Tag: lasercutter

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DXF for LaserCut 5.3

lc014

I’ve been using LaserCut 5.3 to control a G.Weike LC1390N Laser Cutter, and since I use Inkscape to create my files, I thought I’d go over a few of the settings I use so that in the future when I forget I can read this post.

I won’t go too deep into using Inkscape for laser cutting, as it’s a topic I’ve covered before, and besides having to use DXF files instead of PDF files, nothing else has really changed.

lc000-inkscape

In the image above you’ll see a file being exported from Inkscape as a DXF file for a “Desktop Cutting Plotter” which, I guess, is one way to describe a laser cutter. :) I’ve avoided selecting the ROBOMASTER option, as that does strange things to DXF files. I’ve also avoided the LWPOLYLINE option. While the LWPOLYLINE option sometimes works, it sometimes causes issues. Don’t select either option when outputting from Inkscape to import into LaserCut 5.3.

I create my files using millimeters for units, and then export the DXF with pixels (px) specified. I believe there is still a bug in Inkscape that will screw things up if you choose millimeters for the export. (We’ll double check the imported size later to make sure it worked properly.) One more nice thing about Inkscape is that it’s easy to switch between millimeters and inches (or other units) on the fly while drawing.

lc001

When importing the DXF file into LaserCut 5.3 it may show some weird dialog. Ignore it. Files seem to import fine even when this shows up. Also, occasionally LaserCut 5.3 will not import a file, or will get an error. If that happens, just quit and relaunch it. That usually fixes it.

lc003

Our file has imported and looks okay. You’ll notice that the lines in the file are all black, well, actually they are all red here, as they are highlighted because they are selected. (Anyway, I forgot to set colors for some objects, but we’ll touch on that later.)

lc006-scaled

After importing your file you can check the size of it using the “Size” button in the toolbar to bring up the size dialog when your object is selected. It will show the length and height (well, it calls them both “length”) and some boxes where you can type in new values.

lc007.png

Pro-tip: If you fill in one value to scale your object, you can scale it proportionately by clicking the ‘…’ button on the other value. Here I’ve typed “100” in the x value box and then clicked the ‘…’ button on the y value box.

lc010

The other trick I’ve learned from the folks at Brown Dog Gadgets is to use the “Unite Lines” feature.

lc012

I just use the default settings it presents…

lc013

This combines the individual line segments that the DXF file is made up of into continuous lines, like a real vector file. It helps the laser cut things in a way that makes sense instead of jumping all around the object.

lc015

Here’s what I forgot to do in the above example. I’ve set specific items to specific colors in Inkscape, so that when I bring the DXF file into LaserCut 5.3 I can use the colors to change the order of cutting operations.

lc016

Here’s our DXF file imported into LaserCut 5.3 with the colors of the lines showing. Up in the right corner you can see where LaserCut 5.3 recognizes all of the colors in the file and allows you to choose individual settings as well as the order. Typically you want to cut inside pieces first and then outside pieces.

Finally, I’ve relied heavily on the work of others, and here are some links that might prove helpful when using LaserCut 5.3 and a G.Weike laser cutter. (And yes, some of it may conflict with what I’ve posted here. Again, if I got anything wrong, please let me know.)

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LaserCut LetterPress

ART

“LaserCut LetterPress” (for lack of a better name) is a project I worked on in 2014/2015 which was an idea to create a full letterpress set using a laser cutter capable of cutting 3mm Baltic Birch plywood. The idea was that the files would be released that allowed anyone with access to a laser cutter (even lower-powered cutters with small beds) to create the set.

I know there are many ways to create things, but at the time I wanted to limit production to one method, and one particularly fast method, vector cutting with a laser cutter. (Note: If you’re fascinated by the production of wood type, check out Moore Wood Type.)

I mentioned some of the process in a post titled Measure Twice, Laser Once… but never wrote up the whole thing, so here we go.

LaserCut LetterPress Example Print

The typeface I chose was OpenDyslexic, which was inspired by a friend who is Dyslexic. I also thought it would be interesting to use a typeface that was new, and didn’t exist in the time that wooden type was widely used.

Art Letters

I did the design in Inkscape, creating the letter and the pieces that fit under the letter so it could slide into a tray.

Letter and Tray

Wood is such a wonderful material, except when it isn’t. Tolerances caused a number of issues, but I kept going forward, and didn’t worry too much about having things fit together perfectly. (I won’t say this was my downfall, but I spent a lot of time fighting it.)

