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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
    You think that's too expensive? You're not a Model Engineer are you? :D

  3. #13
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,792. Received thanks 189 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.
    You think that's too expensive? You're not a Model Engineer are you? :D

  5. #15
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,792. Received thanks 189 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.
    You think that's too expensive? You're not a Model Engineer are you? :D

  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
    You think that's too expensive? You're not a Model Engineer are you? :D

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