3D Spline with Control Points

[DBC]

Alibre Design Expert 2019 doesn't seem to have a 3D Spline with Control Points tool. In a different forum folks have been taking about modeling the twisted fixture exercise seen here.



It is very easy in SolidWorks. Just a simple loft between two rectangles using tangency to face constraints.



I can do it in MoI using sweep with 3D Spline by Control Points guides in and in TurboCAD using loft with guides made with the 3D Spline by Control Points tool (central twist in MoI shown - looks the same in TurboCAD).



I have been trying in Alibre, but without the 3D Spline by Control Points tool it seems impossible. How would you do this exercise in Alibre Deign Pro 2019?

 

[HaroldL]

Give this a try:

Tutorial: Creating a Twisted Flat Bar in Alibre Design

After trying to create a twist in .25 X 1.00 bar with a Loft and struggling with guide curves to make the 1/4 turn twist I thought I'd try the Helical Boss tool. After working on that for a while and searching the forum for any information I came across an old post where @MilesH suggested a...

www.alibre.com

 

[DBC]

Give this a try:

Tutorial: Creating a Twisted Flat Bar in Alibre Design

After trying to create a twist in .25 X 1.00 bar with a Loft and struggling with guide curves to make the 1/4 turn twist I thought I'd try the Helical Boss tool. After working on that for a while and searching the forum for any information I came across an old post where @MilesH suggested a...

www.alibre.com

Thanks Harold, but I don't see how that can work as it is just using a helical extrude, which appears to require the selection of a single axis, x y or z. In the exercise I am showing, the two profiles are not just rotated 90°, the central axis is offset off from one another. It is so much more complex than just a simple twisted bar.

 

[HaroldL]

It's quite a challenge but doable, with some exceptions. You need to insert a new axis on a new plane that is offset. And that takes quite a bit of tweaking to get the twist to come out just right but is doesn't have the nice transition a loft would have. Having better control of 3D splines would make this a whole lot easier.


Once the part was done I put it into an assembly.
The two highlighted faces in this image are offset by .5 mm so the overall width is 21 mm instead of 20 mm.



It's unlikely that you'll be able to open the package but I'll upload it anyway

 

[DBC]

It's quite a challenge but doable, with some exceptions. You need to insert a new axis on a new plane that is offset. And that takes quite a bit of tweaking to get the twist to come out just right but is doesn't have the nice transition a loft would have. Having better control of 3D splines would make this a whole lot easier.

Once the part was done I put it into an assembly.
The two highlighted faces in this image are offset by .5 mm so the overall width is 21 mm instead of 20 mm.

It's unlikely that you'll be able to open the package but I'll upload it anyway

A good effort Harold. Thanks.

 

[DavidJ]

I managed this part, by adding an intermediate profile. BUT the result depends a lot on how the faces/sketches are formed. I had a disaster trying it with slightly different way of doing the starting sketches. It's a bit 'by eye' - not sure what the 'correct' position for the intermediate profile is.

A really nice touch would to be able to tell the loft tool which vertex to connect to which across the profiles.

ADDED IMAGE for those with older versions

 

[NateLiquidGravity]

In v24 Alibre added the ability to loft directly between two selected faces without using a sketch. That wasn't available to try when that other discussion happened. Give that a try. I would but I'm not near my PC.

 

[Nick952]

When I did the attached twist, I used straight 3D Sketch lines, directly connecting each sketch faces corresponding twisted/rotated corner for Guide Curves (I had to use the four Guide Curves or I had some really strange results).
For reference, that component is made from 1/8" x 1/16" steel section and the twist is an overall 1/2" long.

 

[idslk]

Nick952 was quicker as i see now...
anyway, i used nearly the same attempt with 4 straight 3D-Guidelines...


Regards
Stefan

 

[DBC]

Thanks for everyone's input. Sadly, nothing worked in the version I have. Alibre Design Expert 2019, looks like build 20.

 

[DavidJ]

Nick - well done, it never occurred to me that straight line guide curves would give the desired result!!

 

[HaroldL]

Well that's something new, must be part of the Lofting overhaul in v24. Intended or not it's good to know.

 

[HaroldL]

It is very easy in SolidWorks.

You have a seat of SolidWorks? It also has the Twist feature that can be used for something like this.

 

[NateLiquidGravity]

Yep, directly face to face using 4 straight line 3d guide sketches worked for me too. However I noticed that the material had gotten thinner near the middle of the loft. If you need to maintain a specific thickness I did the following additional steps (using Expert v26 BETA):
I created a surface from one of the major faces of the loft (the one that was on the side of the part that was in alignment before and after the twist).
I cut extruded the loft out of the way.
I thickened that surface.

 

[GIOV]

Hi DBC,
Here is the fastener in AD/GDV14. It's not perfect but it is very similar to you drawing.
1.-Twisted Flat Fastener GIOV-R1.AD_PRT


I hope help.
GIOV

 

[HaroldL]

It looks like some of the uploaded examples are part files with two lofted parts. The image that @DBC uploaded shows an assembly of two identical parts so there is no need to repeat your efforts in a single part file.
just sayin'.

 

[GIOV]

In Two Parts



So it is feasible to do in V14.
1.-Twisted Flat Fastener GIOV-R3.AD_PKG
Just say

 

[GIOV]

Max:
Suggestion to 2D Drawing: Please make the hatch Pattern scale more flexible, so less than 1 and the thickness of the line thinner. Will be a good improvement.