PDA

View Full Version : modeling a spring??


spirogyro
09-09-2003, 07:54 AM
Does anyone know the best way to model a spring???

Ibox
09-09-2003, 08:12 AM
um, ok, how about opening up Wings3d, right clicking and choosing "more>spring", then maybe selecting body/object mode and "duplicate>y" and move said spring to where it look like the both line up, then simply select bottom end face ot the top one, and top end face of the bottom, right click and hit "bridge"... repeat this if ya needs more spring :)

select all and save as say .obj or what have ya then import into whatever app...

melchior_
09-09-2003, 09:05 AM
That was the best method I've ever seen. :eek: :thumbsup:

puzzledpaul
09-09-2003, 10:22 AM
Or...

Prims -> More -> Spring --> Option Box (at right)....

... and then dial in the number of loops you want?

If you need the 2 ends of a spring to start and finish at the same angular location (one section missing by default)

Dial in an extra loop from what you actually need - then loopcut off all of the last loop, but one section.

Some of the issues associated with the default spring geometry (cross-sections not perpendicular to spring centre-line) at linked page - and other info that might be of interest.

<< where it look like the both line up >>

If you do get in this situation - measure the pitch (select 2 verts on same part of spring, but adjacent loops, note distance, top left info) then Move Y this distance for one object (default spring 0.8 units) with respect to other.


pp


www.geocities.com/paulthepuzzles/aasprings.html

bored alien
09-09-2003, 11:24 AM
Cool. Let's try Silo! Go to Create > Arc > ... to edit the options for a new arc. Enter in appropriate values - the outer and inner radii represent the radius at the bottom and the top of the spring, respectively, if you want it to vary in diameter at the top and bottom. The height of course is how tall your spring should be. The degrees determines how tight the sprial should be (i.e. 360 multiplied by however many loops you want.) Radial sections determines how many cross sections the eventual spring will have. (Currently how many vertices the arc will have.) Click create. Now go to Create > Circle and make a new circle of whatever size you would like. (I think you want to check "fill" in the options if it isn't already checked.) Create the circle, and align it parallel to one end of the arc. Select the circle, then Shift-select the arc. Go to Create > Path Extrusion Object (more fun options to play with here if you want) and create a path extrusion. And there is your spring. Took a lot of words to describe, but really it's a pretty quick process. :thumbsup:

puzzledpaul
09-09-2003, 01:03 PM
<< really it's a pretty quick process >>

Yes, for a standard path extrude procedure - but imo the end result appears to suffer from similar issues as previously mentioned - cross section not aligned correctly with the central spline - and this (misalignment) also varies.

pp

bored alien
09-09-2003, 07:45 PM
Okay, plan b. Let's start with an arc just like last time. Only this time we'll flesh out the shape by hand by extruding edges. Set up your view so that it is a split screen with a perspective view and a top view. Select all the edges of the arc and hit extrude. We have two views so that you can easily scale the edges in the plane of the top screen outwards or inwards using Ctrl with the scale manipulator, and then move them in the perspective view using the move manipulator. You can also do this using the numerical editor for precise control. We really only need to do this 4-8 times, and then can subdivide as much as we want. (I used four sets of edges in this example.) Make sure the final set of edges is very closely aligned with the beginning set, switch to vertex mode, select all, and then use merge vertices to close the shape. (Adjust the tolerance if it doesn't work at first.) Note that you can now further edit the cross section by selecting edge loops and scaling or translating them as above. Subdivide and Shfit+C as needed. This produces much nicer cross sections, aligned precisely vertically, though I'm not quite sure if that is what you're looking for.

EDIT: Man, they sure have lowered the attachment size limit from last time I posted an image...

puzzledpaul
09-09-2003, 08:16 PM
<< aligned precisely vertically, though I'm not quite sure if that is what you're looking for >>

I don't particularly want to labour this topic any more than it merits - but if the individual wire cross-sections are circular - and also aligned vertically - then all is not as it should be - imo.

These circular cross-sections should be perpendicular to any tangent to the helical centreline (at same point, of course) - ie tilted over to same angle .

The best implementation of this I've got access to is the 'pipe' tool in Rhino - when applied to a helix.

pp


(The above issues are probably irrelevant for general purposes - I'm just surprised about the default results produced by Silo - that's all :) )

bored alien
09-09-2003, 08:30 PM
yup, sort of an academic discussion at this point. Fun to play with though. And I think you're right about the alignment. Cheers!

puzzledpaul
09-09-2003, 09:50 PM
<< Fun to play with >>

Agreed - as evidenced by the 'blobby stuff' on linked page above :)

<< Cheers! >>

Thx - I'll have a Guinness :)

pp

bored alien
09-10-2003, 10:04 AM
Sorry to belabor the beleaguered point, but I happened across the problem in silo if anyone's interested. Path extrusion doesn't work correctly if you put the cross section at an endpoint. It works much better if you put the cross section in the middle somewhere, aligned with a vertex on the path. Then everything aligns itself peachily. :thumbsup:

Ibox
09-10-2003, 04:44 PM
Hey man, don't be sorry, this is terrific info... keep it coming whom ever :)

PP, thnx for the additional info re options... always good to know bout more options eh... :)

wow, who would have thunk that a simple spring would open so many doors :D

Rabid pitbull
09-10-2003, 06:38 PM
ok in lightwave there are several plugins specific to this. also can be done by extruding a disk along a spline path. Actually there are even more ways too...

CGTalk Moderation
01-16-2006, 03:00 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.