Consumer Tech

3d printing some parts for the house

The end pieces of the pergola above my deck kept blowing off. I finally lost track of them and decided to 3D print a replacement to keep my skills fresh. I will use this as an opportunity to review my process for 3D printing.

The details
For people like me who don’t really know what they are doing, the kinds of objects you can 3D print is pathetically small. Yes, there are sites like But there are so many physical constraints if striking out on your own. If the extruder is pulling the filament horizontally it can only be unsupported for, I forget, 1 cm or so. That may be called a bridge. If you’re going from smaller to wider, the angle of increase cannot be greater than 45 degrees though I think 30 degrees is a safer bet. If you can want to violate either of those contraints you’ll have to include supports which you later saw away (yuck).

So those two constraints, combined, kill just about anything you’d ever want to print.

But, amazingly, my endplates could meet the criteria, if I made a slight compromise, so I went for it.

I use’s software to make a mathematical model of the object, built up from primitive geometric shapes (cubes and cylinders, mainly). When I learned you could write a simple program to generate your figure, and see the results rendered, I was like, sign me up.

Here is my openscad code, with some extra unused stuff left over from a previous design.

// DrJ 4/2020. Parameters in mm
  innerdelta=20; taperdelta=1.5;
  legthick=3; leglength=25;legheight=12;legoffsety=3;
  xteeth = 106; yteeth = ysize - 2*legoffsety - legthick;
  fullthickness=6; taperthickness=3;
  divotrad = 5.1/2;
  Hhole = 15;
  cablewidth = 16; cableheight = 10; cablex=16;
  // min facet angle and facet size (mm)
  $fa = 1.1; $fs = 1.1; 
  hull() {
  translate([0,0,taperthickness]) nice_rectangle(roundness,xsize,ysize);
 // legs
        translate([x*(xsize-2*legoffsety - legthick)/2,0,legheight/2])
// thickeners
  module nice_rectangle(roundness,xsize,ysize)
   xcyl=xsize/2 - roundness;
   ycyl=ysize/2 - roundness;
   height=.02; // basically 2D - expect to 
  // be used within a convex hull
          cylinder(r=roundness,h=height, center=true);
    cube([xsize, ysize-2*roundness, height], center=true);
    cube([xsize-2*roundness, ysize, height], center=true);
Pergola endplate design

You always make mistakes. The question is if you have the trouble-shooting skills to catch them before committing to printing… Anyway, when satisfied, render your object (F6), only then can you export to STL (stereolithography), which I guess is a universal description language.

Then you need a slicer! I think that translates your shape into movements that the 3D printer needs to make to lay down the filament, layer by layer. So import your STL file into Cura.

I think I set up Cura last year. I don’t want to mess with it. And don’t start playing with your model. It’ll do funny things to it. Just save as GCode. That’s it. Cura kindly estimates how long your print will take, and how much filament it will use up.

Anet a8 printer

It can be a royal pain to adjust the Z axis. Usually you have to adjust all four corners so that pulling a paper through gives just a little friction. The screws and assembly is so bad that you are constantly shifting between over-correcting and under-correcting. In this case I divided the problem in two because the plate was so narrow I just adjusted for the two sides, not all four corners, which is a nightmare. And I’m a little ahead of myself, but I have to say that this approach worked brilliantly.

Transfer the file to the micro SD card. Print, and enjoy! More fun is printing something with a lot of holes. The printer makes the coolest electric sounds as it quickly shuttles back and forth and to and fro. This endplate is pretty boring by comparison and mostly consists of long stretches of material.

End result

side by side

With its long flat section, the thing really adheres to the plate, unfortunately. I slightly nicked a corner prying it off with a screwdriver. But I think that beats the alternative of it not adhering to your plate. I’ve seen that once – and the printed thing just gets dragged around, which is fatal.

My piece came out a couple millimeters short in both dimensions. Still functional because of what it is, but still something I need to understand better.

Industrial design
I take it for granted that the PLA I’m printing is not as strong as the original plastic, so I should compensate by making edges thicker than needed. But I have to say the thing came out quite rigid and strong. This cheap 3D printer – if you treat it right – produces some high-quality output!

