# How to model an arc coil spring?

#### ryanmcalister

##### New member
This is my first post to the site. I was wondering how you would model an arc coil spring. There must be a formula I can use under the functional spline form under algebraic equation pick. Then I could do a sweep of a cross section to create the spring but I need help with the equation or a better idea.
Thanks,
Ryan

#### ronaldvandenbroek

##### New member
I'm always using the Helix Function..( Insert-Curve-Helix).

With this function you can state the Nr of Turns, Pitch.
You can either choose to use a radius or a Law (start diameter, end Diameter)
Also you can define a right hand or left hand helix....

After you've constructed the Helix just use the Tube function...(Insert-Sweep-Tube) to make the actual spring.

Good luck...

Last edited:

#### SDETERS69

##### New member
Here is the formula for a function spline The created a Garter type spring.

I use this in I-Deas I do not know how much different it will be to use in UG NX software.

r1 = 100
r2 = 25
q0 = 0
q1 = (2*pi)*u+q0
q2 = 60*q1
x0 = 0
y0 = 0
z0 = 0
x1 = r1*cos(q1)
y1 = r1*sin(q1)
z1 = 8*u
x = x0+x1+r2*cos(q2)*cos(q1)
y = y0+y1+r2*cos(q2)*sin(q1)
z = z0+r2*sin(q2)

r1 = large radius of the torus
r2 = radius of the helix around the torus
q0 = initial angle of rotation of the path
x0,y0,z0 = centerpoint of the torus

#### rushik1986

##### New member
Garter Spring

@ SDETERS69

Hey thanks for the formula above. What does 'u' represent here??

#### SDETERS69

##### New member
I do believe U=1 1 Would equal 360 Degrees

So .5 would be 180 and so on. It is how much of the garter spring you want. If you want a full circle U=1