I have written previously about my SONOS speakers and my family’s frustration with the app that controls them.  See SONOS Speaker API Overcomes App Limitations  In that blog post, I resolved my wife’s biggest issue with the SONOS app. She now has a two-button device that plays and stops her favorite playlist on the speakers in the basement.

But my biggest pet peeve remained unresolved until recently. Each speaker has its own, independent volume control. This is a double-edged sword. It’s great because my wife can blast her playlist in the basement while I’m upstairs playing my classical playlist at a much subdued volume. On the other hand, if we want to play a party mix over all the speakers in the house, I have to set the volume on each speaker individually.

For my wife’s solution, I implemented an MQTT broker, subscriber and publisher.

A Raspberry Pi Zero W runs a Broker program and a Subscriber program at boot.
Both apps are written in Python. The Broker listens on the network for any MQTT traffic and forwards that information to all Subscribers that have expressed an interest in the data. When the Subscriber starts, it tells the Broker what traffic it’s interested in.
The two-button device is the Publisher. When the PLAY button is pressed, the device sends a sonos/play message to the Broker. The Broker forwards this message to the Subscriber. The Subscriber responds by calling the SONOS library (soho) to control the speakers. The Subscriber runs on the Raspberry Pi Zero because the SONOS Library is beefy and needs the power and a lot of dependencies. As long as I had a Pi Zero in the mix, I decided to also use that for the Broker as well. The Broker and Subscriber are just two processes that happen to be running on the same hardware.

I was able to use this existing infrastructure to solve the volume control problem. I just had to write a Publisher app to cause the existing Subscriber to set speaker volumes in addition to launching my wife’s playlist. I decided to write a SwiftUI app for my iPhone for Publisher. Here’s what the new architecture looks:

The iPhone app has a slider and a Volume button that sends a message to the Broker which passes it along to the Subscriber.  With this button, I can set the volume of all the speakers to the same specific value.

The Minimize Volume button tells the Subscriber to scan the volume levels of all the speakers, find the minimum value, and adjust the volume on all the speakers to that minimum level. The Maximize Volume button sets the volume to the same value as the loudest speaker.

Finally, Whisper sets the volumes to a level that is just barely audible — you can tell the speakers are on, but they don’t interfere with phone calls or people at the door.

I collect bottle openers, one for each vacation destination or brewery visit. They’re kept in chronological order on a rack I made in 2017 from the oak cabinetry panel of our old kitchen refrigerator. To be honest, it was 80% full the day I finished it nine years ago. Keeping them under the 3D printers and over the PCs in this high traffic area is problematic, they are frequently knocked down. I needed a new sensible extensible solution.

It makes more sense that they’d be kept on the “beer fridge” so I designed a modular magnetic rack system for them in FreeCAD. The rack is a 290mm x 25mm dovetail that just barely fits on the Prusa2 (Klipper/RAMPS modified Prusa i3 MK2s) print bed. My original design was 300mm long but didn’t fit on the bed, so I shortened it in the spirit of “design for manufacture”. I printed the hooks below on Sam Bell 2 (a home built i3 clone functionally identical to the Prusa2). I chose blue and white to match the colors of the München Biergarten magnet already on the white refrigerator. After some iteration to determine adequate spacing, tolerance for mounting the 4mm x 2mm magnets, and a few more iterations to get a good fit for the hooks on the dovetail, I started cranking them out in PLA. The hooks print best one at a time so I spaced them out and for the first time I configured and used sequential printing. Sequential printing can print multiple parts but it prints each one after the other instead of all at once. They all turned out great.

Side note: My fathers father, William “Herbert” Williamson fixed clocks, watches, and jewelry. He had many unique and interesting tools. When I was four years old I always wanted to play with his brass and rawhide hammers. I remember occasionally seeing them when he opened the lower left drawer of his workbench and I think I only got to touch them once. I can hardly imagine the stress level while handing a four year old a hammer in a small clock workshop. I’ve since inherited them and it gave me great joy to finally be able to use the rawhide hammer to drive in all the magnets.

It’s all done and it turned out better than I expected.

Note: The silver bar on the freezer door contains nine promotional bottle openers from one visit to the 2023 Design-2-Part manufacturing trade show, whereas on the refrigerator door the bottle openers are each unique to a trip in chronological order.

Bonus Content

If you are curious, this is what the inside looks like. I occasionally like to take a picture after restocking which is roughly annually I realized after digging up these photos.

This is probably my biggest fitness headwind but it brings me joy. I’ve veered waaaay off the topics of design, making, and 3D printing.

Now back to your regularly scheduled programming.

What will you make next?

Workshop 88 makerspace is sponsored by Comparion Insurance. Local agents who know insurance inside and out, able to easily guide clients through the complex process of finding policies to match their unique needs.

Benefits:

• The right coverage at the right price
• Insurance options from a wide variety of carriers
• A local expert looking out for their exact needs

Use the QR code or this link get a no-commitment insurance quote and save money today: https://www.comparioninsurance.com/workshop-88…

Workshop 88 had a Makita track saw rail without a saw to go with it so I thought I’d try designing a 3D printed sled for the saw. Workshop 88 has a few circular saws so I was looking for a way to make a “universal” sled. Luckily, I found that a surplus steel bar originally for hanging file folders was a good fit for the tool mount slot at the front of the saws.

