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Modeling a Coil


Doug Pidgen

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Here are a couple of good questions for you folks in designing!!

1. How do you model a coil?

2. How do you then determine the length of this coil?

 

Examples are a coiled up garden hose or a spring coil as in a watch. I used the Helix Tool with a variable radius from say 24" to 12" with 12 coils and a diameter of .750". I couldn't put a zero pitch height so that the coil would be on the same plane, but it would except a pitch of .0001".

 

A second problem I encountered with the Helix Tool was the part rendering setting had to be quite low, around 10. If the rendering was set higher (which is usually the default setting) it would not render. At this low setting it displays the part very coarse looking.

 

CAD/CAM Programming

aero-safe technologies inc.

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With the new 3D Curve/Sweep, you can import 3d points to generate a 3D BSpline Curve. 3D Curves can be swept to produce solid geometry and can be queried for their length (3D Curve Property Page).

 

The hard part is generating the 3D points to import. It looks like Paul is working on this? Once you have determined the mathematical equation used to calculate the points, you can generate a set of points using a spreadsheet. Saving the points as a tab delimited file will then give you the final product to import into IronCAD.

 

John Ohanian

IronCAD Development

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Thanks for the tip John. I have taken a look at the 3D Curve feature and have

figured out a way of making the 24" rad. coiled hose that I proposed as an

example previously.

 

It is a three step process to achieve the final product. As John had mentioned earlier, the difficult part is making a 3D Guide Curve to be used for sweeping the 3/4" dia. circle along, using the Sweep Shape tool.

 

Ok, here goes!! The first step is using the Sweep Shape tool and constructing a 2D Guide Curve by specifing Circular Arc and defining 180 deg. arcs from 24" rad. to 12" rad., all with the same center point (I deleted the default arc, and used the origin of the drawing area for the arcs). I then joined the ends and the start points of these arcs with a second set of arcs. This produced the coil from 24" to 12". Next, I swept a square shape around this coil, after using the Triball to position the square so that the outside of the finished solid would be the 24" rad.

 

Step Two: Producing a 3D Guide Curve using the 3D Curve Shape tool, from the solid produced in step 1. Select Insert Arc in the 3D Curve Tool, and in the same manner above, construct 180 deg. arcs starting at the outside of the solid,while initially holding the shift key (the curves will be produced perpendicular to the surface without the shift key).

This 3D Curve can be queried for it's length.

 

Step Three: Using the Sweep Shape tool once again, pick the newly created 3D Curve as the 3D Guide Curve and sweep a 3/4" dia. circle. Use the Triball to position the circle so that the outside is tangent to the 3D curve. Andddd....like magic, it is done!!! biggrin.gifbiggrin.gifbiggrin.gif

 

I hope you are able to follow my explanation. I have also attached an .ics file with the three elements decribed above.

After practicing a few times to become familiar with the tools, I was able to make this part in about 20 mins. Not bad for an amateur! Right??biggrin.gif

 

Paul, how is the excel project coming? I am curious to see how it will work.

24 inch coil.ics

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i' am still on it. but i'am quite bussy. (need to get some work done here aswell smile.gif ).

 

thing is IronCAD does not like more than 100 coordinates for my 3d spline.

and i had about 30000 so i'am trying to cut back on that

 

by the way the name of the curve u want to use is an arcemedean spiral

i am using that formula in my exel sheet

combined with the formula for anormal spiral

 

i'll keep u all posted

 

 

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Guest Werner Schappacher

I just tried to create a spiral.

 

Calculating the points with excel was the easy part.

(using arcemedean spiral)

I used excel to get af first preview.

 

 

After impoting the points to IC i get the following lines.

 

 

I have no idea how to avoid this points beside the lines which makes the spiral look so bad.

I calculated the points each 15°; 30°; 45°.......

There must be some trick i don't know.

 

Werner

 

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Here are some results I got from the 3D Curve import. These spirals have 1000 imported points. I used the Archimedean spiral equation (polar) and then translated it into x,y,z coordinates. The equation is:

 

Radius = a * Angle ^ (1/n) where a and n are constants

 

n=1 is a Archimedes' spiral (what I used)

n=2 is a Fermat's spiral

n=-1 is a Hyperbolic spiral

n=-2 is a Lituus

 

(Refresher) To translate polar coordinates to cartesian (x,y,z) use the following equations:

 

x = radius * cos(angle)

y = radius * sin(angle)

 

The first one is just a flat spiral, the second is the same spiral with an incremental increase in the z direction.

 

FlatSpiral.jpgSpiral.gif

 

I found that I could also successfully import 2000 points, but at 10000 and 5000 the ACIS and Parasolid Faceter failed (might be complexity or sheer number of points, not sure).

 

John Ohanian

IronCAD Development

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Guest svangeldern

Rick,

 

 

It seems to me that the rotating spiral is somehow linked to the blinking

of my eyes as it changes direction with every blink. I wonder if IC could

code the orbit tool to be "linked to my blink" as well?

 

Steve

 

 

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The spiral is definitely, Yes definitely spinning counter clockwise. I think? Or is it?..... It is verry hypnotic.....whats that.... I can hear voices.......they are saying. Vote... Vote... Yes vote for the space ball. (he he he biggrin.gif).

 

Anyway having studied the spiral for a little while in my opinion it is rotating counter clockwise. That is if you consider the spiral to have a fixed pitch and linear increasing radius. But if you are of the appinion that the pitch , angle and radii are constantly changing as it rotates, it could be rotating clockwise.

 

Maybe we can start a spiral poll?

 

 

Adrian Rideout Programmer

aero-safe technologies inc.

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If you were looking down on the spiral from above (top view), it is rotating counter clockwise. You can tell by the decrease/increase of size of the outer ring as it spins due to perspective rendering (it also helps that I made the model). Yes you can assume that the spiral is rigid, and not changing its geometry in any way while it's spinning.

 

John Ohanian

IronCAD Development

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