F50: Issue Connecting Rail Between Two Sketch Profiles For Loft

[MaxHugen]

I'm trying to create a section of a hydrofoil ffor a SailGP F50, from sketch "Profile2" to sketch "Profile 4", using a rail in sketch "Profile Rail 2-4"

The rail is not connected to one of the profiles, I think the lower one.  In the Edit of "Profile Rail 2-4", I used "Include 3D Geometry" to include edges from both Profile 2 and Profile 4.  Then I tried to use a Coincident constraint to join the rail to each profile. I think it worked on the top foil profile, but when I tried to do it to the bottom profile (4), an error occurs - "sketch geometry is over constrained".

I'm unable to figure out how to resolve this.  Did a screencast, but not very good :  https://autode.sk/3u16m4Q 

Any suggestions would be welcome.

[dsouzasujay]

Hi @MaxHugen ,

Sweep Command

Let me know if this not the output you are looking for.

[jeff_strater · Accepted solution]

OK, this is really weird.  That loft works OK for me.

But, in general, there are a couple of recommendations:

1. avoid point stacks if you can.  Use Select Other (left click and hold) to see what is under the cursor.  In your Profile 2 sketch, there are 3 points here:
   
2. Have a strategy for your profiles and rails.  In this post:  introduction-to-loft-using-rail-curves-in-fusion I talk about 2 main strategies:  profiles first, or rails first.  In reality you can do this in any order, but you need to be methodical - create a profile, create a rail sketch, and then either use Project Intersect or Include 3D Geometry to make certain that the point you reference is exactly in the right place.  Also, once you've intersected or included the point, turn off the other sketch to prevent accidentally selecting it in further sketch operations

Usually that method will result in success.

I have no idea why this loft fails for you.

[MaxHugen]

@dsouzasujay, thanks for your suggestion. A newbie, I haven't tried out the Sweep tool yet, must try it out.

@jeff_strater  Many thanks for the link to your Lofting intro, it's great!  Way better than all the "HowTo" YT videos I've been devouring, which are often not especially helpful.  Do you have a collection of such truly useful posts?

I can see that I got my process somewhat convoluted.  I need to use the Rails approach, because all I have for something like these foils are stills I've taken from videos, which give me outlines in 3 planes. 

I should create 2 Rails (one each for Leading and Trailing edges) that fit my images in each of the X, Y and Z planes.  That may be a bit challenging, as some sections of the foil are parallel when viewed in one plane.

Then add Construction planes and the varying profile sketches, making sure I can join them to the Rails.  Will study your methodology very carefully, and try again with a new component (#3).   🙂   Now that SailGP races have finally started again, I have better and more up-to-date images to work from.

Still a bit puzzled how you managed to loft my last attempt.  Maybe due to my 12 yo 4Gb RAM laptop which regularly gags when using F360 - eagerly awaiting delivery of a new "CAD spec" unit.

Cheers, Max

[MaxHugen]

Jeff, one question pls: is there a way to set a point on a Fit Point Spline curve to exact X, Y & Z coordinates?

I've started afresh with the foil, starting with an YZ construction plane for a Rail, similar to the End Elevation as before.  Once I have that correct, I'll start adjusting it in the XZ direction and so on.  Something I find a nuisance is that I can't seem to move a point to a precise position, for example something like Y=0.    I've tried free moving and using snap, that works but tends to then also snap to a Z position on the grid.

Is there a way to enter the exact XYZ position of one point on a curve?

[davebYYPCU]

Avoid 3d sketches until you can’t do it any other way.

Sketch Plane is Z,

dimension X and Y, at the Z height.  For the point on the curve, no dimensions required, just Project > Intersect the curve, at the Z height.

Might help....

[MaxHugen]

Hi Dave, yes I discovered the benefit of working in 2D, until it was actually necessary to go to 3D.

My sketch below is in the Y plane, and still in 2D.  The top point of the curve shows it is at Y= -3.289E-04, whereas I'd like to set it to Y=0.   I understand that Snap to Grid would do that, but then I risk altering the Z value as well.   I've also tried the Move/Copy command, but despite zooming in until F360  would go no further, I couldn't get it to quite Y=0.

I just thought there would be a way to manually define the XYZ coordinates of any point in a sketch?  (Or just the YZ coords in this 2D example)

[jeff_strater]

@MaxHugen - there is no convenient way to set a fit point at a specific location, unfortunately.  You can do it via some kludgy workaround, like drawing 3 construction curves (one per coordinate) and dimensioning those, but that's all

[davebYYPCU]

Y=0, is vertical above the origin.  

Use Dimensions and or Constraints to control sketches.

Lines and (tangent) arcs are easier to handle for dimensioning.

Tangent to spline and ellipse still needs workarounds, Design dependant.

Might help....

[MaxHugen]

Hey Dave, using a dimension to constrain a 3D curve could be useful indeed.

I might have been able to avoid some issues, where I really wanted a 3D curve to keep certain points to remain at an exact position in one plane by constraining it to a temporary construction curve/line.

Thanks, Max

[MaxHugen]

Woohoo, it's a beautiful thing!  🙂

Many thanks for your help guys.  I've learnt heaps.

@jeff_strater,  I used your linked post to use a better approach, but found I still had to use a "combined" method.   Started with Rails, as I needed these to get planes at the points where the foil changes it's profile, and also to get get dimensions for the profiles along the "horizontal" part of the foil.  Using Intersection, I linked the various profiles to the aft Rail, no problem.  But I was unable to join the profiles to the fore Rail, due to the minute positional differences that I couldn't resolve.  So instead, I recreated the fore Rail from the profiles and adjusted the curve to the original rail.

Sounds a bit messy, but it worked, and the entire foil is one Loft except for the small top bit which needed a lug sticking out.

The next challenge will be to replicate this Port Foil to starboard.  Haven't figured out just how best to do that, certainly don't want to have to recreate every curve, but might have to. Or can a body can be mirrored?

Cheers, Max

[MichaelT_123]

Hi Mr MaxHugen,

As per your unfulfilled thought:

I just thought there would be a way to manually define the XYZ coordinates of any point in a sketch?  (Or just the YZ coords in this 2D example)

Yes, there are ways... although not as convenient as one would like.

• Use Move command on a (unconstrained) point 
• Generate point(s) using a script
• Import an object with the required geometry and relate it to the sketch
• ...

Regards

MichaelT

[MaxHugen]

Thanks for the suggestion Michael.

As I'm on day 27 of learning CAD, I don't know how to do that. Is there a video perhaps that shows how this is done?

Cheers, Max

[MaxHugen]

PS: found I can Mirror a Component. 🙂

[MichaelT_123]

Hi Mr MaxHugen,

... points 2 and 3 at this stage would be to cumbersome for you at this very beginning of learning F360 intricacy... but the point 1 is very basic.

1. select the required sketch point  (unconstrained!)
2. Hit M key (Move command)
3. Tickle synopsis of the displayed DialogBox

Happy Learning

MichaelT