My "go to" glue for gluing brass tubes into pen blanks has been ordinary Gorilla Glue, which is polyurethane glue. I bought the smallest bottle I could find at Home Depot in early December, and I am still using the same bottle after 51 pens. See the attached photo:
* Left: Original Gorilla Glue -
https://www.gorillatough.com/product/original-gorilla-glue/
This is the bottle that I started using on 1 December 2018. I made 51 pens so far with this bottle of original Gorilla Glue, and it still has 1/3 of the bottle left,
and I am generous and messy with the glue. Once I started using this Gorilla Glue (polyurethane glue) for brass pen insert tubes, I use them for nearly all pens. I use other glues only for special needs. (See my previous post above.)
Usage note: I took a wet Q-tip and dampened the inside of the hole before inserting the tube with glue.
Pen blank: Purpleheart wood cut from a board. It will become a matching needle threader to make a set with an existing seam ripper.
* Center: White Gorilla Glue -
https://www.gorillatough.com/product/white-gorilla-glue/
I just bought this glue this morning.
Hype: Same strength, texture, and foaming action as Original Gorilla Glue, except it dries white instead of amber, and cures in half the time. I like white. I might give it a try in a translucent acrylic blank someday.
Actual: White Gorilla Glue is lot more runny than Original Gorilla Glue, so it dripped off the tube while I was applying the glue and inserting the tube. It started foaming about twice as fast as the original Gorilla Glue. I will wait until tomorrow to see how it is when it is fully cured, but I expect something very similar to the Original Gorilla Glue, only white.
Usage note: I took a wet Q-tip and dampened the inside of the hole before inserting the tube with glue.
Pen blank: Gonçalo Alves (Tigerwood) cut from a board. It will become a cat twist pen, which helped dictate the choice of blank.
* Right: Clear Gorilla Glue -
https://www.gorillatough.com/product/clear-gorilla-glue/
This is a Silane-based adhesive. It is very different compared with the two glues above. It is not a polyurethane glue, it is a silane glue. It does not foam. It dries clear.
Usage note: I inserted the tube with glue, but did not apply any moisture.
Pen blank: Coffee and Cream Inlace Acrylester. These are very challenging blanks to make into pens. Someone here on Penturners urged me to try the Clear Gorilla Glue with it.
It is late afternoon here. I will let them cure overnight and report back tomorrow.