I simply do not know how to model the front part of this nose cowl. Also fillets on the top and side.

I'd like to use it for a 3D print.

Help please,

Marv

Hi Marv, well it's pretty complex and has a lot of little elements in it so it's going to take numerous passes probably building one type of shape at a time.

I'd probably start by drawing in a profile curve in the Front view and using Construct > Revolve to build the base shape.

For these cutouts here, draw a 2D curve in the Top view, replicate it using Transform > Array > Circular, and use Construct > Boolean > Difference to cut the holes in the base shape:


For these parts that looks like a cylinder laying on its side, then make a torus going around it by drawing a circle and using Revolve, then use Transform > Array > Dir to replicate it along the cylinder, then Boolean union the cylinder and the torii together, then replicate those around using Transform > Array > Circular, then boolean union those with the main shape:


I'd worry about filleting after more of the main features had been created first, the filleting may be pretty complex and it's possible you may need to use a different CAD program to do that part and bring it back into MoI afterwards. But it depends on how complex it is once all the main features are in place.

- Michael

Maybe I should vacuum form the front part and cement it to the shell

Marv

About those fillets, I really like to 'voxelize' everything now. It's a little bit ... brutal.

I really like Houdini for that process, once the little setup is in place (convert to voxels, small smooth filter on the voxels field, convert back to poly, reduce polycount), you can reload your Moi model in one click,
and get a quick feedback during the modeling process. The voxels conversion will wash out / blend fine detail too, emulating the printing process somehow.

It requires a good amount of memory (min 32Gb for mid size models)

I suppose that will be the same with 3D Coat ? (voxels)

Did a little bit of experimenting this evening. Its quick and easy to make using Moi but would get tricky if you needed to filet it all. I made it as a solid but could not shell it so voxelized it in 3d Coat and extracted a shell. I then exported it as an obj at a poly reduction of 80%. This is the result rendered in simlab. I am happy to share all this in more detail if anyone is interested.

Hi Marv
Not sure if this helps you but I have attached a model that might only need slight modification.
Keith

Marv, have you figured out your problem yet?

I found the model plane that this cowl appears to come from: http://www.itsawingthing.com/index.php?_a=viewProd&productId=76

Looks like it would be thin light plastic. I imagine printing it out and making the model plane would be quite fun. My wife says I don't need a 3d printer as we are surrounded by shops and can buy stuff 24 hours a day. I can therefor only guess at whether it would be possible to print out a thin light cowl from Moi. I know that 3d coat also produces printable models and the shelling and smoothing of the model seems to be easier to achieve than with Moi. Presumably a 3d printer needs a solid rather than joined surfaces?

I'm tempted to model the rest of the aircraft:)
Keith

WOW! You are quite an artist.

You are correct it is a T28 cowl

Yes I would sure like to know how.

The shell can be up to .0625 thick Optimally .03125. I don't know how to make that change

Hi Marv
Thanks for the complement but there are much better artists lurking on this forum.

This is how I approached making it https://youtu.be/oIjFaWogIqs Its speeded up a bit but I think its followable. I can put up the original version if you would prefer. I think the shelling might be difficult to achieve but I suspect that there are others on this forum that know about printing out real objects and they may well help you out. I will continue to experiment but I work full time and have a family so I seldom get more than a few minutes at a streach.
Keith

Thank you Keith,

Short for now. More later.

"seldom get more than a few minutes at a stretch!" I've been working on this for hours (days)

Marv

Hi
Just out of curiosity.

Does anyone know why I can't shell the Radial.3dm (Radial.zip) that I have posted to this thread? I have rebuilt the model and tried again but Moi just says it's "calculating" forever or "calculation failed". Parts of it will shell if separated but not the whole thing in one go.

A bit off topic I know but, while I can shell it in 3d coat I have a simular problem saving it as an STL file as the program uses up lots of processor time and memory without producing any output.
Keith

Hi Keith - shell is probably the weakest function in MoI currently, it's a very complex operation since any surfaces that do not meet up smoothly will not have offsets that exactly meet up and they will need to be extended and intersected with each other. The geometry library that MoI uses doesn't have a very good mechanism for that. It can work for simple cases but with 392 faces in your model that's a lot of extensions and intersections to be calculated. Then on top of that you've got some small sized features and surfaces with tight bends in them and if your shell offset distance is larger than the size of those small feature that's an additional difficulty.

You might try bringing it into something like OnShape which has a much more sophisticated shell function, but it's probably going to be difficult to shell anywhere.

You could probably make some progress on building a shell by using Edit > Separate to break some of the large surfaces out to individual surfaces and then use offset on those surfaces to build some pieces and then work on filling in the gaps.

- Michael

Hi Michael
Thanks for the explanation. I was just curious and you have explained very clearly.
Keith

Wow, Keith that looks super impressive! I haven't modeled anything like this before so it's cool to see someone do it. Also thank you so much for the YouTube link

Hi Kuro
Thank you and you're welcome. It's a shame it doesnt shell very well for the purposes of 3d printing which is what Marv was trying to achieve. Of course with moi there will be a better way of making the same thing.
Keith

Here is a way to work out complex shells.

I take Keith's Radial file, then de-feature and shell the base shape. Then I can join the shelled result onto the top detail:



This is leaving the detail at a larger depth. If that little extra material "Just had to be removed", I would handle this by keeping the original "Spoke" pieces as they were before the Boolean. Most likely these can be shelled as separate objects. They can then, at this stage, be Boolean cut from the underside, to create that part of the shell.

The depth of my shell was a bit greater than was mentioned (.03125). I would have had to remove the cuts between the spokes, then recut them after, because they are deeper than that.

Anyway, hope that helps for this.

Hi There

The zipped file above is printable but does need some fixing by my slicing program. Thats Keiths file

I printed it at .65 x size at 35 micron layer on my Kevvox

there is good detail in the top although the sharp edge on the centre hole peeled away from the centre slightly

I get better prints if the parts are not joined but intersect each other. unless you need fillets on the joined parts




cheers
shayne

Now I look inside Keiths model there are some strange parts that do not make it easy to slice

removing some of the surfaces here is whats inside

perhaps thats why he had problems shelling it or the result of an attempted shell



cheers
shayne