Cnc?

[Gades]

Hi everyone,

I was wondering if any of you has ever used some CNC in the boat industry.

What equipment do you need? Like what software and what hardware to work with.

When should it be applied into production?

So, anyone knows ...

[Steve Hollister]

CNC

I will assume that you mean cutting out 2D parts from plywood, AL, or steel, rather than doing 5-axis milling of a 3D hull model. (see my article called: "5-Axis Milling for Plugs, Molds, and Tooling" at www.newavesys.com/articles.htm, if you are.)

For 2D, start by looking at the following site: BMR Automation (www.bmrautomation.com). They sell an industrial strength CNC cutting system (with large tables) for under $6500. They sell to all industries, but their background is boat design and construction. Looking at this site will give you an idea of what you need to get started in terms of hardware and software. Call them and tell them about what you want to do.

Generally speaking, when you by the CNC hardware, you get some sort of CNC program that will read DXF files (or other types) that contain 2D shapes. The CNC program will then convert the DXF shape geometry to the required 'G' code used to drive the machine.

However, there are a couple of problems. If you want to cut out a lot of small parts, then you need some sort of program to "nest" these parts on a rectangle that is the size of the sheet material you are cutting. Also, if the shape you want to cut is too large for the material, then you have to have some program to break the shape into smaller pieces to fit on the material. Although there are specialized programs that will do this (nesting and splitting) for you, many do this in a general purpose 2D CAD program. Once the shapes are combined and nested in the CAD program, then you can output the entire geometry to a DXF file that can be read by the CNC machine.

The final "gotcha" is a small problem about the diameter of the cutting head. If you are using a router bit on the CNC machine, the machine will cut the material so that the center of the cutting head follows the path of geometry. This means that there will be an error in your parts equal to one-half the diameter of the cutting head. You should check to see if the CNC machine cutting software can compensate for this problem. (They might refer to this as kerf left or right.) If the CNC software does not do this, then you need to look in your CAD or nesting software to see it it can do it for you. In the CAD program, you need to look for a command that can offset a closed 2D polygon shape or an open polyline.

If you want to cut hull surfaces, you need to determine if the surfaces are developable (singly-curved) or expandable (doubly-curved) because some software handles only developable surfaces. See an article I wrote on Developable and Expanded Surfaces at www.pilot3d.com/tutorials.htm.

[Gades]

Thanks for your answer.

Actually, I meant both 2D and 3D. I'll have a look at your article, and the other links.

thanks again

[User_U]

Hi everybody, greetings from germany, my first post - I hope my english is good enough ;-)

so Gades, Steve already wrote something about the basics of developable surfaces and the problems, here now some facts from germany: 'Bavaria Yachtbau' Ltd fixed their production output number with nearly 1900 boats in 2001 - if you want I can give you a detailed list of the production range with the costs...
They use a 20 x 8 metres tall 5-axis 3-d-milling machine where the decks are put in. The stern contour of the deck is also cutted with this machine, e.g. a 40ft-Bavaria has more than 430 holes to drill in the deck (average drilling time per deck: 1 hour including setting up the position of the deck with 30 measure points. (You can be sure I will find some pictures of this machine the next days and you will find it here).
Bavaria uses three 2-d-cutting machines to cut the wood structures for the interieur - the whole interieur is built in a segment system, e.g. the already fitted pantry isjoined with the hull.

The 'Hamburger Schiffbau Versuchsanstalt HSVA' (link here ) uses nearly the same machine with the same size as Bavaria does, they are using a 'solid works' -software to cut a models for the tank towing tests with a length of about 32ft. After milling with the 5-axis-CNC the need only two days for perfect shaping the hull. The differences caused by the machine are only a 1-3 millimeters! (I guess ~0.1 inches). The digital hull model is done with NAPPA.

Bavaria uses the text editor for programming all waypoints and advices for the machine.

I hope I coul help....now searching for pics ;-)

[Gades]

User_U: Thanks for such an accurate answer!

Getting a few numbers really help to understand what's going on; so I appreciate the effort. Do you think you could find a picture of what a deck looks like after the CNC has done it?

I hope to see future posts from you

[Jeff]

Thanks very much User_U for the interesting post - I would also love to see some (even ballpark) cost numbers especially for the 3D operation.

[Steve Hollister]

For 5-Axis Milling, see

www.janickimachine.com

www.mollicam.com

www.necomposites.com

www.formglas.com

I also recall seeing an article in Professional Boatbuilder about Janicki Machine (Marine?) (a year or more back) that might give you some idea of the costs involved.

[User_U]

BAVARIA YACHTS LTD

for general info please visit the homepage www.bavaria-yachtbau.com

--------------------------
Sales volume

sales volume minus trader benefits & minus tax
(per financial year)
- 97-98: 33 802,000 US$
- 98-99: 57 302,000 US$
- 99-00: 92 308,000 US$
- 00-01: 132 218,000 US$

------------------------------
employees

june 2001:
- sailing yachts department: 470
- motor yacht department: 50

-------------------------------
output per employee

finacial year 94/95: 103,600.- US$
finacial year 00/01: 269,800.- US$

-----------------------------------
personnel expenditure development (% of sales volume)

finacial year 92/93: 27,65%
finacial year 93/94: 25,97%
finacial year 94/95: 25,37%
finacial year 95/96: 24,26%
finacial year 96/97: 20,80%
finacial year 97/98: 18,41%
finacial year 98/99: 14,87%
finacial year 99/00: 13,69%
finacial year 98/99: 11,83%

_____________________________________

I've to look for some pictures of the production facilities in our office the next days!

-stay tuned

Udo

[Gades]

Thanks Udo,

do you think, that it'd be possible, as Jeff required, to show some "money" numbers about the 3D CNC operations? Just something approximte, because I guess this is what all is about when you have to take decissions, isn't it?

BTW, I didn't say it before: wellcome to the forum

[User_U]

Thanks Fernando/Gades,

you can be sure, I will find some detailed numbers (sorry: money numbers) about the 3-d cnc, but don't forget the numbers I have allready posted: the cnc-facillities have partially caused the development of personnel expenditure.
Mr. Hermann - the chairman and founder of Bavaria Yachts Ltd. orderd a second 3-d-cnc and is now building new facilities for 27 000,000.- US$ - then it will be possinle to rise the output up to 4000 yachts/year.

So please give me some more days for takin' some new (actual) pictures and to9 get some more data!

stay tuned _/)_/)_/)_/)_

Udo

[Stephen Ditmore]

I expect manufacturers of this equipment may be exhibiting at IBEX <www.proboat.com> and other marine trade shows.

[Gades]

I forgot to mention that I'm looking for CNC information because someone asked me to do it.
It's for a boatyard in Ibiza (Spain), who were thinking about investing in their business and get bigger, but they couldn't get too many people. They prefered to invest in "machines", so that's why they were wondering about CNC.

Thanks for all the replies

[Andre Morf]

Hi, Guys
I came accross your site by chance.
We are a Glulam manufacturers in penticton BC Canada. Two years ago we purchased a 5 axis cnc , a creno industriel.
its a gantry style with a very large working area.

We have never done any manufacturing on boats before, but after, following some of the links that you guys have posted, I noticed that our machine would be very well suited for this work.

If anybody is interested, take a look at our website.

www.structurlam.com

there is a video on this page www.structurlam.com/prod-services.htm

andre@structurlam.com