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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.

project/freeze_dryer.txt · Last modified: 2019/03/05 18:42 by brandon