While the industrial design industry has changed to CAD modeling and drawing, there are many manufacturers and manufacturers that have old designs stored in the form of paper drawings and drawings. In addition, there are engineering design firms in which design engineers and consultants prefer a hand-drawn sketch for initial designs.
But what happens is that these drawings on paper are just physical drawings. They need digital backups (digitized drawings) and the engineers need them in vectorial form as in CAD to edit them without any obstacle. Therefore, this article is a guide on everything you need to know about converting paper drawings to CAD format by scanning the drawings and translating the plot to the 2D / 3D CAD file.
When can a paper drawing be converted to CAD?
Converting designs inherited from paper sketches to CAD is one of the most common scenarios involving CAD scanners and drawing scanners to perform the conversion. For example, as a design company, you may have ventured into a partnership with the manufacturing company to deliver designs for a particular product, such as the commercial sheet metal kitchen counter. He has already done multiple projects for the same industry and has also dealt with the same type of projects in the past.
As a result, your CAD engineers and editors are now experts in this and the 3D CAD modeling project partnership is just like a walk. And the designs for this newly bagged project are also quite common, with some changes and different CAD dimensions.
However, since all your previous products were drawn on a physical paper or on a sheet of drawings, importing the parts from there is not an option open to you. You will have to redraw the entire countertop of the commercial kitchen and the stalls from the counter to the steel frame, the cabinets, the beam and everything else. This will cause you to have a prolonged engineering design cycle and the approvals will also take time. There is a good chance that your design company will lose it to your competitor who uses AutoCAD for a long time.
Such are the instances in which you need to scan the drawings, draw them at the appropriate scale in AutoCAD and share them with the client, the manufacturing company in this case. This channels energy, time, cost and effort in an efficient direction instead of drawing everything from scratch.
In this case, if the commercial kitchen counter manufacturing company has these AutoCAD files, they do not even need to partner with the CAD service provider company. Whenever there are small variations in the designs, an internal editor with an average qualification will do the job.
The importance of the Raster and Vector files during the scan conversion to CAD
One thing is clear: the drawings on paper and the drawings by hand are only for the initial reference, and editing a drawing is difficult. They must be converted to a plane vector by converting to CAD. Digitized drawing means the conversion of drawings on paper to .DWG formats and, later, to .DXF files for perfect manufacturing integration. These are vector formats that contain masses on each individual element of the drawings and are readable by CAD platforms such as AutoCAD.
Second, the vector files are independent of the resolution, that is, the distortion does not matter, regardless of the amount of zoom that is on the screen. While the raster files are graphics made of pixels, vector graphics are made of objects such as lines, arcs, B-Splines, polyethylene lines, types of curves such as Bezier, etc. The CAD designer or operator can easily edit each of these individual entities without affecting the rest of the object.
When the drawings on paper that include images, drawings by hand, sketches and plans are scanned with machines, they are automatically scanned and converted into vectors. Automatic scanning and scanning has an advantage of precision and is efficient over time.
Evaluation of the ability of drawings on paper to scan
Once the designer and the manufacturer do not have vector and raster file formats and the importance of switching to vector formats such as DWG and DXF files, the next question is, what kind of drawings can be scanned?
The conversion software can only work and deliver results based on the quality of the entries. When a drawing is evaluated, it can be converted or not, the size and clarity of the drawing need evaluation. Some sketches and planes too small to be scanned and try to compensate for this with resolution could cause the rest of the scan to faint and decrease the credibility of the scan.
Another factor to take into account for the evaluation of the drawing is the severity of the lines of darkness in the drawings. If too many lines are overlaid with texts and footnotes for manufacturing instructions, it will be almost impossible for the drawing scanner to read the sketch.
By selecting the correct type of scanner, predefining quality, color and output with the client, CAD editors should begin to transform into CAD drawings. The most appropriate resolution taken as input is between 200 and 400 dpi in monochrome or grayscale. Ideally, the scanners will deliver TIFF files, but other formats such as BMP and PNG are also widely used. In addition, it is a common preference that JPEG files are avoided, as they tend to sacrifice image quality and, therefore, design intelligence.
Pre-CAD conversion cleaning
Before the conversion from raster to vector begins, the CAD drawer must eliminate the basic errors. Practically during scans, there are unwanted elements that are included, which are basic errors and cause difficulties to read the file when making CAD models or drawings.
Tools such as "Remove holes" for small holes and "Flood fill" for large spaces are used to correct gaps and holes that are missing. At the same time, the functions "Soft" and "Remove spots" will easily eliminate the hairs and inconsistencies of the line, the marks scanned in the paper and any noise in the background.
Selecting an appropriate CAD file format: DWG or DXF
Once the pre-conversion cleaning is performed, the CAD design engineer must select an appropriate file format for subsequent efficient operations. However, the two most commonly used formats are DWG and DXF. Both allow to edit individual entities, reusing them and saving time in the future to create similar elements, as in the case of the previous example of the counter of the commercial kitchen. Both formats are vectors and, therefore, inherit all the properties of a vector file.
However, the DXF file is a more universal file format and will be supported by any CAD platform and the exchange of data between AutoCAD to SolidWorks or Inventor is possible with it. In addition, when performing CNC machine programs, DXF files are useful for deciding strategic points and developing N-Codes and G-Codes. The selection of a file format should be based on the next immediate stage in the product design stage, since conversion from DWG to DXF and vice versa is always possible.
Steps to convert paper to CAD / Raster to Vector
If you are converting from TIFF or PDF to DWG to DXF, the process remains identical.
Initially, the file is loaded into the appropriate CAD scanner and CAD converter and selecting the type of drawing will establish the appropriate vectorization configuration for the conversion.
Select the part you need to convert into a vector and simply click on vector
Saving this file and changing the preview will allow you to examine different settings and save the one you prefer. After the conversion, the designer or the project engineer performs the cleaning and patchwork to ensure the accuracy of the drawings in CAD format and maintain the quality. In addition, there is a tool for batch processing to automate the process when there are several scans to convert to CAD.
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