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  1. #11
    Still looking around :-x
    Measured the angle and although it might not be dead accurate, it reads 21 degrees.
    (Se Attached sketch)

    Click image for larger version. 

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    I just hope Coventry feedback next week will tell me something...

  2. #12
    I've measured one of my Coventry Easy Change at 20 degrees
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  3. #13
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,490. Received thanks 158 times, giving thanks to others 5 times.
    Standard BT tapers are 7/24, which going by my calculation, works out at 16.26 degrees.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  4. #14
    Quote Originally Posted by m_c View Post
    Standard BT tapers are 7/24, which going by my calculation, works out at 16.26 degrees.
    I've measured Coventry Easy Change and BT30 for comparison/reference with a Moore & Wright Angle Thingy, here's the photos -

    I used BT30 because it's the "Taper Which It Definitely Isn't" which keeps getting rolled out here, it mystifies me and I was tempted to use a MT3 taper, but I'll go with the flow ;-)
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by magicniner; 20-12-2016 at 12:49 AM.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  5. #15
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,490. Received thanks 158 times, giving thanks to others 5 times.
    It really wouldn't surprise me if Boxford used a custom taper and holder design, just so you had to buy holders from them.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  6. #16
    Knowing a change in diameter over a fixed height it's a really easy bit of fag packet sketchery and school trigonometry to calculate the taper angle -
    Sine - Opposite/Hypotenuse
    Cosine - Adjacent/Hypotenuse
    Tangent - Opposite/Adjacent

    Do they still teach the basics at school? I meet so many people who don't seem familiar with them I do wonder,

    - Nick
    Last edited by magicniner; 20-12-2016 at 01:48 AM.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  7. #17
    Quote Originally Posted by magicniner View Post
    I've measured one of my Coventry Easy Change at 20 degrees
    This is why i suspect the tool holders to be Coventry.
    My measurement was not accurate holding 2 steel rulers along each side and then measure With a School Plastic 180 Degree Protractor.

  8. #18
    Quote Originally Posted by m_c View Post
    It really wouldn't surprise me if Boxford used a custom taper and holder design, just so you had to buy holders from them.
    I think Boxford and Coventry used to collaborate previously(at least) on toolholders.
    I seem to remember a chap talking about some Coventry toolholders for his VMC190, and i think it`s the same toolholder.
    Still havent got any answer from Neville at Coventry yet though.

  9. #19
    Quote Originally Posted by magicniner View Post
    Knowing a change in diameter over a fixed height it's a really easy bit of fag packet sketchery and school trigonometry to calculate the taper angle -
    Sine - Opposite/Hypotenuse
    Cosine - Adjacent/Hypotenuse
    Tangent - Opposite/Adjacent

    Do they still teach the basics at school? I meet so many people who don't seem familiar with them I do wonder,

    - Nick
    This is basic Math Nick, but the Challenge is to measure 100% correct top diameter on the taper and correct distance in between(the taper top i slightly rounded).
    Tryed to improve my measurements and got lower dia at 31,61, top dia at 20,9 and length at 30. This gives a Cone angle α = 20.24 = 2014' , taper 35.7%.
    This is definately no standard taper in my opinion...

  10. #20
    Quote Originally Posted by Proteus View Post
    This is basic Math Nick, but the Challenge is to measure 100% correct top diameter on the taper and correct distance in between(the taper top i slightly rounded).
    Tryed to improve my measurements and got lower dia at 31,61, top dia at 20,9 and length at 30. This gives a Cone angle α = 20.24 = 2014' , taper 35.7%.
    This is definately no standard taper in my opinion...
    Your dimensions are almost exactly what I get off the Coventry Easy Change if I try to measure where you have using digital calipers.
    Because of the problems measuring the top edge of a frustum with calipers I chose to measure the OD in two places where an easily measured OD is available, at the bottom edge of the taper and the top edge of the groove, with a micrometer then measure the vertical distance between the two with a vernier, that gives me a calculated angle of 10.02 degrees. (Once I'd downloaded a decent calculator with inverse functions to my phone - what's the use of sine without arcsine Mr Samsung!)

    If you super-glued your two steel rules together in alignment with the taper you could draw a nice big triangle on a piece of A4 and measure/calculate the angle ;-)
    - Nick
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

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