posts tagged with the keyword ‘inkscape’

2014.11.28

Encoding Discs

While Inkscape is a great and powerful open source vector editing application, sometimes it can’t do it all. Since I primarily use it for creating files for laser cutters, vinyl cutters, the Egg-Bot, etc. I need to have lines. No fills, no objects sitting on top of other objects, no crazy intersections of paths, just lines.

I’ve found that on occasion it’s actually easier to export a raster image, re-import it, and trace it to get the needed vector file. I’ve done this for many files from OpenClipArt.org because they weren’t created with CNC uses in mind, but that’s what I use them for.

Back when I wrote my rotary encoding post I mentioned a perl script that could create encoding disks. It’s simple to use, and outputs an SVG file that I can open in Inkscape. Sadly, it’s not exactly what I need, but it’s pretty close, and easy to fix.

Encoding Disc

Here’s the disk that was created, which uses some neat SVG capabilities to generate it, but makes it quite difficult to edit using Inkscape. You can’t ungroup it, or break it apart, or use union or difference commands on it.

Encoding Disc

I’ve placed a smaller disk on top of it, Right now it’s gray (just so you can see it) but I’m going to fill it with white and give it no stroke. (Normally I would place one object on top of the other and use the difference command to cut a hole in the larger object. In this case, that can’t be done.)

Export at PNG

Once that’s done it looks like I want it to look, but it’s not all lines. It’s really overlapping objects. As long as it looks like I want it to look, I can export it as a bitmapped file. (A PNG file, to be precise.)

Import PNG

Here’s the PNG file. It’s raster, not vector, and again, it looks just like I want it to look. Excellent! Let’s go back to Inkscape and import the PNG file.

Trace Bitmap

Once imported I can use the Trace Bitmap command to easily change this black and white image into a vector file. (Yes, make sure it’s just pure black and white, so it can easily separate the two colors and create the needed path.)

Outline

After the bitmap has been traced I’ve got nice vector lines, shown here in outline mode, and it’s ready to be cut with a CNC machine. (Oh, I’ll probably add a center mounting hole, as the encoding disk eventually does need to attach to something.)

2014.11.28

I needed a single stroke font for some laser cutting. You’d think that would be an easy thing… Well, keep reading.

When laser etching any font could be used. You can raster etch the type, or “vector etch” the type. Raster etching takes a long time, and vector etching (basically doing a low-power vector “cut”) is fast. If you’re doing 3,000 pieces, the time can make a huge difference!

Regular font

Here’s a normal font in Inkscape. Fonts consist of an outline which is then filled with a color. In this case, the outline of the font is filled with black and you see what you normally see when viewing a font on a computer screen.

Regular font

Here’s the normal font with the fill set to none and the stroke (outline) set to a thin line. You could laser etch this (and some people do) but you’re now outlining the letters instead of just etching them with a single stroke. This is fine, but takes more time. Since going really fast is our goal, this doesn’t work.

At this point, you may be thinking “No problem! Our pals at Evil Mad Scientist Laboratories have us covered with Hershey text, and engraving font!” Indeed, Hershey text is awesome, but not always the right solution. I use Hershey text often, and it’s lovely, but let’s keep exploring…

CamBam font

I found these CamBam fonts, which probably work quite well for a spinning bit that is cutting material, but there’s an issue:

All the fonts are built using a 100% overlap in the font design, which tricks my TrueType font design program into thinking they are really looped TrueType fonts, when they really don’t have an inside and outside loop.

CamBam font

A spinning bit cutting material is quite different than a laser cutting material. If you use this font to laser etch, it will double up, which mean you’re lasering the same thing twice. This takes longer, and cuts your material twice. No good.

You can manually go in and delete the overlaps, but it’s a time-consuming pain, and you’ve got better things to do.

Machine Gothic

I found Machine Tool Gothic, which looks a bit weird when you first select it, but we’ll fix that. Remember that fonts are typically outlines that are filled with a color. That’s what is happening here.

Fixing Machine Gothic

We just need to set the fill to none, and give it a thin stroke. Much better! We’ve nearly got our clean single-stroke engraving font.

Fixing Machine Gothic

Let’s fix the weird lines that connect everything and close the paths. First you’ll want to convert the type to outlines (that’s the “Object to Path” command in Inkscape) and then select the two nodes at each end of the line you want to delete and use the “Delete segment between two non-endpoint nodes” feature to remove the line.

Fixing Machine Gothic

Oh, it’s worth noting that when you convert the type to paths, you lose the ability to edit it as type. More on that later. Here’s the “L” with no extra line connecting everything.

Now, it may look like only certain letters need the extra line deleted, but they all do. Go through each letter to delete the extra lines! If you’re doing a one-off project this may not matter as much, but if we are laser cutting 3,000 pieces, even an extra 5 or 10 seconds per piece will make a huge difference.

Type on a curve

Here’s the real reason I wanted to use an editable typeface rather than the Hershey text extension. With text, you can place it on a path. This means you can curve the text onto a circle or some other shape. We want to make sure we’ve got the text exactly as we want it before removing the extra lines. (Remember that we need to change the editable type into outlines before we remove those extra lines.)

Type on a curve

Don’t forget to remove the circle, or whatever path you used to place your text on.

Type on a curve

Fire up the laser! Here’s our clean and ready to vector-etch single-stroke type.

2014.10.04

Mounting Plate

It seems that when I ordered parts from Inventables, I forgot one thing! Seems I didn’t have this Motor Sub Plate that I needed.

Mounting Plate Plans

Luckily Inventables provides technical drawings and CAD files, so I grabbed the PDF file and opened it in Inkscape…

Mounting Plate 2D

I had to delete a lot of the measurements on the drawing, but when I was done I had a file that I could easily laser cut. But alas! I have no laser cutter at home… No worries, a bit more work on the file (changing all the curves into segmented lines, connecting all the disconnected lines) and I was able to save a DXF file…

Mounting Plate STL

And the DXF file was easy to import into OpenSCAD and extruder as a 3D (well, 2.5D) file and get an STL file, which can be printed on a 3D printer, which is what will be happening in a few minutes…

Digital Fabrication… it’s a thing.

2014.01.23

XQuartz

Since I still think Inkscape is the best open source vector editing application for the platforms I use, that means I need an X Window System running on my Macs. With the upgrade to Mac OS X 10.9 (Mavericks) Apple has done away with their X11 release, but luckily XQuartz is there to help out.

And once you’ve got XQuartz installed, you’ll want to go into the preferences and change it from this:

Preferences (Default)

to something much more reasonable, like this:

Preferences (Changed)

Yes, deselect that “Updated Pasteboard when CLIPBOARD changes”, because if you don’t, copy/paste will be all screwed up in Inkscape on Mac OS X.

(I’m hoping this post will help future me fix the problem much faster next time someone asks me about it.)

(There might also be useful info on Inkscape.org.)

2014.01.12

We’ve been using the RED ONE a lot in the past few months over at z2 and while we’ve had the matte box for a year now, we never managed to get top or bottom flags for it, so I finally got around to solving that problem.

RED Flag

Camera accessories are notoriously expensive. For some things, that makes sense, and for others, I’m not sure it does. The top/bottom flag for a RED Matte Box is $90 USD. Well, hey, it’s carbon fiber. Yeah, that stuff is pricey! But, don’t worry…

RED Flag

There’s an aluminum version of the top/bottom flag for just $40USD. Hey, you could get two of the aluminum flags for less than the price of one carbon fiber flag!

RED Flag

While I was perusing the RED store, admiring their well done photography, I noticed that the large version of the photo was clean. Really clean, and at the perfect angle, straight on! So… I engaged in what I now like to call “R3Dverse Engineering”. (That’s “reverse engineering” of RED stuff, if that was too subtle.)

RED Flag

I grabbed the image from the web site, opened it in Photoshop, and started to clean it up.

RED Flag

I got rid of the shadow, added a white layer below so I could see things a bit better, and selected the object…

RED Flag

I then filled the whole thing with black so I had a high contrast image…

Once this was done, I saved the file as a PNG and imported it into Inkscape, where I used the ‘Trace Bitmap’ feature to create vector lines defining the image.

Inkscape Flag

The next step involved a lot of precise measurements with the digital calipers on the part of the matte box where the flag mounts. There were many guide lines added.

Inkscape Flag

The lines helped me determine centering of the slots and how wide the slots/tabs needed to be.

Inkscape Flag

I did a few revisions, and here’s the final cleaned up version. with most of the guide lines removed.

Inkscape Flag

Here’s a visual diff to show the tweaks between the original trace of the image I imported, and how much I ended up adjusting the lines a bit for a better fit. (The reddish hue shows the final. I mainly had to add a bit more space around the larger tab.)

I should mention that with each revision, I was printing out a sample on tabloid size paper and cutting it up to test the fit.

Inkscape Flag

Once my paper prototype was good enough to consider “final”, I ended up sitting on this project for a bit trying to determine what material to use, and how to cut it.

I’m still thinking about it… I’d prefer to go CNC versus trying to cut it by hand. Perhaps using the CNC Router at Milwaukee Makerspace would work. A very thin sheet of aluminum perhaps? I thought about laser cutting something, but didn’t think acrylic or wood would be a good option. I’ll need to keep thinking about materials…

Black Flag

Meanwhile, we have lots of black board at work, so I stuck my paper prototype onto a piece and hand cut it with an X-ACTO blade. (I did not round the corners.)

Black Flag

The tabs and slots are a little messier than I’d like, but again, I’ll call this part of the prototyping stage.

Black Flag

But it also totally works… and is probably less than 1/100 the cost of the carbon fiber version. It may not hold up as long, but then again, I can easily make a bunch of these for next to nothing. (I can also just laser cut the black board instead of sliding an X-ACTO around to do it.)

Black Flag

Update! I ended up laser cutting the black boards, and they works great! You can grab the files from Thingiverse.

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