As part of my effort to reduce the noise and vibration in the Y axis, I am going to try using a screw drive instead of the 5mm pitch belt. I rescued a screw drive assembly from a big XY table but it uses a 200W servomotor for which I have neither power supply nor drive electronics. Never fear! The motor was a NEMA-34 size, so I designed an adapter to mount the NEMA-23 stepper that MegaMax uses in the NEMA-34 motor mount. Next I needed a shaft coupler- the screw has a 9mm diameter attachment and the NEMA-23 motor has a 1/4″ shaft.
Adapter plate on NEMA-23 motor
I used DesignSpark Mechanical to design the motor mount adapter and flexible shaft coupler. I uploaded the motor adapter to Thingiverse (http://www.thingiverse.com/thing:526424) and it proved surprisingly popular so I designed another that adapts a NEMA-23 mount for a NEMA-17 motor (http://www.thingiverse.com/thing:526443). I had to make two attempts at the flexible shaft coupler- the first design proved a little too springy and flexible, so I tried again with a more beefy design. It turns out it is pretty easy to design this sort of thing in DSM. I probably spent 30 minutes on the first one and about 10 minutes on the second one.
I sliced in Cura because Slic3r was having some problems. The prints look a little rough because of all the support material required to print the springs, but they work fine.
Flexible shaft couplers- not-so-springy and super-springy.
Adapter and shaft coupler on motor
Motor mounted on screw assembly
I’ll post an update when I get the screw mounted on the machine.
My recent acquisition of a Meade ETX-90 telescope with computer go-to system for locating objects in the sky got me thinking that it would be nice to have a system to locate objects in the sky when you’re looking through binoculars or a telescope that doesn’t have a computer and motors to drive it. To that end I came up with the idea of mounting a green laser pointer, commonly used by astronomy nutz to point out objects in the sky to noobs, on a cell phone or tablet running a program such as Google SkyMap or Skeye.
CAD rendering of the parts
After much thought and a few prototypes I came up with a system that allows a laser to mount on a phone and that assembly to mount on a tripod, a handle, or a telescope. The tube that holds the laser has adjustment screws to allow the laser to be aligned with the SkyMap on the phone. It also has to slots that fit over standard gun sight rails. On one side I have a phone/tablet bracket that has a gunsight rail and slides into the laser tube, and the other side can be used for a rail that mounts on a tripod or a handle. Extra rails can be mounted on telescope tubes. I haven’t yet designed a binocular mount, but will soon.
Parts printing on MegaMax
I printed the parts on MegaMax with Octave fluorescent red filament (that’s why the colors vary in the photos- the flash apparently excites the fluorescence in the picture with the handle). All the parts fit VERY tightly together but I included screw holes for extra security. The phone/tablet mounts on the bracket using velcro tape. I think it may be better to print or buy a cheap case to fit the phone than screw it to the phone/tablet bracket. I’ll be posting the design files to Thingiverse shortly.
Several years ago I played with a lot of audio stuff including making binaural recordings of things like cicadas, train rides, and festivals in Japan, and the singing of tree frogs in my back yard when I lived in a forest in Missouri. Those recordings were done on a MiniDisc recorder because it was the best available audio quality recorder for people on a budget (i.e. cheapskates) like me. Time and technology wait for no one, and I’ve been getting the itch to do some recording again, so I recently picked up a Sony PCM-M10 recorder. This little machine records in many different formats up to and including 24 bit/96 ksps (though self-noise really limits the machine to about 15 actual bits). The audio is recorded onto micro SD cards so unlike the MiniDisc, you get access to the raw digital data without any compression or associated quality degradation.
My previous recordings were done using a DIY binaural microphone that used a roughly matched pair of electret condenser mic capsules mounted on a wire bail that held the capsules inside my ears. Even though those mic capsules were pretty noisy, the recordings came out pretty good. When you listen to them with headphones you get a real “you-are-there”, surround-sound experience that can be quite startling. You can hear those recordings here: http://mark.rehorst.com/Binaural_Recordings/index.html Soon, I’ll be starting a new binaural mic project to go with the new recorder, this time using much higher quality mic capsules.
In the meantime I was looking for a shock mount to use when making recordings using the built in mics. The shock mount prevents low frequency noise from handling, bumping the table the recorder sits on, etc., from being coupled to the mics through the body of the recorder. I did a web search and found only a couple unsatisfactory designs so I did what any maker would do- I made!
One of the flaws in the few designs I saw was that some of the numerous switches and I/O jacks on the recorder would not be accessible when it was bolted to the shock mount. They also didn’t look very nice. After a lot of sketching possible designs on a whiteboard and paring the thing down to a minimal implementation, and spending much too much time making a 3D model of the recorder, I came up with a printable 3-finger design that holds the recorder either on a tabletop or a tripod and keeps ALL the switches and I/Os available. The only thing you can’t do while the recorder is mounted is swap batteries (but with 40 hours record time on a set of two AAs, that shouldn’t be a problem).
I used DesignSpark Mechanical to make the recorder model and design the shock mount. DesignSpark makes rounding corners of complex 3D objects easy (nearly impossible in Sketchup), but I did run into some of its limitations that I hadn’t previously considered. One huge limitation is that there is no way to put any form of text into a drawing without some special work-arounds (use Sketchup to make text, then import into DesignSpark).
Have you heard of littleBits? It’s an open source library of electronic modules that snap together with tiny magnets for prototyping, learning, and fun. If you’re the kind of maker who tends to avoid the Electronics Lab, littleBits might be just what you need to start experimenting with circuits.
