Topic: Making

Battery Holder

2021-05-05 20:15 - Making

A 3D printed battery holder I designed and made.

I love rechargeable batteries. Much cheaper over time, and more convenient: it's pretty easy to keep a few charged and ready, and thus never need to worry about running out or getting more. For a while I had two little plastic buckets (old takeout containers!) to hold charged and used batteries each. But that's still a bit messy, and doesn't allow for even rotation.

It's pretty easy to buy battery holders, but the ones I could find are bulky (almost all including lots of C and D cell slots I don't need) and surprisingly expensive for a little chunk of plastic. So I made my own chunk of plastic! It's just a little box with some circular holes, of the right size to fit AAA and AA cells. I can put them + side up to signal that they're charged, and build a left-to-right kind of plan to make sure I'm always picking up the oldest one to use next, and putting the used ones back in at the "end of the line".

Lights for 3D Printer

2021-04-14 21:44 - Making

I've wanted extra lighting on my 3D printer for a while, but only a little. A while back I replaced the broken extruder(s). The old ones had fans built in, but they always seemed pointless: they were mounted on the outside of the extruder, so they couldn't even cool the stepper effectively. And they were incompatible with the new extruders so they came off.

LED light strips installed on the bottom of the top layer of my 3D printer.

This left extra unused power connectors exactly where I planned on installing lights. Today I finally took the time to put some LEDs from the strip I already had in place, using that connector. They provide decent illumination, but reveal how unreliable the 12v rail is: I can now see as the heaters kick in, because they cause an immediate dip in the brightness of these LEDs. I'll need to try adding capacitor(s), at least.

Mini Tesla Coil Kit

2021-02-10 21:12 - Making

The kit as it arrived.

Stuck at home so much, my habits have shifted a bit. I haven't made much of anything in quite a while. I dropped a whole three dollars (shipped!) on a little mini tesla coil kit just to shake things up a bit. Here's how it arrived, no instructions at all, which worried me at first. But there's very few parts, and it's actually almost impossible to get them wrong. Turns out they're tiny, but the markings right on the board disambiguate everything.

Weird parts: it came with two resistors and two LEDs — and the description called this out specifically — but there's only one place to put each, same for the little capacitors: comes with two but only one spot to put one in. It came with four little feet, but there's only three spots to put them. The component nearest the middle of this shot is a neon lamp, which doesn't connect to anything at all!

The assembled mini tesla coil.

It only took a little while to assemble. Here it is in operation, hooked up to my bench power supply so I could vary, limit, and monitor the power it consumed. It claimed to need 9 to 12 volts, and it works across that range and below. It doesn't actually do very much, but it does cause quite an electric field to be established. As a result, the little neon lamp it comes with will illuminate when it's nearby and the coil is powered on. But not connected at all! Spooky!

To rather dimly illuminate this small bulb, it consumes around six watts. And the little heat sink gets quite hot!

"Fixing" my 3D Printer's Extruders

2021-02-07 15:22 - Making

I got a 3D printer a few years ago when I came into a lucky collection of free filament. Long story short, things were okay, but I had trouble with the (free) ABS filament, it's extra hard to work with. I got some PLA recently, which slightly but not totally improved things.

Broken extruder arm.

I eventually figured out that the cause was a cracked part. The "extruder" of a 3D printer is responsible for pushing the plastic filament down into the "hot end" which melts it, so that it can be laid down into the design in question. This particular part pinches the filament onto the drive gear, so that it can be pushed. And the crack means it wasn't pinching as strongly as it should, so it would slip and not move correctly.

New metal extruder parts, in place.

My 3D printer is "dual extruder", so it's capable of using two different filaments at the same time. I almost never use that, so I simply switched over to the other non-broken extruder for a while, but that wasn't a real fix. I ordered some replacement parts, made of metal instead of plastic, and here they are installed. You can see the (brass) gear in the middle, of the metal extruders in red. The spring pushes the top arm up, which pivots on the top left screw, pinching the silverish roller into the brass gear. The plastic filament goes between them, and down from here.

This much is a nice improvement. No longer does the drive gear turn but just slip past the filament, not pushed strongly into it. Now I've got a new problem to solve: for some reason somewhere around the second layer it stops trying to drive the filament at all!

Finished "Upstairs" Dividers

2020-09-26 16:12 - Making

I live on the back (away from the street) side of my apartment building. So things tend to be pretty quiet, and there's no street lights outside my window. But there is another building, with a hallway with windows and bright fluorescent lights that never turn off. It's not much, but it's enough to be annoying at night.

The partial screening curtain for my sleeping loft.

