I am a 75 year old retiree living in a remote rural area who has one very bad experience with CAD but would really like to try it again. First I need to determine which freeware CAD program is easiest to learn and if it can create the files I need without excessive learning and processing work be me
My hobby is pre WWII aircraft and I have a number of aircraft technical drawings as paper, PDFs and JPGs that I would love to convert to CAD drawings by scanning, converting to vector graphics and then "correcting" in CAD software. The desired end result would be to produce scaled model parts on a 3D printer, I have never seen one but I have seen parts made by them and there is a local school student who advertises he will 3D print parts at what appears to be a very reasonable cost if the customer supplies the DWG or SVG file.
I know that there is software that will convert the PDFs and JPGs to SVG format and the few drawings I have converted this morning and then printed to PDF look usable (though some of the dimensions will need retyping and some lines have gaps).
In the preCAD times this would have been done by using a single layer drawing containing all the data, printing to thin paper, gluing the pieces of drawing to wood then cutting out on a scroll saw.
As far as I can tell in CAD this involves separating the centre-lines, dimension lines, etc, from the scanned drawing. A process which I would hope to be fairly straightforward, and making any corrections.
My questions are
1 - Can LibreCAD accomplish this?
2 - Can older users advise how steep the learning curve is for us old codgers?
3 - Can a line be highlighted and moved from the drawing layer to another (say dimension layer) or must it be redrawn?
4 - Are there tutorials on ALL the steps involved, if yes, which do you recommend and in what order
5 - Where the original scan is "dirty" with fold lines, speckles and shadows etc would you recommend any particular freeware for "pre-processing". I can easily remove fold lines and some other damage in Irfanview but getting rid of the speckles and variable density grey backgrounds is another matter
1 - LibreCAD is a purely 2D CAD program, so you can't make files for 3D printing. It can be used for laser- or watercutting or milling purposes, though.
2 - People often think CAD makes drawing easier than to do it by hand, but the opposite is the case. LibreCad is relatively easy to learn compared to other CAD programs, as it is only 2D and has somewhat restricted capabilities, so not so complex. Still, if you are a complete newbie in that field and concerning your age it will be quite challenging. If you want to give it a try you shouldn't focus too much on what you want to achieve with it but for the experience ("would really like to try it again").
3 - Yes, entities can be moved to other layers.
4 - Manuals and tutorials are a week spot with LC. Those in the WIKI are a bit outdated. The user interface has been changed meanwhile and you have to search for your tools at different places, but they are still there and work the same way. I don't know of a tutorial covering your special use case.
5 - For "pre-processing" Irfanview is quite sufficient, I would say, don't think Gimp or Photoshop can do this much better.
The problem with vectorizing bitmaps is that it normally produces two lines of the one original, the inner and the outer boundary of a line that has a certain width. You have to use a vectorizing software that can calculate a center line. And export to DXF, as this is the native format of LibreCAD, DWG - support is unreliable.
I have just remembered that some time ago I have been searching for a good vectorizing tool myself. I found WinTopo. It is commercial but offers a freeware version. It also includes sophisticated pre - processing. You might have a look at that.
I tried both WinTopo and TotalVectorise and, for
me anyway, I found TotalVectorise significantly better. For
those with a better understanding of CAD WinTopo may well be superior
or maybe its just one of those things like preferring chocolate
On 2017-12-26 4:44 AM, dellus [via
I have just
remembered that some time ago I have been searching for a good
vectorizing tool myself. I found WinTopo. It is commercial but
offers a freeware version. It also includes sophisticated pre -
processing. You might have a look at that.
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