Solace (Alden Triangle) slowly regaining momentum - CAD

[mark ward]

Greetings all, from Seattle, WA. As I am almost finished with Graduate school, I'm able again to work on Solace, my (from scratch) John Alden Triangle. All the plans are lofted, and in the process there were no modifications to any of the lines, the offsets were spot on. The keel is approximately 75% complete(see old threads http://media5.hypernet.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=1&t=006774&p= ). However, I now have the opportunity to draft the stations in CAD and have the moulds cut on a CNC router, which could save an immense amount of transfer and bandsaw time, and the output would be perfect. Would you suggest a spline fairing software plug-in of sorts even though I came across no errors in the offsets? And if so, where should I start software surfing?

BTW, I'm right handed and I did the bend over and look through my legs trick, they were sweet.

Best wishes ,

Mark

[Dave Fleming]

I'm right handed and I did the bend over and look through my legs trick, they were sweet.
Ah, the old faht is vindicated! :D

How about the changing bevels on the moulds? Not being a CAD type I would like to know, please?

[preston]

Originally posted by Dave Fleming:
How about the changing bevels on the moulds? Not being a CAD type I would like to know, please?I expect he'll still have to fair them by hand.
Or perhaps his CNC router can do it for him.

A bit enviously,
Preston

[mark ward]

Dave,
Well now that's an interesting point. Alas I had somewhere gotten the idea that bevels on the moulds were unnecessary so long as the forward moulds were placed aft of the station and vice versa, thus only defining the exact point around the station for the ribands to pass prior to bending the frames in. I suppose then, if the bevels on the moulds are crucial, they would need to be trimmed after the fact (the CNC I have access to, I believe can only do vertical work). If done on a bandsaw, would you cut the bevel by adjusting the table in the process or go back to bevel by hand after the mould was cut out?

Thanks for your reply, and I'm looking forward to your thoughts.

M.

[Ken Hutchins]

Mark, you should be able to fair the splines with whatever CAD sys you have available. Magnify the suspect area, edit spline, delete suspect point and let pooter fair the spline, then create a new point on the spline if needed. I did my boat on Auto Cad 14. It can be done on a 2D system but 3D is a whole lot better and anything newer than 14 would be better still.
But, as a tribute to the old traditional methods I picked up the bevels with a bevel board off the plotted mold stations. Of course I made the bevel board with a computer plot. :D Some things are still best the old way, some things are done best the new way.
I would cut the moulds with bevels with the band saw unless you have a 5 axis router available

[mmd]

I think that if you have already lofted and faired the lines, to re-create them on CAD would be to re-invent the wheel. Unless you use a helluva lot of datum points, the curve you draw on CAD will not match the line on the lofting floor and unfairness will creep in. So the CAM router will produce exactly accurate incorrect moulds, which will still have to be bevelled by hand. The accurate solution is to model the hull in a 3-D modelling program such as Rhino or ProSurf and export the mould lines from there. This would be an expensive and lengthy process.

Cutting bevels in the moulds on the band/shipsaw can be done with two or three experienced hands and carefull planning; without these available it is, IMHO, better to go square and dub with electric and hand planers.

Don't jump horses mid-stream; if you started traditional, stay traditional. Cutting corners and trying to go fast will bite you in the ass eventually.

[Todd Dunn]

I use CorelDraw to generate vector drawings from scanned lines. It has very easy to use spline functions and can output autocad files directly. You can also scale the lines up to the full size you want to work at so that your fitting errors will be within the width of the lines. It takes me about an hour or so so manually convert a set of lines from a scanned image into a vector based file.

You can see lines I have drawn this way on my web site. The image is a set of CorelDraw drawn lines for a Bristol 45.5

http://www.todddunnmicroyachts.com/current_model/Bristol_455_Lines.jpg

Todd Dunn

http://www.todddunnmicroyachts.com