VMC300 Toolholder question

[magicniner]

I've just been and compared one to a BT30, and the Easy Change holders have a steeper taper.

Agreed, but I can't find the taper of the mystery holder, if you can enlighten the group with the exact taper of the mystery holder we could measure the angle of the Coventry Easy Change and compare?

- Nick

[Proteus]

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



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

[magicniner]

I've measured one of my Coventry Easy Change at 20 degrees

[m_c]

Standard BT tapers are 7/24, which going by my calculation, works out at 16.26 degrees.

[magicniner]

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 ;-)

[m_c]

It really wouldn't surprise me if Boxford used a custom taper and holder design, just so you had to buy holders from them.

[magicniner]

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

[Proteus]

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.

[Proteus]

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.