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A New Arm (Part II)

Assembled Arm

In my previous new arm post I banged out a quick ‘n dirty replacement arm to hold an LCD display on a RED camera using some 3D printed parts and a few nuts and bolts.

Arm Parts

Version 1 worked, but I wasn’t totally happy with it. Iteration time! The beauty of digital fabrication using a 3D printer is that it’s easy to revise your design and try something new.

Block 1

One of the issues I had with version 1 is that things spun around too much. Even with the tightening bolts, there was more spinning happening when less spinning was desired. I ended up adding a hex-shaped hole to hold the head of the bolt in place. This resulted in less spinning.

Block 2

I then figured that if one hex hole was good, two were better! Sadly, while this worked well for the first corner piece, it didn’t work as well for the second corner piece that was held in place with the nut knob.

Block 3

No problem! OpenSCAD makes it easy to comment out a piece of code and output a new STL file. I now have two (slightly) different versions of the connecting block. Oh, I also rounded the edges a bit, which resulted in a better print, and a better feel.

One thing to note here. Where I originally posted an image of the connector block (before I even printed it) I made a comment about milling it from Aluminum. (Though ultimately it was decided that a drill press and band saw might be all the tools needed.) Milling this new design would probably still be doable, but until I’m sure we like this version, what’s the point? I may end up revising again.

Nut 1

And then there was the knob… The knob I had previously been using was one of the first things I ever printed on my RepRap. I’m sure I grabbed it from Thingiverse, but I’ll be damned if I can find it now. It may have been removed. Nevertheless, I didn’t love it, so I designed a new one. This is version 1, which was ok…

Nut 2

This is version 2, with a nice hull operation to give it a more rounded feel, and (probably) make it a little bit stronger. This is my new 1/4″ nut knob from now on. (Unless I design a new one!)

Parts

So yeah, a few 3D printed parts, some nuts and bolts from the hardware store, and we’re in business.

Assembled Arm

Oh, there’s also a screw in place of a bolt on the main support, because attaching it to the camera will be ten times easier with this feature, and you may also notice a slightly smaller version of the knob on the lowest mount point. This is (probably) needed to allow clearance to tighten it. (I didn’t have the camera around to test with, but I’ll find out this week if it works.)

Update: Tested it, seems to work well! You can grab the files from Thingiverse.

Arm on RED ONE

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Derby Wheels

If you remember Milwaukee’s last Nerdy Derby, we tried to supply lots of pieces for people to build cars with. I ended up laser cutting a bunch of wheels, as well as 3D printing some wheels… take a look at the junk car post from last year.

Well this year I started printing wheels, and then decided that plain old boring wheels just wouldn’t do, so here I present a progression of wheels I’ve designed so far. I’ve only printed about 1/4 of them, but I’ll probably give them all a try before the big Nerdy Derby event at Milwaukee MakerFest on October 19th, 2013.

wheel001
The plain old boring wheel from last year.

wheel002
Speed holes… should use less material, but may not actually print any faster.

wheel003
Indent, for no particular reason.

wheek004
More speed holes, this time done using a proper for loop.

wheel005
Reverse spokes?

wheel006
Howdy partners! It’s a wagon wheel!

wheel007
And a steering wheel!

wheel008
And an Aperture wheel?

wheel009
Wheel wheel wheel wheel wheel…

wheel010
Tri-force wheel?

wheel011
Weird wheel?

wheel012
Starting to do some hull action for more 3D-ish wheels.

I will say this, I am no expert at designing wheels, but it’s been a lot of fun and a great design challenge, and I really do enjoy tinkering with OpenSCAD to create things.

Oh, and then I wanted to do a spiral wheel, and did some searching, and found this great wheel library, so use that if you really just want awesome wheels and don’t care as much about screwing around with code to learn things on your own. (Or, us the Highly-Configurable-Wheel library and learn from it!)

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GoPro Hero3 Frame

GoPro Hero3 Frame

I like the acrylic housing that comes with the GoPro Hero3, but I tend to run some pretty long time lapses, and the battery doesn’t last long enough, so I made a lightweight frame, and it’s over on Thingiverse.

GoPro Hero3 Frame

I’m (slowly) getting better at OpenSCAD, thanks to projects like this. I’m sure I’ll get even better in 2013.

GoPro Hero3 Frame

I’ve got plenty of long USB cables and USB power supplies, as well as a Minty Boost from Adafruit to provide power for shooting hours and days at a time.

