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johnfulwyler
30th Oct 2003, 02:35 am
I need to create a solid object that is at one end a circle and at the other end an ellipse. Is there some way to extrude a circle into an ellipse, or any other way that this can be done? If there is a way to do this, can it be done with any two regions? Any help would be great.

Thanks,

John

gcp310
30th Oct 2003, 05:57 am
Morfing cant be done with standard autocad tools.
BUT, Fuccaro, the champion Lisper round here could probably
write a lisp routine to create the solid.

G

Mr T
30th Oct 2003, 11:03 pm
Using RULESURF would create a surface between the circle and ellipse.

Extruding an ellipse and then UNIONing it to a cylinder would
do the trick.

Nick

PS explaination and steps if reqd.

fuccaro
31st Oct 2003, 06:50 am
Mr T
My intention was to write a Lisp for this, but you posted your message just in time. Yes, please tell us more about this. Thank you in advance. It is nice to have you around here.

Flores
31st Oct 2003, 03:32 pm
Using RULESURF would create a surface between the circle and ellipse.

Extruding an ellipse and then UNIONing it to a cylinder would
do the trick.

Nick

PS explaination and steps if reqd.
Rulesurf may work if "surftab1" is set to something like 24, but it isn't a solid. Simply extruding an ellipse and then unioning it to a cylinder wouldn't work either because there wouldn't be a transition between the two (even if you extrude it to an angle). If this can be done without one of Fuccaro's LISP's, I would like to know how.

Flores

robfowler
31st Oct 2003, 08:16 pm
It is possible to 3D solid model this transition in plain AutoCAD.

Create the circle on the XY plane and the ellipse at the desired elevation above the circle. Get rid of the right hand half of the circle and the right hand half of the ellipse - trim them to their quadrant points to do this.

Set SURFTAB1 setting to something like 24 - higher value will give you a smoother solid in the end.

Use the RULESURF command to create a surface between the two arcs (the semi circle and semi ellipse).

Rotate the ruled surface about the Y axis.

Use the m2s lisp to change the ruled surface into a solid.

Mirror the solid created to produce the full transition - et voila!

My effort looked quite good. Email me (PM) with your private email address if you want me to send you on the file.

Rob.

fuccaro
1st Nov 2003, 08:40 am
It is possible to 3D solid model this transition in plain AutoCAD...
Use the m2s lisp...
:D :D
How are you today, Rob?
May I write here a small observation? It is possible to "ignore" the half of the model only if the centerpoints are at the same XY co ordinates.
Johnfulwyler
Are the circle and the ellipse in parallel planes?

robfowler
1st Nov 2003, 11:57 am
I'm fine fucarro, hope you are well too.

Yes, I agree with your observations about ignoring the half of the circle and ellipse.

I actually created, as you may have guessed, a transition solid where the centre of the ellipse was directly above the centre of the circle, both of which were on parallel planes.

Other types of transition involving the circle and ellipse on different planes, or with centres offset even if on parallel planes, would be more complicated for sure.

I feel you have done more work in this area than I have and I always appreciate your wise observations which continue to enlighten us in many ways.

These days I get SAD (Seasonal Affected Disorder) at this time of year when the dark nights are here and the forum adds some light to anotherwise gloomy approach to winter. Roll on the Spring :)

Rob.

Mr T
1st Nov 2003, 05:24 pm
[/quote]
Rulesurf may work if "surftab1" is set to something like 24, but it isn't a solid. Simply extruding an ellipse and then unioning it to a cylinder wouldn't work either because there wouldn't be a transition between the two (even if you extrude it to an angle). If this can be done without one of Fuccaro's LISP's, I would like to know how.

Flores[/quote]

Sorry solid wont do it :oops: tried various ways but not accurate (smooth) enough, but RULESURF :lol: or EDGESURF :lol: will.

Draw a cylinder and ellipse, move one up away from the other.
type the command SURFTAB1 and change it 200, type RULESURF
and then click on the same side of the cylinder and ellipse in turn.
Your rulesurf may look twisted, do it again but click directly above the first click. Going into a 'front' 2d viewport would help.

Nick

johnfulwyler
2nd Nov 2003, 04:49 am
I tried rob's advice and it came out exactly how i wanted it! :D Also, thanks for the file you sent me! It took me a while to figure out how to use the lisp because i've never used lisps before but it worked out great!
Johnfulwyler
Are the circle and the ellipse in parallel planes?

Yes they are. Here's how it turned out.

Thanks everyone for the help!

robfowler
2nd Nov 2003, 09:57 am
Congratulations John. :D

If you've learned how to load and run a lisp file for the first time then you are truly progressing your AutoCAD skills.

You'll now be one step ahead of your fellow students and they'll be wondering how you can produce such transitions - lead them to CADtutor :wink:

Rob.

Mr T
3rd Nov 2003, 08:33 pm
I tried rob's advice and it came out exactly how i wanted it! :D Also, thanks for the file you sent me! It took me a while to figure out how to use the lisp because i've never used lisps before but it worked out great!
Johnfulwyler
Are the circle and the ellipse in parallel planes?

Yes they are. Here's how it turned out.

Thanks everyone for the help!

Correct me if I am wrong but it looks like a cylinder with an angular SLICE taken off ?

Nick

johnfulwyler
4th Nov 2003, 01:21 am
Correct me if I am wrong but it looks like a cylinder with an angular SLICE taken off ?

Maybe the picture is at a bad angle, but I think you can see that one end is circular and the other is elliptical. I created it using rulesurf and the M2s lisp, like rob advised.

The mobius thread was interesting to see. I didn't even know what the term meant before now :oops:
Just out of curiousity, what exactly would a mobius be used for?

fuccaro
4th Nov 2003, 07:33 am
Trying to keep some order here I posted the answer about the Mobius strip in the dedicated topic.