I bought a pretty neat house.

I’ve been interest in curing and dry-aging meats for a while, but until I saw a recipe for duck prosciutto that could be prepared in a household fridge I had never considered the possibility of curing meat in my apartment.

I’ve got a separate post in the works for the specifics of curing meat, but for now I’ll just focus on the curing chamber I built over the weekend.

Mini Fridge, Big Potential

So I picked up this 2.7 cu ft mini fridge from Facebook marketplace for $40. I was going to go a size smaller, but this one ending up being perfect. It’s got plenty of space for me to hang larger charcuterie in the future, including lonzino and salami. I’m fairly certain I could fit a decent pancetta in there as well. I don’t think the smaller 1.6 cu ft fridges would have enough space after taking into account the additional electronics needed and unmovable freezer section.

So one of my main concerns with this fridge was the freezer section in the top right. With this type of fridge, the chamber is cooled by the freezer. This leads to two issues: the freezer can’t really be moved, and condensation.

Most meat requires curing conditions of 55-65F, with a relative humidity of 60-75% and circulating air.

Since the fridge will be cycling on and off at a much higher temperature than it was intended to hold, condensation will build up on the freezer box which increases the overall humidity inside the chamber. This ended up not being a huge problem, but I was worried I was going to have to add a dehumidifier.

I haven’t found a safe way to move or bend the freezer box yet without causing damage, so I’m missing out on that extra real estate for now.

If you get a frostless fridge (without a freezer box, cooled externally) for this purpose, you may need a humidifier to keep the internal humidity in the appropriate range for drying meat.

Taking apart the fridge really helped while cleaning. I used a 50-50 mix of vinegar and water in a spray bottle, and later went back over everything with all-purpose cleaner. The rubber seal around the door was the hardest to clean, and was not removable with this model. There was still some discoloration of the rubber by the end, but I was able to remove any mold that had been growing while the fridge sat in storage. Everything is very clean and smelling fresh now.

I removed the internal thermostat module and soldered some wires together so that the fridge would always turn on when connected to power. The fridge needs to be “always-on” so that the new digital temperature controller I added can do it’s job properly.

I also bought a wireless indoor/outdoor thermometer with a sensor that is kept in the fridge. With this I have an additional source to confirm that the internal temperature matches up with the settings of the temperature controller. They were within ~0.2F of each other, which works perfectly for this setup. The thermometer I bought also measures humidity, which is crucial to preventing bad mold from growing on the meat.

For now I’m just using my earlier sous vide temperature controller as a temporary setup until I get some other electronics wired up for a more permanent solution. I plan on adding a BME280 temp/humidity sensor (although I have a K-type thermocouple sitting around that could work too) with an ESP8266 for wireless monitoring and control. This will all be integrated in the back of the fridge, alongside the compressor and other electronics.

So far everything is working well! I’ve got some duck curing in there at the moment as a test. As I mentioned earlier, I was worried about the condensation from the freezer increasing the humidity too much, but so far the chamber hasn’t gone over 78% and typically stays at around 66% RH. I added a computer fan to keep air flowing inside as well.

In part 2 I’ll get more into the electronics and other modifications with some better pictures and lighting. Stay tuned!

Sometimes the battery that comes with an item just isn’t big enough. For example, the 8Bitdo Zero mini bluetooth controller; this controller can be found easily for around $7 and works great with pretty much anything. The problem is that the included 180mAh battery always seems to die at the most inopportune moments. Why not use a spare 18650 you’ve got lying around to upgrade that capacity to something like 2200mAh?

As a bonus, you get those sweet techno-jank points to brag about.

Not much to this one. The longest part was waiting for the holder to finish printing (about 40 minutes). Some glue and solder wrapped up the rest. Easy 10x battery life! Additionally, it’s actually a bit easier to hold now with my big people hands.

Here’s some handy links if you want to make one yourself:
8bitdo Zero $10 – https://bit.ly/2xIFH0V
18650 holder file – https://bit.ly/2I6ZX0W
18650 3.7v Li-ion – Buy online or just salvage a few from an old laptop battery

Most of the objects I have printed so far have served some sort of practical purpose–tools, modifications, or upgrades. I’ve printed a few smaller, “fun” objects for calibration, but nothing really to just keep on my desk and admire. This weekend I tinkered with some print settings and tried my hand at post-processing a few things. The results were very informative and gave me some ideas about what to try in the future.

The Fresh Prints

I found a pretty sweet bust of Gundam 00 Raiser on Thingiverse to use as my test object. I scaled it 50% of the original size. The creator said that support were not needed, but that didn’t work out in my case. I think the model would have printed fine at 100%, but I would definitely recommend supports for anything smaller. I guess I printed the “battle-damaged” version this time. This was printed at 0.1mm layer height at 60mm/s with some generic PLA. I definitely should have slowed it down a bit and checked my retraction settings again, but overall it worked out alright.

Fix it in Post

I removed the broken bits of plastic and then glued both halves together with epoxy. After the epoxy dried, I sanded the model with various grits of sandpaper, from 100 to 220. It was almost impossible to sand the smaller features and angled pieces by hand, which shows in the final iteration. After sanding I sprayed it with some Rustoleum spray primer. I tried to find their filler primer (as it was highly recommended for this type of project) but I couldn’t find any in my area. I may order some for the next time. Filler primer is usually used for 3D prints as it helps hide layer lines and other imperfections. Sanding fixes a lot of that too.

Results

Apologies for the overwhelming HDR bloom in these shots–I wanted to show the detail and texture of the final prints but that made the background weird. Overall, I think it worked out pretty well for my first attempt. Sanding and priming definitely helped improve the appearance of the print. I probably won’t paint this one as it was just an experiment to see how smooth I could get it by hand.

You can see how the larger areas turned out much better than the smaller details–they were much easier to reach and sand. Again, this is an area that would have been improved had I printed the object at 100%.

In conclusion, sanding and priming definitely work as a quick way to improve your prints, but it helps if the objects are simple and/or larger.

Next time I want to try coating the print in some sort of epoxy (like Smooth-On’s XTC-3D) to see how that compares.

So 2 months later, my current 3D printer setup has gone through some significant changes. I’ve completed a removable enclosure, added some performance upgrades, and reduced the sound quite a bit. Dig in!

The enclosure has several benefits, including noise reduction and greater temperature stability for the printer. It is made with two IKEA Lack side tables (about $8/ea) and some 3D printed risers that allow the two to separate. The pegboard sides are only attached to the top table so that it remains removable. The front panel is just an empty picture from, also from IKEA. I moved the printer controller outside of the enclosure because space was tight, and the print bed would ram into it when printing in the far corners. It is much more easily accessible now.

The wires a still a bit of a mess after recently upgrading the auto-leveling sensor. I haven’t made time to re-wrap them since. The new sensor is a clone of the famous BLTouch sensor that I found on Thingiverse. Because this one uses a physical probe to touch each point of the bed when leveling, it is much more precise than the old inductive sensor I was using. My prints are coming out far more consistent and uniform after upgrading.

I also added some practice golf ball feet that greatly reduce noise and vibration while printing. The loudest part of the whole setup at this point is the parts cooling blower fan attached to the front of the hot end.

Additionally, I have added a small relay module so that the main system power, lights, and control board can all be managed by the Raspberry Pi. Pegboard adapters/cases to organize everything.

Some helpful prints I’ve made for my workbench below:

Thanks for stopping by! I’m looking to start printing some larger and more detailed objects now that I’ve got my settings dialed in. I’ll post some updates with the results.