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Brandon Neill is a VMware Certified Instructor and Consultant. He specializes in NSX and vRealize Automation. In addition to teaching Official VMware Classes, he provides contract training and consulting services.

project:freeze_dryer

Freeze Dryer

Type:
project
Status:
Active
Category:
engineering, science
Tag:
food
Priority:
2
NextDate:
0
Note:
No Notes

Project Description

Project Notes

Project Log

20190304

Laser cut .906“ hole in 1/2 acrylic, used 100/Full, 3 passes. was a little overkill as it melted the bottom a little. Tapped using 3/4” NPT tap. Added coupler, and adapter for 1“ vinyl tubing. I should have used the tap to cut deeper in to the plastic so that I could thread it deeper.

Made silicon seal for bowl (I think I'm going to use the larger of my two PYREX bowls) using easy mold. I probably could have used half of it to make seal. It's not pretty, but it should hold under vacuum.

The next step is to use the laser cutter to cut a hole in the freeze chamber for the other end of the tubing. That one I need to cut deeper because it needs to go all the way through so that I can thread the pipe fitting on the bottom.

20190305

Used the glowforge to cut a hole in the top of the lid for the freeze chamber. Turns out the lid is polycarbonate, not acrylic. It smoked and burned a lot, but did cut it in one pass. I tapped this one a little deeper than my last one, I was hoping to get the tubing all the way through, but the lit was slipping in my vise. I may revisit it in the future, to make it easier to run a nipple all the way through, and attach a long tube to the other side. For now I have an iron pipe threaded on the other side of the hole.

First vacuum test revealed a leak in the tubing that will eventually go to a pressure sensor. I was able to seal it using heat shrink tubing and a screw. Combine that with my previous concerns around sealing the pressure sensor, and I may have to find a different method for gathering pressure readings. One possibility would be to embed the wires in a silicone plug connected to the freeze chamber, and put all of the electronics in side the chamber. this is likely how I would do it in a production chamber. Not surprisingly, simply laying the themocouple wire across the top of the silicone seal for the freeze tray did not work.

If I need to create another silicon seal, I may use wood to create a mold to get something a bit more professional looking.

I removed the T adapter from the freeze dryer. I was able to get down to just past .8 bar of vacuum. and after 5 minutes it had only dropped to 0.7. I will have to find another method for measuring temperature and pressure that isn't so bad at holding a vacuum.

20191001

I ordered a pocket labs weather sensor that may be able to help with the temperature and pressure readings without causing a seal issue as it uses bluetooth to talk to my phone or laptop. I don't think it'll read a low enough pressure to give me a good reading, but for now I can use the pressure gauge for that.

I attempted to use a round class container from IKEA with a bamboo lid, hoping it would make a good seal. Attempting to cut through the bamboo with the glowforge did not work. after 6 passes at full power, 150 speed, I hadn't even cut halfway through it. I ended up using a 1” forstner drill bit. I think the hole was slightly too large however, as at the bottom there were barely any threads cut. (Note to self. never use NPT threads for a project like this in the future. I found some fittings on McMaster Carr that may work in the future.)

Once I got the fitting attached and the hoses hooked up, I attempted to form a vacuum. On the first attempt the lid did not seal at all, and I didn't pull any pressure. On the second attempt I got a better seal, but after about 30 seconds it starting making a high pressure whistle and I turned it off. It didn't hold a vacuum for more than a few seconds. On attempt number 3, I left it running after the whistle started, and after about 10 seconds it lost all pressure. It would appear that the ikea jars, at least with the bamboo lots are capable of holding a vacuum. The plastic ones may be, but I“m sure it will severely deform the lid, which will eventually affect the seal, also it's thin enough that it will be hard to attach the pipe fitting.

project/freeze_dryer.txt · Last modified: 2019/10/07 19:11 by brandon