I love the Evil Mad Scientist STEAM T-shirt but I thought there was something missing, so I changed it to STREAM because… Robots.
Remember to stream big, my friends!
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Boom Pole Mount
Recently I’ve been on a few shoots where I’m doing the audio, and if you’re holding a boom pole and trying to keep the mic out of the shot, it can be a bit difficult to adjust the recorder, which you’ve typically got resting on something nearby, or if you’re moving around, holding in your hand. Obviously I needed a “BPM” and this time it’s not “Beats Per Minute” but “Boom Pole Mount”, which will hold the Zoom on the boom pole freeing up one hand to made adjustments or, you know, help steady the boom pole. (Maybe it needs a better name, like “Zoom2Boom” or something.)
As often is the case… 3D Printing to the rescue!
I measured the second segment of the boom pole and it came in at 30.2mm in diameter, so I fired up OpenSCAD and started to design a piece that would mount to the pole. (I should also note at this point that I’m not the greatest at math.)
I thought that instead of printing a test piece I would make a paper prototype to test the fit, so I converted my 3D STL file into a 2D DXF file in OpenSCAD. I figured that wasting a bit of paper was better than wasting a bunch of plastic. It’s also much faster.
I used the Silhouette Cameo to cut my DXF file using a page from an old calendar. (Reuse! Recycle!) Of course once it was cut I realized that I used 30.2mm for the radius instead of 15.125mm. Drat! Lesson learned, you can use d for diameter instead of r for radius in OpenSCAD.
Back to the old drawing board, by which we mean the “constructive solid geometry” software. This is version 2 of the design. Version 1 was lacking the holes for the hex bolt heads to fit into on the flanges, and was a little thin. Version 2 seems to have resolved all the issues that version 1 fell short on.
A few bolts, nuts, and knobs (just like the arm uses) and we’ve got a pretty solid piece that I trust to hold the recorder to the boom pole with. The one thing we may need to watch out for is over-tightening the knobs, as that could lead to cracking the plastic. I can probably solve this by adding more infill to the print (it’s at 35% now) or by a slight redesign. We’ll field test this one first though, to see how it holds up.
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Birth of a Robot (Army)
Sometime in 2013 I stumbled upon the blog of Sarah Petkus titled Robotic Arts. Probably because, you know, I occasionally build art robots. Sarah is a member at SYN Shop, a nice looking hackerspace in Las Vegas, and she’s been working on building delta robots for a while now. She’s got a great post about the journey from using household junk to designing and printing 3D parts to build her robots. Check out Robot Army : From Tupperware to 3D Printing.
She also been collaborating with Mark Koch at SYN Shop and turned this whole delta bot thing into a Kickstarter (successful!) that is going to help fund an art performance with an army of delta robots. And hey, while they’re at it, they’ll also be turning their robot into a kit through ROBOT ARMY, a new venture to manufacture robot kits for the do-it-yourself market.
I started working on a delta robot last year because I’ve got a project planned that requires one, but I still haven’t finished it. I might consider getting a kit if it makes sense to speed up my process and get to the “art” part of a future art robot I’ve got planned.
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A New Arm (Part II)
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.
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.
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.
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.
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.
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…
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!)
So yeah, a few 3D printed parts, some nuts and bolts from the hardware store, and we’re in business.
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.
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Foam Cutting with Stencils
I cut a piece of foam with a stencil, and it turned out terrible! So I tried again, and it turned out better…
A member of Milwaukee Makerspace loaned me his Proxxon Hotwire Cutter Thermocut to cut some foam. If you remember one of my previous foam cutting experiences using a drill press, that worked ok, but I wanted to try another method, the hot wire foam cutter actually designed to cut foam.
I started with not one, but two stencils, with the idea being I’d put them on the top and bottom of the piece, lined up with each other.
Why two stencils? when I tried to just use a top stencil with the wire cutter, the wire flexed a bit and I got not-straight lines.
I attached the top of the “stencil placement guide” to the top of the foam with tape…
…and then attached the bottom to the bottom, lining them up with the corner so they’d be in alignment with each other.
I then spray glued the actual pieces I wanted to stick to the foam with spray glue (using our spray booth!) Note that one piece is flipped upside down and one isn’t, so they match each holder.
Here’s the top piece glued into place…
…and the bottom piece glued into place.
Once glued in place I remove the top stencil holder…
…and the bottom stencil holder. Now we can cut. Hot wire goes through foam so fast I didn’t even get a photo!
Here’s the helmet cut out of foam. Top view…
…and bottom view. Yes, there are some rough spots, but the wire stayed pretty well aligned thanks to the top and bottom stencils. You just need to glide the wire along the paper’s edge. Much easier than trying to freehand a line drawn on the foam, and better results too!
You may have noticed a hole show up in the helmet. The reason for that was to feed the wire through to cut out the middle, but I forgot the wire was on a spool, so… bigger hole!
I cut a hole just large enough to fit the spool through…
…and once it was through, reattached it to the cutter so I could cut out the middle piece.
The middle piece came out pretty good… Now that’s a helmet!
A few of the cuts are a bit rough, but some sandpaper makes light work of them.
Ahh, now here you can see the terrible results of only using a top stencil from my previous attempt. The wire tended to cut deeper into the bottom of the foam where there was no stencil to guide it.
Our new improved helmet cut with top and bottom guides is much better. And hey, now it’s ready to be cast in aluminum!
While the Proxxon is nice, there are a lot of DIY foam cutters that can be built with scrap materials. Ultimately though, I think a CNC cutter would be cool. Just add an XY table and away you go!