Art Letters Tray

Here’s the design for the small tray. Ultimately I wanted a larger tray that had multiple lines so you could do an entire poster. That of course would have required an entire alphabet, and multiples of most letters, and punctuation, and… letterpress is hard.

Oh, somewhere along the way I also started to write code that would generate all the characters needed by outputting the needed SVG files. In theory it was totally doable, but in practice it served as a distraction that I eventually ignored.

Art Letters

With the plan to turn this into a kit that one would assemble, I thought about how one would determine what pieces would go together, and thought that etching the letter onto each piece would be a good idea. (I didn’t get to this step due to being stuck in the prototyping phase.)

Tray

Here’s the letter “A” sliding into the small tray I made. Tolerances were good with the first batch of letters, but with subsequent pieces not so much.

ARTS+TECH

You can see a bit of the height difference with this batch of letters…

Height Comparison

…and you can really see it with these. Yes, this is all 3mm wood. Again, as mentioned with the previous post, there can be quite a difference when the layers add up.

ARTS+TECH

I did manage to create enough letters for one of the Arts + Tech Nights at UWM.

TEACH ART

And oddly enough, I was able to arrange the letters into “TEACH ART”, which I ended up doing six months after I abandoned this project.

LaserCut LetterPress Example Print

Here’s a few test prints I did. They worked fine, which made me think I may have overthought how “perfect” it had to be. In the process of talking to printmakers (who were very interested in the project) they got me thinking about type height, which is useful for a press (and I considered using these letters on a press) but in the end I think I should have stuck with my “hacker ethic” and just made it work with the minimal amount of success.

I don’t consider this a “failed” project because I learned a lot in the process (and got to meet & work with some awesome people) but I’d love to see someone else run with this idea… or maybe it’s something I’ll pick up again in one form or another.

Remember kids, Keep on Making!

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Laser. Cut. Files. (Part IV)

It’s been a few years since I’ve posted about laser cut files, and by that I mean, the files I prepare to be used for laser cutting, so I thought I’d do an update.

Right now I typically use a few different laser cutters in the Milwaukee area. At Milwaukee Makerspace there’s a 60 watt ULS and 50 watt ULS, but using a Windows PC with CorelDraw for control, and at Brown Dog Gadgets there’s a 90 watt Chinese laser cutter using CorelDraw (and LaserCut 5.3) though it seems to be a much newer version than used at the Makerspace. I also use a 40 watt Epilog Zing at UWM’s DCRL. The Zing uses Rhino instead of CorelDraw, which may sound weird, but it works.

I’ve got a file workflow that can work with all of these machines… which I’ll explain below.

Panel Mount

Here’s what my vector art looks like in Inkscape. You’ll notice that the inside lines are blue, and the outside lines are black. This is so we can set a manual cut order for machines that don’t automatically cut inside lines first. (Some software is smart, and always makes inside cuts first, other software… is not.)

lcfiles02

I should note that while doing the design work I may end up with multiple layers. Often I’ll use layers to hold pieces or revisions of a design. For our final file though, we want a single layer.

Let’s pretend my design file is named “Panel Mount.svg”, and it has more than one layer. When I’m happy with my work, and have all the things that will be cut on one layer, I’ll save that file, duplicate it, renaming the dupe to “Panel Mount LC.svg” and then open that file. My original design file (Panel Mount.svg) is now safe and sound, but my new file (Panel Mount LC.svg) is about to get altered.

Files

I usually set all the objects to have no fill. This may not be required for all workflows, but I like to be consistent. (Oh, one more thing… you may need to “convert objects to paths” to get things to work like you expect them to in LaserCut 5.3)

Files

For the stroke I’ll set the outside lines to black… (This may be different depending on your laser cutter software.)

Files

And I’ll set the inside lines to blue. Again, this may depend on the laser cutter software & driver you use. Some allow you to set the order of colors, and some may not. If I need more colors I can use red, green, etc. (Also, if you’re working with a laser cutter operator who is colorblind, ask them what colors they prefer.)

If you want to selectively cut things and only have one color, you can use this trick: Load the file into the laser cutter software (CorelDraw, or whatever) and delete the parts you don’t want to cut, then cut. Then “undo” until all parts are back on the screen, then delete other parts, cut again, and repeat. Not the cleanest method, but it totally works. Don’t move any parts, though you may have to ungroup them, and obviously do not move the thing you are cutting.)

