I needed to drill about 9 holes into the pipe and then seal them so that the pipe maintains a vacuum.
I decided to use one of the vertical mills at TechShop to do the job.
The hole on the photo on this page is 1 1/2" in diameter.
Step 1: Secure the Pipe to the "X" Axis of the Mill
I decided to use the vertical mill at TechShop.
Step one was to secure the pipe to the "X" axis of the mill.
This proved more difficult that expected. Even though the pipe was secured, it still bounced around alot.
Step 2: Use a Center Drill to Start the Hole
In this photo, I'm using a 3/4" bit from Harbor Freight.
Make sure that you drill slowly. I drilled at 200 RPM.
Step 3: Use a Point to Square the Tap - Then Tap the Hole
Applying pressure on the quill of the vertical mill, I then used wrench to start the tap into the PVC.
For plastic, PVC is surprisingly strong and resistant to being tapped.
I used a large tap wrench to continue taping the pipe. About every 1/2 turn, you need to back off the tap wrench to break the material. This is the same process that you would follow if you were tapping a metal pipe too.
Step 4: Finish Tapping All of the Holes
The trick to tapping a pipe is to make sure that everything is square and also drill slowly. If you are tapping metal, you need to use a lubricant when you tap.
The drill bit set and the NTP pipe thread tap set are each less than $40. They both proved to be a great investment.
I made my tapped 12" diameter PVC Pipe at TechShop! I could not have done it accurately if I have not used a vertical mill.