Brew Fridge – Part VII: The Building
To sum up this project so far, I’ve accomplished the following: A fridge has been procured and stripped to its basic function. All internal mounting brackets, shelves, housings, and ancillary components have been removed. The panels on the doors have been scrapped,, and the electrical architecture has been massively simplified. In short, this fridge will run indefinitely if plugged into the wall. Outside of this, I’ve modeled my proposed design in CAD. This includes the fridge, air exchange assembly, tap panel, proposed cap, and all of the relevant build components including the temperature controllers, the taps, and the conical fermenter. The air exchange assembly has been 3D printed, assembled, and validated, and the tap panel has been CNC milled. It’s now time to turn it all into something.
The tap panel support consists of an MDF panel and foam insulator. The build begins by test fitting this stack and positioning the clearance holes for the tap panel. The tap panel is then aligned with this support stack, and it’s mounting holes are marked and transferred to the door. Everything is then removed and the holes are drilled. It’s time to install some Riv-Serts.
This project takes advantage of a lot of captive nuts, much like Donald Trump’s vision for America, but these happen to be much more useful. I use Yarley inserts for plastic, and PEM nuts for small portable panels, but Riv-Serts are rivserved (get it?) for larger sheet metal bodies like these fridge doors. A Riv-Sert is the result of a nut and rivet having a passionate lovemaking session. These flanged beauties are installed through a hole and squished with a specialized tool until they sandwich the panel. Much like a thermal insert, these remove the need for a serviceable nut on the back of an assembly, and they mitigate the woes of sheet metal screws. The result is below.
There are a couple drawbacks to these nuts. For one, they have a flanged head that sits proud of the mounting surface. Since my backing stack is responsible for sealing and insulation, the tap panel doesn’t have to be sealed or fully flush, so the ability to service it without tearing out the back is advantageous. I can live with a miniscule gap. Secondly, they are a bit unforgiving. If the hole isn’t positioned perfectly, these are unfriendly to non-concentric alignment. A screw and nut arrangement can accept larger and larger clearance holes, but captive nuts must be positioned well, especially with flathead, countersunk fasteners like I’ve designated.
The result is pretty slick though. I had to drill-out the middle left Riv-Sert and re-install since the alignment was off, but with some clever install order of operations, the panel mounts to the door quite nicely.
The backside is a little ugly, but the end result will amend this. The MDF is re-aligned and epoxied to the door, and the foam is glued and placed next. The round poppets of foam close the air gap around the faucet shanks when they are installed, but there is still plenty of room to disconnect the lines. After the seals are replaced, this entire surface will be covered with a foil air-gap insulation blanket. I’m feeling good about the tap assembly, so I’m ready to face an ugly reality. I have to make wall cuts for the air exchange assembly.
I don’t have a compressor in my apartment, and having unsuccessfully attempted to cut through the wall with a Dremel, I’ve embarked on a rougher approach. I’m making cuts through the wall using shears. The metal cuts like butter, though positioning is difficult and awkward. Since the exchange housings are flanged, these cuts don’t have to be particularly gorgeous, but I’m trying my best. I’m also saving my neighbors from quite a racket using this method. In all, this took two sessions to finish, but the exchangers fit snug and work as intended. Here is the exploded view for reference.
And here is the final result below. After the fridge gets a good clean, these can be installed permanently.
The tap panel is done, and my air exchangers work, so it’s off to the shop to prepare the doors. Both doors need to be sanded and painted, and my final test of incompetence awaits: integrating a clear panel into the fermentation door.
I bought a transparent 18″x 45″ smoked Acrylic panel from Tap Plastics, but upon inspection at the shop, it’s opaque. I’ll exchange it later, but it will serve as a template for now. For cutting the door, I’m outlining the opening with sharpie and giving myself a half inch border. After the marks are satisfactory, I mask outside and pass the point of no return with a cut-off wheel. The cut goes without a hitch, and all that’s left to do is file the edges and remove Styrofoam from the inside. I’ve thought of a lot of methods for mounting the panel including metal trim bezels, wooded angle mouldings, and serviceable housings, but it’s all to complicated and excessive. I’m going to simply sand the purchase area around the inside of the window cut-out and set the panel in with 3m 5200 seam sealer. It will set semi-hard and form a seal with the door, and if the panel breaks later, it’s semi-serviceable. Plus it will be flush with the door and provide the cleanest look.
The doors are sanded for primer, and the old handle holes are filled with Bondo and smoothed. I haven’t decided on a handle solution just yet, but I can integrate something in the future. \
I’m applying a base coat of paint using black High-Build Primer. This primer is excellent, and generally corrects any sub-par sanding preparation. For finish, I’m using Krylon Chalboard Paint. The overall result is good enough. I’m always been a great 10 foot painter. Up close, the flaws are apparent, but oftentimes, perfect can be the enemy of the good.
The build is almost complete. The circuit has been tested, and I’ve verified that both ITC-308s run the compressor and air exchange system as intended. Without a panel, there is no incentive to start using this system, but the hard work is behind me. In my final post, I will cover the last of the details (window installation, cap/display build, and internal brackets). I imagine my first validation will be a keg of cold brew nitro coffee. Why wait a month?