Stroke 0.03mm

Once I’ve applied all the colors, you can select everything and set the stroke. I set it to 0.03mm. This should set it to “hairline” when you import it into CorelDraw. Rhino also seems to do the right thing. If your stroke is too thick it can cause issues. (Always check for the lines to be set to “hairline” after you import your PDF.)

View

After you change the stroke the lines may appear very faint. If you can barely see them switch the Display Mode to “outline” which makes every stroke appear a black and sort of beefs up the lines.

At this point I run down the checklist…

  1. The file has one layer (If it had more, I duped the file and then adjusted the dupe to have just one layer.)
  2. The file has all objects set to no fill.
  3. The file has all objects set to 0.03mm stroke.
  4. The file has different colors for inside and outside cut lines.

Obviously you can do all the file prep stuff (line colors, stroke, etc.) in your master file, and then dupe that one and delete any extra layers. The order isn’t the most important thing here.

PDF Export

Once we’ve made all the changes, we can save our “LC” version of the file. After that, it’s time to use the File menu’s Save a Copy… command to save it as a PDF file. Note that “Convert texts to paths” is selected. This should create a PDF that does not rely on any fonts being installed. If you used text in your file, this is helpful. It does however mean that you cannot edit any text when you import the PDF into other software, as it will have been converted to lines.

PDF

Oh, one more thing! Some older versions of CorelDraw seem to have issues importing PDF files created in Inkscape. On Mac OS X, I just open the PDF that Inkscape created, and export it. It somehow fixes the PDF so CorelDraw likes it. Whatever… it works, so I do it!

Simple Dual Axis Solar Tracker

(BTW, the piece I used an as example was for the Simple Dual Axis Solar Tracker from Brown Dog Gadgets.)

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Iterate, iterate, iterate.

iterate

The Golden Rule from Phillip Burgess at Adafruit Industries: Iterate, iterate, iterate.

Don’t be discouraged when your case doesn’t work on the first try. Or the second. Once I thought I’d nailed a design on the third try, but was wrong. The most extreme has been our Pi Box enclosure for the Raspberry Pi…this took 23 attempts to get just right! The first few didn’t even hold together. Other projects were initially so discouraging, one was known behind the scenes as the “Piece-o-Crap-o-Tron 9000” …but many attempts later it’s become one of my favorite kits.

Fail quick, fail hard, fail often. Failure is part of the process — perhaps even key to the process. It’s how we learn and improve, and ultimately make a better product. Make mistakes now so your customers don’t have to.

I’ve known for a long time that design is an iterative process, and sometimes I think that’s what I love about it. I tend to be a fan of the process.

I remember once I asked Michael Curry how many attempts it took him to design something and 3D print it before it worked. I thought he said “two or three times”, but maybe he really said “twenty three times”. ;)

But seriously, there’s a lot of great tips not just for laser cutting things, but for designing things in general.

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Measure Twice, Laser Once…

Pegs and Pieces

I’ve been working on a project that involves stacking of laser cut pieces of wood to create blocks. In theory the laser cutter is a precise CNC machine that has an (almost) negligible kerf. (The kerf is the part that gets cut away. With a saw it’s the width of the saw blade, and you need to account for it.)

Height Difference

Typically I’ve been using this 3mm Baltic Birch plywood from Woodcraft, and it’s been pretty darn close to 3mm, at least within 0.1mm. For most projects this is fine. Even at 3.2mm things will fit together, though perhaps a bit snug. You can always sand things a bit to make them fit.

Stacking presents a new problem though, because the extra height adds up and throws everything off. For the last batch of blocks I assembled I wasn’t aware of the issue, even when the pegs wouldn’t fit. I assumed I screwed up the peg slots, so I just sanded the pegs down a bit until they fit. Even then, they were not the right height in the other direction.

Height Difference

After assembly I noticed that the blocks were different heights than the first batch I created! I went back and measured the sheet of wood and it was 3.4mm. I checked a few more and got ranges between 3.0mm and 3.4mm. The image above shows what happens if you use 3mm wood and 3.3mm wood to construct the same block. At just four layers you’re already off by 1.2mm. For small things that can make a huge difference.

So what’s the solution? I can attempt to sand the sheets before cutting, or partially assemble the blocks and sand them to the proper height before the final step. A colleague suggested getting one large sheet of wood assuming the height would be consistent across one piece. I may try all three solutions, but will probably start with the first, and apply the second solution if required.

So yeah, even with digital fabrication, and laser cutters with almost no kerf… Measure twice so you only have to cut once!