RasterWeb!Here’s a video of the Turndrawble in action… Also, as an added bonus you get to hear the strains of a DC motor moving a gearbox to spin the platter. Turn it up, man!
Don’t forget to check out the blog post and the Turndrawble project page.
If you’ve been following any of my adventures since I first mentioned a Turntable Drawing Machine, this is the result. The Turndrawble is a machine that uses a spinning platter and a movable arm to create drawings.
Unlike many of the things I’ve been working on lately, the Turndrawble leans more towards the “art object” side of things than the “here’s all the files/you can easily make one” side of things. That isn’t meant to say you could not make one, but the prime objective was to create an aesthetically pleasing machine that was unique. (I hope I did that!)
I also wanted to build a machine I could bring to events and allow people to use in order to create drawings. Often in the past I’ve brought drawing machines places but I’ve ether operated them or they’ve operated (semi-) autonomously. The Turndrawble presents a chance for the viewer to become a participant.
(I’ll be posting photos of some of the drawings soon as well. There’s also a video.)
Check out the Turndrawble project page for more info, links to files, etc. if case you want to try to build your own. (I’ve been thinking of building a much smaller and simpler version as a kit you can purchase and assemble. Stay tuned for updates on that.)
For the past nine months I’ve been working with Brown Dog Gadgets on a number of projects. It’s been mostly kits for the educational market, and I’ve done a lot of design work, and a bit of electronics prototyping, as well as writing code and lending a bit of advice about marketing. The most recent project is The Badger, a waterproof USB solar charger.
You may remember that two years ago Josh launched a campaign for solar chargers and it did pretty well. Since then he’s taken feedback and requests from customers and came up with The Badger, which offers a number of improvements, mainly the waterproof qualities, but it’s also a damn tough panel! We’ve run it over with a car, dropped a bowling ball on it, and shot at it with a gun. Oh, it also sat it water for two days, and worked just fine when we pulled it out.
Why am I telling you all of this? Well, if you need a solar panel for any outdoor activity, these are pretty awesome. And, if you back the project, not only will you get a great charger, you will help fund my work. Yes, that’s right. Josh and I have a few projects we’d love to launch, but they depend on this Kickstarter campaign being successful. The more successful the campaign is, the more we can produce. What will we be creating? It may be programmable drawing machines, or creative robotics projects, or some combination of those (or something else.) Whatever is it, it will inspire kids (and adults) to learn and be creative and have fun.
So yes, get yourself a panel, or a power bank, or just toss a few bucks our way, and we’ll start cranking out some interesting kits. That’s the plan. Check out the video below, or head right to the Kickstarter page.
One of the pieces I needed for my turntable drawing machine was something to hold a bearing in place underneath the platter to support it and let it spin easily. If you’ve ever taken the plate out of your microwave oven to clean it you may have seen a “Microwave Roller Wheel / Turntable Support” thing. (Really, that’s what it’s called. Check Amazon.)
I decided to use 608 bearings, mainly because I had a lot of them on hand, but they’re also really easy to get for a low price. (I think I got 30 608ZZ bearings for under $20 from Amazon.)
I designed these two arms that would fit into slots cut into the base of the machine, below the platter. Each piece would be locked into place with a 3mm bolt, so there’s holes and t-slots for those. The extra piece you see on the bottom (with the 4 slots and 2 holes) is the mating piece. This was designed based on the arm pieces fitting into it, and I would only need to cut one (hopefully) to test the fit.
The arms are slightly different. The one on the right has a hole large enough for the 8mm bolt to fit through, while the one on the left has a slightly smaller hole. The plan was to tap the smaller hole so the bolt could screw right into it without needing a nut. Do a search for metric tap drill size and you’ll see that a 6.8mm hole is needed to tap it for an 8mm bolt. (Sometimes you can just look on the tap and it’ll tell you what size to make the hole.)
As a bonus, when I share the files for this you can decide which pieces suit you better, depending on the availability of an 8mm tap in your workshop. No tap? Just use the larger hole version and a nut instead.
When you’ve got a laser cutter and lots of scrap acrylic, it makes a lot of sense to make your own washers and spacers and standoffs. (Assuming acrylic is up to the task of what you’re designing.) The spacers were sized to match the inside part of the bearings allowing the outer part of the bearing to spin freely.
I originally was going to make acrylic nuts as well, but decided on tapping the holes with threads. I still wanted the “hex nut” part of the design, as it’s used to hold the platter in place. So that, in conjunction with the tapped parts, prompted me to make the hex shape at the top of the arms. (It’s the details, right?)
The one thing that making and using acrylic nuts would have allowed would have been adjusting the height of the bearing. I could have created a slot for raising or lowering the bolt and bearing combo, so with this design featuring the tapped holes, there was no room for adjustment. Luckily I got it right by the second (or third) attempt.
Here’s a shot of the spacing of the bearing holders below the platter. It worked out well and I got the math (mostly) right. I may end up making a new bottom in the future to account for other faulty measurements this time around, but I’ve already adjusted for them and things work well enough.
(For other posts about this turntable, check the posts tagged with dcrlmtm.)
You can’t have a turntable without an arm! Well, I guess you could, but where would you put the pen? Here’s some of the design files for the arm. The hole pattern on the larger part was made to match a servo hub from SparkFun, which is also from ServoCity, which provided a STEP file. (Ignore the heart-shaped thing for now. It’s experimental!)
Luckily I was able to open the STEP file in both Rhino and in FreeCAD! It’s like I won the CAD file lottery or something. But seriously, if there’s ever a competition to convert from one format to another and then another and another… I think I can win.
I was able to get what I needed to get the hole spacing right, which is all I really needed this time. The holes are tapped for 6-32 screws. Once again I’m mixing Imperial and Metric. Sigh… Mission (somewhat) accomplished, I guess.
The arm consists of three layers of laser-cut pieces stacked up, and screws to hold them together. I played around with materials a little bit, trying wood in the center, but finally choosing the red acrylic. I thought about clear, but there is at least one other red element right now, and possibly more to come, so I chose the black and red combo. Always a good choice!
There’s also a hinge I cut from a 1mm thick plastic I got from the Midland scrapyard. (Windell from EMSL thinks it might be polypropylene.) The laser cut it fine once I figured out the proper settings… and covered it with masking tape on both sides.
And yes, I did borrow a few ideas from the Egg-Bot design. Sharpies, FTW! Pen holder designers unite, and all that. There’s a 8-32 square nut in there, really snug. I do not have a nice thumbscrew like EMSL uses… yet!