Thread: VMC300 Toolholder question
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19-12-2016 #11
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20-12-2016 #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
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20-12-2016 #13
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.
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20-12-2016 #14
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 ;-)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
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20-12-2016 #15
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.
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20-12-2016 #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,
- NickLast 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
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20-12-2016 #17
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20-12-2016 #18
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20-12-2016 #19
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° = 20°14' , taper 35.7%.
This is definately no standard taper in my opinion...
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20-12-2016 #20
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 ;-)
- NickYou think that's too expensive? You're not a Model Engineer are you? :D
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