Saturday, October 17, 2020

A Few Tips For Using Wi-Fi Enabled Light Bulbs

I've been making some lamps using cheap, Wi-Fi enabled light bulbs for a while and I've learned the hard way that there are a few things they don't tell you up-front about getting them working. You can save yourself a lot of trouble by following a few simple rules. These rules apply to every brand of RBG LED bulb.

1) They only work on 2.4 GHz Wi-Fi. If you have a dual band or triple band router, they will only connect on the 2.4 GHz band, so you have to connect your phone to the 2.4 GHz band if you want to control the bulbs from an app on your phone. See #3 below... If you have one of the newer routers that automagically assigns things to 2.4 or 5 GHz bands, you may have to set up a guest network specifically for 2.4 GHz light bulbs and similar IOT devices.

2) The SSID of the 2.4 GHz wireless network should not contain any Chinese characters and/or punctuation including spaces, underscores, or hyphens. Use a simple SSID like XYz1234. The SSID must not be hidden. You have to access your router's control panel to make changes to the SSID.

3) WPA2 security is OK. Set your router to use WPA2 on the 2.4 GHz network that the light bulbs will use.

4) If your phone runs a recent version of the Android operating system and you have a dual or triple band router, your phone will connect to one of the 5 GHz bands by default. You'll need to force it to connect to the 2.4 GHz Wi-Fi band/network to set up the lightbulb(s). You only need to do that for the initial set-up.

My Pixel 3 phone runs Android 11 and it connects to the fastest connection it can find which is one of the 5 GHz bands that my router uses. I had to install a couple apps in the phone to allow me to force it to connect to the slower 2.4 GHz Wi-Fi band that the light bulbs use. I installed "Wi-Fi analyzer" that shows all the Wi-Fi networks within range of the phone and "Wi-Fi connector library" that allows you to force the phone to connect to whatever network you want, in this case, the 2.4 GHz network.

5) If your phone uses a VPN when it connects to Wi-Fi, you'll have to disable it when you want to do the initial set-up of the light bulbs. 

My Pixel 3 uses the GoogleFi VPN.  I had to disable it when setting up the bulbs, and reenable it after I had programmed the bulbs. 

To be clear, after initial set-up, you can control the bulbs with the VPN enabled, and without specifically connecting the phone to the 2.4 GHz network. You only need to make the 2.4 GHz connection and disable VPN for the initial set-up, and each time you add another light bulb.

I use the Feit Electric app to control my bulbs, even though some are made under the label "Tuya".  They all show up and are programmable using the Feit Electric app.

Thursday, October 15, 2020

Coasters, anyone?

I Needed Some Coasters, So...

The coasters are orange, the bottom of the box is yellow, and the top is pink, all at least a little fluorescent. 

I printed some coasters and a storage box for them using TPU filament. I think they came out alright.

These coasters are all 100 mm in diameter and 2.88 mm high (I printed in 0.24 mm layers) and the box holds a stack of six of them.  Each coaster has a different pattern. The patterns and the lip around the edge of each coaster are designed to trap condensation that dribbles off your cold glass so it doesn't end up on your furniture. I kept the patterns shallow in Z. If the patterns get too deep it starts to become a problem keeping them clean.

The box's lid fits loosely so it's easy to remove. You can put it under the bottom of the box if you turn it upside down. The rounded corners have enough space to use a finger to lift the coasters out of the box, one at a time.

Being printed in TPU, the coasters are great for hot and cold drinks, but I would not set a pot right off the stove on them. I tried washing them on the top rack in a dishwasher and they came out looking like they just came off the printer- perfect, but who knows? Maybe they'll show some wear after multiple cycles.


I used TPU because I like the way it looks, especially when it fluoresces. The photo shows the result of four printing sessions split among three colors. The first two sessions were to print three coasters at a time, one more session to print the box bottom, and finally one to print the box lid. 

Another reason to use TPU was because I liked the idea of the surface being a little soft.  Setting a glass or cup down on a soft surface will sound and feel different from setting it down on a hard surface. I have a granite counter top, and setting a glass or cup down on it always makes me feel like I'm going damage either the glass/cup or the counter top.

I printed at 240C- a bit higher than the recommended temperature range for TPU, but the plastic really flows at that temperature, yields a super shiny finish, and the interlayer adhesion is amazing. I get almost no hairs on the prints. They seem to be leakproof. Of course, with use they will probably start to look bad because spills will inevitably find tiny gaps between lines in the print that can't be properly cleaned out. It's no big deal - I have a 3D printer, so I'll just replace them with another set before they start to look bad.

Print speed was 40 mm/sec, no cooling fan, 45C PEI bed.

It should be easy to print these in as many colors as there are pieces (8 in total). You can do all sorts of crazy stuff, if your printer can produce multicolor prints.

You don't have to print with TPU if you don't want to. PC, ABS, PETG, or PLA, will work too, but you might have to be careful about putting hot drinks on PLA.

The box lid is printed with the top side down on the bed. My printer's PEI bed has scratches that transfer to the print, so the top cover doesn't look as perfect as the sides and everything else. I think printing on glass would be a good idea, at least for the top cover. 

It's easy to change the shape and size of the prints by scaling them when you slice the files to print. If you think they aren't deep enough just scale them in Z for the (any) depth you want. If you want larger or smaller or oval coasters (??), just scale the X and Y axes appropriately after you put them on the plater in the slicer.

I printed with concentric infill for the top and bottom layers and they came out with some interesting patterns.

Finally, clean the nozzle thoroughly just before the print starts, while it's at print temperature.  That will help prevent getting little blobs of charred plastic embedded in the print. Avoiding over extrusion helps, too.

STL files are here.