Page 2 of 4 FirstFirst 1234 LastLast
Results 16 to 30 of 53
  1. #16
    Join Date
    Jul 2012
    Location
    Griffith NSW
    Posts
    435

    Default

    I agree with elanjacobs - solidworks puts out a diameter of 2.27mm

  2. #17
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by scottyd View Post
    I agree with elanjacobs - solidworks puts out a diameter of 2.27mm
    Aside from trial and error, how do you calculate/draw it?

  3. #18
    Join Date
    Jan 2012
    Location
    Melbourne
    Posts
    149

    Default

    "I agree with elanjacobs…"
    +1
    I missed by a poofteenth, two or 3 times....!

  4. #19
    Join Date
    Nov 2012
    Location
    Mid North Coast NSW
    Posts
    422

    Default

    Quote Originally Posted by Picko View Post
    what diameter are the circles ?

    2.2332381Ø

    Cheers John

    That doesn't quite work either it seems.
    How did you calculate it ?

  5. #20
    Join Date
    Nov 2012
    Location
    Mid North Coast NSW
    Posts
    422

    Default

    Quote Originally Posted by elanjacobs View Post
    This gets you within 0.4 micron of your required depth

    Attachment 375749
    Yeah ok but 2 different sizes of circles
    I could just guess and make the circles even a 1/4 of a mil out and it would work, it's just a rough plastic thread, but now I'm interested I would like to know the proper way to calculate it.

  6. #21
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by phaser View Post
    Yeah ok but 2 different sizes of circles
    All the circles are the same

  7. #22
    Join Date
    Nov 2012
    Location
    Mid North Coast NSW
    Posts
    422

    Default

    Quote Originally Posted by elanjacobs View Post
    All the circles are the same
    Ah yep okk sorry I thought the middle measurement was radius.
    So how did you get this ? trial & error ?

  8. #23
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Yeah, trial and error in decreasing increments until you get near enough.

    I'll try to remember to ask the CAD wizards at work, there must be a formula or geometric construction to do it but I can't figure out how.

  9. #24
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    837

    Default

    There is a right angled triangle with hypotenuse D, base 2mm (half the thread pitch) and height is D-1.2. Using pythagoras you get
    D^2 = (D-1.2)^2 + 2^2
    expanded
    D^2 = D^2 - 2.4D + 1.44 + 4
    simplified
    2.4D = 5.44
    D= 2.2666666666666666.......

  10. #25
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by lamestllama View Post
    There is a right angled triangle with hypotenuse D, base 2mm (half the thread pitch) and height is D-1.2. Using pythagoras you get
    D^2 = (D-1.2)^2 + 2^2
    expanded
    D^2 = D^2 - 2.4D + 1.44 + 4
    simplified
    2.4D = 5.44
    D= 2.2666666666666666.......
    Actually, I don't think you can do it like that because the centres of the circles do not actually lie on the lines that touch the top/bottom of the thread

  11. #26
    Join Date
    Nov 2012
    Location
    Mid North Coast NSW
    Posts
    422

    Default

    Quote Originally Posted by elanjacobs View Post
    Actually, I don't think you can do it like that because the centres of the circles do not actually lie on the lines that touch the top/bottom of the thread
    I reversed the triangle to the opposing circle tangents and it fits but can't use it to work out the circle sizes. Not that I can see anyway. Picked a curly one didn't I ?

    Green triangle Base 4, height 1.2
    Circles.jpg

  12. #27
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    837

    Default

    Actually, you don't understand what happened there. Consider what D - 1.2 represents. It is actually the vertical distance between the centres of the circles that form the top and bottom threads. This is a mathematically correct solution for calculating the diameter of the circles. Trust me I actually do have a maths degree.

  13. #28
    Join Date
    Oct 2010
    Location
    NSW
    Posts
    177

    Default

    How did you calculate it ?


    Easy!
    After 5 beers I used 1.2 as the circle centres.

  14. #29
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    837

    Default

    Quote Originally Posted by Picko View Post
    How did you calculate it ?


    Easy!
    After 5 beers I used 1.2 as the circle centres.
    The circle centres should be 2mm apart in the direction of the pitch and 1.0666666666666.... (ie D - 1.2mm) apart in the other and as stated above the circles should be 2.2666666666666666.... in diameter (where the dots indicate the last numeral is recurring).


  15. #30
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Quote Originally Posted by lamestllama View Post
    Trust me I actually do have a maths degree.
    Wow.
    Chris

Page 2 of 4 FirstFirst 1234 LastLast

Similar Threads

  1. Another Plasma circle cutting jog
    By BobL in forum WELDING
    Replies: 0
    Last Post: 16th Nov 2016, 09:58 PM
  2. Diameter Of A Circle
    By Keith_W in forum METALWORK GENERAL
    Replies: 56
    Last Post: 27th May 2014, 03:51 PM
  3. Turning a square into a circle
    By Vernonv in forum METALWORK GENERAL
    Replies: 14
    Last Post: 29th Nov 2010, 10:47 AM
  4. Cutting a circle in a cylinder
    By Doc58 in forum METALWORK GENERAL
    Replies: 16
    Last Post: 14th Jul 2009, 12:35 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •