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CAD Drawing Guide - General


If you are supplying CAD files to us for profile cutting, please try and adhere to the following rules as this will make our job easier and in turn cheaper and a quicker turn-around for you, our customers. If you do not have access to  CAD  software you may want to try Draftsight, a free, fully functioning CAD programme to download and use, you can find a link at the bottom of the page. The rules cover general principles that apply to CAD used for profile cutting. (See our waterjet cutting design guide for specific help on issues that you need to consider when drawing profiles for cutting with a waterjet).

Rule 1: Zero width polylines

Draw all geometries as zero-width closed polylines. All outlines or areas to be cut should be presented as zero-width polylines. Areas to be cut should be drawn as polygons rather than adjustments to the width of the drawing pen. In most cases, our translation process will ignore the width of a line.

 

Rule 2: Closed geometries

Join all individual geometries into a single zero-width polyline. A geometry comprising of several entities, such as those shown in figure 1 should be presented as a single zero-width polyline. The use of your drawing package’s ‘Snap to end point’ feature is strongly encouraged. Additionally, the ‘Join’ or equivalent command should be used to join consecutive entities together to form a single polyline. It should be noted that this is not the same as ‘Grouping’ all the entities together.

  

Rule 3: Extra vectors / untrimmed vector intersections

Make sure there are no extra vectors (one line on top of another) and overlapping vectors. Extra vectors can often trigger an error and are not always visible because they are under another vector. If present we have to manually strip them out. Overlapping vectors should be eliminated and this can usually be achieved by using either the fillet command (radius 0) or trim command in CAD programmes (see Figure 2).

  

Rule 4: Interior of closed figures should be connected

Watch out for geometries that look correct on screen but are drawn in an illegal fashion. It is very difficult with AutoCAD to know how a figure has been drawn (see Figure 3).

  

Rule 5: Don’t use hatching

If you need to delineate regions then label with text.

  

Rule 6: Keep geometries to be cut on a single, separate layer.

CAD drawings can be constructed in multiple layers. However, to ensure that all parts of the geometry to be cut are correctly identified, all such geometries should be placed on a single layer. Additional information such as explanatory text, guidelines, dimensions and any line indicating drawing scale and units would by preference be placed on a different layer but this is not essential.

  

Rule 7: Clearly state the units of your drawing

You may use any units for your drawing. However, to ensure that we correctly interpret the drawing, the drawing units should be clearly marked in text on the drawing. We strongly encourage you to include an additional straight line on your drawing, the length of which is clearly marked using text NOT a dimension tool. We recommend that the drawing units are mm.

  

Rule 8: Do not scale drawing or parts of a drawing

Draw all profiles in a scale of 1:1 (you can print it out at whatever PRINT scale you require).

  

Rule 9: Be careful when using fonts

If you use a font which is not present on our computers - the CAD system will ‘interpret’ the font. Although it may display with correct spelling – it may not look anything like it should (See figure 4).

Figure 4: Same font - displayed in two different CAD packages

If you want a particular font the easiest route is to use one that is a standard Windows TRUE TYPE font and tell us what font it is. If you want to use a different font, you can supply us the font file. Whenever using fonts - we will insist that you send us a pdf (or image - .jpeg, .tiff etc) of the drawing to confirm correct representation of the font.

 

ALSO BEWARE: Internals of letters A,B,D,lowercase g,O,P,Q,R will fall out when cut - options to get around this are:

            a: Use a stencil type font. 


            b: Use ‘bridges’ of material so that there are no internals - it is time consuming to modify but retains the majority of the look of the font.

Rule 10: Save file as AutoCAD 2000 DXF format

DXF is a widely used file format for CAD designs and is supported by the majority of CAD packages. However, the DXF format has evolved over the years. To ensure maximum compatibility use the oldest version of the DXF format you have access to. We suggest using the version of DXF released with Autocad 2000 or R12 format. Note: Some ‘graphics’ packages (Corel etc) - although they will offer the option to save the drawing as a dxf file type, often do not work. If in doubt about whether the software you will use to create your profile drawings can save a compatible file - send us a small test file and we can confirm compatibility.


Draftsight download link:

http://www.3ds.com/products/draftsight/download-draftsight/


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