Shell function for a complex boat body.

[peterbalog1990]

Hello all,

I need a help with shell function for a boat model.

I´m trying to create a shell from the solid body of my boat, the boat includes sprayers at the bottom which were created by loft function and ends in a point (so many faces which ends in a point).

If I split the body it works but only for some thickness values for example 2mm-not works but 30mm works.

I need to create shells with different thicknesses and than combine it, but for splitted body one value works and another one not works.

Project you can find in annex.

Please help me what I´m doing wrong 🙂

Thank you in advance!

Peter

[lichtzeichenanlage]

Your sketches are not fully defined and you have way to many control points for your curves. This forces a lot of problems and your surface will not be clean. 

With joining it differently I could create a 1mm top shell.

[peterbalog1990]

Hello,

Thank you for your answer!

Please can you explain me with more details what I need to edit in my model to be able to make shells for this model? (I´m new in 3D modeling...)

Do you edit something in my model? or the 1mm shell worked for you with original model what I sent?

What it means "joining it differently"?

Thanks in advance!

Peter

[TrippyLighting]

Properly surfacing the body of a boat isn't beginner stuff but...

Lets start with something:

1. Toggle on the curvature comb when editing the splines and then reduce the number of spline fit points and work with the tangent handles to get the desired curve. None of your splines should have more than three points, and most of them probably only need two!

[lichtzeichenanlage]

I was like you. One of my first (if not the first) post I've dropped here in the forum was about modeling a boat. I learned a lot here in the forum thanks to people like @TrippyLighting. And he is totally right. Starting with a boat hull is pretty ambitious. 

About the "joining it differently": I tried to find where your project was broken and I've converted your lofts from join to new body and tried to shell them separately. I could shell the individual bodies. So I started to combine the bodies again (not with the loft command but with the join command). One body after the other body and tried to shell them and it worked - but took forever on my 10 year old notebook. I wasn't able to find the broken bit (beside the curves that I haven't touched) but it somehow worked.

Like @TrippyLighting already said, 2  (perhaps 3) points should be enough. I copied one of your curves into a new project and quickly modeled a lookalike in a new sketch. With a minimal effort the surface looks way better hat yours. Here are both curves in one curvature comb. What a difference. Very bumpy vs. one smooth curve. 

Here is a quick and dirty screencast that shows what I did to create the curves:

https://knowledge.autodesk.com/community/screencast/012bf523-dbbd-45be-84e1-cd86d91b25dd

[peterbalog1990]

Hello guys,

For first thank you so much for your answers! After more than a month without any answer I thought I wouldn't get help in my topic 😀

So I tried many variants yesterday and also apply your suggestions. For first I will need to create a 2 mm shell so I tried everything below with this value.

1. - I rework my sketches: now every curve is defined by only 2 points.

2. - I prepared the boat body by LOFT - joining, result: for whole body works 2mm shell, with selecting the middle face the shell not works.

2.1 - I added the sprayers(3 body at the bottom of the boat which ends in a point), result: not working the shell function neither for whole body.

3. - I prepared the boat body by LOFT - new body for every loft function, than I try to shell bodies separately which works properly, than I combine the bodies to 1 body the result is the same as in the 2. case. I tried to shell separately also the sprayers and it works, but if I combine everything to 1 body is not working...

So reducing the curve points not helps here, same result as in case with many points, also creating new bodies and then joining doesn't help.

Any other suggestions?

Thanks in advance!

Peter

[TrippyLighting]

It did help, but isn't the only obstacle to getting this shelled 😉

I split the tip off, then shelled the main body.

Then I re-combined the tip. Lofting into a point is creating curvature problems (in any CAD software) and splitting the tip off is a workaround

I also created the lofts for the ridges on the bottom of the boat after the shelling. Simple geometry is always better for shelling

[peterbalog1990]

Hello,

@TrippyLightingyes it is clear for me what you are saying.

I try to describe my trouble below.

My first prototype of this boat created like you described, after shelling I create a sprayers but during 3D printing it causes problems... so this is a second version and I want to optimize this model also for 3D print what means 2mm shell everywhere to avoid infill the material at sprayers...

The 3D print SW allows print only shell of the body, but my final model contains more components and in some cases I need to print infill. I have a trouble that the 3D print SW not allows me to set up the only shell printing for the hull and infill for other components within one print. 

So this is the reason why I want to fix it in 3D model.

It seems that it is not possible what I need and the solution is split body into more bodies and try shelling.

Anyway, many thanks for your advice!

Peter

[lichtzeichenanlage]

@peterbalog1990 Can you share your updated model so we can play around it? What Slicer are you using. Most slicers allow modifiers or at least multi part printing and you could apply different settings this way. But why is infill in the sprayers a bad thing? 

[barry9UDQ6]

I find shell a bit hit and miss. How about offsetting your outside surfaces as a new surface(s).

Then stitching the 2 sets of surfaces together at the end?

Working with surfaces is really slow going obviously, lots of trimming, test stitching to see if things are behaving as expected at various points in your process helps me. So when you get to the stitch at the end you can be confident that no errors have crept in.

[lichtzeichenanlage]

Offsetting the surfaces is what I do if I cannot make the shell function to work. But I still prefer to spend some time with the shell function. Often it's less work if it comes to changes. 

[lichtzeichenanlage]

Another thought if it comes to 3d printing: The wall thickness should be a multiple of your perimeter thickness in the slicer. The default for PrusaSlicer would be 0.45mm for a 0.4mm nozzle. So in this case a shell of 1,8mm (4 perimeters) or 2,25 (5 perimeters) might be preferable. But this depends what settings you have in the slicer. 

[peterbalog1990]

here is the model with updated sketches. I use Cura slicer, and I have a hobby printer Ender3, so printing PETG with 0% cooling fan for strong print causes stringing a lot (with no infill smooth print result). Also I need  to print servo holders to the hull where infill will be good :). The other parts are separated like jet housing, nozzle... and assembled by screws so there is no problem. what I need only a servo holders to print into the shell which will also creates same srtringing but less than sprayers at whole length.

[peterbalog1990]

@barry9UDQ6  thanks for advice, I never try that but if shell doesn´t works here I will try it.

[lichtzeichenanlage]

I rarely use Cura but I found a little tutorial from CNC_Kitchen that shows the basics of modifiers. Unfortunately you haven't attached the model.  

[lichtzeichenanlage]

BTW: I'm also using a hobby printer (3 years old Prusa i3 MK3) and 80% of my prints are printed in PETG and I'm using 30% - 50% fan speed. Stringing is often an indication for moisture in your filament. A food dehydrator is a wonderful tool to dry your filament and it prints much nicer after that.  Wett printed PETG might also result in a much more brittle print. 

[peterbalog1990]

After some experiments for me works fine the 0,43mm in slicer for 0,4mm nozzle, but the model I always prepared for 0,4mm multiples. In 1. case the shell was modelled for 1,6mm fine strong and tight print but PETG is flexible so for second model I go with 2mm shell 5 perimeters.

and here is the updated model what I forgot attache in previous post.

[peterbalog1990]

Thanks for Cura geometry modifier, I don´t know about it and also a food dehydrator it looks promising I will try it. Generally I think prusa printers handle better the PETG because they have direct drive extruder. The ender 3 uses a bowden extruder, but I converted it to a direct drive so I hope I can set it up correctly for better PETG printing. With PLA the bowden extruder works fine. 

Can I ask you what brand of PETG do you prefer?

[lichtzeichenanlage]

I played with the sprayers. If you shell them with 2mm wall thickness they're still more or less solid. Is it worse the effort?

[lichtzeichenanlage]

I've only tried PETG from das filament. If it's dry it's really easy to work with. Here are some examples I printed during the Christmas time. All prints are done in vase / spiral mode and a 0.8mm nozzle and 0.6mm layer height. Top is printed with variable layer height (0.6mm to 0.2mm) .