Bolt hole cover
In June I decided to print a bolt hole cover, also for the pergola above my deck. Modelling was pretty easy. I used a sphere for the first time to create the curved shape of the cover. Then I had to “get rid” of the rest of the sphere so I swallowed the unwanted portion of it up with a giant cylinder.

Here’s the openscad code.

// DrJ 6/2020. Parameters in mm
  sphereR=26; big=50;
 // min facet angle and facet size (mm)
  $fa = 1.1; $fs = 1.1; 
  difference() {
  translate([0,0,-(sphereR - upperHeight)]) color ([0.2, 0, 0]) sphere(r=sphereR);
  translate([0,0,-big/2]) cylinder(r=big,h=big,center=true);
  translate([0,0,-plugHeight/2]) cylinder(r=innerR,h=plugHeight, center=true);
Bolt hole cover

I installed Cura v. 3.2.1 to make sure I had a version with support for supports, ha, ha. Most views don’t even show the support. I made sure I had it generate supports. Then I found that the layers view, when you drag it through the layers, shows the supports it will make. Some support options definitely would not have worked, by the way, namely, lines.

But, basically, supports are basically impossible to remove. I pried at it and rubbed with sandpaper but my vague hope that the supports might pop off were badly misplaced. The thing looks like a button. But fortunately the plug part was shallow so I just super-glued the thing onto my pergola and it looks like the real deal at a glance. In fact it looks better.

Mailbox plate

If I thought I was a whiz at this sort of thing, this mini-project proved me wrong. I was going to add a semi-circle at the bottom of a rectangle, and work through Pythagorean’s theorem to find the unknowns. I was just spending too much time and really, eye-balling it was more effective. And a more desirable shape was an ellipse. So the good ones make these parameterized models, but I find it’s not so easy and when you want to bang out some custom part quickly, it may not make sense.

There was a gaping hole in my mailbox post. This plate covers it up. Here’s the code.

// DrJ 7/2020. Parameters in mm
xsize=87;ysize=55; ylowest=65;
// min facet angle and facet size (mm)
$fa = 1.1; $fs = 1.1; 
linear_extrude(height = taperthickness, center = true, convexity = 20, twist =0, slices = 20, scale = .98, $fn = 30){
linear_extrude(height = taperthickness, center = true, convexity = 20, twist =0, slices = 20, scale = 0.98, $fn = 60){
translate([0,ysize/2,0]) resize([xsize-xreduce,2*(ylowest-ysize)]) circle(d=30);

// bump out. Color blue.
translate([-xsize/2+35,-ysize/2+20,taperthickness]) color([0,0,1]) cube([10,10,2.9],center=true);
Mailbox plate
What techniques I learned from this simple mailbox plate project

I used the linear extrude method for the first time. Very useful. So, shapes like squares and cirlces (or ellipses) extruded along the Z-asix. My first effort did not include the bump-out, which I needed as a spacer. So I learned that you don’t always have to re-level after every print and this was the first time the dang filament didn’t break on me between print jobs – because I acted within 24 hours. I even re-used the blue tape. All real time-savers. So I used the 3D printer the way you imagine it to be – just there to print stuff, not to worry about fixing all the time.

I also had a reject – a first attempt without the bumpout. I kept it to test the breaking strength. So the thickness is 2.3 mm, right (I have to get calipers!)? It’s pretty darn strong. I was probably applying 10 pounds of force and it was hardly budging. Each layer prints orthogonally and a piece this thin is solid material.

Bird feeder C ring

I have a backyard bird feeder which hangs too low – I fear a squirrel could jump to it. So I wanted a way to shorten the hang by winding the wire around something that will stay. So I designed a C-shaped ring thing. works great. This is a first time for me for using a rotate extrude. I had to chop off the bottom of the ring so that I would not need supports. This is my shortest code yet, and least paraemerized. It’s just easier when you want to knock something out quickly…

// DrJ 7/2020. Parameters in mm
// min facet angle and facet size (mm)
$fa = 1.1; $fs = 1.1; $fn=100;
rotate_extrude(angle=348,convexity = 10)
translate([20, 0, 0])
circle(r = 6);
translate([0,0,-9]) cube([60,60,10],center=true);
Bird feeder C ring

This is my first piece with interior fill. The bird feeder is pretty heavy – 10 pounds. but this little C ring is plenty strong for entwining the hanging string.

