A Variac (also known as an Autotransformer) is a variable transformer, which allows the user a convenient way to control the power to an AC appliance. In our context, it’s typically used to adjust the output of a heating device. The variac currently at the Makery is a 20-amp model manufactured by PowerStat. We’ve configured it to scale voltage only in the down direction, so that the output range is 0-110vac (or whatever line voltage happens to be). The transformer is outfitted with standard AC outlet fittings, and is mounted to a board for easy transport. It should be noted that this transformer is NOT isolated, so the output could still be hazardous, regardless of how low the voltage happens to be set. As with most other equipment, the variac is stored in the TOOLS cabinet.
One of the other projects enhanced by the Variac is the vacuformer. It consists of two parts: a box with a heating element that melts plastic (background) and a perforated box which sucks the softened plastic down over a heat-resistant form (foreground). Prior to the Variac, we’d had problems damaging the plastic sheet, because it was heated too rapidly. Now, we can adjust the heat very precisely and results are much better.
Note: The reason for the incomplete formations in the black plastic (Sintra) is that both the objects used as forms were heavy, metal and cold; The plastic cooled too rapidly, before a good impression could be achieved.
The vacuforming equipment (both the heater box and vacuum bed) are stored in the “TOOLS” cabinet. There are several shop vacs to be had, typically stored below one of the benches in the “less clean” area.
The Makery’s recent acquisition of a Variac has rekindled interest in a few projects that had been on hold. One of those projects was the Acrylic Bender that James had been working on. At it’s core, the bender is just a halogen bulb between two aluminum tubes full of circulating water. The idea is to create a line of focused heat to allow plastics to be bent accurately. We found that it works equally well for acrylic and Sintra (Foamed PVC). The Bender (along with the Variac) is currently stored in the “TOOLS” cabinet.
At next Tuesday’s meeting (December 13th), we’ll be doing a pizza/potluck dinner. The idea is that everyone throw in a few bucks for pizza and bring whatever else they’d like to share. Food is planned for 6:30, but it’s a pretty casual sort of thing. If you’re interested, RSVP here.
The presentation for the meeting will be Dave, talking about the piezoelectric effect, and demonstrating how make Rochelle Salt (a piezoelectric material).
The piezoelectric effect is the linkage between an electric charge and the mechanical distortion of a material. It occurs in many materials, from crystals and ceramics to bone and DNA. We use the piezoelectric effect in many ways, but we most commonly encounter it in small speakers, audio pick-ups, and grill starters and lighters. Most commercial piezoelectric materials are engineered compounds that are relatively tough and exhibit a strong piezoelectric behavior, but are difficult to create for oneself. However, one of the earliest piezoelectric materials, Rochelle salt, can easily and safely be made at home, allowing us to explore the piezoelectric effect from the ground up.
Even if you’ve never been down to the Makery, or you’ll be a little late, please come join us!
Last night, the Makery hosted a Nerf Gun Mod contest, previously announced here. We had 5 total entrants, after a few people had things come up at the last minute, and about twice that many spectators.
Only Brandon and Eric made an attempt in this category; Brandon did a functional “pseudo-steampunk” mod (with an extended brass barrel and integrated laser sight), while Eric gave his Nightfinder a complete color revamp using Sharpie markers (Which did come off on his hands). Eric won almost unanimously, earning him an extra 10% in the distance competition.
The accuracy contest was run next, in a series of 8 rounds, with a point going to the entrant who could hit a whiteboard (At about 15 feet) closest to the center mark. The entrant with the most points won this category. The contest itself came down to a shootout between Brandon and Dave, (2.5 points each) with Brandon emerging victorious. Eric (2 pts) and Kevin (1 pt).
This contest measured total distance to rest, thereby including any beneficial or harmful rolling or tumbling that a dart did. A slight accuracy component was involved, in that if a dart went more than 75 feet or so, it had to clear a 5 foot wide doorway. The low ceiling also proved challenging to some contestants, as it limited the amount that a dart could be arced.
Distance was scored as “best of 8 darts”, with each entrant shooting all 8 in succession. Brandon’s was the only dart to clear the doorway, making him the winner. A few darts bounced off the wall, though. Eric’s 10% bonus (2.2 paces, very scientific) was enough to propel him into 3rd place over Dave, leaving the results Brandon, Kevin, Eric, Dave, Patrick.
Overall, Brandon was the supreme winner, having taken first place in both categories. Even with a smaller-than-expected field, everyone involved had a great time. Thanks to all involved for making last night a success! A few photos from the event are below.
At the Makery lately, Brandon and I [with some help] have been working on a CNC Hot-wire Foam cutter quite a bit like this one. Ours is going to be a bit larger, capable of slicing up a 2×4 foot piece of foam (actually, the X is more like 5 feet than 4). For our Z axis, we are using a salvaged set of rails including a rack and pinion setup, but our X axis is entirely homebrew.
I’d initially lobbied for a belt setup similar to the X-axis on a Prusa Mendel, but Brandon objected on grounds of the cost for a 10 foot piece of belting. He proposed instead using a piece of all-thread as a rack, and a curved gear as the pinion. That was fine, but seemed like the gear would cost more than the belting. In the end, we decided to try making a gear, in the same way that extruder rollers are made for the 3d printers: Hobbing.
