P.S. Here are my latest tricks that help me with assembly:
* Check the milled blank and tube length carefully before turning.
I use digital calipers to verify that the length of the blank (with tube glued inside) is an exact match for the expected tube length. I get the tube length from the instructions or the IAP phone app. ($1, and highly recommended!)
* Make sure the inside of the tubes are clean from glue.
Use a pen mill insert to clear out the glue from inside the tube. If that doesn't get it shiny clean, use a round file to scrape and clean it out gently.
* (Optional, but it helps me) Use a deburring tool to clean and chamfer the tube ends.
I bought this one from Penn State before realizing that it is a generic tool that can be found at local hardware stores:
https://www.pennstateind.com/store/MSDEBURR.html