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| Helix angle |
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| seadog:
You're using the diameter rather than the circumference. Remember that the thread is an inclined plane, the length of the hypotenuse being the circumference. |
| Pete.:
I get it - pitch over 'distance cut'. Had to think about it for a bit. |
| DavidA:
Dave (m), Out of curiosity I did the calculations and came up with the same as you. But what was more interesting to me was that I used, for the first time, a Casio fx85GT PLUS calculator. You need diplomas in computing just to operate this thing. My old fx81 is child's play compared to it. What a performance. But I think I have cracked it. I was wondering if I could down load an application (hate the word 'ap') for my tablet so I could create some programs to do this stuff. Dave. |
| DMIOM:
--- Quote from: seadog on June 19, 2016, 04:53:59 PM ---You're using the diameter rather than the circumference. Remember that the thread is an inclined plane, the length of the hypotenuse being the circumference. --- End quote --- Agree re circumference rather than diameter, but think that "in Tan terms" the circumference is the Adjacent rather than the hypotenuse? Dave M |
| Pete.:
It is, I was using tan because of the (wrong) way I was visualising the problem. That said, I looked at an online calculator and the figure it produces agrees with using tan=O/A using the circumference of the stock material rather than calculating the length of the hypotenuse of the un-wound thread helix and using sin. |
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