Gas station without pumps

2018 July 19

Dropping old LED lighting project

Filed under: Uncategorized — gasstationwithoutpumps @ 14:28
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About 4 years ago, I started a project to replace the breakfast room ceiling fan (which my wife has always hated) with an LED fixture of my own design.  In order to do this, I designed some custom LED boards that could work over a range of voltages with PWM control of the brightness and I made some desk and table lamps using the boards, as well as a stroboscope (Summer project, LED board I-vs-V curve, Summer project 2, Desk lamp, Newer dimmer software, LED strobe using dimmer boardHalloween 2016, … ).

Although I have had the electronics done for the breakfast room fixture for about 3 years, I’ve not been able to come up with a mechanical design that I think will look good.  Also, the task of cutting the conduit in the attic to install an outlet for the wall-wart power supply did not appeal to me, so I kept putting off the project.

Last weekend, my wife, my son, and I went to the local Habitat for Humanity ReStore, ostensibly to look for cabinet handles and doors, but mainly just to browse. While there, we saw a used drum light ceiling fixture that was on sale for only about $16 (it is one that normally sells for around $120 new from Home Depot).  Since I had pretty much given up on coming up with a design using my LED boards that would look good, and my wife liked the drum fixture, we bought it and my son helped me install it.

The hardest part of the installation was probably pulling new wire through the conduit, since I did not want to use the old cloth-covered solid copper wire that was there.  I also added a grounding screw to the junction box for the lamp, since the old ceiling lamp had no ground connection.

Here is the “new” ceiling lamp in daylight.

Here is the ceiling lamp with 3 2700K LED bulbs.

Lining up the screw holes of the fixture with the screw holes of the junction box was also a bit tricky—my son’s holding the fixture while I fussed with that was a big help.

The whole project cost under $30: $16 for the fixture, <$3 for screws and wire, $7.50 for 3 LED bulbs. The new lamp is not dimmable (because of the cheap bulbs I chose), but that feature was not really needed for the breakfast room anyway.

So I now have a lot of spare LED boards that I need to find a project for—I’ve used a few of the boards for the desk lamp and stroboscope projects, but I don’t really need another desk lamp or stroboscope.  Anyone have any ideas?

2017 November 8

Bathroom timer knob

Filed under: Uncategorized — gasstationwithoutpumps @ 10:26
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On Saturday, as a break from the mechatronics midterm, I rode my bike over to Gary’s Plastics (105 Bronson, opposite the Pacific Edge climbing gym) to get some acrylic sheet for cutting out electrode holders for my applied electronics course.  It took me a while to find the place, because 105 Bronson is mainly a metal-working place.  Gary’s Plastics has only a tiny sign on the side of the building, and they are at the back of a junk-strewn parking lot.

I bought the 1/4″ acrylic sheet I needed at a much lower price than San Lorenzo Lumber, which had only 1/10″ sheet, but it was clear that they did not stock a lot of stuff—if you want something specific, you probably have to order it in advance or go over the hill to TAP plastics.

While I was there, I picked up a scrap of white HDPE for another project—fixing the knob on the timer for the fan in my bathroom.  The knob for the timer broke about a year ago, and my first thought would be that it would be a trivial fix, as I had several knobs available that I had bought for various projects.  Unfortunately, none of them fit!  The standard knobs are all for 6mm shafts, and the timer had a 4.77mm shaft.

The bare shaft, which is too skinny for standard knobs, which expect a 6mm shaft.

For a while we used pliers to turn the timer on, but this was inconvenient and ugly, so I kept looking for a different solution. After a while, I found a part that was designed for a 5mm shaft, though it wasn’t intended as a knob—it is an aluminum coupler base for the Eggbot.

The aluminum coupler base from the Eggbot—looks ok but rather hard to turn with wet hands.

We used the Eggbot coupler for quite a while, but we all got irritated by the difficulty in turning it. Eventually, my son noticed that the set screw for the coupler was a standard 10-32 screw thread, and we stuck in the only 10-32 screw I happened to have on hand (I have a lot of 10-24 screws, but those have too coarse a thread).

The result worked well and has a certain “there-I-fixed-it” charm, but did not really appeal to my wife or me.

I took the scrap of HDPE, cut off a chunk with my new bandsaw, drilled a hole through it with my drill press, put it on my wood lathe (a tool that has sat idle in my garage for at least 20 years), and turned a decorative cover for the screw. HDPE is much easier to turn than wood is—there’s no grain to tear out!

I didn’t quite get the dimensions I wanted—the screw head is wider than the handle rather than matching, but the result is much better that the bare screw.

I still have enough of the scrap to make a couple more attempts, and one of these days I’ll redo the handle to be wider with a flat-head screw countersunk in, rather than a pan head sitting on top.

