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Thread: Compound angles

  1. #11
    Join Date
    Mar 2008
    Location
    Kent, U.K.
    Posts
    2,351

    Default

    Quote Originally Posted by winchman
    "...but I bet the first few I made would come out wrong"

    How would you know they're wrong?
    I wouldn't have to. I'd bet they'd be wrong whether I knew it or not
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

  2. #12

    Default More on Compound Angles

    Here is the answer I was looking for. It has been great revision for me and I have had considerable help from a mathematics forum.

    The problem was to find the set-up angles required to make a skewed milling cut in a rectangular block following given angles on three of its surfaces.



    The desired angles are A, B and C in planes YOZ, XOZ and XOY respectively. This is a right handed coordinate system with angles X -> Y, Y -> Z and Z -> X being +ve.

    1. Align vice jaws // X.

    2. Set block in vice so that line at angle A is // to XOY

    3. Tilt vice by angle D to XOY. Where

    D = atan(cosAtanB)

    4. Rotate vice by angle E from XOZ. Where

    E = atan(cosAsinC/(cosCcosD-sinAsinCsinD))

    John.

  3. #13
    Join Date
    Nov 1999
    Location
    SE OZ
    Posts
    3,964

    Default 3-dimensional set-up

    Mark out the OP's job (as per his pic - here):


    Put it in a 3-axis vise like this:


    Put the vise on a flat plate and use a surface guage or a height guage
    - like this:


    http://i200.photobucket.com/albums/a...faceguage4.jpg

    Or a variation like this:


    and set the three axis until the lines on the job are parallel to the mill table.

  4. #14
    Join Date
    Nov 1999
    Location
    SE OZ
    Posts
    3,964

    Default Theme

    More variations on a theme (no maths needed here either):








  5. #15

    Default

    Thanks for the many ways to do it if you have the equipment.

  6. #16
    Join Date
    Jan 2010
    Location
    Kansas City area
    Posts
    5,117

    Default Compound Angle

    You can leave the base of the vise flat on the mill table. Turn the vise to the first angle and clamp to the table. Put an angle block of the correct angle under the part to tilt it sideways in the vise jaws and then tilt the vise for the final angle.

  7. #17
    Join Date
    Oct 2007
    Location
    Demokratik Republik of Washington
    Posts
    278

    Default

    Quote Originally Posted by winchman
    "...but I bet the first few I made would come out wrong"

    How would you know they're wrong?
    Darn... now I have to clean coffee off of my key board........ I have done that before... and had inspection make the same mistake... only on assembly did they find out it was wrong....

    There are only two angle to figure... Tilt and rotate. Use a common leg, the angle you are cutting as the lenght of 1 and work from that. It really is simple.

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