Pizza Potluck and Piezoelectric Presentation – December 13th

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!

Nerf Gun Mod Challenge Results!

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.

Appearance

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.

Accuracy

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).

Distance

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.

Conclusion

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.

Home-made Hobbed Gears

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.

The Why of Makerspaces (Hackerspaces)

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.

Handlebar Camera Bracket

Tonight, I finally got around to finishing up the Handlebar Camera Mount project.  The mount consists of a hunk of printed PLA, sawed in half, and bolted back together around the handlebars. At the moment, I have a piece of rubber tape wrapped around the bar, under the mount, to keep it from slipping, but my Canon S5 is pretty heavy and it needs a bit more wrapping underneath.

The printed portion of the mount weighs around 60 grams, and took about 90 minutes to print on the Makery Mendel.  On the side facing the camera, you can see where we lost a bit of blue tape.  The part has an inner diameter of an inch, and is about 2″ wide, to provide good stability for the camera.

The hardware is 4 1.5″,1/4-20 stainless steel hex head cap screws. I opted for stainless because “It’s a bike, and it’s going to be outside”… The bolts were around a buck a piece, which wasn’t really any more money than the regular steel ones.  Hex-keyed is sorta like metric: It just costs more, and no one knows why.

All this puts total materials cost (including the PLA for printing) at just under $10.  The model for the printed version is available here.

 

Happy Birthday Omaha Maker Group

Tuesday marked the 1 year anniversary of the Omaha Maker Group, known internally as Founding Day. It signifies the first [large] meeting of Makers at Upstream Brewery where the Omaha Maker Group name was chosen.  It wasn’t until later that we were legally organized, but that’s not the point.

In honor of the somewhat momentous occasion, we had a gathering at the Makery including cake and grilling, for around 20 people.  A good time was had by all, and it was a pretty good excuse to clean the place up a bit.

It occurs to me that the most valuable thing that the Omaha Maker Group has given us in the last year isn’t the physical workspace down at the Makery, nor any of the growing collection equipment there, but rather all of the people we’ve met.  We have really great bunch of  Makers, techies, artists and doers of all kinds; People willing to help when you get stuck on a project or to mock you into starting the project in the first place. For my part, I’ve made more than a few friends along the way.  Here’s to many more years of Making in Omaha.

Print heads for the Makery Mendel

Tonight, I was on assignment for Brandon and the Makery Mendel again, this time drilling some really really tiny holes.

These acorn nuts will be used as print heads to extrude the molten plastic on the almost-done Makery Mendel 3D printer. I started the process by holding the piece of allthread (Which has a shallow hole in the end) in the lathe chuck and threading a nut onto the end.  I know that generally a bolt thread isn’t true enough to rely on for machining, but in this case, I want the operations all true to the bolt, as that’s how it’s going to be held in use.

Next, I faced off the rounded end of the nut, being careful not to get too deep (which is what happened on the rightmost unit). I then used a tiny drill bit in the tailstock chuck to ever-so-gently drill the hole.  On the 0.3mm unit, you can see where the drill bit had a slight bend in it, and wanted to drag around the part instead of start drilling in the center.  I was able to change the orientation of the bit in the chuck to correct this.

Finally, I cut a bit of an angle on the side of the nut, making it more conical than round.  Sort of like a cut-off funnel.  Hopefully it works well. One of the nuts turned out to be plated (which, sadly, is one of the sizes I didn’t make a duplicate for)

Stepping Up…

Tonight, I did some prep work on a new EasyDriver (on breadboard) that I ordered for an upcoming project. I mounted a 4-pin Molex Floppy connector for the motor output, and pin-headers reversed for breadboard mounting.

I also milled the gear off of a scrap stepper motor and built a coupler to a fancy leadscrew I had laying around. The leadscrew in question (pictured foreground) is about 9″ long, has 5 starts (5 parallel sets of threads) and has a twist-rate of 1 inch per turn (one TPI).  The screw is further teflon-coated and uses a (probably Delrin) plastic nut.

