RepRap Prusa i3

We’re making good progress on our RepRap Prusa i3 in our Machines that Make class at UWM.

We cut the Lexan frames on the large CNC router after we wrote the G-code in RhinoCam. There was an engraving, and then one inside cut, one outside cut, and some center drill spots we marked before drilling the holes on the drill press and then tapping them for 3mm screws.

We also cut all the threaded and smooth rods on the horizontal bandsaw and then cleaned them all up on the belt sander. I learned a few new tricks for cutting threaded rod as well.

I’m a bit tempted to rebuild my Prusa i2 as a (laser-cut) Prusa i3, or maybe just build a second printer. I’d like to have a 1.75mm machine at some point instead of just 3mm so I can experiment with more filaments.

I’ve also been working on a few new machine design ideas, one will be a drawing machine, and another is a platform for building CNC machines that trade in precision for low-cost. More on those in future posts.

DCRL

A big part of the work I do is the process, and trying to find tools that fit the way I work, and are also available. “Available” may mean open source, or free (as it beer) or multi-platform, or some other criteria I come up with.

In my Digital Craft class we’ve used RhinoCAM to generate the G-code needed to run the 4×8 CNC router in the DCRL. RhinoCAM has a lot of options, as it should for a full-on commercial package. Meanwhile, I’ve been working on a Shapeoko2, which is a small and affordable hobby-level CNC machine. For a machine like this, I’d like to use a workflow that doesn’t require expensive commercial software, because at some point I may not have access to Rhino and I’ll need tools I can afford.

(I should note that I have used CamBam in the past, but being commercial software that is Windows-only doesn’t entice me to want to use it again.)

I’ve played a little bit with Easel from our friends at Inventables, but I’m also not a fan of hosted solutions that can disappear, or start charging for access, etc. At this point I start to sound extremely picky, but really, I’m just looking for tools I can rely on, that are not expensive, and run on the platforms I use. (Easel is actually really nice, and while it’s easy to use, I think that comes at the price of hiding some of the complexity and advanced features I want to learn. Still, if you just want to cut/carve/engrave, check it out.)

I stumbled up MakerCAM, and there’s a bunch more info about it on the Shapeoko wiki. Basically it’s a Flash application (!) that you can use online, or download and run offline, which provides all the basic needs of a CAM application. And it actually works.

Inkscape

I started as I often do, drawing a 2D vector file in Inkscape. (Oh, I should mention there is an extension for Inkscape called Gcodetools, but we’ll skip that for now.) Once I had my Inkscape file I saved it as an SVG, as you normally would with Inkscape.

MakerCAM

I then loaded the SVG into MakerCAM. Note that if you load an SVG from Inkscape you need to set the px/inch to 90 in the preferences. Once in MakerCAM it’s fairly easy to create the toolpaths and generate the G-code. If in doubt, check out the help page and the tutorial page for all the info.

GrblController

After exporting my G-code file I was able to load it into the Grbl Controller and run it on the Shapeoko. Now, Grbl Controller is no Mach3, but it’s also open source, and multi-platform, so there’s that. (Yes, I know the image above does not match the first two images, that’s because I went crazy with the hatch fill from the Egg-Bot extension for Inkscape. Just pretend you know what I’m talking about.)

Oh, if you want to “run” your G-code before you run your G-code to make sure it’s doing what you think it’s doing, check out OpenSCAM, which is a nice little simulator.

(And yes, I know of Chilipeppr for Grbl, but I’ve not dug into it yet.)

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

make it move: Body and Machine

Exciting news in the world of kinetic art! If you enjoyed my recent piece The Hammer of Futility, but would really like to see it in person, you’re in luck! As long as you’re in Minneapolis between March 7th, 2015 and March 21st, 2015.

The arts organization make it move is putting on a show titled Body and Machine and my lovely hammer will be there, and if all goes well, I’ll also be there, at least for the opening on Saturday, March 7th, 2015.

My colleague Broc Toft will also have some work in the show. I enjoy Broc’s work and I think you will too. Speaking of enjoyable work, Savage Aural Hotbed will also be performing at the opening! I saw them at The Hack Factory back in 2013 and they were a lot of fun.

I’ve got a few more kinetic pieces in mind, but I’m really pleased with how the hammer turned out, and I hope to see you (well, my Minneapolis friends) at the opening!

Prusa i3 Parts

I’ve got a box full of Prusa i3 Rework parts! Well, not the full box, but we’re working on it. When I say “we” I mean myself and my team. This is all for a class titled “Digital Fabrication and Craft: Machines that Make”, which Frankie mentioned recently.

The class so far has been a blast! We’ve talked about the RepRap movement, and open source hardware and software used for 3D printing, and we’ve even designed a coat hook (yes, a nod to Adrian Bowyer.)

For the first assignment we are build Prusa i3 RepRaps, hence all the parts. We have a few MakerBots in the DCRL and the other students have been frantically printing parts. Meanwhile, I’ve printed most of my team’s parts on my RepRap Prusa i2. I sort of like the idea of my i2 making an i3. I may print enough parts to build out a frame and then transfer my i2 electronics and extruder over to it. Or I may just build another 3D printer instead.)

We’ve talked a lot about machines that make, and a little bit about MIT and what they’ve done. If you’ve seen the Othermill, you may or may not know it originated from an MIT project called MTM Snap.

And there’s more! For the second assignment each student needs to design and build a machine that can make things, and then we need to make things. Yes, we are rapid-prototyping rapid-prototyping machines. It’s a class made for makers, for sure.

One thing I’ve come to realize over the years is that you can design and build a thing, and you can design a product, and you can manufacture a product, and there are always compromises in process, materials, complexity, cost, quality, and fifty other things. A recommended reading in this area is Confessions of a Hardware Startup. Here’s an excerpt:

Our obstacle was that Jonathan had never intended MTM Snap for production. It was a design challenge experiment: to see if he could build a machine without screws. This is a great feature if you’re trying to save money as a graduate student, but from a manufacturing standpoint it had two major disadvantages.

Go read the whole thing if you’re interested in this. Since I’ve also been designing kits that are meant to be assembled and disassembled multiple times, I’ve seen similar (but different) challenges arise. But honestly, this all fits under the heading of “design” to me, because I still think design is about solving problems.

I’ve also been thinking a lot about the machine I’ll build. I probably won’t build a drawing machine right now (more on that later) but there’s a reason I’ve been researching the Othermill and been hankering to use a Shapeoko. It’s all coming together!

(See also: How To Make Something That Makes (almost) Anything.)

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