posts tagged with the keyword ‘plastic’

2015.07.08

HDPE Brownies

I’m calling these “HDPE Brownies” because I find it slightly amusing. Here’s what’s going on: I’m taking HDPE scrap and putting it in an 8″x8″ glass baking pan (a brownie pan) and popping it in the toaster over at about 270° F for a bit, them smashing it down and repeating the process.

So why am I doing this? Well, at the museum we sometimes mill sheets of HDPE for exhibits, and it creates a lot of chips/sawdust, and I gathered it up remembering that I’ve seem some people heat up HDPE and press it into a mold. Oh, and check out this video for lots more info on melting HDPE.

HDPE Slab

Once I got a full pan I took it out and cut off the sloped sides on the band saw to create a (mostly) squared-off slab. There are some air bubbles and what not, but for a first attempt, it’s pretty good. And what am I going to do with this stuff? I’d like to mill it using a CNC machine, probably a Shapeoko2 to start with. The HDPE cuts well, and shapes well, similar to working with wood. You can sand it, and whittle it too.

HDPE Slab

The white you see is from milk jugs and cat litter jugs, and the yellow and blue are from laundry soap jugs. All the black and pinkish-red are the sawdust bits from the milling of HDPE slabs we purchased. I think the sawdust bits caused more air bubbles than the cut up jugs, but more experimentation is needed.

Besides milling this piece, my plan is to keep collecting HDPE by gathering old jugs and cutting them up and making more blocks. Just making more of these should help me refine the process and work out the bugs, or the bubbles, as it were.

2015.06.29

My plan for Maker Faire Milwaukee’s 2015 Laser Maze got a little sidetracked, but that’s okay, because Vishal ended up writing some of the code I needed for another project and then I decided to just have him take over the some of the build.

Laser Holder

I did get a few more things done in recent weeks, like making these mounts to hold the lasers in place. Adam provided us with these clamp devices meant to hold a flashlight on your bike, but the lasers are a smaller diameter and tended to shift around, which isn’t great when you need to align lasers…

In our first attempt to make something that would go into the flashlight mounts and adapt to the size of the lasers, we ran down to the basement shop at the museum and used a hole saw in the drill press to cut a piece of plastic, and then we drilled another hole, and cut out a piece using the band saw. This was a neat idea, but did not work.

Laser Holder

The hand-fashioned one just wasn’t quite the right size. We didn’t have the exact hole saw or drill bit sizes needed, and the plastic just didn’t flex enough to allow for tightening. I ended up pulling out the calipers to get exact measurements and re-create what we tried to do with 3D printing.

Laser Holder

The 3D printed version sort of worked, but it was tough to slide the laser into place. I could have just kept trying to get the perfect fit, but instead of trying to emulate the limitations of using a drill and saw, I modified the design to have less surface area where the laser was sliding in, and also allow for more flex, and more strength, due to the way 3D printing works.

Laser Holder

These pieces don’t have a lot of infill, and they don’t need them. The shape of the interior section provides extra strength because of the nature of how it’s structured.

Laser Holder

These mount should work well, and the bike flashlight part saves me the trouble of creating an entire mounting system, or modifying previous mount work.

We’ve got less than 90 days until Maker Faire Milwaukee so hopefully we can get a test set-up running within the next 30 days or so.

2015.02.23

DCRL Coat Hook

I’ve printed a coat hook before, but this time I’m doing it for school. This is the DCRL Coat Hook for the class “Digital Craft: Machines that Make” in the Digital Fabrication + Design area at UWM, taught by Frankie Flood.

The assignment was to create a 3D model of a coat hook using Rhino, and then print it. I’ve been using OpenSCAD for years, and before that I used Sketchup, so Rhino is still fairly new to me. I used it a bit last semester, but mostly just to explore it and for 2D laser cutting.

Rhino v1

My first attempt was mainly about getting comfortable in Rhino. I’m so used to the way I work in OpenSCAD, and even the way I work in Inkscape, that I found Rhino a little lacking in certain things. I’ve gotten more used to it since I started, but I still see room for improvements to how it works. Version 1 was all about unions and differences and fillets. It worked, but I wasn’t entirely happy with how rectilinear the form was.

Rhino v2

Version 2 was a bit more curvy, and while I was starting to like it more, the non-symmetrical parts bothered me. I did print out version 1 and 2 for our first class discussion, and I noticed that many students went out there with their designs, while mine tend to be very functional and utilitarian. I also have a good grasp of what is possible (and not possible) using hobby-level FDM/FFF. I don’t know if this helped or hindered my design, as I tend to think about the process I’m using at the time. (Sometimes, but I’ll get into that later.)

Vector outline

Eventually I ended up drawing version 3 in Inkscape, as I knew what I wanted it to look like, and it was an easy path to get exactly what I wanted, design-wise. I exported the file as a PDF, which imports nicely into Rhino, to get my 3D object. I also tend to look at replicating and/or extending existing workflows I already have.

Sketches

I typically find the desired size of objects by drawing them on paper. Here’s some of my early sketches (on the left) and the later ones (on the right) that I did before modeling in software.

DCRL Coat Hook v3

Once I had my vector PDF imported into Rhino I was able to extrude it to the desired height. Rhino lets you type in the height numerically while creating the object, but not after you’ve created it. It’s a bit frustrating, but I’ll get used to it. I then added the screw hole and a counter-sink hole. (I later realized I didn’t properly angle the counter-sink hole, which would have been easy to do. Perhaps for the next revision!)