Tonight, I got around to trying to make the gear. We’d settled on 3/8-16 all-thread, as it’d be sufficiently beefy as to not bend with a gear pressing against it, and to not sag under the weight of a mostly unsupported 5 foot span. I grabbed a piece of (approximately) 1″ round aluminum from the scrap bin, and drilled a 3/16″ hole through. I bolted the cylinder to a bearing I had lying around, and chucked it into a V-jaw in the mill vise, with one end floating free. I chucked up a 3/8-16 tap in the spindle, and set the speed as low as it goes (I around 500rpm, I think).
From there, I aligned the tap so that the centermost full thread was parallel to the bolt through the work, so that I’d be cutting only on full threads. I used the Y-axis of the mill table to position the tap along the length of the work, and advanced the work onto the spinning tap by slowly feeding the X axis as the work turned. (The work spun freely in the bearing, powered by the tap cutting into the aluminum, like when a board lifts as a wood screw is driven.)
I initially had a bit of trouble with the work flexing in the chuck (as I was only supported from one end), but I overcame this by grabbing the outboard end of the bolt with my hand and keeping the bolt parallel to the vise jaws manually.
Overall, the process worked really well. The tap cut nice, deep, uniform teeth into the aluminum. If I were going to do it again, I’d find a better way to hold the work (supported by both ends) in the vise; I’d also pick a better piece of material, as I didn’t bother turning the surface imperfections of out this one before I started.
What’s this strange thing? This is the TacitTheremin, a device which helps blind people understand their surroundings using ultrasonic sound ranging. Designed to work in tandem with a cane, this device allows users to get a greater sense of what’s around them at ranges that exceed a cane and in any direction in which its pointed.
Inspired by the Tacit, an invention made by Grathio Labs, the TacitTheremin is a modification of that design concocted right here at the Omaha Maker Group. It mounts to the wrist, receives distance measurements from an ultrasonic sensor, and outputs sound to the user through a speaker (low tones for far distances, high tones for short distances). It ranges from 16 feet down to 3cm, 5 times per second.
This whole project started as an attempt to replicate a Tacit (because the idea is just so darn cool), and in the end it turned out to look quite different, with different coding as well. You can read about the epic journey in detail, and make your own for a friend (on an individual project basis).
But enough technical stuff. See it in action!
Currently, this prototype is being field tested by a local Omahan named Mike, who happens to be blind. Stay tuned for a followup video.
You can reach me with any comments, questions, or concerns here. Just be sure and put “TacitTheremin” in the subject. Alternatively, feel free to comment below!
Its amazing what you can print these days. We tested out the Mendel Prusa last evening by printing this cool little light bulb sculpture.
If you could make any design in your head come to life, what would it be?
Much of what we can do these days with 3D printing is due to the hard work of Brandon. Be sure and check out the new RepRap piece he’s making to ensure 3D printing just gets better and better: Vertical X-Axis
Be sure to check out our new “Makery Mendel” channel on Ustream, located in the links to the right. Whenever the Makery is printing, you can see it happening.
Ever since I visited Noisebridge in San Fransisco back in November of 2010, I had burned into my head how amazing it was, and how great it’d be when we finally had a space of our own in Omaha. What I didn’t see in my brief visit was all the work that someone’s doing behind the scenes. At the Makery, there’s always something to be cleaned up, fixed up or otherwise looked after, and as a Doocracy, those things tend to fall to whoever cares the most (Did I mention, I’m sort of a neat freak?)
Sometimes, I get lost in the maintenance and wonder why we collectively go to the effort of maintaining an actual space, especially after working on robot arms in Dave’s pretty slick basement workshop. Last night, a few visitors to the Makery reminded me, with phrases like “This place is magic” and “I never thought Omaha could have a hackerspace”. That right there sums up what went through my head when I walked in the door at Noisebridge just a year ago.
I’ve said it before (at the Makery’s Founding Day Celebration), but I’ll paraphrase it again here because it bears repeating: A Makerspace is just a lens that focuses the energy and talents of a creative community. The people are what makes the Makery great. Our people collaborate on art projects, build impromptu electric vehicles, entertain out-of-town guests, have Nerf-modding contests, provide material and technical resources for individual projects and are just a generally great group of friends.
Are you a Maker?
The Omaha Maker Group is hosting a Nerf* dart gun competition for distance and visual improvement modification.
When: 7pm, November 9th
Where: The Makery
Competitors will modify a Nerf ‘N-Strike Nite Finder EX-3‘ to maximize it’s distance and/or aesthetic value. Steampunks, artists, we look to you for inspiration.
The entrance fee for the competition is $10, but anyone can come and watch for free.
The gun may be modified in any way, provided that it remains at least somewhat identifiable as an N-Strike, and does not use pre-compressed air (such as CO2 cartridges) or chemical power. Electric power is permitted, provided the voltages are within reason (meaning the gun won’t cause a power outage).
Ammo will be standard-unmodified Nerf darts. For the contest each contestant will provide with their entry a minimum of three such darts in good condition (a new N-Strike comes with 3 darts), which will be pooled and used for the competition.
The modified weapon in ‘primed to fire’ condition must fit within a 3x7x11 inch container.
Performance for the distance competition will be measured by a maximum range test. The gun may be held by the contestant or mounted in a vice, provided the muzzle does not extend beyond the firing line. Distance will be measured from the firing line.
The cosmetic “Fine Weapon” competition will be judged by majority vote of your fellow participants. The winner will be judged to have a very fine weapon indeed. The winner will also gain a 10% distance bonus in that competition.
The winner of the distance competition gets bragging rights and a 1 month free membership to the Omaha Maker Group.
*’Nerf’ is descriptive of the brand of equipment to be used, and does not imply any other association with the brand.