The twisting sweeping solid problem!

[Greendamo]

Beings there are much more experienced in Inventor and AutoCad people on this forum than me i thought id hit you guys with this question...

 

Firstly I draw 3D curved handrail, mainly just rectangular because i import the geometry in to Alphacam and run tool paths down them, but i keep getting faced with the problem of the twisting of a solid when sweeping along a spline or a 3D poly! This makes my life hell!

 

So my first question is:

Do you know of a way to stop it (ive read at lest 20 posts on this and never found the answer!).

Or, do i quit trying and learn Inventor, that is if Inventor can correct it?? ive heard it can but need to ask someone who would actually know before i waste my time?

 

Thanks in advance for your help.

 

Please check my Linkedin page if you want to see what i do and some examples of my work. here: http://uk.linkedin.com/pub/damian-green/64/b86/272/

[ReMark]

Did you try using the Alignment option?

 

Command: SWEEP

 

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

 

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]: No

 

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

[Greendamo]

Tried that with still bad results.

[ReMark]

Post a drawing that contains your base geometry. Someone here will take a look at it.

[JD Mather]

The only way you will be able to do it in AutoCAD is surface-by-surface and then Sculpt (if sculpt will work, probably need a Stitch).

In any case, this will be a challenging design.

 

Would be easier in Inventor - but still not easy.

[Greendamo]

OK, Here is a an example.

The rectangle 4 corners have to follow the flat plan when looked at on plan, if that makes sense. Like real helical handrail would.

teeeeeeeeeest.dwg

[JD Mather]

This might be easier problem than I thought you were referring to.

Loft the lines along top as surface.

Extrude cylinder with hole beyond the surface.

Slice with surface.

[Greendamo]

Thanks JD Mather

Yes that does seem the way to do it, but, its more complicated than that.

Imagine the solid handrail geometry as an extruded rectangle profile, then think if you were to cut it with a saw from the top surface to the bottom surface (perpendicular), and looked at the end of the piece it should be a rectangle with 90 degree corners and equal lengths to the sides.

 

The way u describe to do it I have tried before and what you get when you cut the piece as above, you get a rectangle that has deformed.

 

I hope this makes sense.

[Greendamo]

Any ideas?

[JD Mather]

Any ideas?

 

The only way you will be able to do it in AutoCAD is surface-by-surface and then Sculpt (if sculpt will work, probably need a Stitch).

In any case, this will be a challenging design.

 

Would be easier in Inventor - but still not easy.

[Greendamo]

JD Mater do you think the transfer to Inventor from Autocad is easy or is it a challenge?

Im very proficient in AutoCad you see.

[JD Mather]

Many have great difficulty making the transistion.

It seems the more someone knows about AutoCAD (or any CAD program) the more difficulty they have in making transition. I have no trouble teaching 14-yr old kids to run Inventor.

 

Even in Inventor this design is not easy. This problem (stair rails) has come up in the forums many times in the past.

[Greendamo]

Can you suggest any good learning material?

[JD Mather]

This problem will require surface modeling.

There are a number of (older) surface modeling tutorials for both AutoCAD and Inventor in my signature.

[the downing effect]

I lofted the sections using the the spline as the path. I'm not sure this is what your looking for as I have a lack of 'real-world' experience as I'm a recent graduate.

rail.dwg

[tonyj]

Greendamo,

Attached is your drawing with the required completed handrail. The reason that it was not working for you is, the spline that you had was inconsistent, so I made a helix to sweep the handrail along and this worked fine.

test with helix(2007).dwg