2014 January 11

First homework for freshman design

Filed under: freshman design seminar — gasstationwithoutpumps @ 23:31
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The first homework for the freshman design course was only turned in by 2/3 of the class—I hope that this is not a trend, as not doing homework is a sure way for engineering students to fail out of college.  I’m not grading students on the quality of this first assignment (their evaluation is primarily dependent on the design project they do in the second half of the quarter), but I am keeping track of who is doing the homework.

The assignment was simple:

Turn in by e-mail by midnight Friday, 2014 Jan 10: Look on-line for projects that might be interesting to design or build this quarter. Look at sites like Pasco and Vernier for ideas about what schools with money have in their labs. Look for do-it-yourself lab equipment ideas on the web. Turn in an annotated list of URLs for interesting sites as plain text, cut-and-pasted into e-mail to me. The annotation need not be extensive—a sentence about each web site, telling us what project(s) it has information about, should suffice.

The students who did do the work found some interesting sites—I’ve been spending much of this weekend reformatting what they sent me, examining the sites they found, and commenting on them. Rather than provide private comments to the individual students, I’m sharing my comments and the web sites that everyone found with the whole class.

2013 June 29

Custom printed fabric

Filed under: Uncategorized — gasstationwithoutpumps @ 22:52
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I just found out today, from a newspaper article in the Santa Cruz Sentinel, that there are now companies doing custom-printed fabrics.  You design your repeat block using whatever tools you like to get a raster image (like GIMP or Photoshop).

The finished block is then … uploaded to an on-demand digital printing service, which can print on all sorts of fabric in quantities of your choosing. Heather uses Spoonflower, which prints swatches, fat quarters, and yards of fabric, plus wallpaper, peel-and-stick wall decals and wrapping paper. … Another site, Fabric on Demand, specializes in custom fabric printing, and offers some fabrics, such as lycra/spandex, not available through Spoonflower.

Both websites are user-friendly, offering several design layout options, step-by-step instructions, and examples. The process is not inexpensive, though. On Spoonflower, for example, cotton fabric starts at $17.50 a yard, and their most expensive option, silk crepe de chine, is $38 a yard.

The prices are pretty high, but it sounds like a cool way to get custom-printed fabrics. (My interests in fiber arts were in weaving, not sewing, so I don’t really have any use for custom-printed fabrics, but the idea is cool.)

2012 March 28

Praise for The Bicycle Trip

Filed under: Uncategorized — gasstationwithoutpumps @ 13:29
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As I mentioned yesterday (Sprockets closed), the neighborhood bike shop I’ve been shopping at closed after 16 years (due to the death of one of the owners, not due to business problems).  I had two repairs that needed to be done (one on my son’s bike and one on my recumbent) that I had been able to diagnose, but did not have the tools to repair, so I rode the bikes the two miles to my second-favorite bike shop (they probably would have been my favorite, if they weren’t so far away): The Bicycle Trip.

My son’s bike had been in low-speed crash (hit by a right-turning car) last Friday, and was having trouble shifting.  I fixed what I could (straightening the fenders, adjusting the brakes, inflating the tires, adjusting the derailleur), but when the rear derailleur was in the lowest gear it hit the spokes.  I figured that either the derailleur or the derailleur hanger had been bent, and I did not have good tools for straightening it.  If I had been in the middle of nowhere on a bike tour, I probably would have tried using a pair of vise grips to straighten the hanger, but it seemed easier to me to ride the bike to a bike shop (staying out of the lowest gear) and ask them to look at it.

At the Bicycle Trip, they put the bike on the stand right away, looked at the problem, took off the rear derailleur, got out their tool for straightening derailleur hangers (a large steel tube with a pivot at one end and an adjustable spacing rod at the other).  With this tool, straightening is easy—screw the pivot into the threaded hole on the hanger, swing the arm back and forth to find out where maximum deflection from parallel to the wheel occurs, use the bar as a lever to adjust the hanger, repeat until straight.  It took them less than five minutes to fix the problem and readjust the derailleur.  They also noticed that the rear rack had been deflected sideways, and straightened that also.  They only charged me their minimum labor charge ($5) for a fix that would have taken me far longer to do (even including the ride to and from the bike shop).

Having been pleased with yesterday’s service, I decided to take in my recumbent today.  Again, I had diagnosed the problem: a few of the teeth on my smallest front sprocket had gotten bent, causing difficulty shifting into low gear.  For me to fix this would have required taking off the crank, taking the front sprocket off, carefully trying to bend the teeth back with pliers and a small vise, and reassembling everything.  It would have taken me an hour, assuming that the crank-puller I have is the right threads for the crank (I bought the crank puller over a decade ago, and I can’t remember whether it was for this bike or a different one—bike component manufacturers love having a dozen different “standards” for everything).