So a while back, I got some black curtains and a rod to hang them from (which friction fits between the support beams). This basically solves the problem. They're thin but good enough to block most of the light from outside in the "upstairs" sleeping loft where my bed is. But it does leave a section open. I always wanted to fix that. When I first set this up, I considered continuing the curtains straight across to the wall. that would have divided the hallway a bit too much though.

Making the curtain rod clips. The completed curtain rod clips.

After quite a long time I finally came up with an idea I like. I've got a standard curtain rod, intended to bridge across the top of a window. But this spot is a concrete support beam: not easy to screw into for mounting. The solution was some tiny brackets, with enough surface area to simply hot glue to the wall. One of them ripped the paint/plaster off after a day or so, but that was a week ago and they've held fast since, after being re-glued to the bare surface beneath.

My completed screening curtain, including a dip under the suport beam and a turn around the corner.

First I had to do some sewing, to fit the curtain around the support beam. Then it turns the corner and covers the remaining open area on this side. It's a minor change but a great improvement in feel.

Making My Own 3.5" → 5.25" HDD Bracket

2020-05-12 22:01 - Making

The brackets, fresh out of the 3D printer. The brackets after cleaning up a bit. Test fit on a spare old drive. Installed!

I haven't used my 3D printer in quite a while. This is the time, it's tough to get things these days. I'll save the long story of many failed attempts and tweaks to get it working again, but I just have done that.

I've had an extra drive in my home server for a while, since I upgraded the main set from a three-drive single parity to four-drive double parity setup. And nowhere good to put it. It's the remote backup for my Mom's files, on the server I keep at her place which is itself the remote backup for my own files. It's been awkwardly perched, upside down, on a piece of cardboard. I've got four unused 5.25" bays in that case, so it should go there!

I found a nice, compact design for brackets to fit a 3.5" drive in a 5.25" bay online and printed a set out. My printer makes "hairy" prints, with fine strands everywhere, due (I think?) largely to its design. And at least while I'm using up the ton of free ABS filament I got, bed adhesion is tough so I tend to print with a brim. First step was quickly cleaning up all that cruft, which is shown in the second picture. They're not pretty (I picked fast rather than high quality print settings), but they'll work.

Next, I drilled out all the holes. Half large enough for a screw to fit cleanly through, so they could screw into the drive. The other half exactly the right size to grab the threads of the screws, the outside holes are for holding the whole thing into the case. I did a test fit (the third picture) and it worked well enough, after a little more adjustment with the hole position. Then it was straightforward to pop the drive in a proper location, and screwed down!

In that last picture, you can see one of my main drives, currently tucked into the floppy drive slot, so the mounting holes don't line up well. I might make a second bracket to hold that one, too.

My Automatic Heater Controller (Thermostat)

2020-02-05 21:03 - Making

Lots of New York apartments are actually too hot in the winter. Steam radiators are common, and they don't offer much control. There's strict laws about lower temperature bounds, but none for upper bounds. And most significant: the building usually shares one control everywhere, but the heat reaches different parts of it differently, and the cold seeps in differently.

In my current place, it's also too hot in the winter. I think that uneven-across-the-building issue is the real one for me. I've heard that other parts of the building are too cold. My heat comes from a forced hot water system, which the building controls. I suppose I'm closer to the feed than other apartments. I've only got standard plumbing style cut-off valves. I can totally disable the heat, but then it often gets too cold. I can enable it, but then it often gets too hot. For a few years I've been hoping to make something to help fix this. The video above is my solution!

I actually got a "test valve" some time ago to play with, when starting this project. My test valve didn't work at all for the project, but I lucked out: the test valve's handle is permanently attached, but my real valve's handle is attached with a hex nut, it's removable. The first part of the project was the handle replacement. It's the round smoky plastic bit. It has a hole in the center that's just the right shape (an eight millimeter hole, but with two sides squared off at six millimeters) to turn the valve. It's got eight small holes around the edges and one late addition hole for a screw to hit the valve's end stops.

Those eight holes are for screws, to attach to the large black 3D printed gear. This is a 180-tooth monster built to fit a GT2 timing belt, as are commonly used in 3D printers. It's big for mechanical advantage. I started with a 30 and 60 tooth pulley (for three and six times advantage). They weren't enough so I got a 20 and a 16 tooth gear, and ended up with the 16 tooth gear, for a slightly greater than ten times mechanical advantage. A straight GT2 belt section was cut to the right length, and belt clamps and tensioner springs turn that into exactly the right size belt for this contraption. The big gear is these two parts screwed together for two reasons. First, it would take a long time to 3D print the whole thing as one part. More importantly: the quarter-inch acrylic plastic is strong enough to turn the valve, but a 3D printed part is not!

