fplot a variable pitch helix???

[Roger Peterson]

Anyone have an equation for creating a variable pitch helix via the fplot chook? I'm actually looking for the 2D (unrolled) geometry but I don't care if the geometry is created rolled or unrolled as it can always be unrolled.

 

How about an equation for a fixed pitch helix? I could possibly get it from that point (hopefully).

 

I have been playing but have had zero success.

[JDowe]

Could not get an equation to do it - but

if all you need is the geometry it can be done

grapically - let me know if that helps - I

can e-mail you the method I use

[crazy^millman]

Could you use asphere ability to create the same effect. Look in your machine builder book for a G7 they have the equations for this. You might be able to plug it into here I do think you can but it might be worth a shot to see. F plot still seem the right way just a real pain sometimes is all.

[HVC]

I remember James making a similar part here you might try to get him to chime in. I still have the part here. He did it on a lathe though if that makes a difference.

 

HVC

[crazy^millman]

Well here is the function:

 

code:

---

Sprial interpolation in the XY plane is defined as follows: 

(X-X_0)^2+(Y-Y_0)^2=(R+Q')^2

X_0 : X COORDINATE OF THE CENTER

Y_0 : Y COORDINATE OF THE CENTER

R : RADIUS AT THE BEGINNING OF SPRIAL INTERPOLATION

Q' : VARIATION IN RADIUS

 

WHEN THE PROGRAMMED COMMAND IS ASSIGEND TO THIS FUNCTION, THE FOLLOWING EXPRESSION IS OBTAINED:

(X-X_S-I)^2+(Y-Y_S-J)^2=((R+(L'+theta/360)Q)^2

X_S : X COORDINATE OF THE START POINT

Y_S : Y COORDINATE OF THE START POINT

I : X COORDINATE OF THE VECTOR FROM THE START POINT TO THE CENTER

J : Y COORDINATE OF THE VECTOR FROM THE START POINT TO THE CENTER

R : RADIUS AT THE BEGINNING OF SPRIAL INTERPOLATION

Q : RADIUS INCREMENT OR DECREMENT PER SPRIAL REVOLUTION

L' :(CURRENT NUMBER OF REVOLUTION)-1

theta: Angle between start point and the current postion(degrees)

---

This is from a fanuc book.

 

HTH