can't get loft to do what I want!

[jonno22FBM]

I'm trying to create a blend between body and neck on a guitar with an unusual neck profile, but I'm struggling to make it do what I know I can carve by hand... as this is eventually for CNC I want to get it right in the model.

Please refer to the pictures - 01 shows a blend I have made that I'm actually quite happy with and would like to use, except for one major issue, that the outline profile isn't where it needs to be. Looking at image 02 on the top of the guitar you can see that the outline shape on the sketch has much tighter radii curves which is necessary as the shapes continues into the body of the instrument.

I couldn't get the original sketch curves to work as rails so I re-drew them as separate new sketches using splines which did work, but now I just can't get the loft to do what I want, I'm getting a pinching and unusable shapes from the loft - see last image. I have tried moving the neck profile further away which improves it a little, but it's still not right. What I want to achieve is image 01 with the correct outline shape using the rails...

And also soften the two edges leading to the corners if at all possible (while leaving the vertical side edges absolutely straight)...

Any ideas?!

[ahreum.ryu]

Hi @jonno22FBM, 

Thank you for posting 

Regarding unusual shape, it wouldn't be hard to create... so I couldn't define what exactly the problem is without model. 

Could you share your model? 

I look forward to your reply. 

Many thanks.

[jonno22FBM]

Hi,

Many thanks for your reply @ahreum.ryu. Here is the model where I have made the blend which doesn't follow the sketch outline, but looks great otherwise. What I want it to do is have the two top outer edges follow the sketch on the top of the guitar neck, where it widens out to the body section - please see the attached image - yet maintain the smooth blend shapes I have currently. In this model I haven't yet used the sketch curves as rails, but when I did manage to do this the loft became really quite distorted as you can see on my previous post.

As you can see, I am having the same problem at the blend from neck to the headstock. I am a Fusion 360 newbie and this is my first attempt at modelling so apologies if I'm asking a simple question, I spent hours and hours trying to get it to work already! I would really like to understand how to so this myself...

Many thanks again

[ahreum.ryu]

Hi @jonno22FBM, 

I'm trying to figure out a solution but it will take a little more time. As soon as I figure it out, I'm going to get back to you. 

Many thanks! 

[jonno22FBM]

Thank you @ahreum.ryu, very much appreciated... Looking forward to seeing how you figure it out!

[ahreum.ryu]

Hi @jonno22FBM, 

Thank you for waiting!  

In your case, I also couldn't succeed to use solid loft. I think it is related with curvatures so I tried to use patch option and then it was succeed. 

I'm sharing how to create it and model file. if you won't able to reproduce it please let me know I'll happy to help you. 

Many thanks! 

[jonno22FBM]

Hi @ahreum.ryu,

Thank you so much for taking the time to work this out, you've done an amazing job! I will study the screencast in detail and try to recreate the patches fully myself in the next couple of days.

In the meantime, the final procedure you make in the screencast is to delete a few faces and create a new patch which smooths out the edges into a softer shape which is exactly what I am after. I have opened your model and am also able to do this at the heel end on one side, but not on the other side at either the head or the heel blends, please see the attached image. I am getting the following error:

Error: SurfacePatch18
Compute Failed

Modeling Error: Can't create patch toolbody, please check the inputs

Could you possibly show me how to achieve this too?

Again, very many thanks! 

[ahreum.ryu]

Hi @jonno22FBM, 

Thank you for replying 

I think your model is a quite hard to create a patch option.

Because filling the area, they need a proper curvature. If it doesn’t fit, the surface will be crumpled some of area. Therefore, even if it succeed to create the surface, the quality is bad.

    

So I would suggest you to create the clean sketch I think you just imported it and sometimes it didn’t fit with each point and also there are no constraints that even it doesn’t have vertical and horizontal constraints.

On top of that your second part has some surfaces issues. The sketch and model has different results. (I guess when you created first loft it already moved a bit.)

 

Can you arrange your sketch again?

And helping to succeed the patch option, we are able to divided surface area. please take a look at this video. But it wouldn’t succeed all the time because it is related with curvature.  

After modifying your sketch, if you still have the same issue please let me know. 

Have a great weekend! 

Many thanks

[jonno22FBM]

Thank you @ahreum.ryu, amazing help!

I can see what you mean about the sketch, I did import a dxf file to generate it and can see that I really need to build it inside Fusion.

I will start over again, but what would be the best work flow using my dxf files if there are minor discrepancies like this? Should I somehow create a series of new sketches using the dxf as a guide, or should I somehow manipulate the single sketch created by importing the dxf again?

I'll have to figure out how to do either of these techniques...

Thanks again for all your help!