should be simple tube loft -- but it isn't

[ta4F8B3U]

I want to create a rectangular tube that is twisted.  I am doing this because I want to push a part through the tube in order to change its orientation by  105 degrees.  That is to say, one end of the tube is 105 degrees rotated from the other end.

Here is what I want to create:

Obviously, I did create this, but I created this the hard way, and now I need to be able to do this several times in order to change the size of the tube.  By the hard way, I mean I created a sketch where I took an outline of the tube and simply moved/copied it perpendicular to the axis while at the same time rotating it.  Here is what I did:

 

This successfully creates the loft and thus my part.

However, now I find that I need to change the dimensions of the tube.

I don't want to have to manually move/copy/rotate the template of the sketch each time.

The obvious thing is to use the beginning and end desired positions of the tube and create a loft from them as follows:

 

As you can see, the automatic loft does not correctly map each corner part at one end to the correct corner part on the other end and fixing this by hand is way more tedious than move/copy/rotate the tube template in the sketch.  (Note: I didn't select the very last template piece intentionally in this particular case, and it is not relevant to what I am asking.)  I created all of the intermediate move/copy/rotate templates because of this problem.

Thus I find that the way I was using the automatic loft with only a beginning and an end doesn't work and so had to create the intermediary templates. 

Is there a way to fix what I am doing with the loft so that I only have to create the beginning and end of the tube? 

Or, is there a way to easily move/copy/rotate my template in my sketch so that I have a path that the loft will like?  I couldn't find a way to create a pattern within a sketch that allows you to move the template a distance of D and at the same time rotate each new template location X degrees. 

 

[g-andresen · Accepted solution]

Hi,

try Sweep & twist 105 deg

Maybe share the f3d file

günther

[ta4F8B3U]

I updated my post and attached the f3d file, with just the sketch and two lofts.

I don't know how to do a sweep and twist but will see if I can I can figure out how those work.

[jhackney1972 · Accepted solution]

Maybe your solution is a Sweep with a Guide Rail.  I had it easy because I used a common corner, of your sketches, for the creation of the of the Guide Rail but you could do it without them and just sketch the 3D Spline.  I had to use another 3D Spline for the path since your sketches did not have a common center but this too could be sketched easier with a straight line.  Model is attached.

[ta4F8B3U]

Doh!  I was so focussed on using a loft I didn't think of using the sweep.  Anyway, this does exactly what I want.

Thanks!

[g-andresen]

Hi,

that would have been my idea

günther

[TrippyLighting]

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@ta4F8B3U wrote:

Doh!  I was so focussed on using a loft I didn't think of using the sweep.

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You should focus on fully dimensioning and constraining your sketches first.

Also, there is not 3D sketch needed for this whatsoever. It is best to only use 3D sketches for the few situations where they are actually needed.

You only need one profile as others have show.

However, you don't need a 3D spline as the rail. A simple straight line down the middle would have been fine as a sweep path. 

[ta4F8B3U]

Okay, I would like to understand what you just said as I am just a hobbyist building something for my garage.

In this case, the example file I posted was just a copy and paste of a sketch from another f3d file.  In that file, there is an axis along which all of the templates are rotated.   In addition, I know the length of the axis, the dimension of the inside of the tube, the size of the opening on the side of the tube, and the thickness of the tube walls.  For example, my tube inside dimensions are 13.2 x 24.8 and the wall is 2 thick.  The length of the tube is 14x13.2.

After you suggested using a sweep, this is two sketches, one, the axis (path for the sweep), which is just a straight line that is 170.8mm.  The other is the template that will be swept along the axis and rotated 105 degrees.  I made the template by using a center rectangle and entering the dimensions, adding two lines where the side opening will be, and then trimming the opening.  I used two sketches because the length of the axis won't change, but the dimensions of the template being swept along it will change and I thought it would be easier to have the axis as "one thing" for the sweep.

I am 3D printing the parts.

How could I do this differently?  What constraints would make sense in this case?

[TrippyLighting]

Can you share that design?

[ta4F8B3U]

Here is the design of my twisted tube using a sweep.  I just updated the previous file.  Is this what you are asking for?

[g-andresen · Accepted solution]

Hi,

This is how the file might look cleaned up and with the sketch defined.

günther