Lofting With Guidelines

[jdpreynolds]

Hi I am new to Fusion 360 but have been using other CAD software for sometime and am visiting to see if F360 can do the attached loft

I am trying to create a  hook with several profiles along a top and bottom Rail but keep getting the message " Rail is not Smooth" and "Selected Rail does not touch all of the Profiles"  

I see that it is a common problem and have been working my way through some of the tutorials but haven't found the solution just yet.  Would appreciate some assistance  

thank you 

Julian

[Intuos5 · Accepted solution]

E: accidentally pressed post, will complete the post first

[laughingcreek]

The error messages appear to be pretty accurate. none of your rails touch the profiles.  the only way to insure they do is to use projections and constrains.

also the inside curve (sketch 0) isn't smooth.  has a G0 connection on a segment at the bottom of the hook.

Moving the profiles off the sketch plane out into 3d space really isn't a good idea unless you REALLY know what your doing.

turning on the timeline and getting to know how to use it would be a good idea.  it will also help others trouble shoot your problems

for a shape like this, I would suggest drawing the rails first, and using those to position the profiles.

[Intuos5]

@jdpreynolds 

Generally, what you want to do is to create all these profiles on seperate construction planes. This way, you can control the distance between sketches parametrically without the need to recreate the model. Moreover, for clarity and management purposes, you should aim to create consistent sketches by for instance, creating one sketch with for the guidelines, rather than having both guidelines and some of the profiles in one sketch and some in other sketches. In this case, did you sketch the entire thing inside Fusion or did you import them? You can always double click on a sketch to edit it after the fact.

You may also want to have a look at constraints & dimensions, there is plenty about this on youtube. As a rule of thumb, you want to fully constrain your sketches to make sure the end result is predictable (and does not change if you change parameter values).

Rule #1 is to create a new component prior to starting with modeling.

Make sure to always model around the origin, because it makes everything much easier.

I would advise you to go through some tutorials first on the specifics about Fusion 360, because I see a lot of beginner mistakes which are addressed in those tutorials, which, if you avoid making those mistakes, will help you get to know Fusion a lot better in the long run.

Model

As for the model itself, you don't really need all of the additional profiles, just a start profile would suffice. The rails should touch the profiles, so I have constrained the plane in such a way that the profile touches the rail. You can then build the cap from the end with a sketch & contruction plane with lofts. 

If you need the additional control, place additional construction planes and loft between two profiles at the time.

[TheCADWhisperer]

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@jdpreynolds wrote:

Hi I am new to Fusion 360 but have been using other CAD software for sometime ....

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I would start by turning on Capture Design History.

Then I would fully define each and every sketch...

Your guide curves must have Tangent constraints.

I would use 2D sketches raterh than a 3D sketch.

Can you post link to image of real world part?

[jdpreynolds]

Thank you for your informative reply I have attached the drawings which I am using for this model.  These were draw over in other software and then imported into Fusion 360.  I will start again in F360 and use your advice which I am sure will lead to a successful loft.

Regards

Julian

[TheCADWhisperer]

Are you modeling an existing hook?

If yes, can you show a picture of the real world part?

[jdpreynolds]

Hi 

I have attached an image of a similar Draw Bar hook as to the one I am wanting to model.  I have drawn most of this wagon up in Turbocad but cant get the Lofting with Guidelines tools to work there.  The Loft profiles were attached to the guiderails but looks like I have lost some of the information when transferring the .DXF file into Fusion 360. I am likeing what I see with F360 so am confident I will get it to loft properly I just now need to learn the steps with this unfamilair (at present!) software.

Thanks

Julian

[Intuos5]

@jdpreynolds 

Sketching the entire thing in Fusion 360 has the advantage that by changing parameters of a fully defined sketch allows you to iterate and to alterate much quicker, because there is no need to remodel the thing.

If the thickness of the hook stays consistent, which seems to be the case in your sketches, sweeping produces a more reliable result, because the geometry is more consistent. You could also simplify your sketch by sweeping a rectangle with an arch on one side to then fillet the model (rather than the sketch) so you can change the fillet radius more easily after the fact.

And in case the loft fails due to self-intersection of some sort, that's when the trick of lofting the profiles by pairs allows you to spot where the issue might be.

[TheCADWhisperer · Accepted solution]

The Attached might give you some ideas.

[jdpreynolds]

Thanks for your work here that is an excellent looking rendition of what I want to achieve. I will study your drawing tomorrow and see if I can do the same. Don’t suppose you would want to do a You tube clip on how you achieved this?

Best regards
Julian

[TheCADWhisperer]

It does deserve a video as there were some interesting hurdles, but I have other projects ahead of this one. 
You will probably need to ask questions when you encounter the same hurdles.  I didn’t try to match the drawing precisely as it was not crisp quality.

 Maybe @Intuos5 can provide an example.

[Intuos5]

@jdpreynolds 

If there's anything you don't understand for the model, I advise you to ask these specific things in this topic, attach your file and we can see how to answer it best. In case you use a canvas to trace over, be sure to include it in the file and use native Fusion 360 geometry, that'll allow us to comment on the workflow as seen in the timeline 😉

[jdpreynolds]

Hi Intuos5 and CadWhisperer

I have spent the last few weeks trying to understand Fusion 360 by viewing You Tube lessons, I have also bought the "Autodesk Fusion 360 A Power Guide for Beginers" by CADArtifex which I am working my way through.

I have re-started the Draw Bar Hook drawing by inserting the Canvas and drawing the guide rails and profiles.  I believe I have all the Profiles correctly touching the guiderails but don't seem to get a continous guide rail,

Am I missing some constraints on the guiderails? I am pretty sure that they are all correctly joined but woulkd appreciate if you can point out what's wrong

Many Thanks

Julian

[TheCADWhisperer]

Your sketches are all blue (not fully constrained).

This is not good.

Hook Hole sketch

Missing Vertical constraint on construction line.

This is what a properly constrained sketch looks like...

If you can click and drag geometry out of position/size - it is not fully defined.

Your Profiles sketch is a 3D sketch - even though all of the geometry is 2D.

A beginner should probably not use 3D sketches. 

[TheCADWhisperer]

Before making a solo attempt, you should reproduce my sketches...

...and ask any questions as you go along. (Post your *.f3d file here after each sketch.)

[jdpreynolds]

Thanks for your reply. 

I still have away to go before I completely grasp the concept of drawing constraints.  I have attempted a copy of your sketch 1 but am still missing some of the constraints hence the drawing is still blue

You have 3 Tangental constraints on the R16mm Arc I have only been able to apply 2

You also have 2 equal constraints on the R9.5mm fillet which I have attempted applying but was not successful.  It may be that I am not getting the order of constraints correct.

I will have a look through some online lessons tonight on constraints

Regards

Julian

[jdpreynolds]

Hi

I am making progress! after comparing my drawing constraints  to yours I see that I was missing quite a few.  I now have both top and bottom guidelines properly constrained and the first 2 profiles also however I am unable to get the third profile to turn black even though it appears to have the same number of constraints.

I am just checking that I have it properly attached to the guidelines and comparing it back to your drawing if you see something obvious please let me know.

Thanks

Julian