Mathematical problem.

[Mjolinor]

Right. Time to give your brain an exercise. I cannot find an answer on the Internet and it is baking my noodle.

Let's say I have a 10 mm bolt that is 20 mm long. It is too long so I cut 5 mm off it.

What shape is the end of the bolt where I sawed it with my laser thickness saw at exactly right angles to the longitudinal axis of the bolt?

I can see that distance from the centre of the bolt when you start cutting at the bottom of a thread is radius (5mm) minus thread depth. As you complete the cut the distance to centre is 5mm. Between those two points every degree your saw edge rotates as you are cutting increases distance from centre by thread depth / 180 so it is a linear increase to maximum.

Several thoughts on it, is it a circle, I think not? Is it an inferior Hypotrochoid? I reckon it is like an egg but am not sure what that two dimensional cross section of an egg is called.

Over to you. If you are not understanding the question then ask for more clarity.

@ gmb45: Yes, I know I talk pish
@ meathead: Don't bother, I probably would not understand your ramblings even if they were correct

[clusters]

Are you looking for a name for the cross section contour? I don't think there is one to describe such an odd shape.

Edit: And the contour may change according to pitch. Is it 1.25, 1.50, acme?

[Mjolinor]

I think the shape is a codiform. I was meaning a normal triangular thread, no acme square, ballscrew or anything, just standard triangular.