Lofts and Guidlines

[Figbash]

I am trying to create a loft in the shape of a bottle with two rectangular profiles for the body and a circular profile, of the same height as the short leg of the rectangles, for the mouth. The problem is that if I just use the profiles, the circle forces the loft to bulge out between the two rectangles. I want the transition from the second rectangle to the circle to be tangent to the loft created by the two rectangles. I tried adding guide curves and that worked well in the immediate vicinity of the curve, but the loft still bulged between them.

Any suggestions to help me win the battle of the bulge?

Thanks,

Tom

 

[TheTick]

Sounds like you may be trying to do too much in one loft. Try making the body first, and then attach the mouth. Use tangency continuity between the body loft and the mouth loft.

If the ladies don't find you handsome, they should at least find you handy.

 

[sirmick]

I would do as Tick suggested and use, for the start tangency, a direction vector parallel to the path of the loft between the two rectangular profiles.

 

[Figbash]

Making separate lofts for the body and the mouth solved the bulging problem (thank you).

Is there a problem with mirroring guide curves? Two of the curves that I was using to form the neck of the bottle were drawn on a vertical plane through the center of the bottle. I drew one of them and them mirrored it for the other and when I selected either one of the curves, I got an invalid guide curve message. My work around for the problem was to create a separate sketch for each curve, even though they are the same.

Thanks for the help.

Tom

 

[PlasticFantastic]

The guide curves have to be separate sketches. While it would be nice to use selected contours from a sketch as guide curves, this is not yet possible in Solidworks. Your workaround is the way to mirror guide curves. Alternatively you can model half the bottle and mirror the body after you are done

 

[sirmick]

Be careful with mirroring lofts based off of splines. C1 and C2 continuity on the mirror plane may be difficult for you to achieve.

 

[SBaugh]

Why don't you just do a Copy of the sketch and paste it in the model. Then use Tools\Sketch tools\Modify to adjust the sketch accordingly?

This way just seems so much easier than going through the trouble of trying to mirror a sketch and loft. If your going to mirror the loft you might as well make the whole thing in one feature.

See my loft example -

http://www.scottjbaugh.com/Design_Portfolio/Lofting Symbols.zip

Regards,

Scott Baugh, CSWP
3DVision Technologies

http://www.3dvisiontech.com

http://www.scottjbaugh.com

faq731-376

 

[TheTick]

This is where it really pays off to have some master sketch geometry to define your shape. Have key profiles and guidelines sketched before you start throwing down surfaces. Then, extract portions of the master sketches as needed using "convert entities" to make pieces as you go along.

If the ladies don't find you handsome, they should at least find you handy.

 

[JNR]

Ahh, once again the voice of reason, Tick!

We have something similar - maybe more complex. It is a rectangular to round CRT shield. It's an old model now but I don't recall any problems. I think we used multiple guidecurves. Does your rectangular section have sharp corners?

Be naughty - save Santa a trip.

 

[Figbash]

No sharp corners. The part is a shell for a D-sub connector and it is nicely radiused on all corners. I posted a jpeg of the part. You can click here to check it out.

Tom

 

[JNR]

Now I'm even more confused, sorry. Do you mean the D submin itself, or the backshell - I'm thinking the latter? Also are you just modelling a library part/purchased item, or are you planning on manufacturing it yourselves. If you are going to make it, you might want to think about the practical machining processes you would use to make the mold and duplicate that geometry methodology on your model. Come to think of it that might work just as well backwards to reverse engineer a purchased item.

Be naughty - save Santa a trip.