I learned a couple of interesting things in the process, like somehow the Ryobi battery operated saw magically had a base that perfectly fit against the side guide in the rail, so it could be used directly without an adapter. The other thing I learned from Jim is that circular saws can be either left-handed or right-handed. The corded Menards Tool Shop circular saw is right handed and the battery operated Ryobi is left handed.

I sketched the profile of the track in FreeCAD and iterated 3D printing profiles that fit snugly but moved freely with the slot, then modeled the slot holes and bosses needed to securely install the steel mounting bar using M3 socket head cap screws.

When happy with the fit I extended the model to a length that would extend under the saw past the blade that would also fit comfortably on the Qidi X-Plus 3 printer. Finally I added a Workshop 88 logo for decoration. Thanks again Canuck Creator for donating the 3D printer to Workshop 88 at the Midwest RepRap Festival (MRRF)! It really has been a great upgrade for the Makerspace.

I cleaned the bed, used a little Aqua Net hairspray for added adhesion security, and loaded up a spool of Polymaker red PLA to match the saw. Thanks Polymaker for the sponsorship!

It fit together beautifully! Only the very astute reader may notice that the picture of the one on the 3D printer is a mirror image of the working one below. After printing for nearly 3 hours I excitedly removed it from the bed to discover that I had extended the wrong end of the thin prototype and the tool mounting bar slot was at the wrong end! I was so confused at the time, but when I realized the mistake at open house, we all laughed. I’ve since corrected the CAD and printed the working non-Bizarro version depicted below.

It turned out great. The bar allows lateral adjustment of the saw to really dial in the clearance between the track and the blade. The broad PLA bottom rides smoothly on the low friction strips, and the tolerances are tight enough for high accuracy cutting without binding. I’m super happy with this design.

It’s a very niche design for a particular saw and track, and the CAD file is a little hackish, but if you are interested, here are the CAD and step files for download:

The new addition to the wood shop lives on the shelf with the circular saws. We all can’t get over how well the Polymaker red PLA matches the color of the saw, too.

What will you make next at your local makerspace?

Workshop 88 makerspace is sponsored by Comparion Insurance. Local agents who know insurance inside and out, able to easily guide clients through the complex process of finding policies to match their unique needs.

Benefits:

• The right coverage at the right price
• Insurance options from a wide variety of carriers
• A local expert looking out for their exact needs

Use the QR code or this link get a no-commitment insurance quote and save money today: https://www.comparioninsurance.com/workshop-88…

A lot of dust can be generated in the workshop, especially with power tools. The dust is neither healthy nor pleasant to breathe. Effective air filtration in small workshops need not be expensive or complicated, here we show how to make a cheap effective versatile air filter for dust and particles from a box fan, furnace filter(s), and 3-D printed clips (or the handyman’s secret weapon: duct tape).

For years in our wood shop we’ve used this 20″ box fan with a fine 20″ wide furnace filter taped over the back or inlet side of the fan. Having served us long and well she’s past retirement condition, so I worked in some upgrades while replacing it.

I love duct tape as much as the next hacker or DIY’er (RIP Red Green), but I never liked its permanence in this application. The fan made a great air filter but no longer could easily be used to move more air for ventilation, so I designed and 3D printed some simple brackets that allow easy placement, removal, and exchange of different filters on two of our fans. At home I also use the more fiberous high flow air filters to collect the majority of over spray when spray painting.

I designed the bracket in FreeCAD, 3D printed it and a mirror copy in Polymaker PLA on the makerspace’s Quidi 3 Plus 3D printer. The source FreeCAD file, STL, and Step files are included in this zip.

The part is simple, but I was sure to design in generous tolerances and an access hole for the screwdriver needed to install the part (two concepts I wish the VORON team had embraced as well as Prusa has).

I had to select longer sheet metal screws from the makerspace’s generous eclectic fastener collection, as the stock screws were only long enough to hold the grating on, with no length to spare.

Now filters are easily dropped into the brackets and removed. There is no need for a tight fit in the brackets as when the fan is on the filter is drawn tightly to the rear grating.

So happy with the first one, I printed and installed a second set on the other fan.

I noticed a slight difference in the dimensions of the second fans plastic grating caused the brackets to be bent outward slightly. I could have updated the dimensions of the design and printed another set, or I could have used a knife to shave a little plastic off the edge of the fan grating, but I decided the easiest thing to do would be use a heat gun to deform the brackets on the fan, which could even have been done with a hair dryer on PLA.

Bonus content: Big Feet

You may have noticed that we replaced our fan’s feet with boards. We find the fans are far less likely to tip, blow, or get knocked over in the shop with the broader base, which also turns out to be more durable than the stock plastic fan feet. (The first thing I ever designed for 3D printing was a replacement foot for a 20″ box fan)

Note the base extends farther from the back of the fan than the front to better handle the force of the airflow.

One fan has a base held on with zip ties, the other employs sheet metal screws.

One of the zip ties had broken, that was an easy repair. While I had the back grating off I replaced the broken zip tie through the spacer we fortunately had not lost, tightened, and cut off the plastic end with end nippers so as not to leave sharp corners.

The other fan had not yet had its base replaced but Tom and I decided to re-use the base from a fan that we wore out last year and chose to install it with more sheet metal screws. We carefully aligned the foot to the bottom of the fan and clamped the foot to the table, then punched the hole locations to the sheet metal. After drilling the pilot holes (not pictured) we selected four matching broad head short sheet metal screws and assembled the fan base.

Voila!

Two affordable versatile shop air filters with the bonus of a sturdy base.

What will you make at your makerspace?