Time-saving tip for leveling the print bed

My anet a8 prints great once I get it set up. But that setup – boy is it a pain. Leveling the print bed being the absolute worst. Because, if you follow their advice and adjust each corner, well, they don’t seem to stay and you end up reversing your direction on the screws of the print bed. Or you’ll get one corner and then the corner you had just done will be off.

But think about it. For these small jobs, it only has to be level at the center. So, the heck with it, just make sure when you drag a piece of paper with the nozzle at the center that it has a bit of resistance, and don’t stress about what happens at the four distant corners. You will maintain your sanity this way.

I found the missing piece after printing this piece out, as luck would have it. BUT, then I found another place, right against the side of the house, that was never covered, but could have been. So I slapped my printed part there – it worked great!

A subsequent bolt hole cover project revealed that supports are nasty and basically impossible to remove. Yet the design was such that the thing worked anyways with a little superglue.

A plate to cover a hole in the mailbox post came next, and then a ring with a little slit for my bird feeder. Those two use an extrusion method.

You have to render your model or export to STL does absolutely nothing, and also does not show an error, except in the console, which you may not be showing.

References and related
Latest in 3D printing

This was the anet a8 printer. I don’t think it’s sold any longer, or not the cheapo $139 version which I was lucky enough to get. In fact someone bought one on my recommendation, parts were missing, and he never could get the missing parts.

This is a great tutorial for openscad and constructive solid geometry:

Lots of free 3D designs are available at Thingiverse:

But there are a lot of other great 3D designs out there beyond just Thingiverse. This site introduces lots of these resources with example pictures from printed models.

Consumer Tech

What’s Next In 3D Printing?

In a lot of ways, the last few years have seen 3D printing “going mainstream,” so to speak. People are no longer astonished by the sheer capabilities of the technology, and we’re getting more accustomed to seeing stories about one interesting product or another having been 3D printed. People are also gaining more access to 3D printing; in some cases the costs of the devices have fallen, though we have posted about building one’s own 3D printer as well, and this is another option some savvier consumers are embracing.

The process of getting to this point, at which 3D printing is at least somewhat familiar to a lot of people, has been complex, fascinating, and enjoyable. But now that 3D printing is mainstream, what’s next for the technology? It’s hard to say with certainty, but we can look to a few current trends and developments and predict some of the ways that the technology could become more popular still.

Further Understanding Of Capabilities

Even if people are no longer astonished by what 3D printing can do in general, further understanding of the full range of the technology’s capabilities is likely to come with time. In a sense, the initial learning curve concerned the basic concept – that a 3D object could be printed into empty space by a machine according to a digital design. Next, people will inevitably come to learn about all of the various twists that can exist within that broad concept. For instance, people will get more used to the idea that 3D printers can create metal objects, and not only work with plastics; people will come to be familiar with larger 3D printers on a scale that can create car parts, or potentially even small homes and urban planning features. Ideas like these don’t necessarily fall into the most basic understanding of 3D printing, but they’ll inevitably be more widely understood in short time.

Combination With Other Advanced Manufacturing

This is perhaps more of a concern for large companies and significant manufacturing operations. Nevertheless, it’s a good bet that the next few years will see more people come to understand 3D printing as one of a few advanced manufacturing methods that can contribute to the creation of modern products. The technology’s most noteworthy counterpart may be injection molding, which is not as new, but which has grown vastly more sophisticated and capable. This is basically a process by which a given material is heated and molded to fit a shape, such that it hardens in that shape and becomes a final product. Fictiv describes injection molding processes as being ideal for design validation or for higher volume production, which largely conveys the idea that they are similarly useful to 3D printing. The truth though is that people may come to realize that the combination of the two technologies can benefit entire industries. For instance, there are some cases in which prototypes and early models are created via 3D printing (a better process for trial-and-error), and then used as the basis for large-scale molding efforts to design product lines.

