# Spiral

#1

I’m new to shapr and would like to draw a spiral shape line. Can anyone point me in the right direction?

#2

Hi fonthill,

EDITED:
This answer is for creating a helix, not a spiral.
Sorry, my mistake…see my second post below

Shapr3d has an elegant method for creating helixs:

1. draw circle of desired radius
2. extruded circle to create cylinder
3. pick point at intersection of seam and circle
and commence line on surface on one side of seam
4. without lifting pencil, cross over to opposite side of
seam, to intersection of circle and seam at the other end of the cylinder.
5. delete cylinder.

It can be a bit finicky, but persistence will pay off.

Hopefully with further development, there will be means to pick end points of helix line for adjustment.
And ideally an option for inputing the number of revolution of the helix (or alternatively: number of degrees i.e. 720 = 2 revolutions)

#3

Hi fonthill,

It is possible to make a spiral, following method above, except using a cone (revolved triangle)

Then use resultant spiral helix as rail for sweep of vertical line. And finally boolean subtract both top and bottom of swept surface.

It is unlikely that this will meet your needs, but it is the best I can do (also a newb’)

#4

Thanks James, I’ve been playing with it and now found a solution

#5

That’s great, fonthill,

Can you explain how you achieved the drawing of a spiral. And maybe image of result

#6

#7

Hi Gensmenger,

Initially I also confused spiral with helix (common mistake…see above posts).

Achieving a spiral is not so simple.
Though there may be something I am overlooking.

#8

Hello dotDash,

When drawing the diagonal line from top to bottom on the cylinder, not only do you not lift off with the pencil, but also the finger that is revolving the cylinder. Once you lift off with your finger the revolving stops. That took some practice (about 10 trys).

However, in practicing, I found a short cut. Start with the pencil, start at the top (on the vertical line), and then draw straight downward, and maybe to the left a bit. A spiral appears that wraps the cylinder, and with care, you can navigate that point to the bottom (right on the bottom of vertical line). This is how I achieved the image above. Then I added a mirror, and then did a copy and move.

Hope that helps. This is a good exercise.

#9

Hi Gensmenger

Thanks for the tip, but again there is some confusion: fonthill was enquiring about spirals not helixes.

sourced from the web:
“A helix is a curve in 3-d space with an axis, where the tangent line makes a constant angle with the axis. Spirals on the other hand do not need to have that property, and are typically curves in a 2-d plane.”

The problem is that in common language these distinct geometrical terms are used interchangeably whereas they actually have different meanings: car suspension spring is a helix whereas watch winding spring is a spiral (or used to be pre-quartz crystal watch mechanisms)

#10

Ah, you are right. A helix is much different than a spiral. What I drew was a helix. Thank you for that clarification.

#11

Thanks very much anyway - at least I now know how to draw a helix so it’s all good! I found that drawing semi circles of reducing sizes linked inversely linked together (not sure that’s the right word - diametrically opposite if you see what I mean) then playing with the scale of the individual pieces and using grid for sizing gives a pretty decent spiral in almost no time.

#12

*i mean using grid for spacing rather than sizing

#13

Attached spiral for @dotDash - setting angles to 180 degrees keeps the shape and as it’s made of smaller semi circles you can push and pull into shape

#14

Awesome! I’m going to try this.

#15

This is exactly what I’ve been trying to achieve!