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+--- Thread: Drawing a SPIRAL (/showthread.php?tid=573)
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Drawing a SPIRAL - williamj - 07-07-2012
Hello, my name is Bill and I just joined the forum because I find myself in need of assistance.
I've been usibg DeltaCAD for (basic drawings) several years now but this is the first time for something (for me) very complex. How do I draw a spiral? By definition... an arc with an increasing or decreasing radius.
I hope you can help.
Thanks in advance,
williamnj
RE: Drawing a SPIRAL - i44troll - 07-07-2012
Bill,
Welcome to the group!
A spiral does indeed have a radius that constantly increases. Since Deltacad is incapable of drawing this type of curve using the drawing tools that are available you might still be able to draw a spiral that will be acceptable in drawing only, but not according to true architecture. Below is a picture of a spiral that is drawn by connecting an "arc with three points" to the intersections of circular and diagonal lines. Additional arcs are included to create a continuous spiral (the drawing shows alternating colored arcs to show the beginning and ending of each arc). Notice also that each arc 'point' must be connected to the next adjacent line and intersecting outer circle. Hope this helps...
[attachment=266]
RE: Drawing a SPIRAL - williamj - 07-08-2012
i44troll,
Thanks so much for the rapid response. I can't tell you how badly this thing has been kicking my butt, I much prefer to solve things on my own but this was getting the best of me. Thanks again.
I had tried something similair using the elliptical arc but that left the connection between arc segments angular and choppy looking. Your solution works but apparently it works only on larger radius archs. I was trying for a smaller radius, say a half inch for the largest arch segment, but with the smaller radius segments the arch connections again looked angular and choppy.
I was able to sidestep this by making a larger radiused spiral and then scaling it down to the appropriate size.
Many thanks,
williamj
ps
please substitute arc for arch in the above
williamj
RE: Drawing a SPIRAL - i44troll - 07-08-2012
Quote:I was able to sidestep this by making a larger radiused spiral and then scaling it down to the appropriate size
Exactly!
Can I ask what your drawing is going to represent?
RE: Drawing a SPIRAL - williamj - 07-08-2012
i44troll,
The "whole" project that I'm working on is conceptually new, and hopefully patentable. So without going into too much detail the spiral is to represent a spring that functions as a pawl working with a ratchet all contained within a small cylinder. So at this point the spiral is representational and precision isn't warrented.
many thanks for your help,
williamj
RE: Drawing a SPIRAL - i44troll - 07-08-2012
Gotcha!
My Brown & Sharpe micrometer set uses a spring as a pawl making it much more sensitive than the ratchet types.
RE: Drawing a SPIRAL - williamj - 07-22-2014
Wanting some down time I was rereading some older posts and I came across this one.
I began rethinking spirals, and using what I have learned since this thread had been started, I was able to come up with a smooth spiral, no adding arcs together, just one simple smooth spiral.
The key is to create a polar grid. At the desired angle and radius connection points start a spline and continue the spline connecting at other continuous angle and radius points as depicted in the attach illustrations.
I haven't figured out how to size the spiral to fit the need but that's for another day.
[attachment=416]
[attachment=417]
RE: Drawing a SPIRAL - AlwMVMO - 07-22-2014
If you have the DeltaCad with Macros there should be a Spiral.bas macro in your Macro subdirectory. Here are some modifications to make any shape and size spring coils.
Code:
Dim s(1000) As Double
.
.
r = InputBox("Enter outside Radius","Spiral","2")
r2= InputBox("Enter inside Radius","Spiral","0")
sp2= InputBox("Enter spacing","Spiral",".18")
sp=sp2/18
a = 0
n = 0
While r > r2
n = n + 1
s(n*2-1) = Cos(a*5/180*3.14)*r
s(n*2) = Sin(a*5/180*3.14)*r
r = r - sp
a = a + 4
WendRE: Drawing a SPIRAL - williamj - 07-23-2014
AlwMVMO,
Thanks for jumpin' in.
And thanks for the hard work on the macro, now... if I just knew anything about macros.
Hmmmmm....
RE: Drawing a SPIRAL - AlwMVMO - 03-24-2016
Here is the complete Edited version of the Spiral macro
Code:
Sub Main
Dim r As Double
Dim a As Double
Dim s(1000) As Double
Dim n As Double
dcUpdateDisplay False
dcSelectAll
If dcIsSelected Then dcEraseSelObjs
dcSetSplineParms dcRED, dcFILL, dcNORMAL
r = InputBox("Enter outside Radius","Spiral","2")
r2= InputBox("Enter inside Radius","Spiral","0")
sp2= InputBox("Enter spacing","Spiral",".18")
a = 0
n = 0
sp=sp2/18
While r > r2
n = n + 1
s(n*2-1) = Cos(a*5/180*3.14)*r
s(n*2) = Sin(a*5/180*3.14)*r
r = r - sp
a = a + 4
Wend
dcCreateSpline s(1), n, False
dcViewAll
dcUpdateDisplay True
End Sub