Sweep parallel

[Greendamo]

Hi All

 

Can any1 tell me if there is a way to sweep a rectangle along a 3D spline and keep the top of the rectangle parallel to the ground?

I make complex spiral handrail and when i sweep and rectangle along a 3D spline normally, it twists and is wrong.

I know that there is a plug-in on sketch that is specifically designd for this called 'Follow me and keep'

 

Any help will make my life much better lol!

Thanks

Damian

[ReMark]

It would be most helpful if you could post a copy of your DWG file. Thanks.

[Dadgad]

Yes it can be done without an add on. Like this?

 

Command: _sweep

Current wire frame density: ISOLINES=4, Closed profiles creation mode = Solid

Select objects to sweep or [MOde]: _MO Closed profiles creation mode

[sOlid/SUrface] : _SO

Select objects to sweep or [MOde]: 1 found

Select objects to sweep or [MOde]:

Select sweep path or [Alignment/Base point/Scale/Twist]: a

Align sweep object perpendicular to path before sweep [Yes/No]: n

Select sweep path or [Alignment/Base point/Scale/Twist]: t

Enter twist angle or allow banking for a non-planar sweep path

[bank/EXpression]:

Select sweep path

Command:

[Greendamo]

Hi

 

Have a look at the DWG i have attached.

This is the result i get with sweep, if you put it in to plan you can see that the ends are ok but in the middle of the sweep you can see is twisted out of shape!

The top can't be parallel with the ground and the sides you can see are not vertical.

 

Any ideas guys?

Thanks

like this.dwg

[Dadgad]

Please try to sweep it using the sequence of inputs in my previous post. I believe that you will be pleasantly surprised.

I tried a few times to loft it, but got the solid shown in the attachment by sweeping, the commandline sequence is shown.

[Greendamo]

Hi Dadgad

 

I followed the exact sequence and that is the result i got. download the dwg i have attached and try it for yourself u'll see what i mean.

 

Thanks

[SLW210]

You did not leave your path and profile in the drawing.

[Greendamo]

Sorry here you go..

like this.dwg

[nestly]

I got the same result, Greendamo. I couldn't keep the top and sides perfectly horizontal/vertical, so I put a guide on each corner, copied the profile to the top, and LOFTed it with the Guide option.

 

I wasn't that familiar with 3D splines, but it was easy to make the guides by making your original spline into block, copying it twice and scaling each of them to the inside and outside of the profile, then manually setting the Z scale back to 1. Then exploding them since you can't use blocks for Lofting guides.

 

*edit. Looking at it closer, what I did isn't right either because the vertical distance between the guides varies depending on the incline of the spline, but I think it would work if the guides were created accurately for each corner of the profile.

Edited February 16, 2012 by nestly

[SLW210]

I believe it is your spline. It works well with a Helix. I will look more when I get time.

[JD Mather]

Please try to sweep it using the sequence of inputs in my previous post. I believe that you will be pleasantly surprised.

 

Attach your "solution" here.

 

I will be surprised if anyone posts a true solution.

[woodworks]

I had asked about this awhile back and Remark suggested using the loft command.

[Dadgad]

Attach your "solution" here.

 

I will be surprised if anyone posts a true solution.

 

This is what I got last night sweeping the helix, time constrained can't play with the OP's spline at the moment.

Handrail sweep model.dwg

[Greendamo]

I have tried with a helix and it works ok.

Its weird that it wont do the same for a 3D spline with all the same options ticked!

This problem must be a hurdle for any like myself who create complex 3D helical handrail in ACAD for machining purposes.

I have managed to wing it most of the time by using lofted surfaces, offsetting then, projecting my 2D plan up to the surfaces then trimming surfaces. But doing it this way is time consuming and often the surface will not offset at the complex areas like at the transition from a voloute, Or an error saying object intersects with its self!

 

Thanks guys, ive got to get to the bottom of this

 

Damian

[Dadgad]

As a woodworker of many years, I have a great appreciation for those who work seemingly freeform, on shapes such as these. I was pretty happy just to be able to get it to work on the helix, without any required add-ons, didn't bother to test on a spline, as I was thinking about the handrail proper, as opposed to return work. I will give it a few more tries, when time permits, a bit busy today. Frustrating as it may be, at least now you can model the helical sections accurately.

 

Perhaps in the future you will just have to stick with simple circular stairs like these youtube.com/watch?v=9bodDIpV1hk&feature=related.

 

You may need to get another guy to help you do a little of the lifting though. :wink:

I'll certainly post it, if I find a workaround, within the confines of Autocad Vanilla, still have a couple of ideas.

 

Then too, minimizing those return segments would reduce the annoyance factor.

youtube.com/watch?v=XuGYz1CLVOg&feature=related

[Greendamo]

Has any1 tried this yet?

[SEANT]

What exactly is the goal? Sections taken from your solid, based on planes radiating from the center of the circle, already show the top surface to be near horizontal. The shaded model gives the appearance of a twisted top surface, but I think that is just a lighting/shading issue.

 

The sides of your model are a bit irregular, i.e., slightly curved and non parallel to the Z axis. Though, if the goal is to have a rectangle always perpendicular to a varying pitch helix path then that would likely be the outcome. In the attached file I have set a rectangle (Cyan entity at the 10 o’clock position) and it is apparent that the top edge and bottom edge could not stayed aligned vertically as they progress around the path.

 

Perhaps the actual goal should be for a fairly regular cross section that is allowed to morph in accordance with a top surface remaining horizontal, and sides always vertical in the radial cross sections.

 

For what its worth, this model was made in the manner you specified in post #14

WithSections.dwg

[Dadgad]

Has any1 tried this yet?

 

I played around with it a bunch on Friday, still not throwing in the towel. Definitely made some headway. Been a busy weekend, friend visiting.

[khama]

I don't think it is possible. The spline is not parallel with the ground so the path will always twist it away from the ground. Is it possible to draw a spline this way? Not likely..

[khama]

I can get it to start parallel but it instinctively follows the path..

spline path.dwg