Digitize plans / prints on a CNC machine?

[TANSL]

most hulls are defined in part by splines and not all software can deal with splines.

Just a small comment, perhaps obsolete: CNC cutting machines cannot draw splines, they can only handle straight lines and curved arcs, and these with a radius of no more than 35000 mm (I seem to remember). This causes the programs that interpret the nestings of parts and translate them into machine language to get lost with the splines, so the designer must convert them into polylines.

 

[Herreshock]

Just a small comment, perhaps obsolete: CNC cutting machines cannot draw splines, they can only handle straight lines and curved arcs, and these with a radius of no more than 35000 mm (I seem to remember). This causes the programs that interpret the nestings of parts and translate them into machine language to get lost with the splines, so the designer must convert them into polylines.

Typical flaw of corporate proprietary wars and lack of 3d design standardisation, the whole 3d software and archive files is a nightmare, they have ruined it in the last decades and you cannot even export files and this includes boatbuilding with all the softwares divided by huge non compatibility walls, not to mention using personal jargon in each software and i have installed almost all of them with flashy propaganda.

And who's going to pay for that? Already there should be a decent open source software with the accessibility of SketchUp but having cfd, structural analysis, hydrostatics, etc and the nearest thing is freecad but it's just a big copy to autocad thick book, and has not been properly developed and made accessible

 

[mc_rash]

I'm not sure wether the question of this thread is just if it could be possible to 'scan' or digitize 2D plans with a CNC machine (tracing the outlines etc. with the tool head -> movement detected by stepper motor/ movement detector -> converted to lines/ curves in CAD)?

If that is the question this shouldn't be a big issue for somebody with some experience in Arduino?
A 2 axis (x and y) would be outperformed by one rotating arm recognizing angle and lenght.. No problem at all with arduino, you wouldn't even need a CNC machine you can just build it yourself (cheaper and customized)

 

[Herreshock]

Yes and probably a simpler way also can be done with a phone and scan app with the phone with some wheeled support or the plans in a wheeled table to keep the same height and moving it to the sides and upward to scan the whole picture at decent resolution

 

[gonzo]

Paper plans usually include a table of offsets which can be easily converted to a DXF. If you don't have the table, making one is easy with a scale ruler. Measure xyz for the intesections of waterlines and stations and enter the data points. If there are diagonals, enter those too.

 

[TANSL]

I don't understand why you need to convert a table of offsets to a dxf file. What do you think a dxf file is?

 

[wet feet]

I suppose if the plan is to cut the components on the same CNC machine,it does make sense to create a file in the format that any related software should be able to read.I may be totally wrong in believing that this is the objective of the project because otherwise it would have been possible to produce the parts manually in less time than this thread has been in existence.

 

[Tops]

It would still be interesting to see/ have a CNC capable of a probe or digitizer mode.
I tried a plan yesterday where scaling the image and drawing over the top of it showed some dimensions were missing (blue curves) and at scale there was a 1% error (.2"/5mm on 20"/500mm) between the graphic and a figure drawn to its listed dimensions. It's from a Spitfire hydroplane, thought @TomA might get a kick out of it...

 

[wet feet]

There are two ways to consider the situation (maybe more) but what you have demonstrated is why lofting is normally done by referring to a table of offsets.You could use CAD to trace the relevant lines from a scan of the drawing and apply a correction or scaling factor to adjust them to the given dimensions.The example in the previous post has a rather "individual" dimensioning style and I can't easily determine what the 1/2" dimension at the lower left corner refers to.

 

[Tops]

There are two ways to consider the situation (maybe more) but what you have demonstrated is why lofting is normally done by referring to a table of offsets.You could use CAD to trace the relevant lines from a scan of the drawing and apply a correction or scaling factor to adjust them to the given dimensions.The example in the previous post has a rather "individual" dimensioning style and I can't easily determine what the 1/2" dimension at the lower left corner refers to.

I think the 1/2 and 3/4" dimensions in the lower left are the relief for a chine member, so 1/2" up aligned from the corner and in 3/4" perpendicular. The one that took me a minute was the 3/4" with the arced extension line and no arrows for the keel strip. 3/4" is the nominal thickness of 'one by' (1 x ...) lumber in the US.

 

[TANSL]

Even if the hull lines are drawn from a table of offset, it is always necessary to loft the resulting shapes.

 

[gonzo]

Is there some way to digitize a print / plan on a CNC machine? Replace the cutting head with a stylus that can be viewed, jog it around the plan with a joystick and output the x and y coordinates when a button is pressed on the joystick. The strings of coordinates would have to be processed into cutting directions.

Tom Alborough

You can enter the drawing a set the proper scale. Then using the mouse, click on point to get the xy location to create a table of offsets. There are many programs that will do that, including pdf programs like Blubeam Revu.