I also thought about how this design could be used in other digital fabrication techniques. For instance, since the form is essentially an extruded 2D form, it would be easy to create a version using a CNC router or mill. After the profile is cut you could rotate it 90 degrees to get the screw hole, or just use a drill press. You could also cut a piece of pink foam, using a CNC machine, or by hand using a hot wire cutter, or any cutting tools, and cast it in metal (again a simple drilling operation would be needed to add the screw hole.)

If you’d like your own copy of this coat hook, you can grab it from Thingiverse or download from Youmagine.

Here’s a few photos of the final printed piece. There’s a few more photos in the DCRL album on Flickr as well.

DCRL Coat Hook

DCRL Coat Hook

DCRL Coat Hook

DCRL Coat Hook

DCRL Coat Hook

2013.05.15

The Liberator

Yes, yes, we now have 3D printed guns, and our world has changed because of it, right? Right.

I’ve written about 3D printed guns before, and I’ve talked about 3D printed guns before, and now they are (somewhat) possible. But don’t be frightened, as there is little new here.

Andy Greenburg at Forbes has been leading the pack on the story of Cody Wilson and Defense Distributed and their attempt (and success?) at 3D printing a gun. And OH NOES! Now other people are printing guns! And some of them are even improving them, but this should be no surprise. Hackers and makers see something that needs improving, and they improve it. When I saw the files for the Liberator the first thing I thought was that it needed work. After I talked to someone who is well versed in 3D printing and gunsmithing, they agreed.

I want to toss out this quote from HaveBlue again:

The one point I try to make (and that they generally fail to grasp) is that if it eventually becomes possible to download a file from a website, feed it to a printer, and have a fully operable handgun a few hours later, the technology will have already impacted our lives in far more incredible ways.

So has our world changed? Yes, I think it has… As I mentioned recently in Your 3D Printed Future, people have created open-source designs for mechanical finger prosthetics. Yeah, that’s pretty amazing. We’re not talking about medical companies charging thousands of dollars for mechanical finger prosthetics, we’re talking about a couple of really awesome people working together on this, and creating something you can 3D print yourself with a sub-$1000 3D printer.

What else is there? Well, bioprinting is progressing nicely. Boprinting sheets of skin for skin grafting procedures, bioprinting a replacement bladder, bioprinting replacement for missing bone for a human skull, and even bioprinting part of a face!

(The joke is that you’ll be able to print out a replacement hand for the one that gets blown off by your 3D printed gun. It’s only half of a joke, because it’s pretty close to being true.)

Now, back to the gun issue. I highly recommend the Hackaday post: The first 3d printed gun has been fired, and I don’t care. Right now the Liberator is little more than a zip gun, which is a simple (single shot) gun that anyone with access to a local hardware store could build. But don’t worry, you’ll be safe:

In late 2000, British police encountered a four shot .22 LR zip gun disguised as a mobile phone, where different keys on the keypad fire different barrels. Because of this discovery, mobile phones are now x-rayed by airport screeners worldwide.

Sigh… more security theater. Just what we need. Do we need regulation on 3D printers? No, just like we don’t need regulation on lathes and mills and hardware stores. So here’s the deal. I have the file for the Liberator, and I’ve held a Liberator, and I’m not a bad person, and I hope to never, ever shoot another person in my life. Why? Because that’s not the type of person I am, and that’s not the kind of world I want to live in.

As for the Liberator, it’s a crappy gun, and if you want a good gun for cheap, there are dozens of ways to get one, both legally, and illegally. And if you want to make one, there are also better ways to go about it than 3D printing one. If the novelty of a cheap, crappy, plastic gun intrigues you, go ahead and print one. Try not to blow your hand off in the process. Guns are dangerous, and even a well made gun can malfunction.

3D printing is all the rage right now, and the media loves hype because it means more attention, more page views, and more dollars. So yeah, go 3D print something, maybe a gun, maybe some mechanical finger prosthetics. Just follow this one simple rule: BE EXCELLENT TO EACH OTHER.

Be Excellent to Each Other.

2013.05.11

Coat Hook

I recently (temporarily) changed offices at work, and with the new office came a new door, and this door has no coat hook! Because I couldn’t drill a hole in the door or mar the surface in any way, I needed an “over the door” style coat hook. Ah yes, the classic coat hook. Adrian Bowyer made one back in 2008, so I decided it was time to make my own.

OpenSCAD Coat Hook

I took a quick measurement of the door to determine how wide it was. I then fired up OpenSCAD and made a bunch of “cubes” of various shapes and sizes, some rotated 90 degrees, but all in all, a pretty simple OpenSCAD model. One thing I did do was add in the “door” based on the measurement I took, so I could see how the coat hook would fit around it.

Plate Coat Hook

After compiling it in OpenSCAD, I exported the STL file, and at this point I usually use Gary Hodgson’s STL Viewer to take a quick look at the file and make sure it’s oriented correctly.

G-code Coat Hook

After viewing the STL file, I use Slic3r to generate the G-code, but hey, let’s check out the G-code while we’re at it! Joe Walnes wrote a great web-based G-code viewer you can use online, or download and run locally. If you want a somewhat improved version, Jeremy Herrman’s got a viewer and some code for you.

Working Coat Hook

Well, after all that generating files, and viewing files, I printed the file. It worked out well! Here’s a terrible photo of it preventing my shirt from falling on the floor. Success! The magic of a home 3D printer pays off again.

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