Program for cutting scanned bulkheads with cnc router?

[Moxis]

I have always thought, how simple it would be to scan the bulkheads from the drawings, and then let the cnc router to cut them. Easy and accurate method to produce bulkheads.

But in reality not so. Because scanned pictures are often in bitmap format and include a lot of faulty points which must first be cleaned away, and then the pictures must be vectorized, to have finally a drawing which can be cut with a router. So I wonder if there exist any programs that would do this cleaning and bitmap/vectorizing conversion automatically to be able to produce bulkheads or frames easily and accurately?

[herask]

vector programs like corel, illustrator and such have the tool to automatically convert bitmap image to vector shape. but as with any automated tool it's prone to errors. the cleaner the bitmap the better the result. for instance if you have nice sharp scan of plans with strong contrast between the lines and background it shouldn't be much of a trouble to convert to good vector shape. but almost always the result is not perfectly clean and manual adjustments are necessary... 

 

cheers

Denis

[thibaultron]

Manual tracing works best. There are NO bitmap to vector tracing programs that work well enough for modeling!

[Moxis]

Thanks Denis and Ron. This is what I was suspecting. No shortcut to happiness.

[Ben752]

I agree on tracing if you're working off of scans.  It's pretty easy to do this in Fusion 360 using "Attach Canvas" then tracing using a spline then use mirror to ensure symmetry.  Then extrude and you have an STL.

 

One thing I found when using attach canvas is it can be tricky to calibrate it accurately.  Through some trial and error I discovered one pixel in an image is represented as 1/2048 of an inch.  This might be useful if you want adjust the scaling factor manually.

Edited October 29, 2017 by Ben752

[Gregory]

What works best for me is to scan the plans, then use a Bézier pen in Corel Paintshop to plot the outline of a bulkhead or other part on a separate layer.

 

I then save that layer as a .bmp which works with my laser engraver.

 

I believe some free programs like Inkscape will convert .bmp to vector drawings, if you need to convert for your CNC.

Edited October 29, 2017 by Gregory

[Williamo]

On 10/29/2017 at 4:55 PM, Ben752 said:

I agree on tracing if you're working off of scans.  It's pretty easy to do this in Fusion 360 using "Attach Canvas" then tracing using a spline then use mirror to ensure symmetry.  Then extrude and you have an STL.

 

One thing I found when using attach canvas is it can be tricky to calibrate it accurately.  Through some trial and error I discovered one pixel in an image is represented as 1/2048 of an inch.  This might be useful if you want adjust the scaling factor manually.

Hi Ben,

i am currently learning F 360, crossing over from Bentley microstation. My immediate issues are importing 2D and 3D drawings to F360 from BMS, and creating a hull surface. The results are variable, to say the least. Tutorials are helpful, but if you have any insights I would be pleased to hear them.

Best regards.

[Ben752]

The approach I've taken so far follows something like this:

 

1.  Draft the sheer plan on a sketch following the approaches outlined in Steel.  I've been using model parameters to define the scantlings to support changing values easily.  The description has been very useful for providing traceability.

 

 

2.  Create a half breadth & body plan sketch.

3.  Start building up additional detail on subsequent sketches on the same plane as the sheer, e.g. deck curves, transom details, etc as it seems fusion works best with more sketches with fewer details.

4.  Build up the profile of the hull using offset planes at station intervals with sketches representing the details of the body plan.

 

 

While I originally used the patch workspace loft command, the t-spline (from the sculpt workspace) loft allows for more flexibility in fairing.

 

 

 

[Ben752]

The zebra analysis tool also has been quite useful in getting a feel for the cursory fairness of the hull.

 

[Moxis]

For our next project, a steam powered tug, made at Ahlstrom in 1877, we have made the keel and bulkheads drawing them on the original plan with Autocad and cutting with laser. So far the ptoject has started nicely.

 

https://api.laivadata.fi/v1/attachments/58e2b648255dbc34a3a83ae0/data