Friday Night Drawbot v1

There haven’t been a lot of updates to my Friday Night Drawbot project lately, but things are picking up again.

Pictured above is version 1, which was built back in 2011, on a Friday night, in my basement. It drew circles. (And that’s it.)

Friday Night Drawbot v3

The programming got much better, and I ended up rebuilding the chassis a few times. This is what I like to call “version 3″ of the Friday Night Drawbot, and is still in use today.

FND

Let’s call this version 3.5. We’ve shed the old corrugated plastic in favor of a replacement designed digitally, and created with laser-cut wood.

The front plate that holds the pen can now easily slide forward and back, and is held in place by a pair of screws and wing nuts.

FND Drawing

I started the redesign process by taking apart the drawbot and measuring things with the calipers. I then used Inkscape to create (on multiple layers) the parts needed, which consists of the main plate, bottom plate, and pen extender plate.

FND Laser Cut

Here are the pieces separated out and ready to be laser-cut, or, cut in some fashion, I should say…

Old Plastic Body

I tore apart the old chassis which was hot glued to the servo motors, and held together with rubber bands. I had to heat things up to release the glue, so it’s a bit destroyed. No loss!

FND Paper Prototype

This is a paper prototype I created with the Silhouette Cameo, which does a fine job of cutting thick paper. I often prototype cutting things with the Silhouette because, well, it’s in my basement, so I always have access to it (unlike a laser cutter.) I could easily print on paper as well, but I find that with the cutter close by and easy to use, I use it a lot. It helps to have physical things cut and in front of you sometimes.

FND Bottom

Here’s the bottom view of the laser-cut version. There’s a lot of 8/32″ hardware holding things together, mainly because SAE is cheaper than Metric around these parts. (Drat!)

You can see that the two wing nuts hold the pen extender plate in place, so it’s easy to loosen the nuts and slide things around. (The slot could probably be a little narrower next time.)

There’s also some regular nuts holding the bottom plate to the main plate to hold the servos in place. The 3mm Baltic Birch flexes a bit though, and may not be the best solution.

Pen Holder (Bottom)

There’s a captive t-nut to hold the pen in place. It’s a good idea, but poorly executed here.

Pen Holder (Bottom)

The screw does hold the pen, but again, the 3mm wood is a little thin for this to work well. It’s also difficult to tighten and loosen the screw without a screwdriver. I really need a screw that allows you to use your fingers, like the one on the Egg-Bot. I’ll probably make a 3D printed screw-thingy for this.

Detour! I often wonder/worry about mixing laser-cut stuff with 3D printed stuff, and I’m not sure why. Maybe it’s due to the recent kit design work I’ve been doing where we try to make everything laser cut, mainly due to speed and efficiency of production. In this case though, I’d see the 3D printed screw-thingy as an “enhanced” piece, so it should be totally fine. Or I could, you know, use a wing nut. (End Detour!)

Pen Holder (Side)

As mentioned, I find the 3mm wood a bit thin. This whole design is really just 2 dimensional, or maybe 2.5 dimensional if you want to stretch things a bit. I want to have the next iteration be much more 3 dimensional. I may stay with laser-cut wood for most of it, but there is a lot to explore in the design for assembly aspect of things.

FND

I may play more with this version, introducing minor improvements, or just move on to the next revision, which will be much more box-like, and move away from the flat plates.

Since I like to build things really fast, it’s hard to know what will happen next.

Rotary Encoding

For an upcoming project we want to use rotary encoding with optical sensors, so I did a bit of hacking testing today…

I’m using two photo interrupters mounted on breakout boards with 220 ohm resistors.

For an encoding disk I searched for a suitable SVG file and found this blog post, which just happened to have a link to a perl script (of course!) to generate encoding disks. A little Inkscape magic and I printed out a disk to test with.

I should note that my original plan was to use the Silhouette Cameo to cut the slots in the disk, but the paper version actually worked fine for testing. In the final piece we’ll probably use a piece of laser-cut acrylic.

With my encoding disk ready I hot glued it to a bolt and chucked it in the drill. This gave me an easy way to vary the speed and direction.

Rotary Encoding

I grabbed the Encoder_Polling library and used the counter example and that was about it. I could now see if the disk was spinning and in which direction (by looking at the numbers increase or decrease.)

I really thought I’d need to mount the photo interrupters more precisely, but I pretty much left them hanging in mid-air supported by wires on a breadboard and it worked fine. (Maybe I just got lucky?) There’s a lot more code to write, but this was a good start.

Oh, if you want to learn way too much about reading rotary encoders with an Arduino, visit the Reading Rotary Encoders page and set aside a few hours…

Note: I also found an online encoder wheel generator.

Mounting Plate

It seems that when I ordered parts from Inventables, I forgot one thing! Seems I didn’t have this Motor Sub Plate that I needed.

Mounting Plate Plans

Luckily Inventables provides technical drawings and CAD files, so I grabbed the PDF file and opened it in Inkscape…

Mounting Plate 2D

I had to delete a lot of the measurements on the drawing, but when I was done I had a file that I could easily laser cut. But alas! I have no laser cutter at home… No worries, a bit more work on the file (changing all the curves into segmented lines, connecting all the disconnected lines) and I was able to save a DXF file…

Mounting Plate STL

And the DXF file was easy to import into OpenSCAD and extruder as a 3D (well, 2.5D) file and get an STL file, which can be printed on a 3D printer, which is what will be happening in a few minutes…

Digital Fabrication… it’s a thing.

Wax Ring

The folks from Solidscape dropped by the DCRL at UWM to talk about their 3D printers that can print with wax. These are typically used in the jewelry industry for lost wax casting, but also used in the medical, dental and engineering fields.

Wax Ring

The resolution of the prints was simply amazing. They’ve also got some unique things that their printers do, like milling the build plate flat before each print.

Wax Ring

Their machines are not cheap, starting at $25,000 and going up to $55,000, but the quality is pretty amazing, and depending on your needs, that price may be cheap.

Wax Turbine

Obviously lost wax casting in metal is a prime use of these pieces, but there were a lot of other applications mentioned, including multiple methods of creating silicone molds.

Wax Turbine

The details was pretty amazing, and not even in the same ballpark as what I’ve seem from any FDM printer. If you get a chance to see the output from a Solidscape printer, do it. It’s pretty impressive!

Wax Head

Wax Head

Wax Tire

Wax Tire

Note: Frankie has better photos and more info!

Grace Choi

Grace Choi is pretty awesome. She’s come up with a way to print makeup using a hacked inkjet printer. Yeah, what? You can check out this HOW TO, or just check out how she plans to disrupt a huge and extremely profitable industry.

I found her demo to be a bit unpolished from the software end, but she seems to know that there’s a great opportunity for developers to fill that gap.

I’m not really into makeup, but I am into 3D printing, and disrupting entire industries is definitely an interesting proposition. Here’s a bit of what Grace had to say that really illustrates the kind of person she is.

“One person alone can’t disrupt this entire beauty market,” Choi says. “Together, as a community, we can disrupt it. I’m willing to take a hit financially because my number one motivation is for change. This is a very important social mission for me. I think of Mink as an educational tool for kids, and one that can get girls interested in technology. I don’t need to be on some billionaires list. I’m aggressive and I’m going to make this happen. Before I die, this [beauty revolution] will happen.”

And if that’s not enough, there’s also this one:

“The makeup industry makes a whole lot of money on a whole lot of bullshit. They charge a huge premium on something that tech provides for free. That one thing is color.”

Definitely one to watch…

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