If you come up with something cool, we’ll help you post a step-by-step Instructable for it, so others can enjoy your creation. If you need some inspiration, check out some of these littleBits projects.
These events will be free, just bring yourself (and your ideas!) to 2555 S. Lenox St. in Bay View and make something cool with littleBits.
Silversark put together an amazing fashion show on Friday to showcase pieces she made inspired by church architecture and her trip to the Netherlands. This is something I cooked up for a background piece for the show.
The design work took several months and the actual creation of the piece took about a week, working 12-16 hours a day. The frame is made from CNC routed aspen (thanks, Jason H.!) which is a rather “fuzzy” wood and required two days to hand finish, including the use of a set of needles files to smooth out the inset edges.
The acrylic panels were hand-stained with Gallery Glass stain and simulated liquid leading. They’re not quite finished yet, but I plan to complete the staining within the next week.
I repaired the Budaschnozzle hot-end over the weekend and bolted the SnakeBite extruder to it and then to MegaMax and tested it last night. There’s plenty of tuning to do, but the first print looks promising:
Well, OK, not the whole enclosure, just the parts that hold it together.
MegaMax can print big stuff but he’s had problems with large prints delaminating. The answer seems to be enclosing the printer to keep the prints warm while printing. I designed this box and 3D printable parts to hold it together so that I can take the box apart easily to work on MegaMax or move him to other locations and put it back together when I’m done. The box is 38″ D x 28″ H x 32″ W.
The box is made of 1″ PIR foam with corners suitably notched to accommodate the printed parts. MegaMax has a 450 Watt heater in the printbed so the box gets super-toasty inside. I suspect it gets a little too toasty but haven’t made any measurements yet. I’ll soon be moving the electronics out of the box. I didn’t do anything to seal the seams in the box because it doesn’t seem to be necessary. I did tape the edges of some of the foam boards with clear packing tape to prevent damage.
When I recently was at the thrift store and saw a pair of ice skates next to a kick-scooter, it got my mind going. “What would a scooter look like with skates in place of wheels!?”
The next time I was at the Makerspace, I saw my old electric scooter over on the Hack Rack. This was a scooter I originally rescued from a dumpster. Although it didn’t have batteries, just adding power and a little tinkering got it up and running again. A few of the EV Club and PowerWheels Racing guys played around with the scooter a bit, but eventually the controller got toasted, and who knows what happened to the front wheel.
Oh well, I’d be replacing that front wheel with an ice skate anyways.
Turns out that the heel of an ice skate is actually sturdy enough to drill right through and use as a mounting point. I simply drilled through the skate, inserted a spacer, and then ran a 3/8″ bolt through the skate and the front fork of the scooter. I finished it off with a couple of washers and a nut.
Then next thing to fix was to get the motor going again. Turns out that it’s a brushless motor. While I have a fair amount of experience now with BRUSHED motors, this was my first experience with brushless. I did a little research, and then ordered a 24V, 250 watt generic brushless controller from a mail-order scooter parts company. Unfortunately, it used a different style of throttle than what was already on the scooter, so I had to order a throttle to match.
Connecting the controller was pretty easy, three wires to the motor and the black and red one to power. I first bench-tested it with an old printer power supply, and once everything was working right, bit the bullet and bought a brand new pair of 12ah SLA batteries. The two batteries are wired in series, along with a 20 amp fuse, and then go to the controller.
I still needed a deck for the scooter. I dug through some scrap materials and found a pair of cabinet doors that were about the right size. I cut them down just a bit and bolted them to the scooter. I even re-mounted a cabinet door handle to have as an attachment point for towing a sled.
With that, I was ready to go for a test ride, so it was off to the lake. Once I was on the ice, I turned on the scooter and gave it a go! What fun! It really zipped along, but it was almost impossible to steer, as the back tire would slip right out from under me! Time for more traction!
I decided to make a spiked tire. I removed the rear wheel, then disassembled the two-part rim and removed the tire and inner tube. I stuck 1/2″ self-tapping, pan-head, sheet-metal screws through the tire from the inside, so that their points stuck out. I evenly spaced out 24 screws and alternated them to be slightly off-center side to side. Next, I put some old scrap bicycle inner tube over them as a liner to protect the scooter tire inner-tube. After that, it was just a matter of reassembling everything.
Now for test #2 out on the ice. Remembering how much it hurt to fall on the ice, I was prepared this time by wearing my motorcycle jacket (which has padding built-in) and my helmet. Good thing too, as I would learn while steering with one hand and holding a GoPro camera in the other…. (Note to self, keep both hands on handlebars at all times.)
Overall, the Ice Scooter works great! I still have a few little things to do on it. For example, the motor is running “sensor less”, and I’d like to learn about how brushless motors use the sensor system. I’d also like to get a small 24V dedicated charger. As it is right now, I have to remove the deck and manually charge with a little 12V charger.
From thrift store idea, to hack rack, to life on the ice, it’s always fun to see what you can do with just a little ingenuity. I hope you like this project. If you want to see more on it, please check out the write-up I did on Instructables. It’s even in a few contests there, and I’d love your vote!
Keep on Making,
At Wisconsin State Fair Park, the same weekend as Harvest Fair. Admission is free. Thanks for a great 2015! See you next year. A joint presentation by the Makerspace and the Betty Brinn Children's Museum.
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