Again I brought the bike in and explained the problem.  This time they didn’t even bother putting the bike on stand, but got out a tool for straightening bent teeth (a steel bar with a slot near the end—the slot being just the width of the sprocket).  In about a minute the bent sprocket had been straightened without having to disassemble anything.  They didn’t charge me anything.  I even asked, “Isn’t there a $5 minimum charge?” and they waved it away.  Now that is friendly service!  I will certainly be doing my next bike-related purchase at The Bicycle Trip.

Both of these repairs (bent derailleur hanger and bent front sprocket) are routine repairs that the bike shop deals with frequently.  Both of them are also repairs that I’ve never needed before in 40 years of using a bicycle as my main form of transportation.  Partly that’s because of changes in bike design: front sprockets are thinner than they used to be and derailleurs used to be mounted directly to the rear fork, not to a deformable hanger. Partly it’s because I’m mainly a bike commuter, and the bending of derailleur hangers is more common with off-road mountain bike riding.

One of the comments on yesterday’s post made some interesting points:

I was a bike mechanic/shop manager for 7 years while teaching at the university and working on the Masters. Working on a bike is so easy and relaxing that it might be worth your while to learn how to do it. A good bike stand (Park PCS-10) is the biggest investment. This stand folds up for easy storage. Tools are fairly minimal cost wise. Finding anyone that can do a good job on a recumbent can be hit or miss; they can have some idiosyncrasies. There are a couple of how-to books out there that are not bad but usually everything you need to know can be learned by just looking closely at the problem. There are some special pullers for the crank arms depending on the crank manufacturer but Park Tools sells them at a good price. I like working on bikes. I can bring everything in the house on a bad weather day and just fuss around cleaning, adjusting and lubing. It isn’t like working on a car or motorcycle where you have to freeze you ass off in the garage. (Although I do occasionally bring the motorcycle in the house to work on in the winter. The wife is not excited by the motorcycle in the living room but she can handle it for a while.) You can become a true Zen master of bikes only by working on them. To achieve true inner peace you must be able to discuss intelligently the structural advantages of have a three cross spoke pattern on the drive side and a radial pattern on the non-drive side of your rear wheel. Not only will you achieve inner peace, you will become widely known as an über bike geek.

I’m not interested in becoming a “true Zen master of bikes”.  If I wanted a meditative physical activity, I would probably take up weaving again (I still have a couple of looms that I’ve not used in a long time).  The repetitive nature of throwing the shuttle exactly the same each time, while maintaining awareness of the pattern of the foot pedals and watching for flaws, did indeed lead me into meditative states.

I do have a bike stand—not a Park but a cheaper Blackburn stand.  I also have several tools acquired over the years (chain link tool, spoke wrench, metric Allen wrenches, metric hex wrenches, crank puller, chain-cleaning tool, floor bike pump, …).  I do the simpler maintenance on my bike: replacing brake pads, patching tubes, changing tires, adjusting derailleurs, minor truing of the wheels, replacing the chain, … . For that matter, I understand the differences between the radial and 3-cross spoke patterns, and why you want the drive side spokes to be tangential to the hub (I’m not sure that I agree about wanting a radial pattern on the non-drive side as that assumes more flex in the hub than I think is warranted unless you are using super lightweight parts).

Unlike the commenter, I do not find working on the bike very relaxing. It is somewhat rewarding to be able to keep things in repair myself, but the actual hands-on part is more irritating than relaxing.  I suppose that if I didn’t drop things and lose them nor bang my knuckles when the wrench slips, I’d find it more relaxing.  I used to do all the bike maintenance myself, but as I’ve aged I’ve decided more and more often that I’m happier paying a professional to do it right than doing it myself.  The two repairs yesterday and today are good examples—I was perfectly happy doing the minor maintenance on my son’s bike, but leaving the straightening of the derailleur to someone who had the right tool. Thirty years ago, I might have preferred jury-rigging something with vise grips.  Twenty years ago, I might have ordered a specialized tool and waited two weeks for it, but now, a trip to the bike shop is faster, cheaper, and less irritating.  And the fix is done properly.

I’ve been finding the same thing for home repairs.  Some things (like using a plunger or a plumber’s snake, hanging a picture, replacing a switch plate, oiling locks and hinges, or fastening a bookcase to wall) are things everyone should be able to do.  I’ve acquired some tools that are a little unusual for a homeowner (like a hammer drill for drilling into my concrete walls and a bench-top drill press), but for bigger jobs (like replacing the windows, framing and installing skylights, building a gate, tiling the kitchen with ceramic tile, or installing insulation on the inside of the concrete walls) I prefer hiring a competent contractor.  Finding a good contractor was difficult at first, but I now have one who I’m quite comfortable with who does both big remodel jobs and smaller ones.  (He’s my age, though, so I expect that in another decade I’ll be looking for a new contractor when he retires.)

I have a great deal of respect for the do-it-yourself and maker movements, and I do get some pleasure out of designing and making things.  But there are times when I prefer buying something ready-made or hiring a professional to do the job right—different people will find different levels of doing-it-themselves optimal.

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