In our last article, we talked about two different branches of image files you may have for your parts. I said that you can also convert EPS, PDF, SVG and PNG files to DXF for cutting, with some caveats. Each file extension has its own quirks, so lets go through these one at a time.
Is a format most commonly used in graphic design. It converts over to DXF very nicely, but not every design software suite can open and alter them. I also haven’t found an online converter that is easy for a layperson to use. If you have an EPS that you can’t convert, send it to us by uploading it to our online quoting and ordering system, and we will get it converted for you.
Generally speaking, the vectors in EPS files are really clean and allow them to convert to DXF with relatively few issues. The trick is to make sure that you are starting with a black and white file that has defined outlines, and no grays or gradiated borders.
I can convert PDF files that have a vector image in them to DXFs. The difficulty here is that you can also get a PDF that is a bitmap image embedded in it. PDFs with embedded vectors do not do so well when I try to trace it. An easy way to test if your PDF has vector or bitmap is to open it in Inkscape and in the menu bar change the Display Mode to the Outline view.
If you see a box with a red X in it, you have a bitmap PDF.
Using bitmap editor Gimp’s contrast and color indexing tools you can probably get a sharp enough black and white image for the Bitmap Tracing tool in Inkscape to trace this. But it is going to come out blobby, organic, and if there is any pixel resolution issues the edges will be all craggy and there may be tiny holes showing up in your part. If you get craggy edges, the quoting system is going to charge you for cutting out those plus all the tiny holes, which means your part will quote much more expensive than it would cost if we ran a clean version through the quoting software. We have cut some decorative parts that were organic in nature from a traced bitmap that came out nicely, but this process can be dodgy in getting you the parts you want.
If you have a scanned copy of a mechanical drawing in your PDF the chances of it not working is extremely high. The resolution and amount of background digital noise on the average scanner is pretty high. Given the tolerances that usually need to be maintained with the parts in mechanical drawings, there are only one realistic way to resolve this. To have a designer (yours or mine) redraw the part completely in CAD software.
If you see your part outlined in a thin black line, then you have a vector file. Yay! First thing you need to do is to check to see if it is the right size, so click on it with the pointer tool. Just below the title bar in Inkscape there is a toolbar that should show you the size of the part. You may need to change the unit of measurement to inches in the pull down box to the right of the height measurement.
Is that the size you intended? If not, select the part profile and any holes. Don’t select any measurements if this is a mechanical drawing, especially if they are laying on top of the part’s edges. Then click the little lock button between the Width and Height boxes so it is closed.
Now if you know the width of your part is supposed to be 3”, type 3 in the width window and hit the Enter key. Now your part is sized proportionally to the correct size. That said, this only works if your part is drawn to scale. So if your designer wasn’t paying attention to the measurements when he or she drew the part or if there are jogs in the part profile, then this isn’t going to fix the sizing. In that instance they need to get you a proportionally drawn part. (Also note that the line width affects the size.)
If it is a mechanical drawing and has a bunch of measurements and sheet notes in it, go ahead and select and delete those now. Their presence in the DXF is only going confuse the quoting software as to what is the inside and what is outside of the part profile.
Save As a DXF. Try uploading it to our main page. If there are errors in the part, click on the diagnostic link to see where they are. Use LibreCAD to connect any endpoints that came unglued and delete any extra lines. You can get LibreCAD for free from the LibreCAD website.
So that covers EPS, PDF, and SVG files. What about PNGs you say? PNGs can also be converted to DXF format, but they take a little doing. So in my next article we will be talking about how to convert PNGs and what that entails.