3D-Printed Food

The very notion of 3D-printed food can sound absurd on its face. It reads very much like something from a science fiction novel or a fantasy film in which food can simply be created, and there are no more resource shortages. Amazingly enough though, while it’s not all quite so glossy and miraculous as the sci-fi version, 3D-printed food has become a reality. Hackaday explains how 3D-printed food can work in a piece written just last year, and the concept is actually surprisingly straightforward. Basically, pastes made of organic materials and broken down ingredients (such as, in one example, peas and seaweed) can be printed into mock versions of regular food items (in the same example, a steak). The same article acknowledges that taste isn’t necessarily ideal just yet, but the very idea of creating food products from a mishmash of edible materials is exciting. It’s a starting point for what could be a massive step toward addressing food shortages, and it’s likely to become one of the main topics driving further interest in 3D printing.

Command-Based Projects

This is something we don’t hear all that much about yet, but which could make for a significant step particularly with regard to consumer 3D printing. Singularity Hub took a look at 3D printing innovations we might see in the next five years or so and introduced this idea in an interesting way, stating that “hey” will become the “most frequently used command in design engineering.” Specifically the suggestion is that we’ll be able to say, “Hey 3D printer, design me a new pair of shoes” in much the same way we ask Alexa or Siri to make shopping lists or tell us the weather. If this proves to be true, it’s likely we’ll see a significant spike in consumer 3D printer purchases. For that matter, it could significantly change much of the retail industry.

Ultimately one of the cool things about 3D printing is that we’re all still figuring it out. It likely has countless applications we have’t yet considered or imagined. The suggestions here are grounded in current trends and speculation though, and should play a significant role in keeping this technology fresh and interesting.

Consumer Tech

Consumer tech: Samsung touchscreen not responsive

This may be really obvious to some, but I did not realize until recently that you can adjust the touch screen sensitivity on a Samsung smartphone. Who knew?

Why it matters
I have a family member with a glass screen protector. I watched her struggle tapping and swiping multiple times to get it to respond. No one mentioned a way to fix it. Then i helped apply a new glass screen protector after the old one broke and i did an RTFM. The directions mentioned you can increase the touch sensitivity in settings. It’s no longer where it said. but in Display settings.

Consumer Tech

Consumer Tech: amazing little Bluetooth adapter for your car

My old car I decided finally needed a touch of Bluetooth connectivity. But how to do it without spending a fortune?

The details
I found this amazingly inexpensive gadget on Amazon that describes itself as follows: Handsfree Call Car Charger,Wireless Bluetooth FM Transmitter Radio Receiver&Mp3 Music Stereo Adapter,Dual USB Port Charger Compatible for All Smartphones,Samsung Galaxy,LG,HTC,etc.

I guess it’s normally $16 but I bought on Cyber Monday so it was about $12. 12 dollars! I think if I had gone to the dealer for an after-market solution it would have been $500.

The bad first
Let’s get the bad out of the way, bearing in mind my expectations were rather low so I may be leaving out some obvious “of course it doesn’t have that…” type of stuff.

This device does an FM broadcast and you pick an unoccupied FM frequency to listen to it. On the other side it connects to a Bluetooth device such as a phone. In IT terms I’d call it a gateway since it converts one protocl to another (Bluetooth to FM). Having read the reviews, but not finding anything addressing my interests, my idea was to continue to use my FM stations, and put the station used by this device on a preset so when a call comes in to my phone I hit the station preset and accept the call on the device.
Well, you basically can’t listen to other FM stations as long as this thing is powered up. So even tuned to 88.7 at the far end of the dial, it interferes with stations up and down the dial for some reason. It’ not impossible but you’d have to have a high tolerance for static to use it that way.

Also, I’ve read that these little things break on some people after a few months. But I would no feel cheated, remember, low expectations?