Brandon questions if “that wimpy stepper” can drive such an aggressive leadscrew, but I don’t think it’ll be a problem.  If it does become a problem, building a new coupler (or finding a motor that has the same shaft size) shouldn’t be hard.

Printer Parts – Heater Tube

Jason notes that I forgot to post a photo of the other Mendel parts I’ve been building for the MakeryMendel.  Below are photos of a stainless steel heater tube (the one that I didn’t ruin by welding a drillbit to the inside) as well as the “order form” that Brandon sent me. His drawings aren’t anything fancy, but we seem to have gotten the job done.  For scale, the bushing in the photo is 1″ OAL, and the threaded rod heater is 1.5″ OAL.  The picture with the fire is a prototype plaster bushing that we were testing.  It’d probably work, but we dried it a bit too fast and it developed a nasty crack.

BrandonSpec (Medium) Plaster Heater

New Ring-Light

People I meet via the Omaha Maker Group often ask me what it is that I make.  I try to avoid the “Everything” answer, popularized by Jason Uher, but it seems to be sort of the truth.  Due to a renewed  interest [by people who aren't me] in things that I’m making, I’m trying to do a better job of actually driving these projects to completion, and maybe even doing a slightly better job than I otherwise might. I’m also trying to do more projects that are more “grand” in scale (for example, building a power supply, instead of a really neat custom connector; Not that either of those are really grand, in the big picture).  Below is one of these projects.

After lots of fiddling with desklamps and bounce cards every time I want to take a decent macro photo, I’d finally had it.  I started looking into buying a ring-flash accessory for my digital camera, but found them to be alternatingly pretty expensive or in the realm of “I could build that”. So I did. Read on for the details and a few more photos.

I determined early on that I didn’t want or need a flash-tube-based solution (like the one built by Patrick), which is a reflective ring illuminated by a standard photo flash.  I didn’t want to spend the money for a fancy “automatic” external flash, and didn’t want the headaches and setup associated with a cheap manual flash.

I did some initial research on running an LED illuminator on the camera’s hot-shoe trigger, but decided that it really wasn’t needed, as LEDs can just be turned on and off and don’t need to be “fired” like a xenon flash. My illuminator is powered by a simple pack of 4 AA batteries (ideally NIZN for the extra .3V).

The illuminator itself  is just 8 banks of 14 (112 total) white LEDs soldered to a piece of perf-board and a connector for power.  To make it run on 6 volts nicely (and to give me more input voltage range), I wired both halves of the LED array in parallel and then the two banks in series. I could have just put the banks themselves in parallel (and run the array on 3ish volts), but that would put my total current draw at over 800ma, which I opted to avoid.

I found a pretty neat online schematic designer, so I whipped up a schematic, in case you can’t picture what I’m saying:

From a physical standpoint, the LEDs are just soldered to the perfboard and surface-wired on the back side. I’m a bit embarrassed by my soldering job, so I won’t be posting any photos of that here.  I cut the hole in the center of the board with a few forstner bits, and finished it out with a sanding drum in a Dremel. I plan on gluing a 58mm filter ring [generously donated by Don] to the back side of the board so that it can attach to my S5′s filter adapter. I’ll probably just Velcro the battery pack to the side of the camera, as this rig is mostly for use on a tripod.

One problem I have come across is the convergence pattern on the LEDs. At distances less than about 8″, there’s a bit of a dim spot at the center of the frame. This should be correctable with some sort of diffuser and a bit of tweaking of the LEDs angle.

As for the LEDs, they were ordered from Tayda Electronics for $8 shipped ($0.04 each, plus $2 shipping). At 3.1ish volts per bank, I’m under-volting them just a bit, but they seem plenty bright.

Below is a few more pictures of the light, plus a photo of another project, demonstrating the dim spot. More photos of the device will follow, as soon as I get it into a more final form.