That's all connecting my big gear to the small pulley on the end of a stepper motor. This is the first real motorized project I've put together myself, and I was not at all confident. When I spotted the uStepper S product on Kickstarter, I knew it was perfect for this. It's a clever combination of stepper driver, Arduino, and hall effect sensor (which uses a simple magnet stuck to the stepper motor's shaft!) to give it closed-loop control abilities.

The stepper is screwed into another acrylic sheet. It's in slotted holes, which gives me some room to adjust the length. This mounting sheet is mostly zip-tied to the copper heating pipes. But it's also screwed down into the floor, through a brace piece of scrap plywood, to keep it in place left/right. Otherwise the tension of the belt would pull it loose!

So there's a simple control loop running on the uStepper, which accepts commands over serial. It's wired into an ESP8266, which has WiFi connectivity. It monitors the temperature sensors I've already got, and sends commands to open and close the valve based on the current temperature. Simple, now that the mechanicals are all there to support it!

I've gotten this working reliably only recently. My problem is the end stops. Even though I have closed loop control, that only gives me relative data about motion, none about absolute position. The uStepper libraries have a convenient "move to end" feature, but it turns out my system is too mushy. I've got tensioner springs on the belt, which can thus stretch a bit. And worse (I think!) the end stop I've got is just a screw in some plastic, and it's longer than the original steel handle part. It flexes a bit when it reaches the end stop, before it pushes hard enough to actually stop the stepper. When it closes (clockwise motion), you can see a big jump backwards as it stops. (There's a smaller one when it stops going the other direction, I believe this to just be the slack from the springs. I never actually open the valve all the way, it's not necessary and why stress the system more than necessary?) The built in "move to end" feature sees that as constant motion: some of it forwards, some of it backwards, but it doesn't distinguish! I had to write my own routine to detect both a lack of forward motion or backwards motion as the end condition, and then the stepper stops turning.

Now I should finally be able to keep myself comfy over the winter! But even more so in the late fall and early spring, when the building has the heat on, but it's not nearly as necessary.

New Bed Light

2019-08-01 22:24 - Making

The prototype light above my bed.

After I built the bedsofa, I rearranged the bed and sleeping area around it. It had to go up against a wall to avoid tipping over when I lean on it. But the head of the bed was previously in open space. When I turned the bed, this made the light there, hanging from the wall, end up at the foot. Not a great way to illuminate the area, like for reading.

For a while, I pointed it at the ceiling and lived with the indirect light. The existing fixture won't work well in the new space that I've got. I've looked for fixtures that would work better, and found nothing pleasing. But I also have this strip of LED lights, which I intended to install in my 3D printer. (And, of course, never quite got around to doing.) It puts out a ton of efficient light, even just a small part of the reel I've got. The picture above is the "prototype", just taped to the wall. It's intended to run from 12V (and I picked that because the 3D printer has ample 12V power available).

In bed, I actually want very subdued lighting. A half meter of that LED strip running at 12V is really brighter than I want. I've got plenty of spare AC adapters lying about, but they're all too high or too low. But I also have some spare DC/DC buck converters! So now I've got a 12V AC adapter, into a buck converter that's infinitely variable, with its output powering the lights. I can tune it to the exact brightness I want. Perfect.

Some aluminum channel turns an LED strip into a nifty light fixture on the cheap.

I recently found this ultra-cheap extruded aluminum channel. Pop an LED strip into it and instant light fixture. I got this V shaped version which mounts at a 45 degree angle. I intend to point it towards the ceiling for primarily indirect light.

3D Printer: Fixed

2019-07-30 18:27 - Making

I got a 3D printer just over 3 years ago. Some months back it stopped working. I've got an OrangePi running OctoPrint to control it. I did a system update of that, and it stopped working. I unhooked everything and tried to figure out why, and failed. And gave up for quite a while.

I've got a thing I want to 3D print, now. So I took another stab. First day, same result: I was trying to set up everything from scratch, but I couldn't get the thing to boot. After switching out every spare power supply and SD card I had, still no dice. Of course, the whole time I wasn't thinking about the cable that carries the power. Turns out that was it. Once I swapped in a different cable, everything was working again. Set up OctoPrint again from scratch, and it's all great.

I just completed a 10mm cube test print, which worked fine. The machine needs a little TLC, it's squeaking a bit as it moves. But it works! Unfortunately, my desired object is too big to produce on my machine. So I'll need to find another way.