The good
– microphone is good
– compatible with Samsung
– capable of audio program controls
– boots up quickly, maybe 10 seconds

My solution
I only really listen to NPR. I tried the WNYC app in the Playstore. I used to think it was buggy – stopping at random times. But I’ve had good luck my first few trips. Plays great through this thing! In many ways it’s better than FM because I don’t have to change NPR stations as I drive to work, etc, and its signal is often better. There is some static background however. Now my phone GPS talks to me through the speakers (it used to be silent in the car).

The unknown
Not sure about outbound calls to much. If you hit the button twice it seems to call the last dialed number. There are these settings U01, U02, U30. maybe those are for speed dialing?
Precisely why it has to so broadly interfere with all FM stations is a mystery.

Being a thoughtful person, I also wonder what it does to the FM reception of cars around me, ha ha? Could they pick up my call? Now that I think of it, I do remember hearing someone’s phone call on my FM radio once, many years ago. Use of an aux cord would be a way around that, but this little device does not support that.

The amazing
How cuold they pack all this tech, make something that basically works as it’s supposed to, and sell it for $12? I’m in awe.

References and related

Consumer Tech

What credit card fraud looks like

A lost credit card. Or was it misplaced? Months later a whole bunch of “modest” charges appear all at once, a couple days after a few lower-value test charges were made.

Thank goodness I had the presence of mind to lower my alert limit on transactions from $200 to $50. I was not too late to have all the charges disputed despite the test charges being two days old.

What fraudulent credit card charges look like

I do not know how these charges were created – what is Google/Walmart or Google/Target.

I can guess how my address was matched to the card – it’s a sufficiently uncommon last name available from simple public records.

Well, now we know the card was lost or stolen, not misplaced. After all these years that’s the first time that has happened to us. We will not be responsible for the disputed charges.

Consumer Tech

Consumer tech: Solar Panels – the things they never tell you

Since solar panels are a major commitment I did some research first. My criteria (high-efficiency, not manufactured in China, carried by a local installer) was met by Sunpower X-series whose panels generate 345 KWh, which was pretty much at the high end in 2017.

The details
I live in a northern latitude area (41° latitude) with plenty of snowfall. I have a sloped roof.

I just assumed that the snow would melt off the panels at more or less the same rate as off the rest of the roof.

That is not at all the case.

I was working from home one day in the kitchen when I heard someone on the roof. At least that’s what it sounded like. The person seemed to be clearing the snow off my panels, how thoughtful of my installer to send someone to do that. The snow was thundering and avalanching off the roof onto my deck. Eventually I realized the mini-avalanches were real, the person up there on the roof was no more real than Santa Claus.

So yes, the snow slides off those panels in thunderous mini-avalanches. So today after a big snow event, this has been going on this morning, the day after, on and off for hours. Around the panels the roof retains its snow, but the panels themselves have lost all theirs. I see my neighbors’ panels are also cleared so this must be a universal phenomenon.

It’s worth mentioning because it’s a little frightening when you first hear it.

Power consumption vastly overestimated
I suppose this next problem is peculiar to just my installation. Sunpower gives you this nice portal so you see what you’re generating and what you’re using. In my case the generation numbers seem plausible, but the usage numbers are way off.

February bill shows 621 KWh metered, 386 KWh out = 235 KWh billed.

Sunpower shows 1442 KWh used, 531 KWh generated, for a net of -910 KWh.

So we can compare 235 to the 910. The should be about the same yet there is a huge difference.

The usage is almost, but not quite doubled. if we add 235 billed to the 531 generated we’d have 766 used. So usage is overestimated by a factor 1.89. But I doubt it’s a simple formula like that to correct their numbers. During the time of generation – daylight – the usage estimates numbers dip. So I don’t know what they’ve done wrong, and my installer says their support is horrible. It’s been nine months and I’ve just asked for an update. It’s more annoyance than anything.

Consumer Tech

Verizon Tips I need but can never easily find

Verizon Phone Finder
They will lead you to some page that seems to suggest you needed to buy a premium service from them if you need to find your phone. Don’t fall for it. Or maybe you will get their other page which only sends you on to Google’s page. So, for Android phones, here is the universal phone finder link:

It’s pretty cool. It shows pretty precisely where the phone is, how much power is left and gives you the chance to ring it for five minutes and even lock it.

