigseb Alibre Super User

    This. Either reduce the diameter of the male thread or increase the diameter of the female thread by 0.1mm to 0.2mm, depending on process and calibration of printer.
     
  7. pridbor

    pridbor Member

    So I did a thread using the (for me simpler) Helical cut tool and it looks good sometimes but mostly it has some really nasty defects. I don't really care about precision (yet) just want to get the consistent and correct output. The simple "hollowing" hole at the end is quite weird too. I have played around a bit move operations up/down, but I always seem to get some unpredictable results to what I consider rather simple operations, or?

    Have you gents observed anything like that in the attachment?

    Update: it looks like it may be related to the 1.5 pitch. If I use 1.499 or anything other than 1.5 then it all seems to work fine! ???
     

    Attached Files:

    Last edited: Dec 15, 2020
  8. HaroldL

    HaroldL Alibre Super User

    The extra surfaces on your part has been a problem with Alibre for a while. I have no idea why they cannot get a helical feature to display correctly. I've seen similar results with the Sweep.

    Start a ticket and send your file to Alibre Support. See if they can figure this out. It should not be happening.

    I had a closer look at your part, specifically the sketch for threads. After adding some constraints to the sketch it looks pretty good. Not sure of the dimensions though. Try fully constraining the Helical sketch and see how it looks for you.

    Cylinder Plug w Metric Thread 3.png
     

    Attached Files:

    Last edited: Dec 15, 2020
  9. pridbor

    pridbor Member

    Thanks, Harold!

    I can upload your attachment, but as soon as I try to just look at the (clicking) Helical cut in the explorer then it "complains" and won't regenerate!

    I will try to figure out how to start a ticket and send it to Alibre.

    Thanks for helping a casual user like me!
     
  10. JST

    JST Alibre Super User

    Alibre likes to find tiny overlaps, and then will scream and refuse to do the operation.

    Usually it IS directly related to the individual dimension. On a thread, if the pitch puts the edges of a cut or helical boss together, it may scream and pout. Oddly, a definite overlap often causes no issue, which I think is why you get just that dimension giving a problem. The edges coincide, and that breaks the rules for Alibre.

    If you do a proper thread that has flats at major and minor diameter, that problem can be avoided.
     
  11. pridbor

    pridbor Member

    Thanks all!
     
  12. pridbor

    pridbor Member

    Plug for Suspension Cyl 3.jpg
    Ordered a prototype "Plug" over the Holidays and got it a few days ago and thought I wanted to share it with you.

    I tried it on my hydraulic cylinder and it works. I'm not sure it will pass muster if it was to be used on the Space Station :)

    Thank you all for advising a novice

    Preben
     
    NateLiqGrav likes this.

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