@The_fat_Hobbit If I remember correctly the helical curve is an approximation based on caclulated points and the accuracy of that can be adjusted in Variable Table after the curve has been created. You might try increasing the accuracy to see if it helps. I believe it is set to a lower accuracy by default as the helical features are compute intensive.
@JasonTitcomb Don't fix it for my sake but that part won't open as a step using a part template. It will open in an assembly template as a part in an assembly but the part contains nothing.
I thought it would be fun to try Goal Seek on this.
If you use a start of 252.0 or an end of 427.5 or an axis length of 105.62 you will get your 100deg sweep.
Maybe Goal Seek can help you find the error.
So I have plotted a law curve in NX10 with a start and end lead angle equal to the start and end pitch of 292.5 and 468 respectively.
Then I performed a wrap curve to turn this into a helix. Sure enough the number of turns equates to 100°.
Then in the same part file I make a variable pitch helix with the start and end pitches equal to 292.5 and 468 respectively.
I then observe the number of turns and this equates to 94.675°.
To my mind this means one can make a helix with a start and end pitch of 292.5 and 468 whilst simultaneously having an axis length of 100 and a number of turns equal to 100°.
I then return to my original query, why does the variable pitch helix not produce the same number of turns?
I have attached the part file, if anyone has any idea of what is going on...