Change your Verizon Wireless Voicemail password
This is even harder to find unless you have just the right search terms.

From a Verizon app on your phone
I haven’t used this method.

From the My Verizon web site
I just used this so it works pretty well:

How to set up your voicemail so as not to enter a password
Basic idea: add a contact for Voicemail tack on two pauses, then append the password. So that will be


For instance I named this contact VM. If my password were 1234 the number would be


To generate the “,” character go to the special characters key to the right of # when typing in the number.

Consumer Tech Network Technologies Raspberry Pi

WAN load-balancing routers

I got an offer for $20/month broadband access from Centurylink. It got me to thinking, could I somehow use that as a backup connection to my current cable ISP? How would that work? Could I use a Raspberry Pi as a WAN load-balancing router?

The details
Well I’m not sure about using Raspberry Pi. It’s not so simple.

But I just wanted to mention there are solutions out there in the marketplace to this very problem. They’re not that easy to find, hence this article. They’re mostly aimed at small businesses where Internet connectivity is very important, like an Internet cafe.

This Cisco dual WAN router for $157 would do the trick:

Or for about the same price, this Linksys Dual WAN router:

Want to go consumer grade and save money? This TP-Link model is only about $85:

But it’s ports are only 100 mbps, which is kind of surprising in this day and age.

We have identified commercial solutions to the question: can I use two ISPs at home to provide high availability and load-balancing. I’m not yet sure about a Raspberry Pi solution.

Consumer Tech Web Site Technologies

White web page: maximizes your backlight with no invasion of privacy

Maybe it’s just me, but I’ve always had some issues getting my flashlight app to work on my phones. First there’s the issue of finding one from a trusted source (many contain spyware: access to my contacts?? for a flashlight?? I don’t think so…). So I trusted Swiss Army Knife, but then I had to launch that, then drill down to the flashlight, blah, blah. And the flashlight app on the Windows phone also looks a little seedy. And anyway sometimes you don’t want to overwhelm with your camera’s LED. Maybe just a simple glow from the backlight of your screen is enough to guide you down the hallway int he dark… I know I found myself using both my Fire HD tablet and my Windows phone in exactly that way.

Then I decided to scan a slide, using the backlight of my tablet to permit the scanner to see the colors, etc. That did not work out, by the way. It sounds like a good idea, though, doesn’t it? i guess the backlight is not sufficiently bright. maybe if I play with screen brightness…

Anyway, for all the above reasons I realized I could use a white backlight app. Rather than pay $0.99 for another dodgy app, I decided to write a web page that displays an all-white background. Then i could bookmark it and use it on both my Windows phone and my tablet!

White backlight web page
This is really complicated – don’t try this for yourself. Ha, ha just kidding. This is about as simple as it gets. Falls into the catgeory of “wish I had thought of it sooner,” or “Duh.”

White backlight web page

The HTML code
Want to put this on your own web server? Here is the code.

<html><head><body bgcolor="white"></htnml>

No banners, no ads, no intrusive permissions: this is a web page that maximizes the soft glow of your device’s backlight. You could play with your screen brightness to possibly make it still brighter, adjust the length it glows for, etc. For convenience to pull it up in a jiffy I’ve bookmarked my White backlight web page.

References and related

White backlight web page.

Consumer Tech

Consumer tech: How to safely add steps to your Fitbit

So my significant other realized after going to the park that she wasn’t wearing her Fitbit Alta. She’s a member of not one but two separate programs that provide certain incentives the more steps taken. So she wanted to add those missing steps – 4000 of them – to her Fitbit.

She put it in the dryer, on a special cycle which doesn’t produce heat. She knew how much it was adding by monitoring it with her smartphone. She believes it only took around 10 minutes to add 4000 steps this way. No harmful effects were noted. I suppose she put it inside of something like a sock or one o those nylons pouches. I was surprised it could have gone that quickly – that’s over 6 “steps” a second. Maybe it took a bit longer she conceded, but not more than 15 minutes.