Tuesday, September 30, 2014

Lighting up a display cabinet

The LED strips that are available very cheaply these days make ideal and beautiful lighting for display cabinets.  They're very easy to install and run off low voltage so there's no danger of shock.

Here's a display cabinet that we've had for over 20 years. It's a nice piece of antique furniture and has a lot of cool stuff in it, but it is quite dark.

I bought a 5 meter roll of this LED strip. Non-waterproof, with connectors. I got warm white, I prefer something around 3000K or a bit lower.

First I plugged the strip in and held it inside to decide how I wanted to place it. Then I cut the strips to length (there are locations marked where you can cut and solder wires on to run power to the next strip), and soldered wires between the strips. A "3rd hand" clamp as shown here helps a lot.

I cut some strips of wood and spray painted them black, then hot glued them to the bottom of the shelves to block direct light from the LEDs which would be ugly.  Finally, I peeled the release paper off the back of the strips, exposing the sticky surface and put them in place, one below each strip.

I used a 12 volt, 2 amp "wall wart" power supply - I have a box of the things, they come with external hard drives of which I have quite a few and I only ever use one or two of them at a time.  I drilled a hole in the bottom corner of the back of the cabinet to admit the power cord.

Here's the result:

Sunday, September 28, 2014

Thing: Case for graphic display

I've posted this derivative of my previous case, modified to work with the RepRapDiscount full graphics display. A friend is building a new printer and wanted to use this, so I whipped this up.

It's at this page on YouMagine.

Saturday, September 27, 2014

Fume/noise hood for 3D printer

My family doesn't like the smell of my 3D printer, even when printing PLA. Here's my solution.

Construction is pretty straightforward. A basic frame is built from 2x4s ripped in half lengthwise, joined with L brackets.
The angle at the front was achieved by just temporarily installing the front bit then drawing a line at about a 45 degree angle and installing a second bit. I just kind of made the whole thing up as I went along.

Before the plywood was installed, the plexiglas was cut to width and clamped at the bottom vertical piece with a small gap up from the table, with a support piece temporarily screwed into place behind and below where the first bend was to be.  I used a heat gun to soften it until I could make a good bend, using another piece of wood and clamps to make the corner well defined. I then repeated for the top bend.

For the sides, Luan plywood was cut to fit. On the angles, I just cut the square sides, temporarily screwed them to the piece, marked, removed, cut and put back.

Since the unit can't be actually sealed due to needing to run the filament and power cords and such in, I didn't make a huge effort to seal the wood joints.  I did install inexpensive 3/16" foam weatherstripping around the bottom where it meets the table, and also along all the sides where the plexi front goes on.

I used four heavy duty magnetic cabinet catches to hold the plexi front on, they are more than sufficient.  The plates are epoxied to the plexi.

Venting is out through a 4 inch flexible clothes drier flexible hose and an outside vent. Since I already had the adapter and hose from the previous attempt at making a hood, but I wanted more air movement than a computer fan would provide, I bought one of the cheap 4 inch "Polar Wind" brand desk fans, took it apart, designed and printed a housing that makes it mount just like a computer fan but thicker.  The design is available by clicking here to go to Youmagine.

 Here it is in place and running:

The fan has plenty of power, with it running I can hold a lit match near any of the openings on the unit and the flame is drawn toward the inside of the box.

I cut a slot on the top about 1/2 inch wide and running most of the length of the unit. This is to allow filaments to enter the top. I lined the edge with duct tape, it just seemed like a good idea.

I hadn't intended this to be a noise proofing measure, but since we also have a video projector in this room to watch movies, it's a great side benefit that with the front in place, even with the fan running, it's much quieter than it would be otherwise.

Both the fan and the printer are plugged into the switched power outlet strip sitting to the right of the box.

Wednesday, September 24, 2014

New media shelf

This is what I'd planned all along for this area, it's why that part of the room was built that way. Today I got around to building it.

The original plan was to use plywood to make the shelves, but I had a huge stack of 1x6s that were a dismantled paperback book shelf, so I rearranged them to go three deep.  In a flash of inspiration while thinking of how to join them together into a solid unit, I ripped one set of shelves to half width, put it in the front, then put full width shelves behind that and screwed them into the uprights.  Since the shelves were each half screwed to one upright and half to the one behind it, it turned the entire thing into a solid unit nicely.

The 7 inch shelf spacing that was already routed into the uprights turned out to be perfect for both the Polk Monitor 40s that I had for the front sides and for the receiver that's coming, which is 6 inches high - enough room for air circulation.

I like to build stuff I want out of stuff I just have lying around - it makes it a challenge and is more fun to have around when I'm done.

The top two shelves are for media, the top one a couple of inches higher to accommodate DVD cases (BD cases are shorter) so they're only one unit deep with a 1/8" plywood backing.

I finally got around to ordering a proper receiver. I ordered a Yamaha RX-V377.  It's a modest receiver but it's got good reviews and good feature sets and is probably more amp than I'll ever need.  It should be here on Friday so I can get busy wiring this up properly, including subwoofer and center channel. I don't have any rear speakers at this point, I'm not sure if I need them.  The Yamaha actually has some kind of funky digital processing that's supposed to model the room (using a microphone that it comes with) and makes it sound like sounds are coming from the back of the room even when there are only front speakers, so we'll see how that goes.

