Redoing Oseberg

[Waldemar]

 

Kris, you are becoming more and more CAD professional.   🙂 

 

I'll give you ways to project lines onto surfaces in a moment.

 

 

On 9/30/2022 at 2:03 AM, KrisWood said:

Question: Is there a good (free?) automated tool for importing ship plan drawings from any raster format into any vector format which can be imported into Rhino?

 

In the simple, soldierly words: forget it, it is all waste of time...

 

 

[KrisWood]

4 minutes ago, Waldemar said:

In the simple, soldierly words: forget it, it is all waste of time...

 

That is what I thought.

 

I found the equivalent of Max's FFD boxes. It's called Cage and CageEdit. It takes a little getting used to but gets it into the right ballpark and I can improvise from there, though it's never going to be exactly accurate.

[Waldemar]

 

 

Project

Project curves/points toward a construction plane to intersect a surface.

 

Pull

Pull curves/points in the surface normal direction to intersect a surface.

 

Intersect

Create point objects or curves at the intersections of curves and surfaces.

 

From the above, choose the most appropriate way for your actual need. In the last case you will only have to make surfaces from your beautiful curves beforehand, too easy to explain this.

 

 

[KrisWood]

Hi all! It's been a while. I had to take some time away while life got in the way of hobbies. Things are settling down now and I'm thinking about picking this up again.

 

This time around I'd like to start over and do it open source. Most of the lines can be derived mathematically. Some of the lines cannot be derived mathematically and must be based on existing reconstructions.

 

My question is, if my CAD files are drawn by hand by me, how different must they be from existing plans to count as original work?

[KrisWood]

First step is trying to read the numbers from https://www.academia.edu/49550641/Rekonstruktion_af_Osebergskibet_Bind_II plan 2 (page 26). This will be necessary for the curvature of the keel, which is what all other numbers are based on.

 

I've got all the numbers plugged in from page 29.

 

The green lines are the stations. Lines below the base line are ones for which no height was given in the plans.

Edited April 23 by KrisWood

[KrisWood]

Re-drawing things I've already drawn a million times is exhausting so I went to dig up my backups of the project. They're gone. The most recent one in the cloud is from three years ago. This will be painful....

[KrisWood]

Anyone want to collaborate? I could use some help with fairing and integrating the various parts into the model. I can do initial drawings of all the parts but they may or may not fit. This part was already done on my lost backups but they're lost. 🤷‍♂️

[henrythestaffy]

I am not sure if i can be of any help but i use fusion 360 and have an interest in oseberg. My services are at your  command if you wish.

 

paul

[KrisWood]

Alright! You'll need to download the plans yourself to use them and I'm not sure how compatible Fusion 360 is with Rhino. First step is coming up with a sane format.

 

Let's see how far we can get. 🙂

[AnobiumPunctatum]

Hi Kris,

 

I am really happy that you continue with your reconstruction of ths beautyful viking ship. I will follow as in the last years with great interest.

[KrisWood]

I worked page 28 into it but it doesn't quite line up with the rest yet.

 

 

[3DShipWright]

Hey Kris,

 

Cool stuff! I'd be happy to do some collaboration with you. I love longships and have even been tinkering with doing one of my own over the last couple of weeks.

 

Let me know if I can be of any assistance.

-Nate

[KrisWood]

I think the problem is going to be polygon modelers vs vector. Rhino doesn't work with solid objects as much as it does curves. Does blender support a common vector format? Maybe DWG?

[KrisWood]

Also we still need to resolve the question of, if the drawings are based on published plans, are they ours to share?

 

Either way, if you want to follow along, the starting point is to download the plans from the link above.

[3DShipWright]

Yes, Blender supports the .svg format if that works.

 

Regarding the published plans question, a few thoughts:

 

1. I think the reason the pdf documents are gated in this case is so that they can run analytics on who is using their research and for what purposes.