Here’s a quick time-lapse test I shot before I had the frame. I ended up balancing the GoPro on a book on top of two water bottles, which was silly, and just one more reason for this thing.

GoPro Hero3 Frame

The frame has a bit of flex to it so you can easily wrap it around the camera. I may play around with some thicker housings, but for now, it does the job.

I ended up printing about 6 versions before I got one that was good. I should probably do more paper prototyping, but with how easy it is to 3D print things, sometimes you just hit “print” and hope for the best. If it doesn’t work out, you tweak things and try again. It’s just the way it works.

(Note: I guess GoPro also sells a frame for the Hero3. Go buy it from them if you want a really nice one and have $40.00 to spend. If you just want this cheap plastic one, print it yourself.)

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Snowflakey

Tennis Man

Here’s a thing I’m calling (for lack of a better name) “Snowflakey”. The idea came from the Kimotion Arts store on Shapeways.

Kimotion Arts

Kimotion Arts has these neat 3D printed ornaments with an object arranged in a circle to make a snowflake-like thing. I dig it, so I decided to dig into it.

Bad Man

The first thing I did was fire up Inkscape and draw a really simple figure. It’s terrible, really, but I did it in less time than it took Inkscape to launch on Mac OS X. I created an SVG file, and then exported it as a DXF file, making sure I converted all the line segments into straight lines first. (Of course there were no curves in this drawing, but if there were, I’d convert them!)

Bad Man Flake

Once I had my DXF file, it was easy to pull that into OpenSCAD, and place six of them in a circle with the following code.


objheight = 4;
objcenterspacing = 20;
objrotate = -70;

for (i = [0:5]) {
  rotate(i*360/6, [0,0,1])
    translate([0, objcenterspacing, 0])
      rotate([0, 0, objrotate]) 
        linear_extrude(height = objheight, center = true) 
          import( "figure.dxf" );
}

The code is not the greatest… in fact there is probably much room for improvement, but it’s the first thing I got working, so I ran with it. My idea for the 3 variables at the top were so you could easily tweak them for different art. Sadly, as you change objcenterspacing and objrotate, they affect each other, so it’s a lot of back and forth between those two values. I also could not find a way to assign a filename to a variable, so your DXF will need to be named “figure.dxf” or you’ll need to edit the import line.

Tennis Man

Since my drawing was so terrible I wanted to try something else, so what better than Land recreation symbols 27, better known as “Tennis Man” by most people.

Tennis Man Flake

A few quick edits and I had this nice Tennis Man Snowflake for that special ball smasher on your list… (Notice the canvas size of 25mm wide by 35mm high. You can do what you want, but the OpenSCAD code will be expecting something close to that. Otherwise you’ll just have to tweak the numbers even more.)

Blobby Man Flake

I decided to try once again to draw something. This one took a little longer than a minute, but turned out just as terrible as the first one I did. Still, maybe you like “Blobby Man” as a snowflake.

Ant Flake

How about ants? This one is interesting. Maybe spiders would have been a better choice. (And yes, I know I could probably do the entire “6 items rotated” thing right in Inkscape, but that wasn’t the goal here.)

Horse Flake

What about the old nag? No, I’m not taking about your mother-in-law (kidding!) but this fine old horse from OpenClipArt.org, where I get many of the SVG files I use. Export this as an STL file and you’re ready to print it on your RepRap!

If you’ve got an improvement to this OpenSCAD code, by all means, let me know. I’m still very much in the learning phase with OpenSCAD, so I do these things to learn, and because of that I’m open to any suggestions.

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Inkscape to OpenSCAD

Gear!

Oh yeah! You can totally draw gears in Inkscape… In fact “draw” isn’t even the right term, as you can “render” them using one of Inkscape’s extensions. Here’s a nice post about laser cutting some gears that explains it quite well.

Gear Rendered!

Normally for 3D printing I’d export something like this as a DXF file and extrude it into a 2.5 dimensional object, like I outlined here, but there is another way… by using the Inkscape to OpenSCAD converter! (Here’s a nice blog post about it as well.)

Gear in OpenSCAD

It may not generate code that’s easy to edit, but it’s fast, and seems to do the job, which is often exactly what you want. I’m also quite pleased that Inkscape is becoming such a valuable tool not just for 2D work, but for 3D work as well. I might consider teaching an Inkscape class at Milwaukee Makerspace once we get our classroom up and running.

3D Printed Plastic Gear