Saturday, September 20, 2014

New headlight

Pretty much all bicycle headlights available in the US are pretty horrible for road use. They're almost all conical beam (like a flashlight) which means that they throw a lot of light above the horizon where it can glare into the eyes of oncoming drivers. 20 years ago when bicycle headlights were dim, pathetic incandescent bulbs with a couple of C cells, this wasn't really a problem, but these days with high power LED headlights approaching (or even exceeding) the brightness of automobile headlights, it's a case of the law simply not keeping up (partially because bicycles are largely considered toys in the US, not serious forms of transportation).

I've been looking for a headlight with a full cutoff beam for years. They're required by law in Germany and a few other countries.  Most of those that are imported are intended for dyno setups though and I'm not really interested in doing that much work on multiple bikes, and I don't consider charging batteries to be a big deal.

I've been watching the market - last year I very nearly ordered an Ixon IQ but I felt it was still not quite as bright as I would like for the type of roads I ride on (sometimes really not great).  Finally this year they upgraded the LED and I thought it was worth ordering, so here it is - purchased from a German eBay vendor: the B&M Ixon Core IQ2-50.

It's pretty cute and tiny.  At 50 lux, it's not as bright as my bigger (500 lumen) headlights, but it produces a very high quality beam that makes better use of the light that it does put out, and the cutoff is quite sharp so oncoming drivers should not be uncomfortable.

In case you care, here's the packaging and included stuff:

For the beamshots in this article, I put the camera in manual mode, attempting to get a setting that I thought reflected what the light looked like in real life. I wound up at ISO 3200, F/3.3, 1/8 sec.

Here's the light on high beam in my driveway. The far end of the beam is probably about 50 feet away.

Low beam:

For comparison, here's my MagicShine light, which is rated at 800 lumens but is in reality probably something like 450:

This seems great, but the very hot center tends to cause your eyes to miss stuff that's not as well lit, so I think the flat pattern of the IQ2 is likely to be about equivalent for spotting potholes and other obstacles. Also, since the beam is unshaped, you should realize that as much light as is hitting the ground just outside that hot spot is the same amount of light hitting an oncoming driver's eyes.

Here's a garage door shot showing the cutoff of the optics:

I have not ridden with this light yet, I will update in a few days when I've commuted to work with it.
The light is rated at a bit over 3 hours on high, 12 hours on low.
The light does not have any flashing modes, since flashing front lights are illegal in Germany.

I very much like the light switch - 2 second hold for on/off, press once to switch high/low.  Having to click through strobe and then off to get back to high beam from low in pitch black conditions is irritating.

The button has a blue light for high, red indicates the light is on low. The button blinks between 1 and 5 times to indicate current battery condition - it does this 3 times in a row, then stays on for 2 minutes, then does it again (or it also does it again right after being switched high/low beam).

The light has a built in LiIon battery (non-changeable) and charges from a MicroUSB connector. It ships with a USB cable and a USB charger, though this has an EU AC connector on it so you'll probably just have to use your own if you're in the US.

Here's a closeup of the optics in case you dig that sort of thing:

Wednesday, September 10, 2014

Heated print beds and PLA

I played around with my heated print bed and Kapton tape again.  I did a few prints and it was OK, but challenging objects just failed.  In particular, the LM8UU bearing holders for the i3 have an overhang and I just could NOT get it to print properly.  Not only did the overhang cause the piece to curl up and whack the nozzle, as the nozzle whacked it, the heated bed caused the PLA to be soft enough that it got pushed back and forth so the layers wandered all over, and eventually the head picked the entire piece off the print bed.

I put blue tape down, turned off the heat and got a beautiful print.

Here's the failures next to the successes. You can see on the failures that the layers on the overhanging bits (toward the top of each piece) are inconsistent and just generally horrible.

Friday, September 5, 2014

Printer tune-up

I didn't use my 3D printer for several weeks, then this week it seemed like I was needing one or two things a day printed.  Then I got an order for a full set of printer parts from a friend, which is about 20 hours of printing.

I was about to start the print, but decided that it was a good time to do some tune-ups.

First, I decided to see if I could make the heated print bed work a bit better. I've had trouble in the past.  I removed the blue tape and put down kapton on the glass.  Powered it up, but the temperature control was very bad.  I tried something different - I put a small dab of heat sink compound on the thermistor sticking through the middle of the heater, then clamped the glass down on to the bed, squishing the compound down.  Powered it up again and the temperature control is excellent now, reading spot on what the IR thermometer reads on top of the glass.  Cool.

The blob of heatsink compound under the glass

Then I tackled the fact that the hotend was kind of wobbly - I have been using a piece of plywood as a groove mount and on the E3D it's way too thin.  I cut a new groovemount out of a piece of 1/4" aluminum bar stock.  It would have gone a lot faster if I had more tools, but I made do with a hacksaw, drill press and hand files. I may pick up a disc/belt sander at HF tomorrow.

The old plywood groovemount and the shiny aluminum one

Anyway, I have the first plate printing now.  It seems to be going quite well.  I won't know if the new groovemount improves prints until it gets up 20 or 30 mm, which will not happen for a couple of hours.  I'll see in the morning how it goes.

New printer: JGAurora A3

This week I decided I'd had it with all the other printers in my stable.  The CTC is stable and decent but it just bugs me (can't st...