 

2. I would also argue that research by itself, is not intellectual property. I am in no way diminishing the scholars' effort, but the work was derivative; it can't be patented. And if there's anything I know about academics, it's that if they could monetize their work, they would've. To draw a parallel to the NMM in Greenwich, the RMG does sell copies of admiralty plans because they hold accurate, original copies of the plans and the ships themselves (other than those they stole) were property of the English government. Even so, the licensing is unrestricted aside from commercial use, and their site says simply to credit them and contact them and they may "support education and scholarship and encourage research in our collections by waiving licensing fees for certain uses."

 

3. Finally and most importantly - To even be considered a 'reproduction' the copy must be the same media or type as the original. To my knowledge, nothing published on the Oseberg site has been digital cad files for the purpose of 3D printing, nor making templates from which to construct a model ship. Think about it this way, they transcribed a physical object into print media, now you are transcribing print media into digital media. If anyone is owed royalties here has been dead for over a thousand years.

 

So yes, I would recommend crediting your source material wherever possible. I also think it may be courteous to thank them via an email, a good review, or a small donation (whichever you feel appropriate). But I don't think sharing a free document for purposes of a non-commercial project should even be a factor here.

Edited April 24 by 3DShipWright

[KrisWood]

I'd disagree on one point only. The paper and its contents are intellectual property of the Viking Ship Museum in Roskilde, Denmark. 

 

I think as long as we don't redistribute the original PDFs we'll be ok.

 

Edit: I've got the keel and stem cross sections done. Next step is fairing them together and drawing the 3D curves.

 

Edit: The paper's measurements for the keel do not fair, at least at my skill level, so I'm trying again with the numbers from the Saga Oseberg book. I'll update this in a bit when I get a chance.

Edited April 25 by KrisWood

[KrisWood]

Got the keel faired. The numbers in the paper are more accurate than those in the Saga Oseberg book.

 

 

 

Edited April 30 by KrisWood

[KrisWood]

I've redrawn the fore stem. The cross sections in the original drawings are not to scale so they can't be used directly. I've redrawn the widths of the sections to scale using the numbers from the paper, but cannot reconcile them with the curves of the stems. Can anyone help? I've put my newly drawn stem at 1:10 here as an SVG.

 

How do you draw this in 3D?

stem.svg

Edited May 2 by KrisWood

[KrisWood]

I got frustrated with trying to make the stems 3D so I focused on 2D instead. All carvings complete!

 

 

[KrisWood]

Whoops, right after that last one I realized I'd only done the carvings in profile view. NOW all the carvings are done.

[KrisWood]

Ok I'm stumped. Can anyone help me make this 3D in Rhino?

[Kevin-the-lubber]

In what way are you stumped? I don’t use Rhino, only F360, but the principles are broadly the same.

[KrisWood]

Here's the problem.

 

The blue lines are easy. They are given in the paper. The stem is 5.5cm wide at the forward edge and at the top of the stem-top, 10.7cm along the inner edge of the rabbet, 15cm at its widest point at the aft edge of the base of the stem-top.

 

The green lines are of unknown length. Their length is determined by where you draw the cross section through the stem, and at what angle. You'll get a different number every time on these depending on how you slice it.

 

You can't just use the cross sections because the length is undetermined in them.

 

I try sweeping the rails using the known dimensions but it comes out all wavy, not a nice straight line like in the plans.

[KrisWood]

Ok I figured out how to get it into 3D by using crv2view since I've done the math in front and profile views. Now to figure out how to get solids out of these.

Edited May 10 by KrisWood

[Kevin-the-lubber]

Glad you’ve got it figured. That’s quite a different way to how I’d do this in F360 and it would probably just confuse the issue by getting into that.

 

Can I ask, what are you aiming for as an end product? A CNC-milled kit, or something like that?

[KrisWood]

Yeah, vector CAD is an entirely different animal than poly modelers. I actually started learning CAD with 3DS Max a couple decades ago but switched to Rhino for this project. I'll never go back, when it comes to ships at least. It's far easier to draw curves accurately.

 

As for end product, my goal is a paper or wood model. I can't afford a CNC mill at the moment, but I can probably get a laser cutter in the next year or so.

 

In the meanwhile I can print on card to my heart's content so I'm going to do that and cut the layers out by hand and glue them together.

 

I just have to get all the parts into 3D so I can slice them into layers for printing. 🙂